Beijing, China

The Beijing University of Posts and Telecommunications is a key national university distinguished by the teaching and research in the field of cable communications, wireless communications, computer, and electronic engineering. BUPT comprises 17 schools, and has an international school program with Queen Mary, University of London.The university was created in 1955 under the Ministry of Posts and Telecommunications and the Communications Department of the General Staff Department of the People's Liberation Army. The name was changed from Institute to University in 1993. It is the most famous and renowned university in the field of telecommunications in China. Wikipedia.


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Zhang X.,Beijing University of Posts and Telecommunications | Zhang Y.,Simula Research Laboratory | Yu R.,Guangdong University of Technology | Wang W.,Beijing University of Posts and Telecommunications | Guizani M.,Qatar University
IEEE Wireless Communications | Year: 2014

The development of LTE-Advanced and beyond cellular networks is expected to offer considerably higher data rates than the existing 3G networks. Among the many potential technologies in LTE-Advanced systems, users' characteristics and social behavior have been studied to improve the networks' performance. In this article we present the concept of user social pattern (USP), which characterizes the general user behavior, pattern, and rules of a group of users in a social manner, and utilize USP as an optimization basis for network performance enhancement. From large-scale traffic traces collected from current mobile cellular networks, the USP model is evaluated and verified. Furthermore, to evaluate the potential of spectral efficiency and energy efficiency enhancement based on USP in LTE-A HetNets, we establish a complete system and link-level HetNet simulation platform according to 3GPP LTE-A standards. Then, based on the platform, simulations are performed to evaluate the impact of USP on spectral and energy efficiency in an LTE-A network, and a USP-based spectral efficiency and energy efficiency enhancement scheme is proposed for a HetNet of the LTE-A system. Simulation results validate that USP can be used as an effective concept for network performance optimization in an LTE-A system. © 2014 IEEE.


Zhang J.,Beijing University of Posts and Telecommunications | Pan C.,Beijing University of Posts and Telecommunications | Pei F.,Beijing University of Posts and Telecommunications | Liu G.,China Mobile | Cheng X.,Peking University
IEEE Communications Magazine | Year: 2014

The explosive increase of mobile traffic demands higher spectrum efficiency for future wireless communications. By properly configuring a 2-dimensional (2D) antenna array at the basestation, the system capacity can be improved with 3 dimensional (3D) multiuser Multiple Input and Multiple Output (MIMO) techniques without modifying the terminal antennas. Therefore, the signal will propagate in a 3D space with angle dispersion in both horizontal and vertical planes. Due to its role in facilitating research and development of 3D MIMO technology, the 3D fading channel model is receiving increasing attention. However, existing fading channel models mostly focus on the azimuth angle characteristics, while neglecting the elevation angle impact. This article provides a state of the art review on 3D fading channel models, emphasizing research related to the elevation angle. We also report some recent field measurements for 3D MIMO and investigate the comprehensive propagation characteristics of the elevation angle. © 1979-2012 IEEE.


Xie X.,Beijing University of Posts and Telecommunications | Peng M.,Beijing University of Posts and Telecommunications | Zhao B.,Cambridge Silicon Radio | Wang W.,Beijing University of Posts and Telecommunications | Hua Y.,University of California at Riverside
IEEE Transactions on Wireless Communications | Year: 2014

Wireless network coding can significantly improve the spectrum efficiency for relaying transmission when receivers can acquire accurate channel state information (CSI). In this paper, the channel estimation problem for two-way relaying channels is considered where two sources exchange information through an amplify-and-forward relay employing analog network coding protocol. By taking advantage of the apriori information of wireless channels to further improve channel estimation accuracy, the maximum a posteriori (MAP) based estimation schemes are developed to estimate the composite source-source channel coefficients and the amplitude of individual sourcerelay channels with apriori knowledge of channel distribution information (CDI). Variations of MAP estimation algorithms are also developed for systems under practical constraints where channel CDI needs to be estimated. In particular, scale MAP estimator as well as a long term estimation algorithm is developed to effectively control the negative impact of CDI estimation error on MAP estimation performance. The simulation results show that the MAP based estimation strategies consistently outperform maximum likelihood estimation methods in the measure of mean square error, thus establishes the advantage of presented MAP based schemes. © 2014 IEEE.


Miao J.,Beijing University of Posts and Telecommunications | Hu Z.,Beijing University of Posts and Telecommunications | Yang K.,University of Essex | Wang C.,Beijing University of Posts and Telecommunications | Tian H.,Beijing University of Posts and Telecommunications
IEEE Communications Letters | Year: 2012

Heterogeneous wireless networks give rise to a multi-radio access environment which becomes crucial for load balancing to avoid network congestion and providing high quality services to maximize radio resource utilization. To this end, a joint power and bandwidth allocation with QoS support algorithm is proposed using convex optimization method in this letter. The algorithm achieves the goal of the total system capacity maximization, while efficiently satisfying the minimum rate constraint of delay-constraint service traffic and proportional fairness of best-effort service traffic. The simulation results show that the proposed algorithm significantly outperforms the existing scheme in QoS guarantee. © 1997-2012 IEEE.


Yu J.,Wuhan University of Technology | Wang Y.,Beijing University of Posts and Telecommunications | Lei M.,Beijing University of Posts and Telecommunications
ACS Applied Materials and Interfaces | Year: 2013

The reduction of graphene oxide (GO) with a large-scale production has been demonstrated to be one of the key steps for the preparation of graphene-based composite materials with various potential applications. Therefore, it is highly required to develop a facile, green, and environmentally friendly route for the effective reduction of GO. In this study, a new and effective reduced method of GO nanosheets, based on the dye-sensitization-induced visible-light reduction mechanism, was developed to prepare reduced GO (rGO) and graphene-based TiO 2 composite in the absence of any additional reducing agents. It was found that the dye-sensitization-induced reduction process of GO was accompanied with the formation of TiO2-rGO composite nanostructure. The photocatalytic experimental results indicated that the resultant TiO 2-rGO nanocomposites exhibited significantly higher photocatalytic performance than pure TiO2 because of a rapid separation of photogenerated electrons and holes by the rGO cocatalyst. © 2013 American Chemical Society.


Zhang L.,Beijing University of Posts and Telecommunications | Liu B.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2015

A secure enhanced coherent optical multi-carrier system based on Stokes vector scrambling is proposed and experimentally demonstrated. The optical signal with fourdimensional (4D) modulation space has been scrambled intra- and inter-subcarriers, where a multi-layer logistic map is adopted as the chaotic model. An experiment with 61.71-Gb/s encrypted multi-carrier signal is successfully demonstrated with the proposed method. The results indicate a promising solution for the physical secure optical communication. © 2015 Optical Society of America.


Deng W.,Beijing University of Posts and Telecommunications | Hu J.,Beijing University of Posts and Telecommunications | Lu J.,Advanced Digital science Center | Guo J.,Beijing University of Posts and Telecommunications
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2014

We develop a transform-invariant PCA (TIPCA) technique which aims to accurately characterize the intrinsic structures of the human face that are invariant to the in-plane transformations of the training images. Specially, TIPCA alternately aligns the image ensemble and creates the optimal eigenspace, with the objective to minimize the mean square error between the aligned images and their reconstructions. The learning from the FERET facial image ensemble of 1,196 subjects validates the mutual promotion between image alignment and eigenspace representation, which eventually leads to the optimized coding and recognition performance that surpasses the handcrafted alignment based on facial landmarks. Experimental results also suggest that state-of-the-art invariant descriptors, such as local binary pattern (LBP), histogram of oriented gradient (HOG), and Gabor energy filter (GEF), and classification methods, such as sparse representation based classification (SRC) and support vector machine (SVM), can benefit from using the TIPCA-aligned faces, instead of the manually eye-aligned faces that are widely regarded as the ground-truth alignment. Favorable accuracies against the state-of-the-art results on face coding and face recognition are reported. © 2013 IEEE.


Chen Z.,Peking University | Luo B.,Beijing University of Posts and Telecommunications | Guo H.,Peking University
Optics Express | Year: 2014

Absorption-free Bragg reflector has been studied in ions doped in crystals. We propose a new scheme using Zeeman sublevels of atoms to construct an absorption-free Bragg reflector with practical laser power. Its spatial period of refractive index equals half of the wavelength of the incident standing-wave coupling light. The proposal is simulated in a helium atom scheme, and can be extended to alkali earth atoms. © 2014 Optical Society of America.


Huang S.,Beijing University of Posts and Telecommunications | Guo B.,Peking University | Li X.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Express | Year: 2014

This paper focuses on random multi-link failures protection in optical mesh networks, instead of single, the dual or sequential failures of previous studies. Spare resource efficiency and failure robustness are major concerns in link protection strategy designing and a k-regular and k-edge connected structure is proved to be one of the optimal solutions for link protection network. Based on this, a novel pre-configured polyhedron based protection structure is proposed, and it could provide protection for both simultaneous and sequential random link failures with improved spare resource efficiency. Its performance is evaluated in terms of spare resource consumption, recovery rate and average recovery path length, as well as compared with ring based and subgraph protection under probabilistic link failure scenarios. Results show the proposed novel link protection approach has better performance than previous works. © 2014 Optical Society of America.


Yan H.,National University of Singapore | Lu J.,Advanced Digital science Center | Deng W.,Beijing University of Posts and Telecommunications | Zhou X.,Capital Normal University
IEEE Transactions on Information Forensics and Security | Year: 2014

In this paper, we propose a new discriminative multimetric learning method for kinship verification via facial image analysis. Given each face image, we first extract multiple features using different face descriptors to characterize face images from different aspects because different feature descriptors can provide complementary information. Then, we jointly learn multiple distance metrics with these extracted multiple features under which the probability of a pair of face image with a kinship relation having a smaller distance than that of the pair without a kinship relation is maximized, and the correlation of different features of the same face sample is maximized, simultaneously, so that complementary and discriminative information is exploited for verification. Experimental results on four face kinship data sets show the effectiveness of our proposed method over the existing single-metric and multimetric learning methods. © 2012 IEEE.


Qin W.,Tsinghua University | Qin W.,Tsinghua National Laboratory for Information Sciences and Technology | Wang C.,Beijing University of Posts and Telecommunications | Long G.L.,Tsinghua University | Long G.L.,Tsinghua National Laboratory for Information Sciences and Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

In this paper, we investigate a high-dimensional quantum state transfer protocol. An arbitrary unknown high-dimensional state can be transferred with high fidelity between two remote registers through an XX coupling spin chain of arbitrary length. The evolution of the state transfer is determined by the natural dynamics of the chain without external modulation and coupling strength engineering. As a consequence, entanglement distribution with a high efficiency can be achieved. Also the strong field and high spin quantum number can partly counteract the effect of finite temperature to ensure the high fidelity of the protocol when the quantum data bus is in the thermal equilibrium state under an external magnetic field. © 2013 American Physical Society.


Li T.,Beijing Normal University | Yang G.-J.,Beijing Normal University | Deng F.-G.,Beijing Normal University | Deng F.-G.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

Atomic ensembles are effective memory nodes for quantum communication network due to the long coherence time and the collective enhancement effect for the nonlinear interaction between an ensemble and a photon. Here we investigate the possibility of achieving the entanglement distillation for nonlocal atomic ensembles by the input-output process of a single photon as a result of cavity quantum electrodynamics. We give an optimal entanglement concentration protocol (ECP) for two-atomic-ensemble systems in a partially entangled pure state with known parameters and an efficient ECP for the systems in an unknown partially entangled pure state with a nondestructive parity-check detector (PCD). For the systems in a mixed entangled state, we introduce an entanglement purification protocol with PCDs. These entanglement distillation protocols have high fidelity and efficiency with current experimental techniques, and they are useful for quantum communication network with atomic-ensemble memories. © 2014 Optical Society of America.


Li F.,Hong Kong Polytechnic University | Li Q.,Peking University | Yuan J.,Hong Kong Polytechnic University | Yuan J.,South China Normal University | And 2 more authors.
Optics Express | Year: 2014

The low coherence of the supercontinuum (SC) generated using picosecond pump pulses is a major drawback of such SC generation scheme. In this paper, we propose to first self-similarly compress a high power picosecond pump pulse by injecting it into a nonlinearity increasing fiber. The compressed pulse is then injected into a non-zero dispersionshifted fiber (NZ-DSF) for SC generation. The nonlinearity increasing fiber can be obtained by tapering a large mode area photonic crystal fiber. The fiber nonlinearity is varied by varying the pitch sizes of the air holes. By using the generalized nonlinear Schrödinger equation, we show that a 1 ps pump pulse with random noise can be compressed self-similarly down to a pulse width of 53.6 fs with negligible pedestal. The noise level of the compressed pulse is reduced at the same time. The 53.6 fs pulse can then be used to generate highly coherent SC in an NZ-DSF. By using the proposed scheme, the tolerance of noise level for highly coherent SC generation with picosecond pump pulses can be improved by 5 order of magnitude. ©2014 Optical Society of America


Wei H.-R.,Beijing Normal University | Deng F.-G.,Beijing Normal University | Deng F.-G.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

We present some compact quantum circuits for a deterministic quantum computing on electron-spin qubits assisted by quantum dots inside single-side optical microcavities, including the CNOT, Toffoli, and Fredkin gates. They are constructed by exploiting the giant optical Faraday rotation induced by a single-electron spin in a quantum dot inside a single-side optical microcavity as a result of cavity quantum electrodynamics. Our universal quantum gates have some advantages. First, all the gates are accomplished with a success probability of 100% in principle. Second, our schemes require no additional electron-spin qubits and they are achieved by some input-output processes of a single photon. Third, our circuits for these gates are simple and economic. Moreover, our devices for these gates work in both the weak coupling and the strong coupling regimes, and they are feasible in experiment. © 2013 Optical Society of America.


Wang Y.,Nanjing University of Posts and Telecommunications | Wang Y.,Japan National Institute of Information and Communications Technology | Wang Y.,Beijing University of Posts and Telecommunications | Nakao A.,University of Tokyo
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

In overlay networks, the interplay between network structure and dynamics remains largely unexplored. In this paper, we study dynamic coevolution between individual rational strategies (cooperative or defect) and the overlay network structure, that is, the interaction between peer's local rational behaviors and the emergence of the whole network structure. We propose an evolutionary game theory (EGT)-based overlay topology evolution scheme to drive a given overlay into the small-world structure (high global network efficiency and average clustering coefficient). Our contributions are the following threefold: From the viewpoint of peers' local interactions, we explicitly consider the peer's rational behavior and introduce a link-formation game to characterize the social dilemma of forming links in an overlay network. Furthermore, in the evolutionary link-formation phase, we adopt a simple economic process: Each peer keeps one link to a cooperative neighbor in its neighborhood, which can slightly speed up the convergence of cooperation and increase network efficiency; from the viewpoint of the whole network structure, our simulation results show that the EGT-based scheme can drive an arbitrary overlay network into a fully cooperative and efficient small-world structure. Moreover, we compare our scheme with a search-based economic model of network formation and illustrate that our scheme can achieve the experimental and analytical results in the latter model. In addition, we also graphically illustrate the final overlay network structure; finally, based on the group selection model and evolutionary set theory, we theoretically obtain the approximate threshold of cost and draw the conclusion that the small value of the average degree and the large number of the total peers in an overlay network facilitate the evolution of cooperation. © 2006 IEEE.


Zhang X.,Peking University | Li Z.,Peking University | Chen J.,Peking University | Chen J.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Express | Year: 2013

An asymmetric T-shape nanoslit in a metal film is proposed to act as an efficient dichroic surface-plasmon-polariton (SPP) splitter, which is composed of a single nanoslit in immediate contacting with two nanogrooves with different widths. Simulations show that, due to the interferences of SPPs in the upper part of the asymmetric T-shape nanoslit, the generated SPPs propagating to the left and right directions on the front metal surface can be manipulated nearly independently by altering the right and left groove widths, respectively. Based on such effects, a dichroic SPP splitter is demonstrated and the splitting wavelengths can easily be adjusted. High splitting ratios of 31:1 and 1:12 at splitting wavelengths of 680 nm and 884 nm are numerically presented with a device's lateral dimension of only 1200 nm. Further experimental results match the simulations well. © 2013 Optical Society of America.


Wang S.,Beijing University of Posts and Telecommunications | Hu G.,Beijing Normal University
Information Sciences | Year: 2012

A new hash function based on a coupled chaotic map lattice is proposed. By combining floating-point chaotic computations with algebraic operations as well as local and global couplings, the system reaches high bit confusion and diffusion rates and thus desirable collision resistance with even one-iteration computation. The algorithm can be used to calculate hash values of 128, 160, 192, 256, 384 and 512 bits with little difference in performance for the different hash values. The algorithm has both strong collision resistance and high efficiency and can serve as a new type of candidate hash function in software. © 2012 Elsevier Inc. All rights reserved.


Su Z.,Shanghai University | Xu Q.,Shanghai University | Zhu H.,Shanghai JiaoTong University | Wang Y.,Beijing University of Posts and Telecommunications
IEEE Network | Year: 2015

With the rapid development of mobile communication technologies, various kinds of content can be delivered among mobile users for content sharing. Due to the complexity of networks and particular features of mobile behaviors, to manage networks efficiently, SDMSNs are advocated where the control plane and data plane can work separately but cooperatively. In this article we outline how to deliver mobile content over SDMSNs. We first design the flow table based on the social features including social tie, mobility, and community. Then a novel social switch is introduced to deliver content among mobile users by using the proposed social degree and social stay time. In addition, the process of content delivery is presented according to different scenarios, and extensive experiments are given to prove the efficiency of this approach. © 2015 IEEE.


Li Q.,Beijing University of Posts and Telecommunications | Feng Z.,Beijing University of Posts and Telecommunications | Li W.,University of Victoria | Gulliver T.A.,University of Victoria | Zhang P.,Beijing University of Posts and Telecommunications
IEEE Transactions on Smart Grid | Year: 2014

Real-time demand response management (DRM) in smart grid (SG) requires a reliable wireless communication network with sufficient spectrum resources. However, the allocated spectrum for wireless communications is heavily under-utilized in the spatial and temporal dimensions. To solve the spectrum scarcity problem, cognitive radio (CR) and dynamic spectrum sharing have been proposed, but this can result in poor reliability. In this paper, the influence of wireless communication reliability on DRM is analyzed and the relationship between outage and DRM performance is derived. Outage results from not only interference and noise, but also the unavailability of spectrum resources. Therefore, joint spatial and temporal spectrum sharing is proposed to improve spectrum utilization. The SG network is divided into a Temporal Spectrum Sharing Region (TSSR) and a Free Spatial Spectrum Sharing Region (Free-SSSR). SG nodes in the TSSR can utilize the licensed spectrum when primary users (PUs) are idle, while in the Free-SSSR they can simultaneously share this spectrum with the PUs without using power control. Performance results are presented which show that joint spatial and temporal spectrum sharing can increase the SG spectrum utilization opportunities and lower the outage probability, which is beneficial for DRM performance. © 2014 IEEE.


Xie G.,Peking University | Wang F.,Beijing University of Posts and Telecommunications | Dang A.,Peking University | Guo H.,Peking University
IEEE Photonics Technology Letters | Year: 2011

In this letter, a novel polarization-multiplexing system for free-space optical links is proposed. Data is specially designed at the transmitter while received by coupling two lights in different states of polarization (SOP) after polarization rotation at the receiver. Based on this design, the closed form expression for bit-error-rate (BER) performance of the system is given. Our results indicate that polarization control error has no obvious influence on the system performance when it is less than 10°. Performance of our system is superior to the traditional binary phase-shift keying (BPSK) scheme on overcoming phase fluctuation. © 2011 IEEE.


Zhang L.,Beijing University of Posts and Telecommunications | Yang J.,Beijing University of Posts and Telecommunications | Fu X.,Beijing University of Posts and Telecommunications | Zhang M.,Beijing Normal University
Applied Physics Letters | Year: 2013

We report a plasmonic structure consisting of a graphene ribbon and a graphene disk. The plasmonic structure can work as a promising waveguide-ring resonator in ultra compact devices, in which the ribbon and the disk support different surface plasmons. We prove that disk's resonant modes are edge propagating surface plasmons. Strong optical coupling between the ribbon and the disk occurs when the momentum mismatch between plasmons in the ribbon and plasmons in the disk is weak. We also investigate the dependence of the optical coupling on the distances between the ribbon and the disk in parallel and vertical directions. © 2013 AIP Publishing LLC.


Wu G.,Beijing University of Posts and Telecommunications | Guo H.,Peking University | Yu S.,Beijing University of Posts and Telecommunications | Luo B.,Peking University
Optics Letters | Year: 2010

We show that the far-field beam spreading and direction of partially coherent Gaussian-Schell model (GSM) beams are independent on the spatial coherence of the source through non-Kolmogorov atmospheric turbulence, which has potential applications in long-distance free-space optical communication. The effects of spatial coherence, exponent value a, and inner scale and outer scale of atmospheric turbulence on beam spreading are studied in details. The GSM beam has greater spreading for smaller inner scale or bigger outer scale through non-Kolmogorov turbulent atmosphere. © 2010 Optical Society of America.


Wang Y.,Beijing University of Posts and Telecommunications | Wang Y.,National University of Singapore | Wu X.,National University of Singapore | Scarani V.,National University of Singapore
New Journal of Physics | Year: 2016

Self-testing refers to the possibility of characterizing uniquely (up to local isometries) the state and measurements contained in quantum devices, based only on the observed input-output statistics. Already in the basic case of the two-qubit singlet, self-testing is not unique: the two known criteria (the maximal violation of the CHSH inequality and the Mayers-Yao correlations) are not equivalent. It is unknown how many criteria there are. In this paper, we find the whole set of criteria for the ideal self-testing of a singlet with two measurements and two outcomes on each side; it coincides with all the extremal points of the quantum set that can be obtained by measuring the singlet. © 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Wang B.,North China University of Technology | Tang C.,Peking University | Qi Y.,Peking University | Qi Y.,Aisino Corporation Inc. | And 3 more authors.
IEEE Transactions on Information Theory | Year: 2012

Cyclic codes with two zeros and their dual codes as a practically and theoretically interesting class of linear codes have been studied for many years and find many applications. The determination of the weight distributions of such codes is an open problem. Generally, the weight distributions of cyclic codes are difficult to determine. Utilizing a class of elliptic curves, this paper determines the weight distributions of dual codes of q-ary cyclic codes with two zeros for a few more cases, where q is an odd prime power. © 1963-2012 IEEE.


Feng Z.,Beijing University of Posts and Telecommunications | Li W.,Victoria University of Wellington | Li Q.,Beijing University of Posts and Telecommunications | Le V.,Beijing University of Posts and Telecommunications | Gulliver T.A.,University of Victoria
IEEE Transactions on Wireless Communications | Year: 2011

This paper proposes a novel Dynamic Spectrum Management (DSM) scheme for Wideband Code Division Multiple Access (WCDMA) / Digital Video Broadcasting (DVB) heterogeneous systems. Capacity estimation algorithms for both WCDMA and DVB are developed which consider both the user distribution and characteristics of the hybrid services. Based on these algorithms, a new dynamic spectrum allocation scheme is presented which allows for optimum allocation of resources and maximum secondary spectrum usage. Coloring theory is used to significantly reduce DSM complexity while providing near-optimal performance. Numerical results are given which show that the proposed DSM scheme has better performance than Fixed Spectrum Management (FSM). © 2011 IEEE.


Hou W.,Northeastern University China | Guo L.,Northeastern University China | Guo L.,Beijing University of Posts and Telecommunications | Wei X.,University of California at Riverside | Gong X.,Northeastern University China
Computer Networks | Year: 2012

Previous studies on the power efficiency or port savings in IP over WDM networks have required explicit knowledge of the traffic between each network node pair and the resource assignment of each fiber link. However, it is difficult to estimate this information accurately in live networks, due to the inherent features of IP traffic, e.g., bursts, unpredictability, and variability. Furthermore, the granularity of the demands on an IP-level connection tends to be diverse, and the number of ports consumed in Optical Cross-Connects (OXCs) tends to grow due to the use of hybrid grooming (i.e., traffic grooming with an optical bypass) for power savings. Therefore, it is critical to achieve both power efficiency and port savings in realistic IP over WDM networks. In this paper, we investigate the problem of multi-granularity and robust grooming for power- and port-cost-efficient IP over WDM networks. First, a key parameter, the Multi-Granularity Power Ratio (MGPR), which is the sum of the different single-granularity power ratios, is proposed. Second, the MMPR (Minimizing Multi-granularity Power Ratio) method is used to compute the Traffic Distribution Vectors. Finally, we present the multi-granularity and robust grooming approach, called the Maximizing Hop First (MXHF) approach, where hybrid grooming is adopted to improve power efficiency and waveband merging is utilized to reduce the port cost. Simulation results demonstrate that the MXHF approach can achieve power efficiency and port savings comparing with state-of-the-art robust grooming methods. © 2012 Elsevier B.V. All rights reserved.


Li X.,Beijing University of Posts and Telecommunications | Niu J.-W.,Beihang University | Ma J.,Beijing University of Posts and Telecommunications | Wang W.-D.,Beijing University of Posts and Telecommunications | Liu C.-L.,Fujian Normal University
Journal of Network and Computer Applications | Year: 2011

Recently, Li and Hwang proposed a biometrics-based remote user authentication scheme using smart cards [Journal of Network and Computer Applications 33 (2010) 15]. The scheme is based on biometrics verification, smart card and one-way hash function, and it uses the nonce rather than a synchronized clock, so it is very efficient in computational cost. Unfortunately, the scheme has some security weaknesses, that is to say Li and Hwang's scheme does not provide proper authentication and it cannot resist the man-in-the-middle attacks. If an attacker controls the insecure channel, she/he can easily fabricate messages to pass the user's or server's authentication. Besides, the malicious attacker can impersonate the user to cheat the server and can impersonate the server to cheat the user without knowing any secret information. This paper proposes an improved biometrics-based remote user authentication scheme that removes the aforementioned weaknesses and supports session key agreement. © 2010 Elsevier Ltd. All rights reserved.


Chen J.,Beijing University of Posts and Telecommunications | Chen J.,Peking University | Li Z.,Peking University | Yue S.,Peking University | And 2 more authors.
Nano Letters | Year: 2012

By utilizing a dielectric-film-coated asymmetric T-shape single slit, comprising two grooves of slightly detuned widths immediately contacting with a single nanoslit, the plasmon-induced transparency was experimentally demonstrated. Because of the symmetry breaking in the unit-cell structure, the scattered lights from the two grooves with slightly detuned widths interfere destructively, leading to the plasmon-induced transparency. As a result, a response spectrum with nearly the same interference contrast but a much narrower bandwidth emerges in the unit-cell structure with the footprint of only about 0.9 μm 2, compared with that in the symmetric T-shape single slit. These pronounced features in the structure, such as the increased quality factor, ultracompact size, easy fabrication, and experimental observation, have significant applications in ultracompact plasmonic devices. © 2012 American Chemical Society.


Cai Y.-F.,CAS Academy of Mathematics and Systems Science | Qian J.,Beijing University of Posts and Telecommunications | Xu S.-F.,Peking University
Automatica | Year: 2012

In this paper, we consider the partial pole assignment problem (PPAP) for high order control systems. It is shown that solving the PPAP is essentially solving a pole assignment for a linear system of a much lower order, and the robust PPAP is then concerning the robust pole assignment problem for this linear system. Based on this theory, a rather simple algorithm for solving the robust PPAP is proposed, and numerical examples show that this algorithm does lead to comparable results with earlier algorithms, but at much lower computational cost. © 2012 Elsevier Ltd. All rights reserved.


Han J.,Beijing University of Posts and Telecommunications | Haihong E.,Beijing University of Posts and Telecommunications | Le G.,Beijing University of Posts and Telecommunications | Du J.,Super Instruments Corporation
Proceedings - 2011 6th International Conference on Pervasive Computing and Applications, ICPCA 2011 | Year: 2011

With the development of the Internet and cloud computing, there need databases to be able to store and process big data effectively, demand for high-performance when reading and writing, so the traditional relational database is facing many new challenges. Especially in large scale and high-concurrency applications, such as search engines and SNS, using the relational database to store and query dynamic user data has appeared to be inadequate. In this case, NoSQL database created. This paper describes the background, basic characteristics, data model of NoSQL. In addition, this paper classifies NoSQL databases according to the CAP theorem. Finally, the mainstream NoSQL databases are separately described in detail, and extract some properties to help enterprises to choose NoSQL. © 2011 IEEE.


Sun X.,Beijing University of Posts and Telecommunications | Zheng Y.,Fujian Normal University
International Journal of Bifurcation and Chaos | Year: 2014

We investigate the effects of time-periodic intercoupling strength on the spiking regularity of a clustered neuronal network. Inside the clustered neuronal network, each cluster has the same regular structure with each node modeled by a stochastic Hodgkin-Huxley neuronal model. From simulation results, we find that there exist some optimal frequencies of the time-periodic intercoupling strength, at which the spiking regularity of the considered clustered neuronal network becomes higher. When we consider the effects of the amplitude of time-periodic intercoupling strength, we find that the clustered neuronal network could exhibit more regular spiking activity at some intermediate amplitude for higher noise level; while for lower noise level, the spiking regularity of the neuronal network decreases with the amplitude increase. And the obtained results are independent of the cluster number. © 2014 World Scientific Publishing Company.


Niu K.,Beijing University of Posts and Telecommunications | Chen K.,Beijing University of Posts and Telecommunications | Lin J.,Beijing University of Posts and Telecommunications | Zhang Q.T.,Nanjing University of Posts and Telecommunications
IEEE Communications Magazine | Year: 2014

Polar codes represent an emerging class of error-correcting codes with power to approach the capacity of a discrete memoryless channel. This overview article aims to illustrate its principle, generation and decoding techniques. Unlike the traditional capacity-approaching coding strategy that tries to make codes as random as possible, the polar codes follow a different philosophy, also originated by Shannon, by creating a jointly typical set. Channel polarization, a concept central to polar codes, is intuitively elaborated by a Matthew effect in the digital world, followed by a detailed overview of construction methods for polar encoding. The butterfly structure of polar codes introduces correlation among source bits, justifying the use of the SC algorithm for efficient decoding. The SC decoding technique is investigated from the conceptual and practical viewpoints. State-of-the-art decoding algorithms, such as the BP and some generalized SC decoding, are also explained in a broad framework. Simulation results show that the performance of polar codes concatenated with CRC codes can outperform that of turbo or LDPC codes. Some promising research directions in practical scenarios are also discussed in the end. © 2014 IEEE.


Cheng X.,Peking University | Yu B.,Colorado State University | Yang L.,Colorado State University | Zhang J.,Beijing University of Posts and Telecommunications | And 3 more authors.
IEEE Wireless Communications | Year: 2014

Spectrum efficiency has long been at the center of mobile communication research, development, and operation. Today it is even more so with the explosive popularity of the mobile Internet, social networks, and smart phones that are more powerful than our desktops used to be not long ago. The discovery of spatial multiplexing via multiple antennas in the mid-1990s has brought new hope to boosting data rates regardless of the limited bandwidth. To further realize the potential of spatial multiplexing, the next leap will be accounting for the three-dimensional real world in which electromagnetic waves propagate. In this article we discuss fundamentals and key technical issues in developing and realizing 3D multi-input multi-output technology for next generation mobile communications. © 2014 IEEE.


Zhu Y.,Jiangxi University of Science and Technology | Zheng Z.,Beijing Normal University | Yang J.,Beijing University of Posts and Telecommunications
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

The model of nonlocally coupled identical phase oscillators on complex networks is investigated. We find the existence of chimera states in which identical oscillators evolve into distinct coherent and incoherent groups. We find that the coherent group of chimera states always contains the same oscillators no matter what the initial conditions are. The properties of chimera states and their dependence on parameters are investigated on both scale-free networks and Erdös-Rényi networks. © 2014 American Physical Society.


Lin P.,Chongqing University | Lin P.,Beijing University of Posts and Telecommunications | Ren W.,University of California at Riverside
IEEE Transactions on Automatic Control | Year: 2014

In this note, a constrained consensus problem is studied for multi-agent systems in unbalanced networks in the presence of communication delays. Here each agent needs to lie in a closed convex constraint set while reaching a consensus. The communication graphs are directed, dynamically changing, and not necessarily balanced and only the union of the graphs is assumed to be strongly connected among each time interval of a certain bounded length. The analysis is performed based on an undelayed equivalent system that is composed of a linear main body and an error auxiliary. To tackle the loss of symmetry caused by unbalanced graphs and communication delays, a novel approach is proposed. The idea is to estimate the distance from each agent to the intersection set of all agents' constraint sets based on the properties of the projection on convex sets so as to show consensus convergence by contradiction. It is shown that the error auxiliary vanishes as time evolves and the linear main body converges to a vector with an exponential rate as a separate system. It is also shown that the communication delays do not affect the consensus stability and constrained consensus is reached even if the communication delays are arbitrarily bounded. Finally, a numerical example is included to illustrate the obtained theoretical results. © 2013 IEEE.


Du F.F.,Beijing Normal University | Deng F.G.,Beijing Normal University | Deng F.G.,Beijing University of Posts and Telecommunications
Science China: Physics, Mechanics and Astronomy | Year: 2015

We present two nonlocal entanglement concentration protocols (ECPs) to distill a subset of N-photon systems in a Greenberger-Horne-Zeilinger (GHZ) state or a W state from a set of photon systems in a partially entangled GHZ-like pure state or a less-entangled W-like state with known parameter, respectively. Our ECPs have some advantages. First, our ECPs work in a heralded way with linear-optical elements only, without the postselection based on nonlinear optics, far different from the previous ECPs. Second, they require only a copy of the less-entangled photon system in each round of the entanglement concentration process, not two copies, which decreases the difficulty of their implementation in experiment largely. Third, our ECPs avoid checking the photon number in the output modes of linear-optical elements with the sophisticated single-photon detectors. Moreover, all parties can operate the process for concentration simultaneously and independently, which leads to flexible operations and improves the performance greatly in experiment. These advantages make our ECPs useful in practical applications in long-distance quantum communication network. © 2015, Science China Press and Springer-Verlag Berlin Heidelberg.


Gao L.,Texas A&M University | Zhang R.,National University of Singapore | Zhang R.,Institute for Infocomm Research | Yin C.,Beijing University of Posts and Telecommunications | Cui S.,Texas A&M University
IEEE Journal on Selected Areas in Communications | Year: 2012

Consider a wireless network that has two tiers with different priorities: a primary tier vs. a secondary tier, which is an emerging network scenario with the advancement of cognitive radio technologies. The primary tier consists of randomly distributed legacy nodes of density n, which have an absolute priority to access the spectrum. The secondary tier consists of randomly distributed cognitive nodes of density m=n with 2, which can only access the spectrum opportunistically to limit the interference to the primary tier. Based on the assumption that the secondary tier is allowed to route the packets for the primary tier, we investigate the throughput and delay scaling laws of the two tiers in the following two scenarios: i) the primary and secondary nodes are all static; ii) the primary nodes are static while the secondary nodes are mobile. With the proposed protocols for the two tiers, we show that the primary tier can achieve a per-node throughput scaling of p(n)=(1/\log n) in the above two scenarios. In the associated delay analysis for the first scenario, we show that the primary tier can achieve a delay scaling of Dp(n)=(\sqrt{n\log n}p(n)) with p(n)=O(1/\log n). In the second scenario, with two mobility models considered for the secondary nodes: an i.i.d. mobility model and a random walk model, we show that the primary tier can achieve delay scaling laws of (1) and (1/S), respectively, where S is the random walk step size. The throughput and delay scaling laws for the secondary tier are also established, which are the same as those for a stand-alone network. © 2006 IEEE.


Ke P.,Fujian Normal University | Zhang J.,Beijing University of Posts and Telecommunications | Zhang S.,Fujian Normal University
Designs, Codes, and Cryptography | Year: 2013

In this article, new classes of generalized cyclotomic binary sequences with period 2pm are proposed. We determine the linear complexity and autocorrelation of these sequences. The results show that the proposed generalized cyclotomic binary sequences have high linear complexity, but do not have desirable autocorrelation properties. © 2012 Springer Science+Business Media, LLC.


Zhang J.,Beijing University of Posts and Telecommunications | Ji Y.,Communication University of China | Song M.,Beijing University of Posts and Telecommunications | Zhao Y.,Communication University of China | And 3 more authors.
Journal of Lightwave Technology | Year: 2015

Traffic grooming has evolved to present some new features in sliceable bandwidth-variable transponder enabled elastic optical networks (SBVT-EON). One of the new features is 'optical traffic grooming,' in which multiple optical flows from/to different sources/destinations can be groomed onto a sliceable transponder. When establishing a new connection request in SBVT-EON, a key problem is how to coordinate electrical and optical traffic grooming. In this study, we propose a three-layered auxiliary graph (AG) model to address mixed-electrical-optical grooming under dynamic traffic scenario. By adjusting the edge weights of AG, we can achieve various traffic-grooming policies for different purposes. Also, we propose two spectrum reservation schemes that can efficiently utilize the capacity of a transponder. We compare different traffic-grooming policies under two spectrum reservation schemes, and a tradeoff is shown to exist among the policies. We also evaluate their performances for different network topologies with different resource provisions. © 2014 IEEE.


Zhu T.,Beijing University of Posts and Telecommunications | Wang B.,Beijing University of Posts and Telecommunications | Wu B.,Beijing University of Posts and Telecommunications | Zhu C.,Nanchang University
Information Sciences | Year: 2014

Information flows in a network where individuals influence each other. In this paper, we study the influence maximization problem of finding a small subset of nodes in a social network that could maximize the spread of influence. We propose a novel information diffusion model CTMC-ICM, which introduces the theory of Continuous-Time Markov Chain (CTMC) into the Independent Cascade Model (ICM). Furthermore, we propose a new ranking metric named SpreadRank generalized by the new information propagation model CTMC-ICM. We experimentally demonstrate the new ranking method that can, in general, extract nontrivial nodes as an influential node set that maximizes the spread of information in a social network and is more efficient than a distance-based centrality. © 2014 Elsevier Inc. All rights reserved.


Li T.,Beijing Normal University | Deng F.-G.,Beijing Normal University | Deng F.-G.,Beijing University of Posts and Telecommunications
International Journal of Theoretical Physics | Year: 2014

We present an efficient entanglement concentration protocol (ECP) for partially entangled four-photon χ-type states in the first time with only linear optical elements and single-photon detectors. Without any ancillary particles, the parties in quantum communication network can obtain a subset of four-photon systems in the standard {pipe}χ 00〉 state from a set of four-photon systems in a partially entangled χ-type state with the parameter-splitting method developed by Ren et al. (Phys. Rev. A 88:012302, 2013). The present ECP has the optimal success probability which is determined by the component with the minimal probability amplitude in the initial state. Moreover, it is easy to implement this ECP in experiment. © 2014 Springer Science+Business Media New York.


Chen J.,Beijing University of Posts and Telecommunications | Li Z.,Peking University | Zou Y.,University of Alabama at Birmingham | Deng Z.,Beijing University of Posts and Telecommunications | And 2 more authors.
Plasmonics | Year: 2013

Fano resonances are numerically predicted in an ultracompact plasmonic structure, comprising a metal-isolator-metal (MIM) waveguide side-coupled with two identical stub resonators. This phenomenon can be well explained by the analytic model and the relative phase analysis based on the scattering matrix theory. In sensing applications, the sensitivity of the proposed structure is about 1.1 × 103 nm/RIU and its figure of merit is as high as 2 × 105 at λ = 980 nm, which is due to the sharp asymmetric Fano line-shape with an ultra-low transmittance at this wavelength. This plasmonic structure with such high figure of merits and footprints of only about 0.2 μm2 may find important applications in the on-chip nano-sensors. © 2013 Springer Science+Business Media New York.


Zhang M.,Beijing Normal University | Yang J.-Z.,Beijing University of Posts and Telecommunications
Communications in Theoretical Physics | Year: 2011

In this work, we consider an evolutionary prisoner's dilemma game on a homogeneous random network with the richest-following strategy adoption rule. By constructing homogeneous random networks from a regular ring graph, we investigate the effects of topological randomness on cooperation. In contrast to the ordinary view that the presence of small amount of shortcuts in ring graphs favors cooperation, we find the cooperation inhibition by weak topological randomness. The explanations on the observations are presented. © 2011 Chinese Physical Society and IOP Publishing Ltd.


Cheng H.,Beijing University of Posts and Telecommunications | Cheng H.,Beijing Normal University | Li H.,Beijing University of Posts and Telecommunications | Dai Q.,Beijing University of Posts and Telecommunications | And 2 more authors.
New Journal of Physics | Year: 2010

In the evolution of cooperation, the motion of players plays an important role. In this paper, we incorporate, into an evolutionary prisoner dilemma's game on networks, a new factor that cooperators and defectors move with different probabilities. By investigating the dependence of the cooperator frequency on the moving probabilities of cooperators and defectors, μc and μd, we find that cooperation is greatly enhanced in the parameter regime of μc < μd. The snapshots of strategy pattern and the evolutions of cooperator clusters and defector clusters reveal that either the fast motion of defectors or the slow motion of cooperators always favors the formation of large cooperator clusters. The model is investigated on different types of networks such as square lattices, Erdös-Rényi networks and scale-free networks and with different types of strategy-updating rules such as the richest-following rule and the Fermi rule. The numerical results show that the observed phenomena are robust to different networks and to different strategy-updating rules. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Wang Z.,Nanjing University of Posts and Telecommunications | Wang Z.,Beijing University of Posts and Telecommunications
Mathematical and Computer Modelling | Year: 2012

Low-power devices tend to have a feature in common: limited computational capabilities and equally limited power (as most operate on batteries). This makes them ill-suited for public key signatures. However, their weakness in computation is offset by their communication strength and operation fashion. A server-aided verification signature scheme is very suitable for this scenario, which is composed of a digital signature scheme and a server-aided verification protocol. With the help of a powerful server, a verifier can check a signature with less computational cost compared with the original verification algorithm. This paper provides three specific contributions. First, we define a new security model of server-aided verification signature (SAV-σ) scheme. Then, we design an efficient (SAV-σ) based on the Paillier signature scheme [6] by using its homomorphic property. Finally, we prove that our scheme is secure under our security model. © 2011 Elsevier Ltd.


Lin J.,Beijing University of Posts and Telecommunications | Lin J.,Nanjing University of Posts and Telecommunications | Fei S.,Nanjing Southeast University | Wu Q.,Hong Kong Polytechnic University
Circuits, Systems, and Signal Processing | Year: 2012

This paper is concerned with the reliable H8 filtering problem against sensor failures for a class of discrete-time switched singular systems with time-varying delay. A practical sensor failure model, which consists of a scaling factor with upper and lower bounds to the output measuring is considered. The purpose is to design a switched full-order H8 filter such that, for all possible sensor failures, the resulting filtering error system is regular, causal, and uniformly asymptotically stable with a guaranteed H8 performance index under arbitrary switching signals. By using the switched Lyapunov function approach and establishing a finite sum equality, a delaydependent bounded real lemma (BRL) for the filtering error systems is derived via linear matrix inequality (LMI) formulation. An improved BRL is also established by introducing additional slack matrix variables to realize the decoupling between the filtering error system matrices and the Lyapunov matrices. Then, based on the decoupled BRL, the existence criterion of the desired filter is obtained by employing the LMI technique. Some numerical examples are provided to illustrate the effectiveness and the potential of the proposed methods. © Springer Science+Business Media, LLC 2011.


Chen Y.,Beijing University of Posts and Telecommunications | Cao Z.,CAS Academy of Mathematics and Systems Science | Wang S.,Beijing University of Posts and Telecommunications | Hu G.,Beijing Normal University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2015

Very recently, a first-order phase transition, named explosive synchronization (ES), has attracted great attention due to its remarkable novelty in theory and significant impact in applications. However, so far, all observations of ES have been associated with various correlation constraints on system parameters, which restrict its generality and applications. Here we consider heterogeneous networks around Hopf bifurcation point described by chemical reaction-diffusion systems and also by their reduced order parameter versions, the complex Ginzburg-Landau equations, and demonstrate that explosive synchronization can appear as an emergent feature of oscillatory networks, and the restrictions on specific parameter correlations used so far for ES can be lifted entirely. Theoretical analyses and numerical simulations show with a perfect agreement that explosive synchronization can appear in networks with nodes having identical natural frequencies, and necessary correlation conditions for ES can be realized in a self-organized manner by network evolution. © 2015 American Physical Society.


Grant
Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2007.1.1 | Award Amount: 18.27M | Year: 2008

The End-to-End Efficiency (E3) project is an ambitious FP7 EC Integrated Project (IP) aiming at integrating cognitive wireless systems in the Beyond 3G (B3G) world, evolving current heterogeneous wireless system infrastructures into an integrated, scalable and efficiently managed B3G cognitive system framework. The key objective of the E3 project is to design, develop, prototype and showcase solutions to guarantee interoperability, flexibility and scalability between existing legacy and future wireless systems, manage the overall system complexity, and ensure convergence across access technologies, business domains, regulatory domains and geographical regions.\n\nCognitive radio systems are seen by many actors of the wireless industry as a core technical evolution towards exploitation of the full potential of B3G systems. It is under way to revolutionize wireless communications just as the PC revolution. E3 will ensure seamless access to applications and services and exploitation of the full diversity of corresponding heterogeneous systems, in order to offer an extensive set of operational choices to the users, application and service providers, operators, manufacturers and regulators. E3 will optimise the use of the radio resources and spectrum, following cognitive network paradigms. The management functions will be distributed over different network elements at various levels of the system topology.\n\nThe E3 consortium will bring together major key European players in the domain of cognitive radios and networks, self-management and end-to-end reconfigurability. E3 will build on several key achievements from the successful FP6 E2R Programme, pursuing research into the most promising directions, in order to facilitate the vision of true end-to-end connectivity.\n\nThe E3 project addresses the core of the Strategic Objective ICT-2007.1.1 The Network of the Future from Challenge 1 Pervasive and Trusted Network and Service Infrastructures.


Zhang S.,University of California at Davis | Tornatore M.,Polytechnic of Milan | Tornatore M.,University of California at Davis | Shen G.,Soochow University of China | And 2 more authors.
Journal of Lightwave Technology | Year: 2014

Recently, flexible grid and elastic-rate transponders have emerged as evolutionary technologies to satisfy the ever-increasing demand for higher spectrum efficiency and operational flexibility. In this study, we first briefly review the evolution of traffic grooming from SONET/SDH to currently-deployed WDM networks, and summarize the essence of the current traffic-grooming paradigm based on electronic circuit or packet switching and multi-layer collaboration. Then, the role of traffic grooming in flexible-grid and elastic-rate optical networks is re-examined. The impact of some new optical-layer technologies on traffic-grooming paradigm is discussed. Particularly, sliceable optical layer based on sliceable transponders and BV-ROADM is identified as a novel technology that could impact the future grooming paradigm by offloading considerable amount of traffic and part of electronic grooming function to the optical layer. We propose two novel network architectures based on sliceable optical layer and numerically compare them with the traditional packet-over-optical network architecture. It is found that packet-over-sliceable network architecture consumes the fewest transponders and at the same time achieves either the 'lowest-possible' latency or least spectrum usage. Finally, traffic grooming, which involves multi-layer resource orchestration, should be controlled by software with a centralized view of the network to accommodate the dynamic requirements of applications. © 1983-2012 IEEE.


Li Z.,Peking University | Zhang Y.-C.,Beijing University of Posts and Telecommunications | Xu F.,University of Toronto | Peng X.,Peking University | Guo H.,Peking University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We propose a continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocol, in which detection is conducted by an untrusted third party. Our protocol can defend all detector side channels, which seriously threaten the security of a practical CV QKD system. Its security analysis against arbitrary collective attacks is derived based on the fact that the entanglement-based scheme of CV-MDI QKD is equivalent to the conventional CV QKD with coherent states and heterodyne detection. We find that the maximal total transmission distance is achieved by setting the untrusted third party close to one of the legitimate users. Furthermore, an alternate detection scheme, a special application of CV-MDI QKD, is proposed to enhance the security of the standard CV QKD system. © 2014 American Physical Society.


Zhang Z.,Beijing University of Posts and Telecommunications | Lv T.,Beijing University of Posts and Telecommunications | Su X.,Tsinghua National Laboratory for Information Sciences and Technology
IEEE Communications Letters | Year: 2011

In this letter, we propose a round-robin (RR) based fair scheduling scheme (RRFS) to achieve both cooperative diversity (CD) and multiuser diversity (MUD) in multi-source, multi-relay amplify-and-forward (AF) cooperative networks. Different from traditional schemes in multiuser scenarios which only allow the "best" source to transmit and cause transmission unfairness, all the sources transmit in a RR fashion first in RRFS. In order to achieve both kinds of diversity in the relay phase, we then exploit a joint source-relay selection strategy which selects the "best" relay to help the "worst" source's transmission in each relay time slot. Therefore, RRFS brings MUD benefit to cooperation communication systems while maintaining transmission fairness. © 2006 IEEE.


Grant
Agency: Cordis | Branch: H2020 | Program: CSA | Phase: ICT-37-2016 | Award Amount: 2.56M | Year: 2017

Europe and China are at the forefront of technological advances in areas related to the Future Internet (especially 5G and IoT). While both parties share common technological objectives, there is still room for improvement in what concerns bilateral co-operation. As a result, the main purpose of EXCITING is to support the creation of favourable conditions for co-operation between the European and Chinese research and innovation ecosystems, mainly related to the key strategic domains of IoT and 5G. EXCITING will study the research and innovation ecosystem for IoT and 5G in China and compare it with the European model. EXCITING will identify and document the key international standards bodies for IoT and 5G, as well as other associations and fora where discussions take place and implementation decisions are made. Going beyond standardisation, interoperability testing is a key step towards market deployment. EXCITING will identify and document the key international InterOp events at which European and Chinese manufacturers can test and certify their IoT and 5G products. It will also explain the rules for engaging in these events. EXCITING will produce Best Practice guidelines for establishing and operating practical joint collaborations, in order to stimulate further such co-operations in the future on IoT and 5G Large Scale Pilots. As a result of the above investigations EXCITING will produce a roadmap showing how research and innovation ecosystems, policy, standardisation, interoperability testing and practical Large Scale Pilots should be addressed during the H2020 timeframe, and make recommendations for optimising collaboration between Europe and China for IoT and 5G.


Grant
Agency: Cordis | Branch: FP7 | Program: CSA | Phase: ICT-2011.1.3 | Award Amount: 1.39M | Year: 2011

Many projects are currently undertaking research and development in order to gain results in the short and medium term, whilst others are focusing on long term strategies for IoT deployments and future research needs. In all cases, securing all research investment in particular in Europe with worldwide market accepted standards is vital. Unfortunately there is a vast amount of evidence based upon market successes and failures, that without standards accepted worldwide as validated by solid and cooperative actions, research investment can be wasted or in other cases the market could be fragmented by many technical solutions which are not interoperable between each others.\nIn order to effectively capitalize on European research advances, Europe needs to ensure interoperability and acceptance of its solutions in a global context. For that, it is important to conduct key benchmarks and look at existing roadmaps in order to provide elements at European level, and study whether all of these technical issues on validation and interoperability are efficiently considered. In doing such an analysis, all research projects and international initiatives will be considered and therefore a global coordination will be put in place in full synchronisation with existing support actions.\nSo whilst PROBE-IT will fully implement the objectives of the call, it will not provide overlap and support as large as the international collaboration and standardisation already provided by CASAGRAS2 or on global vision and collaboration as provided by IOT-I project. PROBE-IT will cooperate with these two projects in complementing the global portfolio with benchmarks, roadmaps and other key inputs on validation and interoperability. PROBE-IT will focus on providing overall support to current and future IoT research programmes addressing all of these important and technical issues that no project is actually delivering.


Song X.,Beijing University of Posts and Telecommunications | Yin C.,Beijing University of Posts and Telecommunications | Liu D.,Beijing University of Posts and Telecommunications | Zhang R.,National University of Singapore
IEEE Journal on Selected Areas in Communications | Year: 2014

This paper studies the opportunistic spectrum access (OSA) of the secondary users in a large-scale overlay cognitive radio (CR) network. Two threshold-based OSA schemes, namely the primary receiver assisted (PRA) protocol and the primary transmitter assisted (PTA) protocol, are investigated. Under the PRA/PTA protocols, a secondary transmitter (ST) is allowed to access the spectrum only when the maximum signal power of the received beacons/pilots sent from the active primary receivers/transmitters (PRs/PTs) is lower than a certain threshold. To measure the resulting transmission opportunity for the secondary users by the proposed OSA protocols, the concept of spatial opportunity, which is defined as the probability that an arbitrary location in the primary network is detected as a spatial spectrum hole, is introduced and then evaluated by applying tools from stochastic geometry. Based on spatial opportunity, the coverage (non-outage transmission) performance in the overlay CR network is analyzed. With the obtained results of spatial opportunity and coverage probability, we finally characterize the spatial throughput, which is defined as the average spatial density of successful transmissions in the primary/secondary network, under the PRA and PTA protocols, respectively. © 1983-2012 IEEE.


Fu X.,Beihang University | Jia Y.,Beihang University | Du J.,Beijing University of Posts and Telecommunications | Yu F.,Henan Polytechnic University
IET Control Theory and Applications | Year: 2010

This study is devoted to the problem of state estimation of discrete-time stochastic systems with Markov switching parameters. Three improved interacting multiple model (IMM) algorithms for manoeuvring target tracking are presented, in which the filter outputs are combined based on three optimal multi-model fusion criterions weighted by scalars, diagonal matrices and general matrices, respectively. The proposed algorithms can receive the optimal state estimations of target in the linear minimum variance sense. It is proved that the traces of variance matrices of tracking errors in three proposed algorithms are less than the trace in the classical IMM algorithm. Extensive Monte Carlo simulations verify that the proposed algorithms are effective and have an absolute advantage in the velocity estimation. In particular, one of the proposed algorithms is obviously better than the IMM algorithm in accuracy and elapsed time and, therefore, can be a competitive alternative to the classical IMM algorithm for the tracking of manoeuvring target in real time. © 2010 The Institution of Engineering and Technology.


Li J.,Beijing University of Posts and Telecommunications | Huang Z.,Beijing University of Posts and Telecommunications | Liu X.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2015

A novel hybrid time-frequency domain equalization scheme is proposed and experimentally demonstrated to mitigate the white light emitting diode (LED) nonlinearity in visible light communication (VLC) systems based on orthogonal frequency division multiplexing (OFDM). We handle the linear and nonlinear distortion separately in a nonlinear OFDM system. The linear part is equalized in frequency domain and the nonlinear part is compensated by an adaptive nonlinear time domain equalizer (NTDE). The experimental results show that with only a small number of parameters the nonlinear equalizer can efficiently mitigate the LED nonlinearity. With the N-TDE the modulation index (MI) and BER performance can be significantly enhanced. © 2015 Optical Society of America.


Wang Z.,Beijing University of Posts and Telecommunications | Feng Z.,Beijing University of Posts and Telecommunications | Zhang P.,Beijing University of Posts and Telecommunications
IEEE Communications Letters | Year: 2011

Coordinated spectrum sensing ensures Cognitive Radio systems to get the usability of every channel within the entire spectrum of interest by assigning terminals to detect different channels simultaneously. This letter proposes an optimized channel-assignment strategy for coordinated spectrum sensing based on an Iterative Hungarian Algorithm. Simulation results show that the proposed strategy performs excellently in improving the overall sensing performance of the system. © 2011 IEEE.


Hua C.-C.,Beijing University of Posts and Telecommunications | Hua C.-C.,Yanshan University | Ding S.X.,University of Duisburg - Essen | Guan X.-P.,Yanshan University | Guan X.-P.,Shanghai JiaoTong University
Automatica | Year: 2012

This paper considers the controller design problem for a class of uncertain systems with unknown actuator parameters. The considered systems are with multiple time delays and nonlinear uncertainties, and the uncertain nonlinearities are bounded by nonlinear functions with unknown coefficients. The actuator parameters are time-varying and their bounds are unknown, moreover the signs of them are not available. To deal with unknown actuator parameters problem, we decompose the system into two subsystems. For the resultant system, we develop the corresponding tolerant controller design method with the help of Nussbaum function. By constructing the Lyapunov Krasovskii functional, we prove the asymptotical stability of the closed-loop system. Finally, simulations are performed on a chemical reactor system to show the effectiveness of the proposed method. © 2011 Elsevier Ltd. All rights reserved.


Liu Y.-L.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2014

The optimization of wireless multipoint multimedia broadcasting system layered source transmission was studied and analyzed. The introduction of continuous layered source with superposition coding model infinite layer in this article, the optimal inter-layer power distribution function is given by variation method, then an average per user up to speed is obtained. In the simulation, the LSSC which introduces a layered source coding scheme compared with the traditional CB Scheme. LSSC transmit multiple data streams to meet different end user channel conditions is verified by the results. The problem of system performance loss due to channel asymmetry between the center of the cell edge users and users bring have been effective solved. © (2014) Trans Tech Publications, Switzerland.


Peng M.,Beijing University of Posts and Telecommunications | Zhang X.,Beijing University of Posts and Telecommunications | Wang W.,Beijing University of Posts and Telecommunications
IET Communications | Year: 2011

The femto-cell base station (BS) is presented as a promising consumer electronic device to provide the wireless multi-medium services in the family or office environments. Radio resources allocated to femto-cell and macro-cell users should be made orthogonal to reduce interferences. The radio resources for the femto-cell and macro-cell users can also be reused to improve spectrum efficiency at the expense of increasing the cross-layer interference. This study investigates the uplink interference and derives the exact cumulate distribution function (CDF) expressions for the signal-to-interference ratio distributions in these two radio resource scenarios. Their throughputs are expressed according to the derived CDF expressions. It is shown that the simulation results match to the theoretical analysis very well, illustrating that the radio resource allocation in these two scenarios is related strictly to the path loss exponent and the number of femto-cells in a macro-cell. Furthermore, the average distance between the macro-cell and the femto-cell BSs has significant impact on the user performance of femto-cells. © 2011 The Institution of Engineering and Technology.


Liu D.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications
China Communications | Year: 2011

This study uses TAM to examine the factors that influence the adoption of mobile payment in China. The proposed model is empirically evaluated based on TAM by using data collected from 370 users concerning their perceptions of mobile payment. The findings indicate that perceived usefulness and perceived ease of use have significant effects on users'attitude. Furthermore, network externality is also an important factor influencing the adoption. But customers have weak perceptions of the risks of M-payment. The results may provide further insights into mobile payment strategies.


Zhao C.,Inha University | Zhao C.,Beijing University of Posts and Telecommunications | Kwak K.,Inha University
IEEE Communications Letters | Year: 2010

The jointly optimal allocation of sensing time and power for a two-user amplify-and-forward overlay cognitive network is developed by maximizing the averaged aggregate throughput of the secondary network. In particular, observing that the sensing duration lies within a strict interval, the jointly optimal strategy of sensing time and power allocation is proved to be tractable by sequential optimization. © 2010 IEEE.


Zhu Y.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications
Science China: Physics, Mechanics and Astronomy | Year: 2012

The quantum discord (QD) of a three-qubit Heisenberg XXZ system with the Dzyaloshinskii-Moriya (DM) interaction parameter is investigated, and the three-qubit QD under Ornstein-Uhlenbeck noise is calculated. We find that both DM interaction parameter Dz and anisotropic parameter Jz can increase QD and entanglement but Dz is a more efficient parameter in the antiferromagnetic case. We observe a complex range of QD with the change of Dz and a sudden change of QD with the variation of Jz in the ferromagnetic case. We show that the decrease durations of both QD and entanglement can be prolonged by increasing DM interaction and reducing noise bandwidth γ in the evolutionary process. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.


Ge Z.-G.,Beijing University of Posts and Telecommunications
Journal of Donghua University (English Edition) | Year: 2015

With the development of mobile technologies, mobile learning has become a trend and a necessary means in the e-learning environment. E-learners' autonomous learning processes can also be facilitated through the adoption of various mobile learning tools. Mobile learning tools can be classified into different types according to their different features and functions. Mobile learning devices, mobile learning software, mobile learning resources, and mobile learning services are the four types of learning tools suggested in the paper. Different mobile learning tools are proven to be able to fulfill different needs of autonomous learning. Copyright © 2015 Editorial Department of Journal of Donghua University. All rights reserved.


Liu B.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications | Zhang L.,Beijing University of Posts and Telecommunications | Yu J.,Beijing University of Posts and Telecommunications | Yu J.,Zte United States Inc.
Optics Express | Year: 2012

This paper proposes a novel wavelength division multiplexing-orthogonal frequency multiple access (WDM-OFDMA) union passive optical network (uni-PON) architecture with dynamic resource allocation and variable rate access. It can offer an infrastructure with different access solutions. According to the quality of service (QoS) requirement of different services, the optical local terminal (OLT) can dynamically assign different resources as well as the access rates to different services. An experiment has been demonstrated with 4 wavelengths achieving combined signal at 109.92-Gb/s. A physical-layer adaptive algorithm is employed for the resource allocation and variable rate access. The different services with different resource allocations and variable access rates are also demonstrated in the experiment. © 2012 Optical Society of America.


Han J.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2012

We propose and describe a physical model of polarization-dependent principal modes (PDPMs) in a given setting of dual-LP11 mode and dual-polarization transmission over weakly guiding few-mode fibers (FMFs). Proof-of-concept numerical simulations illustrate that the PDPMs do not suffer from both mode dispersion and polarization mode dispersion to first order of frequency variation, even in the presence of random spatial- and polarization-mode coupling. The proposed PDPM model can be a basic formalism for analyzing and controlling of mode coupling/ dispersion-induced distortion, in the given optical multiple-input multiple-output scheme of dual-LP11 mode and dual-polarization transmission over FMFs. © 2012 Optical Society of America.


Zhang X.,Beijing University of Posts and Telecommunications | Dubrovskii V.G.,RAS Ioffe Physical - Technical Institute | Sibirev N.V.,St Petersburg Academic University | Ren X.,Beijing University of Posts and Telecommunications
Crystal Growth and Design | Year: 2011

In view of a continuously growing interest in monolithic integration of dissimilar semiconductor materials in a nanostructure form, we present an analytical study of elastic strain energy in nanostructures of different isotropic geometries grown on lattice mismatched substrates. An analytical solution for the elastic stress field is derived, which is not restricted by the small aspect ratio or particular geometry. It is shown that, at a large enough aspect ratio, the relaxation of displacement fields with the vertical coordinate is exponential. This allows us to find an analytical expression for the strain energy density. The cases of rigid and elastic substrates are considered simultaneously. By minimizing the total energy, we obtain the elastic energy density as a function of aspect ratio for given nanostructure geometry. Our data indicate that the elastic energy is highly dependent on the island shape, with the relaxation becoming faster as the contact angle increases. We also present a simple expression for the elastic relaxation where the fitting coefficient depends on the geometry. A dislocation model is then considered to analyze the competition between the elastic and dislocation energies. We calculate the critical radius below which the plastic deformation is energetically suppressed. Our results demonstrate a good quantitative correlation with the available experimental data on III-V semiconductor nanowires grown on silicon substrates. © 2011 American Chemical Society.


Cui M.,Key Laboratory of Cluster Science | Cui M.,Hebei University of Science and Technology | Xu B.,Beijing University of Posts and Telecommunications | Hu C.,Key Laboratory of Cluster Science | And 2 more authors.
Electrochimica Acta | Year: 2013

Direct electrochemistry of glucose oxidase (GOD) on three-dimensional (3D) interpenetrating porous graphene electrodes has been reported, which have been fabricated by one-step electrochemical reduction of graphene oxide (GO) from its aqueous suspension. The electrochemically reduced GO (ERGO) modified electrodes exhibited excellent electron transfer properties for GOD and enhanced the enzyme activity and stability by the assistance of chitosan. The immobilized GOD shows a fast electron transfer with the rate constant (ks) of 6.05 s-1. It is worth mentioning that in the air-saturated phosphate buffer solution without any mediator, the resultant modified electrodes exhibited low detection limit of 1.7 μM with wide linear range of 0.02-3.2 mM and high sensitivity and high selectivity for measuring glucose. It would also be extended to various enzymes and bioactive molecules to develop the biosensor or other bio-electrochemical devices. © 2013 Elsevier Ltd. All rights reserved.


Cao Y.,Beijing University of Posts and Telecommunications | Xia H.,Beijing University of Posts and Telecommunications | Feng C.,Beijing University of Posts and Telecommunications
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2013

In this paper, we investigate how picocells overlaid in macrocells expand their coverage areas under different Cell Range Expansion (CRE) strategies in a macro-pico heterogeneous network. Through system level simulations, the relationships among the presented CRE strategies are specified from both qualitative and quantitative perspective, in which network topologies using different CRE strategies are displayed, and load balancing performance is compared in terms of CRE user ratio. Relatively good CRE strategies are derived from statistics. Furthermore, as CRE will largely decrease network throughput due to unexpected interference on the downlink path from Macrocell Base Stations (MBSs) to CRE users, we then apply Coordinated Multi-Point (CoMP) transmission in heterogeneous deployment to deal with the inter-cell interference. Intensive simulations show that CoMP could significantly improve both cell average Spectrum Efficiency (SE) and 5% cell edge SE, and a recommended value of CoMP bias which decides CoMP user ratio is given at last. © 2013 IEEE.


Cai J.,University of Tokyo | Ma X.,South China University of Technology | Li Q.,South China University of Technology | Li L.,Beijing University of Posts and Telecommunications | Peng H.,Beijing University of Posts and Telecommunications
International Journal of Electrical Power and Energy Systems | Year: 2010

Since the environmental issues caused by the pollutant emissions from fossil-fueled power plants are concerned, it is necessary to develop the conventional economic dispatch (ED) into environmental/economic dispatch (EED) which considers both economic and environmental issues. This paper developed a multi-objective chaotic ant swarm optimization (MOCASO) method for solving the multi-objective EED problems of thermal generators in power systems. The proposed MOCASO method was applied to three test power systems. Simulation results demonstrated that the MOCASO method can obtain feasible and effective solutions and it is a promising alternative approach for solving the EED problems in practical power systems. © 2010 Elsevier Ltd. All rights reserved.


Wei Y.,Beijing University of Posts and Telecommunications | Yu F.R.,Carleton University | Song M.,Beijing University of Posts and Telecommunications
IEEE Transactions on Vehicular Technology | Year: 2010

Relay selection is crucial in improving the performance of wireless cooperative networks. Most previous works for relay selection use the current observed channel conditions to make the relay-selection decision for the subsequent frame. However, this memoryless channel assumption is often not realistic given the time-varying nature of some mobile environments. In this paper, we consider finite-state Markov channels in the relay-selection problem. Moreover, we also incorporate adaptive modulation and coding, as well as residual relay energy in the relay-selection process. The objectives of the proposed scheme are to increase spectral efficiency, mitigate error propagation, and maximize the network lifetime. The formulation of the proposed relay-selection scheme is based on recent advances in stochastic control algorithms. The obtained relay-selection policy has an indexability property that dramatically reduces the computation and implementation complexity. In addition, there is no need for a centralized control point in the network, and relays can freely join and leave from the set of potential relays. Simulation results are presented to show the effectiveness of the proposed scheme. © 2010 IEEE.


Kang G.,Beijing University of Posts and Telecommunications
2012 IEEE 14th International Conference on e-Health Networking, Applications and Services, Healthcom 2012 | Year: 2012

Recently, the R&D and applications of M2M systems are booming in China, especially after it is written in the 2010 Government Work Report. In this paper, the R&D works of wireless eHealth (WeHealth) are overviewed, the concept of which was proposed by our group in 2005. Some key techniques of WeHealth system are discussed, and some practices based on the concept of WeHealth are introduced. Besides, a recent WeHealth pilot trial on chronic disease monitoring is also introduced, which is reported as "The First Wireless Healthcare Chronic Disease Monitoring Project in China Based on Internet of Things Technology". There are 30 community hospitals up to now applying our WeHealth blood pressure monitoring system for chronic disease management. The practical data clearly demonstrate the effectiveness of our WeHealth system in hypertension disease control. © 2012 IEEE.


Hu A.,Beijing University of Posts and Telecommunications | Lv T.,Beijing University of Posts and Telecommunications
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2013

In this paper, a distribution fitting approach is proposed to estimate the angular parameters of multiple incoherently distributed sources with large antenna arrays. The estimator utilizes the approximate orthogonality of the array response vectors of large arrays to obtain a vector which is the superposition of the probability distributions of the direction-of-arrivals (DOAs) of the sources. Then, the angular parameters can be estimated by fitting distribution functions to this vector successively. Hence, the complexity of the proposed approach is much lower than that of other well-known estimators which require the fitting of a matrix. Analysis and numerical results show that the proposed estimator can achieve better performance than other estimators. © 2013 IEEE.


Xu L.,Beijing University of Posts and Telecommunications | Du J.,Beijing University of Posts and Telecommunications | Li Q.,Beijing University of Posts and Telecommunications
Mathematical Problems in Engineering | Year: 2013

In the nonsubsampled contourlet transform (NSCT) domain, a novel image fusion algorithm based on the visual attention model and pulse coupled neural networks (PCNNs) is proposed. For the fusion of high-pass subbands in NSCT domain, a saliency-motivated PCNN model is proposed. The main idea is that high-pass subband coefficients are combined with their visual saliency maps as input to motivate PCNN. Coefficients with large firing times are employed as the fused high-pass subband coefficients. Low-pass subband coefficients are merged to develop a weighted fusion rule based on firing times of PCNN. The fused image contains abundant detailed contents from source images and preserves effectively the saliency structure while enhancing the image contrast. The algorithm can preserve the completeness and the sharpness of object regions. The fused image is more natural and can satisfy the requirement of human visual system (HVS). Experiments demonstrate that the proposed algorithm yields better performance. © 2013 Liang Xu et al.


Zhu L.,Beijing University of Posts and Telecommunications
Proceedings of 2015 4th International Conference on Computer Science and Network Technology, ICCSNT 2015 | Year: 2015

Speaker clustering, in a speaker diarization system is of great importance since the result of speaker clustering impacts deeply on the final diarization result. However, errors can happen in every step in the clustering process, such as the estimation of the cluster number, the initialization of the cluster centers and so on. Therefore, it is necessary to modify the clustering result and improve the accuracy of the diarization system. In this paper, a modified clustering refinement approach based on cross EM refinement is presented to solve these issues. According to the experiment results, the performance of diarization result improved a lot with our modified refinement, and can handle much more badly speaker clustering results than the original cross EM refinement method. The experiments are carried out three datasets of different types-meeting, broadcast news and talk-show. © 2015 IEEE.


Lin W.,Beijing University of Posts and Telecommunications
Proceedings of 2015 4th International Conference on Computer Science and Network Technology, ICCSNT 2015 | Year: 2015

In large population speaker identification (SI) system, likelihood computations during testing stage can be time-consuming. In such a case, clustering method is applied to this situation. But the traditional clustering algorithm based on K-means is sensitive to the randomly chosen initial cluster centers. To address this issue, the paper proposes an improved clustering algorithm which uses an initial clustering method to choose the cluster centroids and utilizes T-Test metrics as the distance measure. In fact, the proposed initial clustering method is of the same essence to the subtractive clustering algorithm. However, it differs from the subtractive clustering in two aspects of candidate selection and cluster radius. According to the experimental result, the improved GMM-based clustering algorithm shows the better performance both on recognition rate and accuracy of clustering, compared to the conventional clustering algorithm. © 2015 IEEE.


Chen Z.,Beijing University of Posts and Telecommunications | Yu L.,Beijing University of Posts and Telecommunications
IEEE Photonics Journal | Year: 2014

Multiple Fano resonances are numerically investigated based on different waveguide modes in a nanoscale plasmonic waveguide resonator system, which consists of two grooves coupled with a metal-insulator-metal (MIM) waveguide. Simulation results show that by introducing a small structural breaking in the plasmonic resonator, both symmetric and antisymmetric waveguide modes can be excited. Due to the interaction of the symmetric and antisymmetric waveguide modes, the transmission spectra possess a sharp asymmetrical profile. Because of different origins, these Fano resonances exhibit different dependence on the parameters of the structure and can be easily tuned. These characteristics offer flexibility to design the device. This nanosensor yields a sensitivity of ∼820 nm/RIU and a figure-of-merit of ∼3.2 × 105. The utilization of the antisymmetric mode in the MIM waveguide provides a new possibility for designing high-performance plasmonic devices. © 2009-2012 IEEE.


Tian L.,Beijing University of Posts and Telecommunications
Proceedings of 2nd International Conference on Computer Science and Network Technology, ICCSNT 2012 | Year: 2012

This paper briefly introduces the concept of the Internet of Things, the convergence trend analysis of the current situation of the mobile communication network and mobile communication network and the Internet of Things. It explores applications and prospects of the Internet of Things in the era of mobile communications from the telecom service providers' perspective. © 2012 IEEE.


Ren X.,Beijing University of Posts and Telecommunications
Asia Communications and Photonics Conference, ACP | Year: 2013

This talk is an anniversary summary of the works on the theory of electron-statesarchitecture (ESA) and its dimensionality in a crystalline material, on the assumptions of the energy-level dispersion (ELD), the spatial extension shrinkage (SES), the di-convergence conservation law (or the "bivergence" conservation law, BCL) and the lower limit velocity (LLV) for real objects, on the proof of the existences of the LLV and the upper one (ULV), and eventually on the modifications of Schrödinger equation, Newtonian equation and the theory of relativity. © OSA 2013.


Yang Y.-G.,Beijing University of Technology | Yang Y.-G.,Xidian University | Yang Y.-G.,University of Chinese Academy of Sciences | Wen Q.-Y.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2010

We give an arbitrated signature protocol of classical messages over a collective amplitude damping channel. We analyze its security and prove that it is secure over such a noisy quantum channel even if the arbitrator is compromised. The involvement of the arbitrator is also an appealing advantage in the implementation of a practical quantum distributed communication network. © 2010 Elsevier B.V. All rights reserved.


Liu X.,Beijing University of Posts and Telecommunications | Liu X.,Yanshan University | Qiao Y.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2010

In this paper, optical phase conjugation (OPC) located in the transmitter based on four wave mixing (FWM) in a semiconductor optical amplifier (SOA) is first simulated in 40 Gb/s CO-OFDM systems, and the fiber nonlinearity impairment of the transmission link is precompensated before OPC by transmission through a fiber with large nonlinearity coefficient. Simulation results show that the nonlinear threshold (NLT) can be increased by about >3 dB and maximum Q factor can be increased by about 2 dB for the single-channel system. For 50-GHz-Spacing WDM systems, the maximum Q and NLT are increased by about 1 dB, even in the presence of cross phase modulation (XPM) from neighbouring WDM channels. It is found that this OPC subsystem located in the transmitter, not necessary to be inserted into the middle of link, can mitigate the fiber nonlinearity impairment for both single-channel and WDM systems. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved.


Gao F.,Beijing University of Posts and Telecommunications | Qin S.-J.,Beijing University of Posts and Telecommunications | Wen Q.-Y.,Beijing University of Posts and Telecommunications | Zhu F.-C.,National Laboratory for Modern Communications
Optics Communications | Year: 2010

We analyze the security of multiparty controlled quantum secure direct communication using Greenberger-Horne-Zeilinger (GHZ) state. It is shown that the receiver, using a special property of GHZ state, can illegally obtain 33.3% of the sender's secret without any controller's permission. The attack strategy is demonstrated in detail and an improvement of this protocol is discussed. The idea of this attack might be instructive for the cryptanalysis of quantum cryptographic protocols. © 2009 Elsevier B.V. All rights reserved.


Sun Y.,Beijing University of Posts and Telecommunications | Sun Y.,Xidian University | Wen Q.-y.,Beijing University of Posts and Telecommunications | Zhu F.-c.,National Laboratory for Modern Communications
Optics Communications | Year: 2010

The security of the multiparty quantum secret sharing protocol presented by Zhang [Z.J. Zhang, Physica A, 361 (2006) 233] is analyzed. It is shown that this protocol is vulnerable to the insider attack since eavesdropping detection is performed only when all states arrive at the last agent. We propose an attack strategy and give an improved version of the original protocol. The improved protocol is robust and has the same traits with the original one. © 2009 Elsevier B.V. All rights reserved.


Zhang X.,Beijing University of Posts and Telecommunications | Liu J.,Beijing University of Posts and Telecommunications | Du Y.,Beijing University of Posts and Telecommunications | Lv T.,Beijing University of Posts and Telecommunications
Expert Systems with Applications | Year: 2011

Time series is a very popular type of data which exists in many domains. Clustering time series data has a wide range of applications and has attracted researchers from a wide range of discipline. In this paper a novel algorithm for shape based time series clustering is proposed. It can reduce the size of data, improve the efficiency and not reduce the effects by using the principle of complex network. Firstly, one-nearest neighbor network is built based on the similarity of time series objects. In this step, triangle distance is used to measure the similarity. Of the neighbor network each node represents one time series object and each link denotes neighbor relationship between nodes. Secondly, the nodes with high degrees are chosen and used to cluster. In clustering process, dynamic time warping distance function and hierarchical clustering algorithm are applied. Thirdly, some experiments are executed on synthetic and real data. The results show that the proposed algorithm has good performance on efficiency and effectiveness. © 2011 Elsevier Ltd. All rights reserved.


Chen X.-B.,Beijing University of Posts and Telecommunications | Xu G.,Taiyuan University of Technology | Niu X.-X.,Beijing University of Posts and Telecommunications | Wen Q.-Y.,Beijing University of Posts and Telecommunications | Yang Y.-X.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2010

The central theme of this paper is that we propose an efficient protocol for comparing the equal information with the help of a third party (TP). We assume that TP is semi-honest, i.e., TP executes the protocol loyally, keeps a record of all its intermediate computations and might try to steal the players' private inputs from the record, but he cannot be corrupted by the adversary. The security of this protocol with respect to various kinds of attacks is discussed. Our protocol utilizes the triplet entangled states and the simple single-particle measurement. The particles carried the secret messages do not be repeatedly transmitted. The players' messages are divided into many groups. Sometimes, the protocol is already successfully completed, but all data are not compared. Thus, many time and huge quantum resources can be saved. © 2009 Elsevier B.V. All rights reserved.


Lu X.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications
Nonlinear Analysis: Real World Applications | Year: 2013

A coherently-coupled nonlinear Schrödinger system in the optical fiber communications, with the mixed self-phase modulation (SPM), cross-phase modulation (XPM) and positive coherent coupling terms, is studied through the bilinear method with an auxiliary function. Solutions for that system are found to be of two types: singular and non-singular ones, and the latter appear as the soliton-typed. Vector bright one- and two-solitons are derived with the corresponding phase-shift parameter constraints. In virtue of computerized symbolic computation and asymptotic behavior analysis, elastic collision mechanisms of such vector solitons are investigated. With the aid of graphical simulation, vector solitons are displayed to be of the single- or double-hump profiles. The formation and collision mechanisms of the vector bright solitons for that system are generated based on the combined effects of SPM, XPM and coherent coupling. Only elastic collisions of the vector solitons occur for that system, which is a distinctive feature amid those of other coherently-coupled nonlinear Schrödinger systems. © 2012 Elsevier Ltd. All rights reserved.


Yu Y.,Beijing University of Posts and Telecommunications
Chinese Journal of Electronics | Year: 2013

In digital communications, the channel affects the transmitted sequence with both linear and nonlinear distortions. We address the blind detection over time-varying frequency-selective and nonlinear channels in this paper. A blind detector is derived within the Bayesian framework and implemented via the Particle filtering (PF) method. The proposed PF-based detector incorporates auxiliary PF strategy and a hybrid importance distribution to improve the efficiency and effectiveness. A delayed-weight estimation method is also presented to further improve the performance of the detector. Simulations are provided that demonstrate the performance of the detector under different system settings.


Liu H.,Beijing University of Posts and Telecommunications | Hu Z.,Beijing University of Posts and Telecommunications | Mian A.,Beijing University of Posts and Telecommunications | Tian H.,Beijing University of Posts and Telecommunications | Zhu X.,Beijing University of Posts and Telecommunications
Knowledge-Based Systems | Year: 2014

Collaborative filtering has become one of the most used approaches to provide personalized services for users. The key of this approach is to find similar users or items using user-item rating matrix so that the system can show recommendations for users. However, most approaches related to this approach are based on similarity algorithms, such as cosine, Pearson correlation coefficient, and mean squared difference. These methods are not much effective, especially in the cold user conditions. This paper presents a new user similarity model to improve the recommendation performance when only few ratings are available to calculate the similarities for each user. The model not only considers the local context information of user ratings, but also the global preference of user behavior. Experiments on three real data sets are implemented and compared with many state-of-the-art similarity measures. The results show the superiority of the new similarity model in recommended performance. © 2013 Elsevier B.V. All rights reserved.


Rangayyan R.M.,University of Calgary | Wu Y.,Beijing University of Posts and Telecommunications
Biomedical Signal Processing and Control | Year: 2010

Pathological conditions of knee joints have been observed to cause changes in the characteristics of vibroarthrographic (VAG) signals. Several studies have proposed many parameters for the analysis and classification of VAG signals; however, no statistical modeling methods have been explored to analyze the distinctions in the probability density functions (PDFs) between normal and abnormal VAG signals. In the present work, models of PDFs were derived using the Parzen-window approach to represent the statistical characteristics of normal and abnormal VAG signals. The Kullback-Leibler distance was computed between the PDF of the signal to be classified and the PDF models for normal and abnormal VAG signals. Additional statistical measures, including the mean, standard deviation, coefficient of variation, skewness, kurtosis, and entropy, were also derived from the PDFs obtained. An overall classification accuracy of 77.53%, sensitivity of 71.05%, and specificity of 82.35% were obtained with a database of 89 VAG signals using a neural network with radial basis functions with the leave-one-out procedure for cross validation. The screening efficiency was derived to be 0.8322, in terms of the area under the receiver operating characteristics curve. © 2009 Elsevier Ltd. All rights reserved.


Yuan M.,Zhejiang Sci-Tech University | Liu A.,Zhejiang Sci-Tech University | Liu A.,Zhejiang University of Technology | Zhao M.,Zhejiang Sci-Tech University | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

A bimetallic PdCu nanoparticle (NP) decorated three-dimensional graphene hydrogel (PdCu/GE) was developed by a simple one-step hydrothermal method. The PdCu/GE hybrids exhibited an interconnected microporous framework with PdCu NPs dispersed and encapsulated within the GE layers. The PdCu/GE hybrids showed significant electrocatalytic activity toward glucose oxidation due to the synergistic effect of PdCu NPs and GE sheets in the alkaline solution containing chloride ions, presenting a substantial increase in the oxidation current and decrease in the onset potential of oxidation compared to the monometallic modified GE hybrids. At an applied potential of -0.4 V, the PdCu/GE modified electrode with optimized bimetallic ratio presented quick respond to glucose oxidation with a wide linear range up to 18 mM and a reproducible sensitivity of 48 μA (mg mM)-1 in the presence of chloride ions. Furthermore, the PdCu/GE modified electrode exhibited high selectivity to glucose and resistance against poisoning by commonly interfering species such as dopamine, ascorbic acid, uric acid, acetamidophenol and some monosaccharides. The PdCu/GE hybrid hydrogels with 3D micropores were therefore promising for the future development of non-enzymatic amperometric glucose sensors with improved electrochemical performances. © 2013 Elsevier B.V.


Li D.,Tsinghua University | Li D.,Beijing University of Posts and Telecommunications | Li Y.,Tsinghua University | Wu J.,Tsinghua University | And 2 more authors.
IEEE/ACM Transactions on Networking | Year: 2012

Multicast benefits group communications in saving network traffic and improving application throughput, both of which are important for data center applications. However, the technical trend of data center design poses new challenges for efficient and scalable multicast routing. First, the densely connected networks make traditional receiver-driven multicast routing protocols inefficient in multicast tree formation. Second, it is quite difficult for the low-end switches widely used in data centers to hold the routing entries of massive multicast groups. In this paper, we propose ESM, an efficient and scalable multicast routing scheme for data center networks. ESM addresses the challenges above by exploiting the feature of modern data center networks. Based on the regular topology of data centers, ESM uses a source-to-receiver expansion approach to build efficient multicast trees, excluding many unnecessary intermediate switches used in receiver-driven multicast routing. For scalable multicast routing, ESM combines both in-packet Bloom Filters and in-switch entries to make the tradeoff between the number of multicast groups supported and the additional bandwidth overhead. Simulations show that ESM saves 40%\sim50% network traffic and doubles the application throughputs compared to receiver-driven multicast routing, and the combination routing scheme significantly reduces the number of in-switch entries required. We implement ESM on a Linux platform. The experimental results further demonstrate that ESM can well support online tree building for large-scale groups with churns, and the overhead of the combination forwarding engine is light-weighted. © 2012 IEEE.


He J.,Beijing University of Posts and Telecommunications | Pan W.,Beijing University of Posts and Telecommunications
Proceedings - 2nd IEEE International Conference on Advanced Computer Control, ICACC 2010 | Year: 2010

In order to solve the problems of difficulty to determine the number of partitions and rule redundancy in neuro-fuzzy system modeling, this paper presents a new approach based on DENCLUE using a dynamic threshold and similar rules merging (DDTSRM). By introducing DDT, which uses a dynamic threshold rather than a global one in merging density-attractors in DENCLUE, our approach is good at determining the number of partitions because DDT does not depend on input parameters. Additionally, the modeling performance is improved for DDT can find arbitrary shape and arbitrary density clusters. After structure identification we merge similar rules by considering similarity measures between fuzzy sets. Finally, BP method is used to precisely adjust the parameters of the fuzzy model. For illustration, we applied DDTSRM to a nonlinear function and Box and Jenkins system. Experimental results show that DDTSRM is effective to solve the problems with a good performance. © 2010 IEEE.


Jianfeng Q.,Beijing University of Posts and Telecommunications
International Journal of Control and Automation | Year: 2014

It is the common issue for all of countries that lots of safety risk accidents happen in large scale engineering projects. To save cost, generally, no enough resource is booked, or not very qualified resource is selected, which is one of the import safety risk factors in large scale engineering projects. But less scientific strategies are available to balance between safety risk values and safety risk investment. In the large scale engineer safety risk management filed, currently most of methods are qualitative, so it is a hot and difficult topic that constructs a quantitative model for practical problems, especially based on optimal control theory. In this paper, we will take both advantages of maximum principle and dynamic programming to solve the large scale engineering project safety risk issues caused by resource numbers and resource quality. Firstly, by maximum principle, establishes safety risk model considering resource numbers, and give iterative steps of the gradient descent method for numerical solution; Secondly, by dynamic programming, establishes safety risk economic model which takes into account the quality of resource; In the end, both the models are validated in one practical equipment case by combining the advantages of each algorithms. © 2014 SERSC.


Ma W.-M.,Beijing University of Posts and Telecommunications | Meng X.-W.,Beijing University of Posts and Telecommunications | Zhang Y.-J.,Beijing University of Posts and Telecommunications
Ruan Jian Xue Bao/Journal of Software | Year: 2012

The improvements of random walk search mainly depend on allocating weight for neighbor peers, which is always incurred on a high overhead and are not very helpful for rare items. This paper proposes a bidirectional random walk search mechanism (short for BRWS) for unstructured P2P network, according to the analysis of basic properties about random walk as well as the special property that random walk tends toward high degree nodes. The mechanism is proved theoretically in this paper, and can improve search success rate, including searching for rare items. It also has a high tolerance for churn. In the static and dynamic environment, comparisons were made among Random Walk, APS (adaptive probabilistic search), PQR (path-traceable query routing), P2PBSN (peer-to-peer based on social network) and BRWS based on three topologies: Random graph, scale free, small world. The experimental results show that BRWS can actually improve the search success rate with lower overhead even when searching rare resources. The method proposed in this paper can apply in P2P file sharing networks. © 2012 ISCAS.


Yuan W.,Guangzhou University | Li Y.,Beijing University of Posts and Telecommunications | Lin J.,Guangzhou University of Chinese Medicine
Mathematical Methods in the Applied Sciences | Year: 2013

In this paper, we employ the complex method to obtain first all meromorphic solutions of an auxiliary ordinary differential equation and then find all meromorphic exact solutions of the classical Korteweg-de Vries equation, Boussinesq equation, (3 + 1)-dimensional Jimbo-Miwa equation, and Benjamin-Bona-Mahony equation. Our results show that the method is more simple than other methods. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.


Yan H.,Beijing University of Posts and Telecommunications
Neurocomputing | Year: 2016

In this paper, we propose a transfer subspace learning approach cross-dataset facial expression recognition. To our best knowledge, this problem has been seldom addressed in the literature. While many facial expression recognition methods have been proposed in recent years, most of them assume that face images in the training and testing sets are collected under the same conditions so that they are independently and identically distributed. In many real applications, this assumption does not hold as the testing data are usually collected online and are generally more uncontrollable than the training data. Hence, the testing samples are likely different from the training samples. In this paper, we define this problem as cross-dataset facial expression recognition as the training and testing data are considered to be collected from different datasets due to different acquisition conditions. To address this, we propose a transfer subspace learning approach to learn a feature subspace which transfers the knowledge gained from the source domain (training samples) to the target domain (testing samples) to improve the recognition performance. To better exploit more complementary information for multiple feature representations of face images, we develop a multi-view transfer subspace learning approach where multiple different yet related subspaces are learned to transfer information from the source domain to the target domain. Experimental results are presented to demonstrate the efficacy of these proposed methods for the cross-dataset facial expression recognition task. © 2016 Elsevier B.V.


Yan H.,Beijing University of Posts and Telecommunications
Neurocomputing | Year: 2016

In this paper, we propose a biased subspace learning approach for misalignment-robust facial expression recognition. While a variety of facial expression recognition methods have been proposed in the literature, most of them only work well when face images are well registered and aligned. In many practical applications such as human robot interaction and visual surveillance, it is still challenging to obtain well-aligned face images for facial expression recognition due to currently imperfect computer vision techniques, especially under uncontrolled conditions. Motivated by the fact that interclass facial images with small differences are more easily mis-classified than those with large differences, we propose a biased linear discriminant analysis (BLDA) method by imposing large penalties on interclass samples with small differences and small penalties on those samples with large differences simultaneously, so that discriminative features can be better extracted for recognition. Moreover, we generate more virtually misaligned facial expression samples and assign different weights to them according to their occurrence probabilities in the testing phase to learn a weighted BLDA (WBLDA) feature space to extract misalignment-robust discriminative features for recognition. To better exploit the geometrical information of face samples, we propose a weighted biased margin Fisher analysis (WBMFA) method by employing a graph embedding criterion to extract discriminative information, so that the assumption of the Gaussian distribution of samples is not necessary. Experimental results on two widely used face databases are presented to show the efficacy of the proposed methods. © 2016 Elsevier B.V.


Li B.,Beijing University of Posts and Telecommunications | Zhou Z.,Beijing University of Posts and Telecommunications | Zhang H.,Beijing University of Posts and Telecommunications | Nallanathan A.,King's College London
IEEE Transactions on Vehicular Technology | Year: 2014

In this paper, we formulate realistic beamforming (BF) training (or beam steering) in the emerging 60-GHz millimeter-wave communications as a numerical optimization problem. To maximize the receiving SNR, it aims to identify the optimal beam pair from a prescribed codebook using as little overhead as possible. Being a promising numerical method that excludes a functional derivative, the Rosenbrock numerical search may be of great significance to such applications. Nevertheless, for the encountered nonsmooth objective function, a search failure is inevitable due to the local optimum. To meet this challenge, we further present an appealing global numerical algorithm inspired by simulated annealing (SA) mechanics. In sharp contrast to classical schemes, numerical probes that lead to reward improvement are always accepted, and search moves toward worse solutions are also permitted, with a probability associated with an external temperature parameter. By relying on a newly designed two-level annealing schedule, the temperature decreases; thereby, permitting movements to worse solutions is progressively restricted. Consequently, it can basically escape from the local optimum. We then apply this new numerical search to beam switching of 60-GHz communications. Experimental simulations have demonstrated that the developed beam-switching scheme can efficiently discover the optimal beam pair by considerably reducing protocol overhead and energy consumption. © 2013 IEEE.


Zheng K.,Beijing University of Posts and Telecommunications | Ou S.,Beijing University of Posts and Telecommunications | Alonso-Zarate J.,Catalonia Technology Center of Telecomunications | Dohler M.,King's College London | And 2 more authors.
IEEE Wireless Communications | Year: 2014

Machine-to-machine wireless systems are being standardized to provide ubiquitous connectivity between machines without the need for human intervention. A natural concern of cellular operators and service providers is the impact that these machine type communications will have on current human type communications. Given the exponential growth of machine type communication traffic, it is of utmost importance to ensure that current voice and data traffic is not jeopardized. This article investigates the limits of machine type communication traffic coexisting with human communication traffic in LTE-A networks, such that human customer churn is minimized. We show that under proper design, the outage probability of human communication is marginally impacted whilst duty cycle and access delay of machine type communications are reasonably bounded to ensure viable M2M operations. © 2002-2012 IEEE.


Zhai S.,Beijing University of Posts and Telecommunications | Jiang T.,Beijing University of Posts and Telecommunications
Knowledge-Based Systems | Year: 2014

Detection and recognition of targets that are embedded in foliage is of interest to both military and civilian research. Due to multipath propagation effects of rough surfaces, scattering from trees and ground tend to overwhelm the weak backscattering of targets, which makes it more difficult for sense through foliage target detection and recognition. In this paper, a novel intelligent recognition model based on support vector machine (SVM) and novel particle swarm optimization for sense through foliage targets recognition is proposed. SVM is a powerful novel tool for solving the recognition problem with small sampling, nonlinearity and high dimension. A new adaptive chaos particle swarm optimization (ACPSO) is developed in this study to determine the optimal parameters for SVM with the highest accuracy and generalization ability. Moreover, the measured real target echo signals are processed using sparse representation. Principal component analysis (PCA) is performed to extract the features of targets. Then, a hybrid feature selection is used to remove the redundant and irrelevant information of the features. The computational results on different real measurement datasets validate the effectiveness of the proposed approach. © 2014 Elsevier B.V. All rights reserved.


Zhao Z.,Beijing University of Posts and Telecommunications | Peng M.,Beijing University of Posts and Telecommunications | Ding Z.,Northumbria University | Wang W.,Beijing University of Posts and Telecommunications | Chen H.-H.,National Cheng Kung University
IEEE Transactions on Vehicular Technology | Year: 2014

In this paper, we propose a denoise-and-forward network coding (DNF-NC) transmission scheme for its applications in two-way relay multiple-input and multiple-output (MIMO) systems. We first consider a scenario with a single pair of source nodes, and minimum mean square error (MMSE) receiver is applied at each node. The global optimal precoding design based on the mean square error (MSE) criterion can be achieved by solving two independent convex optimization problems. To achieve a better tradeoff between performance and complexity, an alternative power optimization approach is proposed using a channel diagonalization technique. Then, we proceed to considering a more challenging bidirectional communication scenario with multiple pairs of source nodes. With intrapair coordination at the sources, we modify DNF-NC by employing a signal alignment technique to combat interpair interference. The numerical results demonstrate that the proposed DNF-NC schemes can significantly improve bit error rate (BER) performance in both two scenarios, and such performance gains can be achieved with relatively low computational complexity. © 2013 IEEE.


Zhang H.,Beijing University of Posts and Telecommunications
Chinese Journal of Electronics | Year: 2015

Multicast has become increasingly important in multi-hop wireless networks for such applications which deliver shared media and data to multiple receivers. However, the existing multicast protocols for wireless network have large control overhead, and cannot adequately take the advantage of broadcast communication mode in multicast structure for sharing the forwarding path. This paper proposes a Cluster-based opportunistic multicast (COM) algorithm, which constructs multicast tree structure based on clusters by utilizing a stability greedy algorithm to achieve the minimum total Cluster-based expected transmission count (CETX). In this multicast tree structure, the edge is created between the kernel sets respectively belonging to two clusters for improving the forwarding efficiency and the stability of this structure. In the process of data distribution, our multi-layer solution combines multicast and opportunistic routing to improve the efficiency of transmission. Simulation results show that COM scheme can achieve the less total number of sending packets, and higher stability than other topology-based solutions and opportunistic multicast.


Zhou S.,Beijing University of Posts and Telecommunications
International Journal of Information and Communication Technology | Year: 2016

A simplified serial concatenated overlapped code division multiplexing (SC-OVCDM) system is proposed in this paper, in this scheme, inner overlapped code division multiplexing (OVCDM) code matrix is simplified into multiplexing matrix with constraint length 1, which can obtain two benefits. Firstly, system complexity has significant reduction. Moreover, the output constellation diagram distribution is close to the Gaussian distribution and can obtain better BER performance. Secondly, higher spectral efficiency greater than 4 bit/s/Hz can be achieved for its low complexity. Coded simplified SC-OVCDM system is studied at the first time, BCH (Bose, Ray-Chaudhuri and Hocquenghem) code correcting multiple errors is selected as error correcting code through error histogram analysis, simulations show shorten BCH codes which code rate is close to 1 can effectively eliminate high error floor and reduce loss of spectral efficiency. Proposed system performance needs joint optimisation of encoders, signal sets and multiplexing matrix. Novel multipexing matrices are given for systems that spectral efficiency equals to and greater than 4bit/s/Hz. Simulation results show the effectiveness of the optimal new scheme in AWGN channel. Copyright © 2016 Inderscience Enterprises Ltd.


Jiang Y.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications | Li M.,Beijing University of Posts and Telecommunications | Wang P.,Beijing University of Posts and Telecommunications
Nonlinear Dynamics | Year: 2013

Under investigation is the higher-order nonlinear Schrödinger equation with the third-order dispersion (TOD), self-steepening (SS) and self-frequency shift, which can be used to describe the propagation and interaction of ultrashort pulses in the subpicosecond or femtosecond regime. Through the introduction of an auxiliary function, bilinear form is derived. Bright one- and two-soliton solutions are obtained with the Hirota method and symbolic computation. From the one-soliton solutions, we present the parametric regions for the existence of single- and double-hump solitons, and find that they are affected by the coefficients of the group velocity dispersion (GVD) and TOD. Besides, propagation of the one single- or double-hump soliton is observed. We analytically obtain the amplitudes for the single- and double-hump solitons, and calculate the interval between the two peaks for the double-hump soliton. Moreover, soliton amplitudes are related to the coefficients of the GVD, TOD and SS, while the interval between the two peaks for the double-hump soliton is dependent on the coefficients of the GVD and TOD. Interactions are seen between the (i) two single-hump solitons, (ii) two double-hump solitons, and (iii) single- and double-hump solitons. Those interactions are proved to be elastic via the asymptotic analysis. © 2013 Springer Science+Business Media Dordrecht.


Guo J.,Beijing University of Posts and Telecommunications | Guo H.,University of Southern California | Wang Z.,China Mobile
PLoS ONE | Year: 2014

The temporal order of cancer gene mutations in tumors is essential for understanding and treating the disease. Existing methods are unable to infer the order of mutations that are identified at the same time in individual tumor samples, leaving the heterogeneity of the order unknown. Here, we show that through a complex network-based approach, which is based on the newly defined statistic -carcinogenesis information conductivity (CIC), the temporal order in individual samples can be effectively inferred. The results suggest that tumor-suppressor genes might more frequently initiate the order of mutations than oncogenes, and every type of cancer might have its own unique order of mutations. The initial mutations appear to be dedicated to acquiring the function of evading apoptosis, and some order constraints might reflect potential regularities. Our approach is completely data-driven without any parameter settings and can be expected to become more effective as more data will become available. © 2014 Guo et al.


Zhang B.,Beijing University of Posts and Telecommunications
IET Conference Publications | Year: 2010

With the proliferation of Web services and the evolution towards the Semantic Web comes the opportunity to automate various Web services tasks. A number of approaches have been proposed to tackle the problem of automatic web service composition. Most of them are inspired by the researches in AI planning. As heuristics plays a key role in the promotion of planning efficiency, the selection of heuristic mechanism is very important. In this paper, we propose the conception of composition distance, and propose a heuristic bidirectional search algorithm based on composition distance. The most contribution of this paper is: (1)propose the conception of composition distance; (2)a heuristic bidirectional search algorithm. The algorithm we proposed is effective and efficiency when applied in web service composition engine.


Tang Y.,Beijing University of Posts and Telecommunications
International Journal of Control | Year: 2016

In this paper, we consider a coordination problem for a class of heterogeneous nonlinear multi-agent systems with a prescribed input–output behaviour which was represented by another input-driven system. In contrast to most existing multi-agent coordination results with an autonomous (virtual) leader, this formulation takes possible control inputs of the leader into consideration. First, the coordination was achieved by utilising a group of distributed observers based on conventional assumptions of model matching problem. Then, a fully distributed adaptive extension was proposed without using the input of this input–output behaviour. An example was given to verify their effectiveness. © 2016 Informa UK Limited, trading as Taylor & Francis Group


Yin J.,Beijing University of Posts and Telecommunications | Xu W.R.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2014

The aim of the system is to achieve query expansion. The method works combining clustering of hierarchical methods. Through the information proffered by a background document, doc_ID, concerning the initial query, a cluster containing doc_ID can be produced by hierarchical clustering. And the word co-occurrence information can be extracted from the candidate documents in this cluster. Compared with the content in doc_ID, the result of the experiment using the system shows an expected performance to develop expanded terms which are qualified to add to original query. © (2014) Trans Tech Publications, Switzerland.


Liu L.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2014

Heterogeneous cellular network (HCN) is a key technology in the future mobile communication system. In this paper, the theoretical analysis results as a guide, HCN frequency resource allocation method based on ASID is proposed. The method first defines a macro base station receiver sensitivity loss limits, it uses the theory of direct communication users on average interference macro base stations closed expressions, then the radius of ASID is derived from the theoretical analysis. In conclusion, the rationality of frequency resource allocation method based on ASID by simulation is verification. © (2014) Trans Tech Publications, Switzerland.


Siyang Z.,Beijing University of Posts and Telecommunications
Proceedings - 2015 7th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2015 | Year: 2015

This paper proposes a recognition algorithm for solving the puzzle of Quickly Response (QR) identification at highly deviated shooting angle. This algorithm includes five procedures, i.e. Binarization processing, edge detection, Hough transformation, morphological processing and projective geometry transformation, and it has been simulated and verified by Java language environment and android mobile terminal environment, and some operation had been implemented, such as write and find information by scanning or reading two-dimension code. © 2015 IEEE.


Wang T.-J.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications | Wang C.,Beijing University of Posts and Telecommunications
Laser Physics Letters | Year: 2014

Exploiting the giant optical circular birefringence induced by the double-sided quantum-dot-cavity system, we construct a deterministic hybrid hyper-controlled-not (hyper-CNOT) gate, in which the spatial-mode and polarization states of a photon act as the two control qubits, whereas two stationary electron spins in quantum dots confined inside the optical microcavities serve as the two target qubits. In our scheme, the control qubits are easily manipulated with simple optical elements and the target qubits are suitable for storage and processing use. With our hybrid hyper-CNOT gates, we design a high-capacity direct transmission quantum communication network which requires neither the establishment of entanglement between remote locations nor the use of long-lived quantum memories. We discuss the feasibility and efficiency of our hybrid hyper-CNOT gate, concluding that it is feasible with current technology. © 2014 Astro Ltd.


Zhang T.,Beijing University of Posts and Telecommunications | Wu B.,Beijing University of Posts and Telecommunications
Proceedings of the 2012 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining, ASONAM 2012 | Year: 2012

Currently, the detection of global community structure in networks has gathered a lot of attention. Most of the methods need global knowledge of the graphs which would be unrealistic to get when the graphs are too large or evolve too quickly .Moreover ,sometimes we are only interested in the community structures of some given nodes ,not all nodes .So detecting the community of a given node i.e. local community detection is more appropriate .Most of the proposed solutions for local community detection built upon the source nodes are sensitive to the position of source nodes .In this paper ,we propose a method to detect local community of a given node by finding the core node of the community firstly .Then expand the core node's cliques to get community of the given node. We validate our method on real-world networks whose community structures are available .The result shows that our method can get high recall and precision score and is quite effective and flexible to identify local communities, irrespective of the source node position. © 2012 IEEE.


Lei Q.S.,Beijing University of Posts and Telecommunications | Zhou L.Y.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2014

Traditional supply chain theory often assumes perfect alignment between system inventory and actual inventory. However, inventory information is usually inaccurate due to many reasons in practice. We hereby describe an expended newsvendor model with inventory inaccuracy who wants to remove this negative effect by investing RFID system. By analyzing the best respond to market factors (commodity availability caused by inventory inaccuracy and tag price of RFID), we generate the optimal order quantity of newsvendor (retailer in this paper) and his minimal regret value. Unlike other paper describing uncertain parameters with probability function, we use only upper limit and lower limits to display demand. We adopt robust deviation criterion to minimize the absolute regret and treat it as the determine principle. Finally, we achieve a result that when commodity availability or tag price meets some specific conditions, investing RFID can be rather profitable. © (2014) Trans Tech Publications, Switzerland.


Wang C.,Beijing University of Posts and Telecommunications | Wang T.-J.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications
Laser Physics Letters | Year: 2014

We investigate an efficient quantum repeater protocol based on quantum dots (QDs) and optical microcavity coupled systems. The proposed system can be used for long-distance quantum entanglement distribution, exploiting the interaction between single photons and QDs embedded in optical microcavities. We present the entanglement generation and entanglement swapping modules with QDs in microcavity systems and generalize it to quantum repeaters. The utilization of QDs and coupled cavities leads to a high success probability for the generation of entanglement. By using current and near future technology, entanglement with a high fidelity can be achieved and robust quantum communication over long-distance channels is feasible. © 2014 Astro Ltd.


Meng D.,Beihang University | Jia Y.,Beihang University | Du J.,Beijing University of Posts and Telecommunications | Yu F.,Henan Polytechnic University
Systems and Control Letters | Year: 2012

In this paper, the tracking control problem for multi-agent systems is considered, where all agents in a directed graph are enabled to track a time-varying reference trajectory perfectly over a finite interval. A unified algorithm is presented for agents described by both discrete-time and continuous-time models through using the iterative learning approach. Even under the condition that the reference trajectory is available to not all but only a portion of agents, all agents can be guaranteed to (1) obtain the finite-time tracking except the initial time step in the discrete-time domain and (2) follow the reference trajectory with constant shifts at all the time in the continuous-time domain. If an initial rectifying action is used to continuous-time agents, then the finite-time tracking can be derived on an interval that can be specified. The proposed algorithms are also extended to achieve the formation control for multi-agent systems. Moreover, design conditions are developed for all algorithms, and two examples are given to demonstrate the effectiveness of the theoretical results. © 2012 Elsevier Ltd. All rights reserved.


Zhou H.,Beijing University of Posts and Telecommunications | Wang S.,Beijing University of Posts and Telecommunications
Neurocomputing | Year: 2012

The security of a parallel keyed hash function based on two-layer neural network is investigated. The collision examples and the theoretical analysis show that the original algorithm is insecure. An improved hash function is proposed. Theoretical analysis and simulation experiments indicate that the improved algorithm is more secure, keeping the parallel merit of the original hash function. © 2012 Elsevier B.V.


Si P.,Beijing University of Technology | Ji H.,Beijing University of Posts and Telecommunications | Yu F.R.,Carleton University | Leung V.C.M.,University of British Columbia
IEEE Transactions on Vehicular Technology | Year: 2010

Spectrum pooling in cognitive radio systems is an approach to manage the available spectrum bands from different licensed networks. Most previous work on spectrum pooling concentrates on the system architecture and the design of flexible-access algorithms and schemes. In this paper, we present a cooperative scheme for internetwork spectrum sharing among multiple secondary systems, which takes into account the price and spectrum efficiency as the design criteria. Specifically, the spectrum-sharing problem is formulated as a stochastic bandit system; thus, the optimal spectrum-sharing scheme is simply allocating the new available band to the secondary network with the lowest index. Extensive simulation examples illustrate that the proposed scheme significantly improves the performance compared with the existing scheme that ignores optimal spectrum sharing. © 2006 IEEE.


Zhou Y.,Beijing University of Posts and Telecommunications
IEEE Transactions on Components, Packaging and Manufacturing Technology | Year: 2015

Serious environmental pollution degraded the reliability of gold-plated connectors in many-handed terminals. It was found that gold-plated contacts disassembled from failed mobile phones were tarnished and worn out. The main compositions of the contaminants on the failed contacts were dust particles, organic compounds, and worn contact materials with their oxide. The micromotion between contacts abrasively wore the contacts with the dust particles and organic compounds. Contact resistance on the tarnished contacts increased with the thickness of contaminants on the contacts. The combined effects of dust particles, organic compounds, and micromotion on the electrical behaviors of the gold-plated contacts were simulated and studied by adapting a fretting simulation system. The hard particles caused seriously abrasive wear of gold plating and quickly formed fretting corrosion to shorten the contact life. Tiny content of organic compounds supplied certain adhesion function of dust particles, which made it easy for the dust particles to insert the contact interfaces. The contaminants and wear debris with their oxide formed complexly tarnished morphology under micromotion conditions, which finally caused contact failure. © 2015 IEEE.


Liu B.,Beijing University of Posts and Telecommunications | Zhang L.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications | Wang Y.,Beijing University of Posts and Telecommunications
IEEE Photonics Technology Letters | Year: 2014

A physical layer security enhanced orthogonal frequency division multiplexing (OFDM) passive optical network based on dimension-transformed chaotic permutation is proposed and experimentally demonstrated. In this scheme, a large key space is obtained by multidomain jointed Rossler permutation, and the corresponding complexity scale caused by multidomain encryption can be reduced through dimension-transformed permutation. An experiment with 10.61-Gb/s encrypted optical OFDM access system is performed to demonstrate the proposed method. © 1989-2012 IEEE.


Sun X.,Beijing University of Posts and Telecommunications | Shi X.,Beijing University of Posts and Telecommunications
Science China Technological Sciences | Year: 2014

In this paper, we discuss the influences of channel blocks on the spiking regularity in a clustered neuronal network by applying stochastic Hodgkin-Huxley neuronal models as the building blocks. With the aid of simulation results, we reveal that the spiking regularity of the clustered neuronal network could be resonantly enhanced via fine-tuning of the non-blocked potassium channel fraction x K . While the non-blocked sodium channel fraction x Na can enhance the spiking regularity of the clustered neuronal network in most cases. These results indicate that not only sodium channel blocks but also potassium channel blocks could have great influences on the regularity of spike timings in the clustered neuronal networks. Considering the importance of spike timings in neuronal information transforming processes, our results may give some implications for understanding the nonnegligible role of randomness in ion channels in neuronal systems. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg.


Zheng K.,Beijing University of Posts and Telecommunications | Ou S.,Beijing University of Posts and Telecommunications | Yin X.,Tongji University
International Journal of Antennas and Propagation | Year: 2014

The exponential traffic growth of wireless communication networks gives rise to both the insufficient network capacity and excessive carbon emissions. Massive multiple-input multiple-output (MIMO) can improve the spectrum efficiency (SE) together with the energy efficiency (EE) and has been regarded as a promising technique for the next generation wireless communication networks. Channel model reflects the propagation characteristics of signals in radio environments and is very essential for evaluating the performances of wireless communication systems. The purpose of this paper is to investigate the state of the art in channel models of massive MIMO. First, the antenna array configurations are presented and classified, which directly affect the channel models and system performance. Then, measurement results are given in order to reflect the main properties of massive MIMO channels. Based on these properties, the channel models of massive MIMO are studied with different antenna array configurations, which can be used for both theoretical analysis and practical evaluation. © 2014 Kan Zheng et al.


Liu B.,Beijing University of Posts and Telecommunications | Zhang L.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications | Yu J.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Express | Year: 2012

This paper proposes a novel secure communication technique using constellation masking for applications in orthogonal frequency division multiplexing passive optical network (OFDM-PON). The constellation masking is applied both on each subcarrier and among different subcarriers. The Arnold mapping is utilized as the parameter function for the mask factors. A interleave length is employed to provide a scalable masking granularity for different ONUs. A 15.54 Gb/s constellation-masked 32QAM-OFDM signal has been successfully transmitted over 25-km single mode fiber in the experiment. Experimental results show that the proposed scheme can effectively protect the system from illegal ONU without wasting the bandwidth. The constellation-masked technique suggests an effective solution for the physical secure communication in future OFDM access network. © 2012 Optical Society of America.


Xiao H.,Beijing University of Posts and Telecommunications | Zuo Y.,Beijing University of Posts and Telecommunications | Wu J.,Beijing University of Posts and Telecommunications | Li Y.,Beijing University of Posts and Telecommunications | Lin J.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2012

In non-line-of-sight (NLOS) UV communication links using intensity modulation with direct detection, atmospheric turbulence-induced intensity fluctuations can significantly impair link performance. To mitigate turbulenceinduced fading and, therefore, to improve the bit error rate (BER) performance, spatial diversity reception can be used over NLOS UV links, which involves the deployment of multiple receivers. The maximum-likelihood (ML) spatial diversity scheme is derived for spatially correlated NLOS UV links, and the influence of various fading correlation at different receivers on the BER performance is investigated. For the dual-receiver case, ML diversity detection is compared with equal gain combining and optimal combining schemes under different turbulence intensity conditions. © 2012 Optical Society of America.


Gao F.,Beijing University of Posts and Telecommunications | Gao F.,Xidian University | Liu B.,Beijing University of Posts and Telecommunications | Wen Q.-Y.,Beijing University of Posts and Telecommunications | Chen H.,Science and Technology on Communication Security Laboratory
Optics Express | Year: 2012

By adding a parameter θ in M. Jakobi et al's protocol [Phys. Rev. A 83, 022301 (2011)], we present a flexible quantum-key-distributionbased protocol for quantum private queries. We show that, by adjusting the value of θ, the average number of the key bits Alice obtains can be located on any fixed value the users wanted for any database size. And the parameter k is generally smaller (even k = 1 can be achieved) when θ < π/4, which implies lower complexity of both quantum and classical communications. Furthermore, the users can choose a smaller θ to get better database security, or a larger θ to obtain a lower probability with which Bob can correctly guess the address of Alice's query. © 2012 Optical Society of America.


Han D.,Beijing University of Posts and Telecommunications | Liu Y.,Beijing University of Posts and Telecommunications | Zhang K.,Beijing University of Posts and Telecommunications | Luo P.,Beijing University of Posts and Telecommunications | Zhang M.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2012

Diversity reception technology is introduced into ultraviolet communication area in this article with theory analysis and practical experiment. The idea of diversity reception was known as a critical effective method in wireless communication area that improves the Gain significantly especially for the multi-scattering channel. A theoretical modeling and simulation method are proposed to depict the principle and feasibility of diversity reception adopted in UV communication. Besides, an experimental test-bed using ultraviolet LED and dual receiver of photomultiplier tube is setup to characterize the effects of diversity receiving in non-line-of-sight (NLOS) ultraviolet communication system. The experiment results are compared with the theoretical ones to verify the accuracy of theoretical modeling and the effect of diversity reception. Equal gain combining (EGC) method was adopted as the diversity mechanism in this paper. The research results of theory and experiment provide insight into the channel characteristics and achievable capabilities of ultraviolet communication system with diversity receiving method. ©2012 Optical Society of America.


Zhuang Y.,Beijing University of Posts and Telecommunications | Hu X.,Beijing University of Posts and Telecommunications | Zhai Y.,Beijing University of Posts and Telecommunications
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2014

Aiming at the nonlinear characteristic between the weighing sensor output and the weight of capsule unit in micro scale capsule dynamic weighing system, a nonlinearity compensation scheme based on BP neural network is proposed. A BP neural network model is established based on Levenberg-Marquardt algorithm. The model implements the nonlinearity compensation between the output voltage of weighing sensor and the input of capsule unit weight. The proposed method was compared with bfgs quasi-Newton algorithm and scaled conjugation gradient algorithm, and the model performances of forecasting output, error performance analysis and regression analysis were compared. Simulation results show that the BP neural network model based on Levenberg-Marquardt algorithm has high performance in terms of convergence rate and error performance. The model is more suitable for the nonlinearity compensation in micro scale capsule dynamic weighing system.


Song J.-H.,Beijing University of Posts and Telecommunications | Hou S.-F.,Beijing University of Posts and Telecommunications
Proceedings of 2012 3rd International Asia Conference on Industrial Engineering and Management Innovation, IEMI 2012 | Year: 2013

In order to regulates mart home system without manual intervention, a kind of infrared device and a wireless transmission device has been designed. Its main function is to execute terminal air conditioning through automatic switch and temperature control. The device combines infrared human testing with wireless transceiver module. It choose AT89C51 to meet the control requirement as the core, use the pyroelectric infrared sensor, and send wireless signals by PT2262/2272 wireless transceiver module. If the infrared module detects that somebody entered, the air conditioning will receive the wireless signal and start to work. Moreover, if the number reaches one certain level, you will see temperature fall. When all the people leave, it will automatically shut down. Because this system can work automatically, it can satisfy the intellectualization and humanity of the smart home system. The experimental result demonstrates that this system can operate reliably. © 2013 Springer-Verlag Berlin Heidelberg.


Peng M.,Beijing University of Posts and Telecommunications | Wang C.,Inter Digital Communications | Lau V.,Hong Kong University of Science and Technology | Poor H.V.,Princeton University
IEEE Wireless Communications | Year: 2015

As a promising paradigm for fifth generation wireless communication systems, cloud radio access networks (C-RANs) have been shown to reduce both capital and operating expenditures, as well as to provide high spectral efficiency (SE) and energy efficiency (EE). The fronthaul in such networks, defined as the transmission link between the baseband unit and the remote radio head, requires a high capacity, but is often constrained. This article comprehensively surveys recent advances in fronthaul-constrained CRANs, including system architectures and key techniques. Particularly, major issues relating to the impact of the constrained fronthaul on SE/EE and quality of service for users, including compression and quantization, large-scale coordinated processing and clustering, and resource allocation optimization, are discussed together with corresponding potential solutions. Open issues in terms of software-defined networking, network function virtualization, and partial centralization are also identified. © 2002-2012 IEEE.


Lin S.,Beijing University of Posts and Telecommunications | Tian H.,Beijing University of Posts and Telecommunications
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2013

The deployment of femtocells is uncoordinated and opportunistic, especially in urban environment where a large number of femtocells are overlapped. Therefore, it is likely that serious femto-femto interference (FFI) may cause when they operate on the same channel. In this paper, the FFI minimization problem is mapped to Max K-Cut problem in graph theory. Based on this model, a heuristic cluster-based FFI minimized sub-channels allocation algorithm (HCFM) is proposed, in which cluster is the sub-channel assignment unit. First, by using stochastic geometry to model the distribution of femtocells, the maximum femtocell cluster size is deduced to guarantee the target downlink Outage Probability (OP) for Femtocell User Equipment (FUE). Then, disjoint femtocell clusters with dynamic size and number are simultaneously generated to minimize FFI. Finally, capacity maximized sub-channels allocation algorithm is executed. Simulation results have shown that HCFM outperforms its counterparts and provide statistical Quality of Service (QoS) guarantee (in term of OP). © 2013 IEEE.


Ma Y.,Beijing University of Posts and Telecommunications | Lv T.,Beijing University of Posts and Telecommunications | Lu Y.,Beijing University of Posts and Telecommunications
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2013

In this paper, we analyze the non-cooperative power control algorithm based on game theory in the two-tier femtocell networks, and find that the outcome of the game in a Nash equilibrium (NE) is inefficient. That is to say, there are still many users that can not achieve the target Signal-to-Interference-Plus- Noise Ratio (SINR) at the NE point, especially femtocell user equipments (FUE). Therefore, we propose a novel power control scheme in heterogeneous Femto-Macro cell networks, which can guarantee the target SINR of the macrocell user (MUEs), and make as many as possible FUEs to achieve their target SINRs. The proposed power control algorithm introduces the user selection and channel re-allocation in the conventional non-cooperative power control game. In addition, to further optimize the proposed scheme, we propose a novel FUE-SINR based MUE link quality protection algorithm. The propose scheme is able to improve the efficiency of Nash equilibrium, i.e., ensure more users to attain the target SINRs. Numerical simulations verify the conclusions. © 2013 IEEE.


Chen J.,Beijing University of Posts and Telecommunications | Wang C.,Beijing University of Posts and Telecommunications | Zhang R.,Beijing University of Posts and Telecommunications | Xiao J.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2012

Multiple plasmon-induced transparencies are numerically predicted in an ultracompact plasmonic structure, comprising series of stub resonators side-coupled with a metal-isolator-metal waveguide. Because of the phase-coupled effect, electromagnetically induced transparency (EIT)-like spectral response occurs between two adjacent stub resonators with detuned resonant wavelengths. In this approach, multiple EIT-like spectral responses, with bandwidths of the order of several nanometers, are obtained in the plasmonic structure with a small footprint of about 0.6 μm2. An analytic model and the relative phase analysis based on the scattering matrix theory are used to explain this phenomenon. © 2012 Optical Society of America.


Li X.,Beijing University of Posts and Telecommunications | Yang Y.,Beijing University of Posts and Telecommunications
China Communications | Year: 2011

Cloud computing is a new paradigm in which dynamic and virtualized computing resources are provided as services over the Internet. However, because cloud resource is open and dynamically configured, resource allocation and scheduling are extremely important challenges in cloud infrastructure. Based on distributed agents, this paper presents trusted data acquisition mechanism for efficient scheduling cloud resources to satisfy various user requests. Our mechanism defines, collects and analyzes multiple key trust targets of cloud service resources based on historical information of servers in a cloud data center. As a result, using our trust computing mechanism, cloud providers can utilize their resources efficiently and also provide highly trusted resources and services to many users.


Xu X.,Beijing University of Posts and Telecommunications
International Journal of Data Warehousing and Mining | Year: 2016

Data prediction approaches are proposed in many fields to approximate time series data with a tolerable error. These approaches typically build prediction functions based on assumptions of the data variation. Nonetheless, if the variation of real-world time series data does not follow the assumption, the performance of data prediction will be limited. This paper presents a lightweight data approximation approach for time series data. This approach utilizes binary codes to represent original values, directly shortening their lengths in the cost of data precision. Then the author implements this approach in the WSN scenario. Two types of application layer messages and their transmission scheme are presented. These approaches are employed in WSN applications to: (1) report abnormal conditions in time, and (2) reduce data transmissions independently of data variations. Series of simulations are built on the basis of five real datasets. Simulation results based on five real datasets validate the performances of the proposed approach. Copyright © 2016, IGI Global.


Xia J.,Beijing University of Posts and Telecommunications
Telecommunications Policy | Year: 2011

Since the inception of telecom reform in 1994, structural reform has been a main thread surrounding the course of the development of Chinas telecommunications industry. In structuring the 2008 reform and the 2009 3G rollout Chinas government adopted a relatively balanced approach in the hope of creating level-playing-field in 3G era. Nevertheless, due to the presence of substantial switching costs, substitution effects from the present technology mode, that is, 2.5G, the absence of killer applications, among other technological and institutional factors, China may not have a realistic 3G era before moving toward 4G and beyond. At the bare minimum, currently there is a lacking of either adequate technological-push or demand-pull for a full-scale 3G commercializationthere is no sign that this situation will change in the near term. Triggered by recent initiatives of market convergence between the telecommunications, Internet, and cable, a renewed circle of market, and regulatory reform is probably necessary to cast a sounder industry basis for a timing migration toward the next-generation-networks (NGNs). The timing migration toward 4G (and beyond) may provide a chance for a late-mover nation like China to leapfrog its western counterparts in leading the industry in the era of NGNs. To this end, China is confronted with a challenge in re-examining its industry policy as well as technological strategies for a sustainable development in the era of NGNs. This study offers heuristic analysis and insights on the above issues based on archival documents and interviews. While implications are suggested for Chinas circumstances, the Chinese experiences may also be considered by other countries and investors when it comes to 3G (and beyond) policies, regulations, deployments, and evolutions. © 2010 Elsevier Ltd. All rights reserved.


Chen X.-B.,Beijing University of Posts and Telecommunications | Xu G.,Taiyuan University of Technology | Yang Y.-X.,Beijing University of Posts and Telecommunications | Wen Q.-Y.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2010

Through designing a quantum communication network, we propose a protocol for the teleportation between multiple senders and multiple receivers via only one controller. In order to rationally employ the quantum entanglement resources, the controller shares the entangled state with every sender, while there is no directly shared entanglement link between sender and receiver. The security is analyzed in detail. Moreover, this protocol reduces the classical communication cost in the public channel by means of the coding. © 2010 Elsevier B.V. All rights reserved.


Zhu T.,Beijing University of Posts and Telecommunications | Wang B.,Beijing University of Posts and Telecommunications | Wu B.,Beijing University of Posts and Telecommunications | Zhu C.,Nanchang University
Expert Systems with Applications | Year: 2011

Understanding the individual behavior has shown to be of paramount importance to the triumph of the telecommunication operators to retain customers, enhance their purchasing capacity, and predict the churn rate. Different behavior patterns can be observed for different groups of users. Hence, there is an interesting problem posted in telecommunication network that how to define the users' role according to their behavior patterns. Traditionally, user behavior characterization methods generally based on their call detail record (CDR), which are user's individual features, are not appropriate to identify the role in network. In this paper, we develop a new methodology for identifying users' role based on their behaviors in telecommunication network using the social features instead of their individual features. Experiments have tested on synthetic data and large real datasets, and reveal good results on both of them. Finally, the methodology is not only limited to call graphs but also apply to other networks for role defining. © 2010 Elsevier Ltd. All rights reserved.


Zhang J.,Beijing University of Posts and Telecommunications | Liang X.-J.,Beijing University of Posts and Telecommunications
Telecommunications Policy | Year: 2011

In order to define the mobile network operators strategies of building value network in the 3G era, this paper applies the ecosystem principles to the mobile industry through a China Mobile case study. Based on an analytical framework of such principles, this paper reviews China Mobiles ecosystem, and identifies its success factors and problems. The results indicate that a complete ecosystem, where mobile network operators collaborate closely with value-added service providers, content/application providers, equipment and device manufacturers, and other involved organizations, can promote the development of mobile data services substantially. Therefore, mobile network operators should play a central role in the ecosystem by managing the entire value-chain and setting up proper value-sharing mechanisms. However, while doing so, problems may arise because of regulatory issues and information asymmetry. High-value common assets, a centralized management system, partner selection schemes and continuous innovations are important success factors. © 2010 Elsevier Ltd. All rights reserved.


Liao X.,Beijing University of Posts and Telecommunications | Wen Q.-Y.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications
Journal of Visual Communication and Image Representation | Year: 2011

To improve the embedding capacity and provide an imperceptible visual quality, a novel steganographic method based on four-pixel differencing and modified least significant bit (LSB) substitution is presented. The average difference value of a four-pixel block is exploited to classify the block as a smooth area or an edge area. Secret data are hidden into each pixel by the k-bit modified LSB substitution method, where k is decided by the level which the average difference value falls into. Readjustment will be executed to guarantee the same level that the average difference value belongs to before and after embedding, and to minimize the perceptual distortion. By proving that the readjusting procedure works, a theoretical proof is given to justify our method succeeded in embedding and extracting. Our experimental results have shown that the proposed method not only has an acceptable image quality but also provides a large embedding capacity. © 2010 Elsevier Inc. All rights reserved.


Wang W.,Zhejiang University | Shin K.G.,University of Michigan | Wang W.,Beijing University of Posts and Telecommunications
IEEE Transactions on Mobile Computing | Year: 2011

We propose a new framework of joint spectrum allocation and power control to utilize open spectrum bands in cognitive radio networks (CRNs) by considering both interference temperature constraints and spectrum dynamics. We first address a simpler problem for the case of a single flow. A TDM-based power-control strategy is adopted to achieve maximum end-to-end throughput by choosing an appropriate multihop route and spectrum combination for each single flow. Then, the simpler solution is extended to the multiflow case in which interflow interference and cumulative interference temperature must be considered. Considering the overhead of switching route and spectrum, the optimal waiting time before making a switch is derived. Our in-depth simulation study has shown that the proposed algorithms utilize spectrum more efficiently than other existing algorithms. © 2011 IEEE.


Zhou J.,Beijing University of Posts and Telecommunications | Qiao Y.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2015

In this Letter, we propose a discrete Hartley transform (DHT)-spread asymmetrically clipped optical orthogonal frequency-division multiplexing (DHT-S-ACO-OFDM) uplink transmission scheme in which the multiplexing/demultiplexing process also uses the DHT algorithm. By designing a simple encoding structure, the computational complexity of the transmitter can be reduced fromO=Nlog2=Nto O=N. At the probability of 10-3, the peak-to-average power ratio (PAPR) of 2-ary pulse amplitude modulation (2-PAM)-modulated DHT-S-ACO-OFDMis approximately 9.7 dB lower than that of 2-PAM-modulated conventional ACO-OFDM. To verify the feasibility of the proposed scheme, a 4-Gbit/s DHT-S-ACO-OFDM uplink transmission scheme with a 1:64 way split has been experimentally implemented using 100-km standard single-mode fiber (SSMF) for a long-reach passive optical network (LRPON). © 2015 Optical Society of America.


Zhang L.,Beijing University of Posts and Telecommunications | Liu B.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2015

A secure optical generalized filter bank multi-carrier (GFBMC) system with carrier-less amplitude-phase (CAP) modulation is proposed in this Letter. The security is realized through cubic constellation-masked method. Large key space and more flexibility masking can be obtained by cubic constellation masking aligning with the filter bank. An experiment of 18 Gb/s encrypted GFBMC/CAP system with 25-km single-mode fiber transmission is performed to demonstrate the feasibility of the proposed method. © 2015 Optical Society of America.


Xu W.,Beijing University of Posts and Telecommunications | Niu K.,Beijing University of Posts and Telecommunications | Lin J.,Beijing University of Posts and Telecommunications | He Z.,Beijing University of Posts and Telecommunications
IEEE Communications Letters | Year: 2011

This letter studies generalized resource allocation in multiple description coding multicast (MDCM) orthogonal frequency division multiplexing (OFDM) systems, where many multicast groups are served simultaneously by base station (BS). Due to non-tractable nature, the problem is reformulated to weighted-capacity maximization by resource distribution among virtual multicast groups (VMGs). Then, the relaxation of exclusively-used constraints allows us to provide both upper and lower bounds for the original problem. A suboptimal algorithm is also proposed based on Newton's method to reduce the computational complexity. Simulation results show the proposed algorithm approximately reaches the optimal capacity within 2 iterations for multicast waterfilling, and MDCM is more bandwidth-efficient for multicast services than conventional multicast (CVM). © 2011 IEEE.


Lei M.,Beijing University of Posts and Telecommunications | Li P.G.,Beijing University of Posts and Telecommunications | Tang W.H.,Beijing University of Posts and Telecommunications
Journal of Alloys and Compounds | Year: 2011

Cathodoluminescence (CL) spectra are taken from the spots with different diameters on a single tapered CdS nanowire to investigate the size-dependent surface effects. Strong deep level (DL) emission is detected at the spots with small diameter, and the intensity ratio of deep level (DL) to the near band gap emission (NBE) emission is gradually enhanced with shrinking diameter. The experimental results demonstrate that surface effects strongly modulate the luminescence of the tapered nanowire and dominate the DL emission in the tapered nanowire. The CL spectra of a single straight nanowire with uniform diameter are also studied. The straight nanowire only exhibits perfect luminescence properties with NBE emission centered at 511 nm, revealing that surface effects do not affect the straight nanowire with relatively large and uniform diameter. © 2011 Elsevier B.V.


Lei M.,Beijing University of Posts and Telecommunications | Fu X.L.,Beijing University of Posts and Telecommunications | Li P.G.,Zhejiang Sci-Tech University | Tang W.H.,Beijing University of Posts and Telecommunications
Journal of Alloys and Compounds | Year: 2011

We developed a metalorganic chemical vapor deposition to synthesize ZnS nanowires with high purity on Au-coated sapphire substrates at low temperatures. The ZnS nanowires have zinc blende structure, and most of them have raw-like surface on one edge, while is smooth on the other. High-resolution transmission electron microscopic investigations show that the nanowires are well crystalline single crystal grown along [1 1 1] and are free of bulk defects. The growth mechanism is confirmed as a typical vapor-liquid-solid process. The photoluminescence spectrum reveals two prominent blue emissions centered at 452.2 and 468.6 nm, respectively. It is found that sulfur vacancies and surface states should be responsible for the two blue emissions, respectively. © 2011 Elsevier B.V.


Jiang D.,Northeastern University China | Jiang D.,Beijing University of Posts and Telecommunications | Xu Z.,Northeastern University China | Zhang P.,Northeastern University China | Zhu T.,Binghamton University State University of New York
Journal of Network and Computer Applications | Year: 2014

Traffic anomalies contain existing abnormal changes in network traffic, which are derived from malicious and anomalous behaviors of users or network devices, such as network faults, abuses, network attacks, etc. These anomalies often damage our operation networks and even lead to network disruptions. In the present paper, we propose a novel method for detecting traffic anomalies in a network by exacting and capturing their features in the transform domain. Here, we take in consideration network topology information and network-wide traffic jointly. We find that anomalous network-wide traffic usually exhibits distinct high-frequency nature. This motivates us to utilize transform domain analysis theory to characterize network-wide traffic to identify its abnormal components. Besides, we group all origin-destination flows in the network in accordance with common destination nodes. By combining network topology information and transform-domain analysis in the given time window, the specious traffic components can be found and identified. Simulation results show that our detection algorithm exhibits a fairly robust detection ability and provides the better detection performance than previous algorithms. © 2013 Published by Elsevier Ltd.


Xin Y.,Beijing University of Posts and Telecommunications | Liu Z.,Shandong University | Zhang H.,Shandong University
Applied Optics | Year: 2012

Finger vein verification is a promising biometric pattern for personal identification in terms of security and convenience. The recognition performance of this technology heavily relies on the quality of finger vein images and on the recognition algorithm. To achieve efficient recognition performance, a special finger vein imaging device is developed, and a finger vein recognition method based on sparse representation is proposed. The motivation for the proposed method is that finger vein images exhibit a sparse property. In the proposed system, the regions of interest (ROIs) in the finger vein images are segmented and enhanced. Sparse representation and sparsity preserving projection on ROIs are performed to obtain the features. Finally, the features are measured for recognition. An equal error rate of 0.017% was achieved based on the finger vein image database, which contains images that were captured by using the near-IR imaging device that was developed in this study. The experimental results demonstrate that the proposed method is faster and more robust than previous methods. © 2012 Optical Society of America.


Duan X.,Beijing University of Posts and Telecommunications | Zhou G.,Beijing University of Posts and Telecommunications | Huang Y.,Beijing University of Posts and Telecommunications | Shang Y.,Beijing University of Posts and Telecommunications | Ren X.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2015

We propose a planar dielectric reflector with focusing ability using concentric circular subwavelength gratings (CC-SWGs). The two-dimensional focusing ability of CC-SWGs is investigated by the rigorous coupled-wave analysis (RCWA) and finite element method (FEM). By designing the concentric circular pattern of the grating surface, a focusing reflector with high numerical aperture (NA) and high reflectivity is constructed. A CC-SWG reflector with a diameter of 32.6μm and a focal length of 6μm is investigated, which exhibits high focusing ability at normal incidence with a radially polarized plane wave. At the reflection focal plane, the full-width-half-maximum (FWHM) of the electric field intensity is 0.89μm. Numerical aperture value as high as 0.93 is achieved for the reflector with very high reflectivity of 92%. © 2015 Optical Society of America.


Wang T.-J.,Beijing University of Posts and Telecommunications | Liu L.-L.,Beijing University of Posts and Telecommunications | Zhang R.,Beijing University of Posts and Telecommunications | Cao C.,Beijing University of Posts and Telecommunications | Wang C.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2015

We investigate a new approach for achieving hyperdistillation and hyperentanglement purification operations simultaneously on two-photon systems, whose state is described by nonlocal hyperentangled Bell states on both the spatial mode and polarization degree of freedoms. Exploiting linear optics and local entanglement resource, the quantum nondemolition (QND) parity-checking measurement and the heralded two-qubit amplification could are key steps in our scheme. With the QND parity-checking measurement and heralded qubit amplification operations, both the bit-flip (phase-flip) errors caused by decoherence in noisy channels and the vacuum errors caused by the transmission losses can be corrected. We show that the proposed scheme provides a new solution to overcome the problem of photon losses and decoherence simultaneously, which could be achieved with current technologies. © 2015 Optical Society of America.


Chenglin Z.,Beijing University of Posts and Telecommunications | Xuebin S.,Beijing University of Posts and Telecommunications | Songlin S.,Beijing University of Posts and Telecommunications | Ting J.,Beijing University of Posts and Telecommunications
Expert Systems with Applications | Year: 2011

Fault diagnosis of sensor timely and accurately is very important to improve the reliable operation of systems. In the study, fault diagnosis of sensor by chaos particle swarm optimization algorithm and support vector machine is presented in the paper, where chaos particle swarm optimization is chosen to determine the parameters of SVM. Chaos particle swarm optimization is a kind of improved particle swarm optimization, which can not only avoid the search being trapped in local optimum and but also help to search the optimum quickly by using chaos queues. The wireless sensor is employed as research object, and its four fault types including shock, biasing, short circuit and shifting are applied to test the diagnostic ability of CPSO-SVM compared with other diagnostic methods. The diagnostic results show that CPSO-SVM has higher diagnostic accuracy of wireless sensor than PSO-SVM and BP neural network. © 2011 Published by Elsevier Ltd.


Wang Z.,Beijing University of Posts and Telecommunications | Peng Q.,University of Electronic Science and Technology of China | Milstein L.B.,University of California at San Diego
IEEE Transactions on Wireless Communications | Year: 2011

In this paper, we consider an adaptive multi-user resource allocation for the downlink transmission of a multi-cluster tactical multicarrier DS CDMA network. The goal is to maximize the sum packet throughput, subject to transmit power constraints. Since the objective function turns out to be noncovex and nondifferentiable, we propose a simple iterative bisection algorithm. At each iteration, a closed-form expression is derived for the transmit power, subchannel, and modulation assignment, which significantly reduces the computational complexity. We also provide an optimization algorithm for the downlink transmission under the condition of imperfect channel knowledge, and investigate the effects of both channel estimation error and partial-band jamming. © 2006 IEEE.


Yang H.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications | Zhao Y.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications | And 4 more authors.
Optics Express | Year: 2015

Inter-data center interconnect with IP over elastic optical network (EON) is a promising scenario to meet the high burstiness and highbandwidth requirements of data center services. In our previous work, we implemented multi-stratum resources integration among IP networks, optical networks and application stratums resources that allows to accommodate data center services. In view of this, this study extends to consider the service resilience in case of edge optical node failure. We propose a novel multi-stratum resources integrated resilience (MSRIR) architecture for the services in software defined inter-data center interconnect based on IP over EON. A global resources integrated resilience (GRIR) algorithm is introduced based on the proposed architecture. The MSRIR can enable cross stratum optimization and provide resilience using the multiple stratums resources, and enhance the data center service resilience responsiveness to the dynamic end-to-end service demands. The overall feasibility and efficiency of the proposed architecture is experimentally verified on the control plane of our OpenFlow-based enhanced SDN (eSDN) testbed. The performance of GRIR algorithm under heavy traffic load scenario is also quantitatively evaluated based on MSRIR architecture in terms of path blocking probability, resilience latency and resource utilization, compared with other resilience algorithms. ©2015 Optical Society of America.


Yang H.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications | Tan Y.,Beijing University of Posts and Telecommunications | And 3 more authors.
Optics Express | Year: 2015

Data center interconnection with elastic optical network is a promising scenario to meet the high burstiness and high-bandwidth requirements of data center services. In our previous work, we implemented cross stratum optimization of optical network and application stratums resources that allows to accommodate data center services. In view of this, this study extends the data center resources to user side to enhance the endto- end quality of service. We propose a novel data center service localization (DCSL) architecture based on virtual resource migration in software defined elastic data center optical network. A migration evaluation scheme (MES) is introduced for DCSL based on the proposed architecture. The DCSL can enhance the responsiveness to the dynamic end-to-end data center demands, and effectively reduce the blocking probability to globally optimize optical network and application resources. The overall feasibility and efficiency of the proposed architecture are experimentally verified on the control plane of our OpenFlow-based enhanced SDN testbed. The performance of MES scheme under heavy traffic load scenario is also quantitatively evaluated based on DCSL architecture in terms of path blocking probability, provisioning latency and resource utilization, compared with other provisioning scheme. © 2015 Optical Society of America.


Tao Z.,Engineering School of Information Technology and Communication | Hong Y.,Engineering School of Information Technology and Communication | Luo B.,Beijing University of Posts and Telecommunications | Chen J.,Engineering School of Information Technology and Communication | Guo H.,Engineering School of Information Technology and Communication
Optics Letters | Year: 2015

We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope 87Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope 87Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications. © 2015 Optical Society of America.


Huang X.,Beijing University of Posts and Telecommunications | Ma H.,Beijing University of Posts and Telecommunications
Proceedings - International Conference on Pattern Recognition | Year: 2010

Video scene text contains semantic information and thus can contribute significantly to video indexing and summarization. However, most of the previous approaches to detecting scene text from videos experience difficulties in handling texts with various character size and text alignments. In this paper, we propose a novel algorithm of scene text detection and localization in video. Based on our observation that text character strokes show intensive edge details in the fixed orientation no matter what text alignment and size are, a stroke map is first generated. In the scene text detection, we extract the texture feature of stroke map to locate text lines. The detected scene text lines are accurately located by using Harris' corners in the stroke map. Experimental results show that this approach is robust and can be effectively applied to scene text detection and localization in video. © 2010 IEEE.


Wu Y.,Beijing University of Posts and Telecommunications | Yan X.,Beijing University of Posts and Telecommunications | Zhang X.,Beijing University of Posts and Telecommunications | Ren X.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2015

An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays. © 2015 Optical Society of America.


Wang T.-J.,Beijing University of Posts and Telecommunications | Wang C.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2015

We illustrate an entanglement distillation protocol (EDP) for a mixed photon-ensemble which composed of four kinds of entangled states and vacuum states. Exploiting the linear optics and local entanglement resource (four-qubit entangled GHZ state), we design the nondemolition parity-checking and qubit amplifying (PCQA) setup for photonic polarization degree of freedom which are the key device of our scheme. With the PCQA setup, a high-fidelity entangled photon-pair system can be achieved against the transmission losses and the decoherence in noisy channels. And in the available purification range for our EDP, the fidelity of this ensemble can be improved to the maximal value through iterated operations. Compared to the conventional entanglement purification schemes, our scheme largely reduces the initialization requirement of the distilled mixed quantum system, and overcomes the difficulties posed by inherent channel losses during photon transmission. All these advantages make this scheme more useful in the practical applications of long-distance quantum communication. © 2015 Optical Society of America.


Zou C.,Beijing University of Posts and Telecommunications | Lu Y.,Beijing University of Posts and Telecommunications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

As consistent time scale is essential to facilitate group operations and improve network performance, time synchronization is regard as a critical piece of infrastructure for distributed network measurement and control systems, especially for wireless sensor networks (WSNs). However, existing time synchronization algorithms for WSNs either do not provide enough scalability to achieve compatibility with other sync protocols, or do not fully take into account the characteristics of WSNs. This paper proposes a time synchronization method (TSM) to achieve precise time synchronization and reach the frequency drift compensation in WSNs at the same time. Evaluations show that TSM synchronizes wireless sensor nodes precisely with a magnitude of microsecond. Moreover, it has a good performance of stability and energy efficient. © 2012 Springer-Verlag.


Qi X.,Beijing University of Posts and Telecommunications | Xiao R.,Microsoft | Guo J.,Beijing University of Posts and Telecommunications | Zhang L.,Microsoft
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

In this work, we introduce a novel pairwise rotation invariant co-occurrence local binary pattern (PRI-CoLBP) feature which incorporates two types of context - spatial co-occurrence and orientation co-occurrence. Different from traditional rotation invariant local features, pairwise rotation invariant co-occurrence features preserve relative angle between the orientations of individual features. The relative angle depicts the local curvature information, which is discriminative and rotation invariant. Experimental results on the CUReT, Brodatz, KTH-TIPS texture dataset, Flickr Material dataset, and Oxford 102 Flower dataset further demonstrate the superior performance of the proposed feature on texture classification, material recognition and flower recognition tasks. © 2012 Springer-Verlag.


Zhou J.,Shanghai JiaoTong University | Cao Z.,Harbin Institute of Technology | Dong X.,Harbin Institute of Technology | Lin X.,Beijing University of Posts and Telecommunications | Vasilakos A.,National Technical University of Athens
IEEE Wireless Communications | Year: 2013

M-healthcare mobile social network has emerged as a promising next-generation healthcare system increasingly adopted by the US and European governments, with the rapid development of sensor and wireless communication technologies. In this paper, we describe the goals and tactics, and present a distributed architecture of m-healthcare social networks. Following each kind of security and privacy challenge, we define a series of basic and sophisticated cyber attacks and give substantial and promising solutions to satisfy the unique security and privacy requirements in m-healthcare social networks. Last but not least, several interesting open problems are pointed out with possible addressing ideas to trigger more research efforts in this emerging area. © 2002-2012 IEEE.


Li S.,Beijing University of Posts and Telecommunications | Li S.,Shandong Institute of Business and Technology | Li L.,Shandong Institute of Business and Technology | Yang Y.,Beijing University of Posts and Telecommunications | Luo Q.,Beijing University of Posts and Telecommunications
Nonlinear Dynamics | Year: 2012

In this paper, concerned with the highestload attack (HL) and random attack (RA) on one edge or one node, we model the cascading dynamics in scale-free networks (SF), WS small-world networks (WS) and ER random networks (ER). How long the cascade propagation in networks will persist and what features the avalanche edges or nodes at each time step will show in cascading failures are questions investigated. We find that, under both HL and RA attack, the persistent time of cascade propagation in SF networks is always longer than in ER and WS networks (except p = 0.1). Under HL attack, there exists a threshold α c of tolerance parameter a making the cascading propagation in SF and WS networks longest-running. Moreover, under HL attack, the avalanche edges and nodes in WS and ER networks always reach a peak over a period of time, while the SF network shows similar characteristics only in some field of a. However, under RA attack, in the case of big a, most of the avalanche edges and nodes in SF, WS and ER networks always occur at the beginning of the cascading failures. Fur- thermore, under node-targeted attack, SF shows to be more vulnerable than under edge-targeted attack and most of avalanche nodes occur at the beginning of failures. The results remind us to grasp the rhythm of controlling disasters according to the features of cascading failures in different networks. © Springer Science+Business Media B.V. 2011.


Sun F.,Beijing University of Posts and Telecommunications | Peng H.,Beijing University of Posts and Telecommunications | Xiao J.,Beijing University of Posts and Telecommunications | Yang Y.,Beijing University of Posts and Telecommunications
Nonlinear Dynamics | Year: 2012

We explore a process for identifying the topology of networks. We find that it is possible to estimate the accurate topological structure of synchronous networks by analyzing their transient processes. Some novel conditions are given to ensure the uncertain connection topology approach to the true value. Our examples further illustrate the feasibility of these proposed methods. © 2011 Springer Science+Business Media B.V.


Yuan Y.,Beijing University of Posts and Telecommunications | Han Q.,Beijing University of Posts and Telecommunications
Chinese Journal of Electronics | Year: 2012

This paper presents a method which applies software trustworthiness measures to the dynamic behavior feature datasets generated at software running time compared with the static attribute feature datasets generated at software testing time in order to make recommendations for users in services selection time under the environment of SaaS. The measurement method is carried out in three stages: firstly, defining the concept of trust, software trustworthiness, static and dynamic feature datasets with fundamental calculating criteria; secondly, providing a group of formulas to illustrate congruence measurement approach for comparing the two types of feature datasets; lastly, giving the trustworthiness concept hierarchies to evaluate software trustworthiness.


Shi D.,Beijing University of Posts and Telecommunications
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2011

Shielding effectiveness of enclosure with off-center aperture is investigated by using analytical method. Through modeling the shielding and propagation characteristic of enclosure with high order mode equivalent transmission line, the shielding effectiveness of enclosure with aperture is formulated when plane wave is incident with arbitrary incident angle and polarization direction. Relationship between shielding effectiveness and incident angle, polarization direction, aperture size, loss of enclosure wall, test point location and frequency are investigated. The result is verified by enclosure resonant theory. This analytical method with higher speed is suitable for parameter analysis and valuable for shielding enclosure design. © 2011 by Editorial Department of Chinese Journal of Radio Science.


Wang W.,Beijing University of Posts and Telecommunications | Wang W.,Zhejiang University | Wang W.,University of Michigan | Yu G.,Zhejiang University | And 3 more authors.
IEEE Communications Magazine | Year: 2013

Adopting small cells, including femtocells, is a promising evolution of future wireless cellular systems to meet the explosive demand for high data rates. As the number of distributively deployed femtocell access points increases rapidly, interference coordination becomes the primary challenge in such heterogeneous networks. In this article, we apply several cognitive radio inspired approaches to enhance the interference coordination for femtocell networks. First, we apply spectrum sensing and statistical analysis to estimate the cross-tier interference between macrocells and femtocells. Based on this, interference coordination is investigated considering two kinds of spectrum sharing approaches. Finally, we introduce a cognitive relay scheme to improve interference coordination performance further. © 2013 IEEE.


Gao J.,Beijing University of Posts and Telecommunications | Xie G.,Beijing University of Posts and Telecommunications
Chinese Journal of Electronics | Year: 2012

Dust contamination is one of the major causes of electrical contact failure in the electronic system. This paper describes the characteristics of electric charges carried by dust particles and their effects on connector failure. A Millikan testing method was used for measuring the electric charges. The results show that the variation of electric charges carried by dust particles is located in a band region, and the trend of charges can be expressed as a third order equation. The morphology and surface seem to be the major factors which influence the electric charge. It is found that dust particles carry negative charges or positive charges, these particles will be attracted to both electric contact surfaces in connector respectively, and thereby increasing the probability of connector failure. The selective deposition of particles was found on electric contact surface. The failed connectors were investigated by using SEM/EDS (Scanning electron microscope and Energy dispersive X-ray spectroscopy) and protection from dust particles was recommended.


Lu X.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications | Qi F.H.,Beijing University of Posts and Telecommunications
Nonlinear Analysis: Real World Applications | Year: 2012

The Kortewegde Vries (KdV)-type models are of significance in describing many physical situations in fluid flows (particularly for surface and internal waves), plasma physics, and solid state physics. In fluid dynamics, for example, the shallow water wave equation is utilized as a mathematical description of regular and generalized solitary waves in shallow water. Further, higher-order dispersive (e.g., the Lax fifth-order KdV equation) and higher-dimensional [e.g., the (2+1)- and (3+1)-dimensional breaking soliton equations] generalized nonlinear models are useful in analyzing and obtaining modulation theory, existence and stability of solitary waves, bores, and shocks, as well as other integrable properties. With symbolic computation, Bell-polynomial-typed Bäcklund transformations (BTs) are constructed for some single-field bilinearizable nonlinear evolution equations including the shallow water wave equation, Lax fifth-order KdV equation, and (2+1)- and (3+1)-dimensional breaking soliton equations. Bell-polynomial expressions are derived, which can be cast into the bilinear equations with one Tau-function. Key point lies in the introduction of certain auxiliary independent variable in the Bell-polynomial expression. With one auxiliary independent variable, the Bell-polynomial-typed BTs are then constructed according to the coupled two-field conditions between the primary and replica fields with both the fields satisfying the Bell-polynomial-expression equations. Auxiliary-independent-variable-involved Bell-polynomial-typed BTs are changed into their bilinear forms. Aforementioned equations turn out to be integrable in the sense of possessing the Bell-polynomial-typed BTs. © 2011 Elsevier Ltd. All rights reserved.


Jia H.,Beijing University of Posts and Telecommunications
Sensors and Transducers | Year: 2014

Limited display space of mobile devices is inadequate for simultaneous display of all the information needed in context. Practical guidelines for how to tailor information remain a longstanding challenge for mobile human-computer interaction (MHCI) optimization. With the help of RFID, GPS and sensors, mobile devices can perceive context of themselves. In this paper, principles of MHCI optimization for field mobile devices (FMD) from the perspective of distributed cognition theory and context-awareness technology is explored. Context factors which are perceived by FMD sensor networks and analyzed, based on which, we concluded the practical guidelines which are easy for people to implement MHCI optimization. We confirm the effectiveness of the guidelines by optimizing MHCI of FMD for a storage management system and illustrate how to utilize these design principles to support FMD HCI optimization and verify the effectiveness. At last we reassure the user experience with user experience testing for five dimensions of learnability, memorability, efficiency, error prevention and satisfaction. © 2014 IFSA Publishing, S. L.


Liu J.,Beijing University of Posts and Telecommunications | Ansari N.,New Jersey Institute of Technology
Computer Communications | Year: 2014

With the rapid development of mobile devices and wireless technologies, mobile internet websites play an essential role for delivering networked services in our daily life. Thus, identifying website communities in mobile internet is of theoretical and practical significance in optimizing network resource and improving user experience. Existing solutions are, however, limited to retrieve website communities based on hyperlink structure and content similarities. The relationships between user behaviors and community structures are far from being understood. In this paper, we develop a three-step algorithm to extract communities by affinity measurement derived from user accessing information. Through experimental evaluation with massive detailed HTTP traffic records captured from a cellular core network by high performance monitoring devices, we show that our affinity measurement based method is effective in identifying hidden website communities in mobile internet, which have evaded previous link-based and content-based approaches. © 2014 Elsevier B.V. All rights reserved.


Guo Y.,Beijing University of Posts and Telecommunications | Joshi J.B.D.,University of Pittsburgh
HT'10 - Proceedings of the 21st ACM Conference on Hypertext and Hypermedia | Year: 2010

Collaborative tagging has become a very popular way to share, annotate, and discover online resources in Web 2.0. Yet as the number of resources in Collaborative tagging system grows over time, sifting through the large amounts of resources and finding the right resources to recommend to the right user is becoming a challenging problem. In this paper, we investigate a probabilistic generative model for collaborative tagging, explore the implicit semantic connections in the sparse and noisy information space of heterogeneous users and unsupervised tagging. First, a modified Latent Dirichlet Allocation (LDA) model is used to cluster the tags and users simultaneously. The generalization of resource description and user could alleviate the tag noise and data sparseness of recommendation effectively. And then, considering that topic-based recommendation only takes the users' global interest into consideration without the capability of distinguishing users' interest in detail, we combine the global interests with the individual interest and community interest. Experimental results demonstrate the topicbased personalized recommendation method, which integrate both the commonality factor among users and the specialties of individuals, could alleviate data sparsity and provide a more flexible and effective recommendation than previous methods. Copyright 2010 ACM.


Jiang Y.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications
EPL | Year: 2013

In this letter, dark and dark-like-bright solitons will be investigated for a higher-order nonlinear Schrödinger equation with such higher-order effects as the third-order dispersion (TOD), self-steepening (SS) and self-frequency shift, for the ultrashort pulses in the subpicosecond or femtosecond regime. Via the Hirota method and symbolic computation, the bilinear forms are obtained, while the dark single-hump, dark double-hump and dark-like-bright soliton solutions are constructed. Parametric regions for the existence of the three types of solitons are related to the TOD and SS coefficients. When the TOD and SS coefficients change, the amplitudes of the dark single-hump, dark-like-bright solitons and the interval between the two peaks of a dark double-hump soliton will change, while the amplitude of the dark double-hump soliton will be invariant. Through the asymptotic analysis, we prove that the two-soliton interactions are elastic. With the group-velocity-dispersion coefficient changing, the type of the solitons and interactions may change, e.g., from the overtaking interaction to the head-on one. With the TOD and SS coefficients changing, interactions can be seen between i) two dark single-hump solitons, ii) two dark double-hump solitons, iii) one dark single-hump and one dark double-hump solitons, and iv) two dark-like-bright solitons. © Copyright EPLA, 2013.


Zhu Y.-Y.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications
Communications in Theoretical Physics | Year: 2013

Quantum correlations measured by quantum discord (QD), measurement-induced distance (MID), and geometric measure of quantum discord (GMQD) in two-qubit Heisenberg XY spin chain are investigated. The effects of DM interaction and anisotropic on the three correlations are considered. Characteristics of various correlation measures for the two-qubit states are compared. The increasing Dz increases QD, MID and GMQD monotonously while the increasing anisotropy both increases and decreases QD and GMQD. The three quantum correlations are always existent at very high temperature. MID is always larger than QD, but there is no definite ordering between QD and GMQD. © 2013 Chinese Physical Society and IOP Publishing Ltd.


Wu Y.,Beijing University of Posts and Telecommunications | Liu Y.,Beijing University of Posts and Telecommunications
Journal of Electromagnetic Waves and Applications | Year: 2012

A new coupled-line circuit structure is proposed to design compact wideband Gysel power dividers with function of impedance matching between source and load. Based on traditional even- and odd-mode technique, closed-form equations are obtained for direct and accurate synthesis. By applying coupled lines and reducing their electrical lengths, this novel Gysel power divider has four main advantages: high power-handling capability, small size, enhanced bandwidth, and source-to-load impedance matching. The measured bandwidth (|Sii| i=1,2,3 & |S23|< - 15 dB) of the fabricated Gysel power divider operating at 2 GHz is 62.6%, while the traditional one is 40.8%. Meanwhile, the size of this novel Gysel power divider is only 25.5% of the traditional one when the same substrate is used and the same operating band is considered. © 2012 Taylor & Francis.


Li X.,Fudan University | Dong Z.,Zte United States Inc. | Yu J.,Fudan University | Yu J.,ZTE Corporation | And 2 more authors.
Optics Express | Year: 2013

We experimentally demonstrate heterodyne coherent detection of 8 × 112-Gb/s ultra-density wavelength-division-multiplexing (WDM) polarization-division-multiplexing quadrature-phase-shift-keying (PDMQPSK) signal after 1120-km single-mode fiber-28 (SMF-28) transmission. The spectral efficiency (SE) is 4b/s/Hz. It is the first time to realize WDM signal transmission with high SE by adopting heterodyne coherent detection. At the heterodyne coherent receiver, intermediate frequency (IF) down conversion is realized in digital frequency domain after analog-todigital conversion. A digital post filter and 1-bit maximum likelihood sequence estimation (MLSE) adopted after carrier phase estimation (CPE) in the conventional digital-signal-processing (DSP) process is used to suppress the enhanced noise and crosstalk as well as overcome the filtering effects. The bit-error ratio (BER) for all channels is under the forwarderror-correction (FEC) limit of 3.8 × 10-3 after 1120-km SMF-28 transmission. © 2013 Optical Society of America.


Wang Z.,Beijing University of Posts and Telecommunications | Qiao Y.,Beijing University of Posts and Telecommunications | Xu Y.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2013

We show for the first time through comprehensive simulations under both uncompensated transmission (UT) and dispersion managed transmission (DMT) systems that the statistical distribution of the nonlinear interference (NLI) within the polarization multiplexed 16-state quadrature amplitude modulation (PM-16QAM) Coherent Optical OFDM (CO-OFDM) system deviates from Gaussian distribution in the absence of amplified spontaneous emission (ASE) noise. We also observe that the dependences of the variance of the NLI noise on both the launch power and the transmission distance (logrithm) seem to be in a simple linear way. © 2013 Optical Society of America.


Cao C.,Beijing University of Posts and Telecommunications | Wang C.,Beijing University of Posts and Telecommunications | He L.-Y.,Beijing University of Posts and Telecommunications | Zhang R.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2013

We investigate an atomic entanglement purification protocol based on the coherent state input-output process by working in low-Q cavity in the atom-cavity intermediate coupling region. The information of entangled states are encoded in three-level configured single atoms confined in separated one-side optical micro-cavities. Using the coherent state input-output process, we design a two-qubit parity check module (PCM), which allows the quantum nondemolition measurement for the atomic qubits, and show its use for remote parities to distill a high-fidelity atomic entangled ensemble from an initial mixed state ensemble nonlocally. The proposed scheme can further be used for unknown atomic states entanglement concentration. Also by exploiting the PCM, we describe a modified scheme for atomic entanglement concentration by introducing ancillary single atoms. As the coherent state input-output process is robust and scalable in realistic applications, and the detection in the PCM is based on the intensity of outgoing coherent state, the present protocols may be widely used in large-scaled and solid-based quantum repeater and quantum information processing. © 2013 Optical Society of America.


Li Y.,Chinese People's Liberation Army | Wen Q.,Beijing University of Posts and Telecommunications | Zhang B.,Chinese People's Liberation Army
Nonlinear Dynamics | Year: 2012

Chaotic ant swarm optimization (CASO) is a powerful chaos search algorithm for optimization problems, but it is often easy to be premature convergence. To overcome the weakness, this paper presents a CASO with passive congregation (CASOPC). Passive congregation is one type of biological information sharing mechanisms that allow animals to aggregate into groups and help to enhance the exploitation of animals. By introducing passive congregation strategy into the CASO, a modified evolution equation based on the CASO is proposed in the CASOPC. The modified evolution equation cannot only employ the parallel search of all ants and the well exploration ability of the CASO, but also stress and control the exploitation by passive congregation coefficient c in the stage of evolution. Due to linearly increasing c in the CASOPC, the exploration and exploitation ability of ants are well balanced so that premature convergence can be avoided and good performance can be achieved. In order to estimate the capability of the CASOPC, it is tested with a set of 5 benchmark functions with 30 dimensions and compared to the CASO. Experimental results indicate that the CASOPC improves the search performance on the benchmark functions significantly. © 2011 Springer Science+Business Media B.V.


Gao Y.,Beijing University of Posts and Telecommunications | Jiang Y.,Norwegian University of Science and Technology
IEICE Transactions on Communications | Year: 2012

In this paper, performance analysis of a cognitive radio network is conducted. In the network, there is imperfect sensing and the wireless channel is a Gilbert-Elliott channel. The focus is on the network's capacity in serving traffic with delay constraints. Specifically, the maximum traffic arrival rates of both primary users and secondary users, which the network can support with guaranteed delay bounds, are investigated. The analysis is based on stochastic network calculus. A general relationship between delay bounds, traffic patterns and important characteristics such as spectrum sensing errors and channel fading of the cognitive radio network is derived. This relationship lays a foundation for finding the capacity under different traffic scenarios. Two specific traffic types are exemplified, namely periodic traffic and Poisson traffic. Analytical results are presented in comparison with simulation results. The comparison shows a good match between them, validating the analysis. © 2012 The Institute of Electronics, Information and Communication Engineers.


Zhang Y.,Beijing University of Posts and Telecommunications | Chen J.-L.,Beijing University of Posts and Telecommunications
Proceedings - 32nd IEEE International Conference on Distributed Computing Systems Workshops, ICDCSW 2012 | Year: 2012

With the rapid application of service-oriented technologies, service and data outsourcing has become a practical and useful computing paradigm. Combined use of access control and cryptography was proposed by many researchers to protect sensitive information in this outsourcing scenario. However, the rigid combination in existing approaches has difficulty in satisfying the flexibility requirement of access control for diverse applications. In this paper, we propose an access control service for public cloud storage, where authorization is controlled by the data owner, and the PDP (Policy Decision Point) and PEP (Policy Enforcement Point) can be securely delegated. In order to implement the service, an attribute-full proxy re-encryption scheme is presented as its corner stone. The other features of our service are as follows: simple key management without the need of key derivation for users to decrypt cipher texts, composing attributes for accessing resources with subject attributes' having inner structures, and authorization relatively separating from encryption. We also give some proofs and analysis of our implementation. © 2012 IEEE.


The rapid growth of visualization technologies and Cloud computing have opened a new paradigm for utilizing the existing resource pools for on-demand and scalable computing, which enables the workflow management system to meet quality-of-service (QoS) requirements of the applications. It becomes crucial for cloud customers to choose the best Cloud services in order to minimize the running costs, and how to match and select the optimum cloud service will be a challenge problem. In this paper, we present an efficient Cloud services workflow scheduling and optimization schema using heuristic generic algorithm, and focus on the hierarchical Cloud service workflow scheduling, Cloud workflow tasks parallel split, syntax and semantic based Cloud workflow tasks matching algorithm, and multiple QoS constraints based Cloud workflow scheduling and optimization, and also presents the experiment conducted to evaluate the efficiency of our algorithm.


Liao J.,Beijing University of Posts and Telecommunications | Wang J.,Beijing University of Posts and Telecommunications | Wu B.,China Mobile | Wu W.,China Mobile
IEEE Communications Magazine | Year: 2012

The next generation service overlay network will enable the provision of pervasive services over a common IP-based transport infrastructure. However, along with the service consolidation over IP and the rapid increase of network scale, the task of service and network management has become extremely complex and disordered. Efforts are being made in various areas, such as SOA, web services, IMS, P2P/CDN overlay, and cloud computing, to achieve a scalable, secure, converged, and selfmanaged service network framework to shorten the time to market of new services, as well as lower the management costs of network/service providers. Nevertheless, these technologies are not developed in a coordinated manner for optimal scalability, resource utilization, and QoS performance. In this article, we propose a multiplane framework (MPF) for NGSON based on the integration of service composition, management, and delivery, which is a top-down reference model to achieve pervasive services and efficient resource utilization. © 2012 IEEE.


Song Z.,Beijing University of Posts and Telecommunications
Frontiers of Electrical and Electronic Engineering in China | Year: 2010

A novel adaptive cooperative medium access control (MAC) protocol, which is completely backward compatible with the legacy IEEE 802. 11 distributed coordination function (DCF), is proposed in this paper. To adapt to dynamic channel variation and network topology, the sender adaptively selects transmission scheme based on the instantaneous channel measurements. Analytical and simulation results show that the proposed protocol outperforms the existing one in terms of throughput, delay, energy and mobility. © 2010 Higher Education Press and Springer-Verlag Berlin Heidelberg.


Zhang G.,CAS Institute of Microelectronics | Zuo X.,Beijing University of Posts and Telecommunications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

Public cloud providers provide Infrastructure as a Service (IaaS) to remote users. For IaaS providers, how to schedule tasks to meet peak demand is a big challenge. Previous researches proposed purchasing machines in advance or building cloud federation to resolve this problem. However, the former is not economic and the latter is hard to be put into practice at present. In this paper, we propose a hybrid cloud architecture, in which an IaaS provider can outsource its tasks to External Clouds (ECs) without establishing any agreement or standard when its local resources are not sufficient. The key issue is how to allocate users' tasks to maximize its profit while guarantee QoS. The problem is formulated as a Deadline Constrained Task Scheduling (DCTS) problem which is resolved by standard particle swarm optimization (PSO), and compared with an exact approach (CPLEX). Experiment results show that Standard-PSO is very effective for this problem. © 2013 Springer-Verlag Berlin Heidelberg.


Li A.,University of Melbourne | Al Amin A.,University of Melbourne | Chen X.,University of Melbourne | Chen S.,University of Melbourne | And 3 more authors.
Journal of Lightwave Technology | Year: 2012

We demonstrate the use of mechanical grating based mode converters to achieve two forms of dual-spatial-mode transmission: LP 01 and LP 11, and dual LP 11 modes. High modal extinction ratio (> 20 dB) is shown for the mode converter within a 10-nm wavelength range. We first present 107-Gb/s coherent optical OFDM (CO-OFDM) transmission over a 4.5-km two-mode fiber using LP 01 and LP 11 modes where the mode separation is performed optically. We then show 58.8-Gb/s CO-OFDM transmission using dual LP 11 modes where the mode separation is achieved via 4 × 4 electronic MIMO processing. © 2006 IEEE.


Liu H.-L.,Chongqing University of Posts and Telecommunications | Zhang B.,Beijing University of Posts and Telecommunications | Shi S.-L.,Chongqing University of Posts and Telecommunications
Journal of Lightwave Technology | Year: 2012

Wavelength conversion is an efficient way to improve the optical packet blocking performance for all-optical packet switching networks. The synchronous OPS node architecture, with a hybrid shared wavelength conversion (HSWC) scheme based on shared per output fiber and shared per node wavelength conversion, is put forward to reduce the packet loss probability in this paper. A heuristics is developed into assigning the wavelength channels for packets in the proposed optical nodes. The limited range wavelength converters first available (LFA) algorithm and parametric wavelength converters first available (PFA) algorithm are used to schedule contending optical packets to available wavelength channels. Simulation results show that the hybrid shared wavelength conversion scheme has significant performance improvement in terms of packet loss probability. And the utilization of wavelength converter is greatly improved for OPS node with hybrid shared wavelength conversion scheme. Furthermore, the PFA scheduling algorithm compared with LFA algorithm is validated to improve the wavelength assignment efficiency and reduce the required total wavelength converters for OPS nodes. © 2006 IEEE.


Zhang W.,Beijing University of Posts and Telecommunications | Zhang W.,Columbia University | Wang H.,Columbia University | Bergman K.,Columbia University
Journal of Lightwave Technology | Year: 2012

The communication requirements imposed by the unabated growth in both the size and computational density of modern data centers will soon outpace the fundamental capabilities of conventional electronic interconnection networks. Optical interconnects represent a potentially disruptive technology that can simultaneously satisfy the throughput, latency, and energy demands of these next-generation systems. In this paper, we propose an end-to-end photonic networking platform for future optically-interconnected data center networks. A reconfigurable hybrid photonic network building block and a protocol-agnostic optical network interface comprise the key elements of our proposed system. A modular optical switch fabric prototyping platform is designed and implemented to support a wide variety of potential photonic technologies. We successfully demonstrate nanosecond-scale optical packet-switching at 1-Tb/s per port (40-Gb/s ×25λs) through our prototype, configured as a 4×4 switch, and confirm error-free transmission across all wavelengths. In order to flexibly allocate appropriate bandwidth for heterogeneous applications, we further implement and evaluate a novel wavelength-reconfigurable optical packet-and circuit-switch by utilizing our optical switch platform. Finally, we detail our implementation of an optical network interface card (O-NIC) designed to bridge the gap between the well-established protocol layers utilized in current networks and the physical layer of the proposed photonic networks and demonstrate its functionality by the streaming of high-definition video through the end-to-end optical network. © 2012 IEEE.


Li A.,University of Melbourne | Chen X.,University of Melbourne | Gao G.,University of Melbourne | Gao G.,Beijing University of Posts and Telecommunications | Shieh W.,University of Melbourne
Journal of Lightwave Technology | Year: 2012

Conventional coherent optical orthogonal frequency-division multiplexed (CO-OFDM) system has inferior nonlinear tolerance due to high peak-to-average power ratio (PAPR). Discrete Fourier transform spread OFDM (DFTS-OFDM) has recently been proposed as a promising candidate that possesses similar spectral characteristics as conventional CO-OFDM, but has much better nonlinear tolerance. We demonstrate experimentally the transmission of 1.0 Tb/s unique-word DFTS-OFDM superchannel signal over 8000 km standard single-mode fiber with 80 km span engineering and erbium-doped fiber amplification (EDFA) using quadrature phase shift keying (QPSK) modulation, representing a record spectral efficiency and reach product in transmission systems compatible with most of the deployed links. © 2012 IEEE.


Zuo X.,Beijing University of Posts and Telecommunications | Xiao L.,Beijing University of Posts and Telecommunications
Soft Computing | Year: 2014

Many real world optimization problems are dynamic in which the fitness landscape is time dependent and the optima change over time. Such problems challenge traditional optimization algorithms. For such problems, optimization algorithms not only have to find the global optimum but also need to closely track its trajectory. In this paper, a new hybrid algorithm integrating a differential evolution (DE) and a particle swarm optimization (PSO) is proposed for dynamic optimization problems. Multi-population strategy is adopted to enhance the diversity and try to keep each subpopulation on a different peak in the fitness landscape. A hybrid operator combining DE and PSO is designed, in which each individual is sequentially carried out DE and PSO operations. An exclusion scheme is proposed that integrates the distance based exclusion scheme with the hill-valley function to track the adjacent peaks. The algorithm is applied to the set of benchmark functions used in CEC 2009 competition for dynamic environment. Experimental results show that it is more effective in terms of overall performance than other comparative algorithms. © 2013 Springer-Verlag Berlin Heidelberg.


Wang T.-Y.,Beijing University of Posts and Telecommunications | Wang T.-Y.,Luoyang Normal University | Wen Q.-Y.,Beijing University of Posts and Telecommunications | Zhu F.-C.,National Laboratory for Modern Communications
Optics Communications | Year: 2011

The security of multiparty quantum secret sharing with Bell states and Bell measurements [R.H. Shi et al., Opt. Commun. 283 (2010) 2476] is analyzed. It is shown that the first agent and the last one can gain access to the dealer's secret if they collaborate in this protocol. Therefore, this protocol does not satisfy the security requirement of quantum secret sharing. © 2010 Elsevier B.V. All rights reserved.


Liu W.-J.,Beijing University of Posts and Telecommunications | Lei M.,Beijing University of Posts and Telecommunications
Nonlinear Dynamics | Year: 2014

With symbolic computation and Hirota method, analytic two-soliton solutions for the coupled nonlinear Schrödinger (CNLS) equations, which describe the propagation of spatial solitons in an AlGaAs slab waveguide, are derived. Two types of coefficient constraints of the CNLS equations to distinguish the elastic and inelastic interactions between spatial solitons are obtained for the first time in this paper. Asymptotic analysis is made to investigate the spatial soliton interactions. The inelastic interactions are studied under the obtained coefficient constraints of the CNLS equations. The influences of parameters for the obtained soliton solutions are discussed. All-optical switching and soliton amplification are studied based on the dynamic properties of inelastic interactions between spatial solitons. Numerical simulations are in good agreement with the analytic results. The presented results have applications in the design of birefringence-managed switching architecture. © 2014 Springer Science+Business Media Dordrecht.


Jia H.-Y.,Beijing University of Posts and Telecommunications | Jia H.-Y.,Xidian University | Wen Q.-Y.,Beijing University of Posts and Telecommunications | Song T.-T.,Beijing University of Posts and Telecommunications | Gao F.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2011

We present a quantum protocol for the solution of a two-party comparison task with the help of a semi-honest third party, which can be used to solve the millionaire problem. The secrets are coded into the phases of d-level entangled states by local operations and read by the third party's collective measurements. The two parties can deduce the results of comparisons based on the secret bits shared between them beforehand and the announcement of the third party. Moreover, others will learn no information of the comparison results, even the third party. Our scheme is private and fair, and the security has also been discussed. © 2010 Elsevier B.V. All rights reserved.


Deng W.,Beijing University of Posts and Telecommunications | Hu J.,Beijing University of Posts and Telecommunications | Guo J.,Beijing University of Posts and Telecommunications | Cai W.,University of Sydney | Feng D.,University of Sydney
Pattern Recognition | Year: 2010

Current face recognition techniques rely heavily on the large size and representativeness of the training sets, and most methods suffer degraded performance or fail to work if there is only one training sample per person available. This so-called "one sample problem" is a challenging issue in face recognition. In this paper, we propose a novel feature extraction method named uniform pursuit to address the one sample problem. The underlying idea is that most recognition errors are due to the confusions between faces that look very similar, and thus one can reduce the risk of recognition error by mapping the close class prototypes to be distant, i.e., uniforming the pairwise distances between different class prototypes. Specifically, the UP method pursues, in the whitened PCA space, the low dimensional projections that reduce the local confusion between the similar faces. The resulting low dimensional transformed features are robust against the complex image variations such as those caused by lighting and aging. A standardized procedure on the large-scale FERET and FRGC databases is applied to evaluate the one sample problem. Experimental results show that the robustness, accuracy and efficiency of the proposed UP method compare favorably to the state-of-the-art one sample based methods. © 2009 Elsevier Ltd. All rights reserved.


Tian Y.,Beijing University of Posts and Telecommunications | Liu X.,Beijing University of Posts and Telecommunications
Mathematical Methods in the Applied Sciences | Year: 2014

In this paper, we study Sturm-Liouville boundary-value problem for fourth-order impulsive differential equations. Applying variational methods, several new existence results are obtained. Copyright © 2013 John Wiley & Sons, Ltd.


Wang J.,Beijing University of Posts and Telecommunications | Liao J.,Beijing University of Posts and Telecommunications | Li T.,Technical University of Madrid
Journal of Network and Computer Applications | Year: 2012

One major problem of concurrent multi-path transfer (CMT) scheme in multi-homed mobile networks is that the utilization of different paths with diverse delays may cause packet reordering among packets of the same flow. In the case of TCP-like, the reordering exacerbates the problem by bringing more timeouts and unnecessary retransmissions, which eventually degrades the throughput of connections considerably. To address this issue, we first propose an Out-of-order Scheduling for In-order Arriving (OSIA), which exploits the sending time discrepancy to preserve the in-order packet arrival. Then, we formulate the optimal traffic scheduling as a constrained optimization problem and derive its closed-form solution by our proposed progressive water-filling solution. We also present an implementation to enforce the optimal scheduling scheme using cascaded leaky buckets with multiple faucets, which provides simple guidelines on maximizing the utilization of aggregate bandwidth while decreasing the probability of triggering 3 dupACKs. Compared with previous work, the proposed scheme has lower computation complexity and can also provide the possibility for dynamic network adaptability and finer-grain load balancing. Simulation results show that our scheme significantly alleviates reordering and enhances transmission performance. © 2011 Elsevier Ltd. All rights reserved.


Yin S.,Beijing University of Posts and Telecommunications | Chen D.,Hong Kong University of Science and Technology | Zhang Q.,Hong Kong University of Science and Technology | Li S.,Beijing University of Posts and Telecommunications
IEEE Transactions on Vehicular Technology | Year: 2011

Cognitive radio (CR) for dynamic spectrum sensing and access has been a hot research topic in recent years. To avoid collision with the primary users, secondary users need to sense the channels before transmitting on them, which is referred to as sensing time overhead. Our previous work shows that the spectral correlations between the channels within the same service are sufficiently high for accurate prediction, which can further be used to reduce the sensing time. With such motivation, in this paper, we propose a new definition, i.e., channel availability vector (CAV), to characterize the state information of a group of licensed channels by introducing spectrum prediction while focusing on the scenario of a single secondary user with multiple channels and leverage it by formulating the throughput optimization problem as a Markov decision process, which is further solved by our optimal sensing scheme and verified with the real spectrum measurement data. The results show that our prediction-based sensing scheme outperforms one existing work. © 2011 IEEE.


Sheng Z.,Orange S.A. | Yang S.,Orange S.A. | Yu Y.,Imperial College London | Vasilakos A.,Beijing University of Posts and Telecommunications | And 2 more authors.
IEEE Wireless Communications | Year: 2013

Technologies to support the Internet of Things are becoming more important as the need to better understand our environments and make them smart increases. As a result it is predicted that intelligent devices and networks, such as WSNs, will not be isolated, but connected and integrated, composing computer networks. So far, the IP-based Internet is the largest network in the world; therefore, there are great strides to connect WSNs with the Internet. To this end, the IETF has developed a suite of protocols and open standards for accessing applications and services for wireless resource constrained networks. However, many open challenges remain, mostly due to the complex deployment characteristics of such systems and the stringent requirements imposed by various services wishing to make use of such complex systems. Thus, it becomes critically important to study how the current approaches to standardization in this area can be improved, and at the same time better understand the opportunities for the research community to contribute to the IoT field. To this end, this article presents an overview of current standards and research activities in both industry and academia. © 2013 IEEE.


Zhen H.-L.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications | Wang Y.-F.,Beijing University of Posts and Telecommunications | Liu D.-Y.,Beijing University of Posts and Telecommunications
Physics of Plasmas | Year: 2015

For the interaction between the high-frequency Langmuir waves and low-frequency ion-acoustic waves in the plasma, the Zakharov equations are studied in this paper. Via the Hirota method, we obtain the soliton solutions, based on which the soliton propagation is presented. It is found that with λ increasing, the amplitude of u decreases, whereas that of v remains unchanged, where λ is the ion-acoustic speed, u is the slowly-varying envelope of the Langmuir wave, and v is the fluctuation of the equilibrium ion density. Both the head-on and bound-state interactions between the two solitons are displayed. We observe that with λ decreasing, the interaction period of u decreases, while that of v keeps unchanged. It is found that the Zakharov equations cannot admit any chaotic motions. With the external perturbations taken into consideration, the perturbed Zakharov equations are studied for us to see the associated chaotic motions. Both the weak and developed chaotic motions are investigated, and the difference between them roots in the relative magnitude of the nonlinearities and perturbations. The chaotic motions are weakened with λ increasing, or else, strengthened. Periodic motion appears when the nonlinear terms and external perturbations are balanced. With such a balance kept, one period increases with λ increasing. © 2015 AIP Publishing LLC.


Peng H.,Beijing University of Posts and Telecommunications | Li L.,Beijing University of Posts and Telecommunications | Yang Y.,Beijing University of Posts and Telecommunications | Liu F.,Beijing University of Posts and Telecommunications
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

Through the construction of suitable objective function, the parameter estimation of the dynamical system could be converted to the problem of parameter optimization. Based on the chaotic ant swarm optimization approach, we investigate the problem of parameter optimization for the dynamical systems in the presence of noise. We systematically analyze the basic relationships among the complexity of objective function, the length of time series, and the performance of the searching algorithm. Furthermore, we consider the effect of measurable additive noise on the objective function. Numerical simulations are also provided to show the effectiveness and feasibility of the proposed methods. © 2010 The American Physical Society.


Wang Y.,Beijing University of Posts and Telecommunications | Nakao A.,University of Tokyo | Vasilakos A.V.,University of Western Macedonia
ACM Transactions on Autonomous and Adaptive Systems | Year: 2012

Currently, on one hand, there exist much work about network formation and/or growth models, and on the other hand, cooperative strategy evolutions are extensively investigated in biological, economic, and social systems. Generally, overlay networks are heterogeneous, dynamic, and distributed environments managed by multiple administrative authorities, shared by users with different and competing interests, or even autonomously provided by independent and rational users. Thus, the structure of a whole overlay network and the peers' rational strategies are ever coevolving. However, there are very few approaches that theoretically investigate the coevolution between network structure and individual rational behaviors. The main motivation of our article lies in that: Unlike existing work which empirically illustrates the interaction between rational strategies and network structure (through simulations), based on EGT (Evolutionary Game Theory), we not only infer a condition that could favor the cooperative strategy over defect strategy, but also theoretically characterizes the structural properties of the formed network. Specifically, our contributions are twofold. First, we strictly derive the critical benefit-to-cost ratio (b/c) that would facilitate the evolution of cooperation. The critical ratio depends on the network structure (the number of peers in system and the average degree of each peer), and the evolutionary rule (the strategy and linking mutation probabilities). Then, according to the evolutionary rules, we formally derive the structural properties of the formed network in full cooperative state. Especially, the degree distribution is compatible with the power-law, and the exponent is (4-3v)/(1-3v), where v is peer's linking mutation probability. Furthermore, we show that, without being harmful to cooperation evolution, a slight change of the evolutionary rule will evolve the network into a small-world structure (high global efficiency and average clustering coefficient), with the same power-law degree distribution as in the original evolution model. © 2012 ACM.


Liu R.H.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2014

Aiming at the difference between satellite’s signal frequency spectrum and satellite signals under specific channel condition, larger fluctuation and ineffective threshold searching method by adopting traditional energy, the paper improved singular point’s performance detection of traditional wavelet transform, selected suitable searching threshold by ultimately combining with both advantages and promoted searching performance of satellite signals under specific channel condition. Based on preprocessed order-1 subspace tracing algorithm of space sign function and infinite norm normalization, the paper solved the problem of degenerating performance of regular order-1 subspace tracing algorithm under noise environment of a stationary distribution effectively. © (2014) Trans Tech Publications, Switzerland.


Li W.,George Washington University | Cheng X.,George Washington University | Jing T.,Beijing Jiaotong University | Cui Y.,Tsinghua University | And 2 more authors.
IEEE Journal on Selected Areas in Communications | Year: 2013

This paper investigates the problem of spectrum assignment and sharing to minimize the total delay of multiple concurrent flows in multi-hop cognitive radio networks. We first analyze the expected per-hop delay, which incorporates the sensing delay and transmission delay characterizing the PU activities and spectrum capacities. Then we formulate a minimum delay optimization problem with interference constraints, and propose an approximation algorithm termed MCC to solve the problem. According to our theoretical analysis, MCC has a bounded performance ratio and a low computational complexity. Finally, we exploit the minimum potential delay fairness in spectrum sharing to mitigate the inter-flow contentions. Extensive simulation study has been performed to validate our design and to compare the performance of our algorithms with that of the state-of-the-art. © 2013 IEEE.


Zhou M.,Beijing University of Posts and Telecommunications | Cui Q.,Beijing University of Posts and Telecommunications | Jantti R.,Aalto University | Tao X.,Beijing University of Posts and Telecommunications
IEEE Communications Letters | Year: 2012

In this letter, we consider a two-way relay channel (TWRC) with two end nodes and k relay nodes, where end nodes have the full channel-state information (CSI) and relay nodes only have the channel-amplitude information (CAI). With the objective of minimizing transmit power consumption at required end-to-end rates, energy-efficient relay selection (RS) and power allocation (PA) scheme is studied for TWRC based on analog network coding (ANC). Firstly, we propose an energy-efficient single RS and PA (E-SRS-PA) scheme, where the best relay node is selected to minimize total transmit power. Then, we prove that E-SRS-PA scheme is the optimal energy-efficient RS and PA (OE-RS-PA) scheme in ANC-based TWRC, and thus the optimal number of relay nodes to be selected in energy efficiency sense is equal to one. In addition, the closed-form expressions of optimal power allocation of E-SRS-PA scheme are derived. Numerical simulations confirm the optimality of proposed E-SRS-PA and demonstrate the energy efficiency of ANC-based TWRC compared with the other relaying schemes. © 2012 IEEE.


Xu T.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications | Tian B.,Beihang University
Journal of Physics A: Mathematical and Theoretical | Year: 2010

The coupled nonlinear Schrödinger (NLS) equations are usually used to describe the dynamics of two-component solitons in optical fibers. Via the Darboux transformation, the coupled NLS equations of the Manakov type are found to have triple Wronskian solutions. Proof is finished by virtue of some new triple Wronskian identities. By solving the zero-potential Lax pair, the triple Wronskian solutions give the bright N-soliton solutions which are characterized by 3N complex parameters. To obtain an understanding of the asymptotic behavior of the bright N-soliton solutions with arbitrary N, some algebraic properties of the triple Wronskian are analyzed and an algebraic procedure is presented to derive the explicit expressions of the asymptotic solitons as t → ∓∞. © 2010 IOP Publishing Ltd.


Li S.N.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2013

In this paper, we will focus on channel estimation (CE) in orthogonal frequency-division multipleing (OFDM) systems. The time-varying (TV) channelsare modeled by a basis epansion model (BEM). Due to the time-variation, the channel matri in the frequency domain is no longer diagonal, but approimately banded.We use a pilot-aided algorithm for estimation of rapidly varying wireless channels in OFDM systems. Theperforms is goodwhen the channels vary on the scale of a single OFDM symbol duration, which occurs in mobile communication scenarios such as WiMA, WAVE, and DVB-T.We recover Fourier coefficients of the channel taps by the pilot information.We then estimate the BEM coefficients of the channel taps from their respective Fourier coefficients using a recently developed inverse reconstruction method.We compare some BEM models in inverse methodsto find out the best ones in certain conditions. © 2013 Trans Tech Publications Ltd, Switzerland.


Sun M.,Beijing University of Posts and Telecommunications
Communications in Computer and Information Science | Year: 2012

This paper proposes a risk evaluation model to solve the problems of risk control in network transactions. Possible risks in network transactions during the payment activities are recognized and analyzed, and different risk evaluation index systems and risk evaluation models according to different corresponding risk are discussed. Then, some corresponding risk control and management measures are put forward. During the process of research and analysis, the corresponding control methods of various risks based on customer perspective are put forward. © 2012 Springer-Verlag.


Ma J.,Beijing University of Posts and Telecommunications | Zhou W.,Beijing University of Posts and Telecommunications
IEEE Photonics Journal | Year: 2015

The signal-to-interference-plus-noise ratio of the noised single-sideband optical orthogonal frequency-division multiplexing (SSB-OOFDM) signal in a direct-detection OFDM system is first deduced theoretically. The relationship of the carrier-to-sideband ratio (CSR) and guard band (GB) to the signal-to-signal beat interference (SSBI) is explored. According to our theoretical analysis, the degradation caused by SSBI on the SSB-OOFDM signal becomes worse as the GB reduces, whereas the increase in the CSR can loosen this degradation. Therefore, a tradeoff between the GB and CSR balances their joint influence on system performance. The simulation for the 20-km optical link with 40-Gb/s 16-quadrature amplitude modulation (16-QAM) noised SSB-OOFDM signal is conducted to confirm our theoretical results. It shows that, without any complex device or algorithm, the GB can be reduced to 40% only by increasing the CSR to ∼8 dB, and thus, the spectral efficiency of the DDO-OFDM link is improved after optimizing the CSR and GB of the SSB-OOFDM signal. In addition, the influence of the optical signal-to-noise ratio and the electronic filter on the optimum CSR of the system is further analyzed. © 2015 IEEE.


Zeng X.,Beijing University of Posts and Telecommunications | Gao Z.H.,Beijing University of Posts and Telecommunications
Applied Mechanics and Materials | Year: 2014

NDN (Named Data Networking) is "clean-slate" architecture for future networking, in which packets carry data names rather than source or destination addresses, being a sharp contrast to today IP architecture. The default routing strategy for NDN is flooding the interest packets to all the possible interfaces which could reach for the data provider or data cache container. Obviously, the default routing strategy is not best way in the actual networking for the heavy load of routing items. This article proposes an interface rank-based routing strategy (RBRS), in which the PIT and FIB structures are detailed and expanded to satisfy the Interest and Data packets transmission, and the interfaces are ranked through a cumulative algorithm for route selection. Through the simulation, RBRS has been proved an adaptive routing mechanism with better performance of network load balance, while reducing the average routing hops and the centric nodes load. © (2014) Trans Tech Publications, Switzerland.


Zhen H.-L.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications | Sun Y.,Beijing University of Posts and Telecommunications | Chai J.,Beijing University of Posts and Telecommunications | And 2 more authors.
Physics of Plasmas | Year: 2015

In this paper, we study the Klein-Gordon-Zakharov (KGZ) system, which describes the interaction between the Langmuir wave and ion sound wave in a high-frequency plasma. By means of the Hirota method and symbolic computation, bright and mixed-type soliton solutions are obtained. For the one soliton, amplitude of E is positively related to β 2, and that of n is inversely related to β 2, while they are both positively related to α, where E refers to the high-frequency part of the electrostatic potential of the electric field raised by the electrons, and n represents the deviation of ion density from its equilibrium, β 2 and α are the plasma frequency and ion sound speed, respectively. Head-on interactions between the two bright solitons and two mixed-type ones are respectively displayed. With β 2 increasing, the head-on interaction is transformed into an overtaking one. Bright bound-state solitons are investigated, and the interaction period decreases with α increasing. Furthermore, with the external forces Γ 1 (t) and Γ 2 (t) introduced, the perturbed KGZ system is studied numerically for its associated chaotic motions. Both the weak and developed chaotic motions can be observed. Γ 1 (t) and Γ 2 (t) have different effects on the chaotic motions: the chaotic motion can be weakened by decreasing the amplitude of Γ 1 (t) or increasing the amplitude and frequency of Γ 2 (t). © 2015 AIP Publishing LLC.


Ming Y.,Beijing University of Posts and Telecommunications
Neurocomputing | Year: 2015

The times of Big Data promotes increasingly higher demands for fine-motion analysis, such as hand activity recognition. However, in real-world scenarios, hand activity recognition suffers huge challenges with variations of illumination, poses and occlusions. The depth acquisition provides an effective way to solve the above issues. In this paper, a complete framework of hand activity recognition combined depth information is presented for fine-motion analysis. First, the improved graph cuts method is introduced to hand location and tracking over time. Then, combined with 3D geometric characteristics and hand behavior prior information, 3D Mesh MoSIFT feature descriptor is proposed to represent the discriminant property of hand activity. Simulation orthogonal matching pursuit (SOMP) is used to encode the visual codewords. Experiments are based on the public available depth datasets (ChaLearn gesture dataset and our captured RGB-D dataset). Compared with the previous popular approaches, our framework has a consistently better performance for real-world applications with fine-motion analysis in terms of effectiveness, robustness and universality. © 2014 Elsevier B.V.


Yu Y.,Beijing University of Posts and Telecommunications | Zheng X.,Henan University
Signal Processing | Year: 2011

Orthogonal frequency division multiplexing (OFDM) is sensitive to carrier frequency offset (CFO) that causes inter-carrier interference (ICI). In this paper, a particle filter (PF) method augmented with ant colony optimization (ACO) is developed to estimate the CFO. The ACO for continuous domains is incorporated into PF to optimize the sampling process. Unlike the standard PF, resampling is not required in the method. Moreover, it does not require the noise distribution. Simulation results show that the proposed method is effective when estimating the CFO and can effectively combat the effect of ICI in OFDM systems. © 2010 Elsevier B.V. All rights reserved.


Li G.,Beijing University of Posts and Telecommunications | Wang Y.,Beijing University of Posts and Telecommunications | Zhang P.,Beijing University of Posts and Telecommunications
IEEE Communications Letters | Year: 2011

This letter addresses the beamforming issues for two way relay systems assuming that two source nodes S1 and S2 are equipped with single antenna each and relay node R with multiple antennas. We derive the optimal linear beamforming matrix at R in closed form based on convex optimization techniques, aiming to minimize the weighted mean squared error (MSE). To reduce complexity for implementation, two alternative relay schemes are also presented. In addition, all the proposed schemes' performance are analyzed and compared in terms of mean squared error (MSE) and computation complexity. © 2006 IEEE.


Huang H.,Beijing University of Posts and Telecommunications | Ren X.,Beijing University of Posts and Telecommunications | Ye X.,Beijing University of Posts and Telecommunications | Guo J.,Beijing University of Posts and Telecommunications | And 4 more authors.
Nano Letters | Year: 2010

Vertical GaAs nanowires on Si (111) substrate were grown by metal organic chemical vapor deposition via Au-catalyst vapor-liquid-solid mechanism. Stacking-faults-free zinc blende nanowires were realized by using AIGaAs/GaAs buffer layers and growing under the optimized conditions, that the alloy droplet act as a catalyst rather than an adatom collector and its size and composition would keep stable during growth. The stable droplet contributes to the growth of stacking-faults-free nanowires. Moreover, by using the buffer layers, epitaxial growth of well-aligned NWs was not limited by the misfit strain induced critical diameter, and the unintentional doping of the GaAs nanowires with Si was reduced. © 2010 American Chemical Society.


Haneef M.,Beijing University of Posts and Telecommunications | Deng Z.,Beijing University of Posts and Telecommunications
Proceedings - 2011 7th International Conference on Mobile Ad-hoc and Sensor Networks, MSN 2011 | Year: 2011

LEACH (Low energy adaptive clustering Hierarchy) is considered to be a first dynamic routing protocol used in Wireless Sensor Networks. It effectively increases the network life time and out perform the direct communication protocol, minimum-transmission-energy protocol and static clustering protocol. In recent years, number of variants has been proposed. This paper is based on the comparative analysis of different updated variants after defining the shortcomings associated with LEACH. © 2011 IEEE.


Liu W.,Beijing University of Posts and Telecommunications | Li X.,Beijing University of Posts and Telecommunications | Huang D.,Institute of Information Security
2011 International Conference on Computer Science and Service System, CSSS 2011 - Proceedings | Year: 2011

We have reviewed the research of context awareness of recent years in this paper. First of all, we describe the definitions of context and context awareness which are made by different scholars in different fields, and propose our own definition. In addition, different classifications of context and context awareness are analyzed. We focus on context acquisition and sensing, context modeling and representation, context filtering and fusion, context storage and retrieval in context awareness computing. Finally, the context awareness application of domestic and foreign are discussed, and the development of the context awareness is prospected. © 2011 IEEE.


Liu W.-J.,Beijing University of Posts and Telecommunications | Tian B.,Beijing University of Posts and Telecommunications | Lei M.,Beijing University of Posts and Telecommunications
Laser Physics | Year: 2013

Elastic and inelastic interactions between optical spatial solitons in nonlinear optics, which to our knowledge have not been reported before, are investigated in this paper. Analytic soliton solutions for the coupled nonlinear Schrödinger equation are obtained using the Hirota method. The coefficient constraints, which can be used to determine whether the soliton interactions are elastic or inelastic, are presented. With different coefficient constraints, the characteristics of soliton interactions are exhibited. The results of this paper may have applications in the design of directional couplers and all-optical logical gates. © 2013 Astro Ltd.


Xinyu Z.,Beijing University of Posts and Telecommunications
2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011 | Year: 2011

As widespread pseudo-random sequences in spread spectrum communication system, M-sequence and Gold-sequence have their own characteristics. However, there are some differences between them. We will analysis these two different kinds of sequences in detail. And then we analyze and compare their correlation. At last, we analyze their typical applications in CDMA spread spectrum communication system. © 2011 IEEE.


Li X.,Beijing University of Posts and Telecommunications | Wang H.,Beijing University of Posts and Telecommunications
Progress in Electromagnetics Research | Year: 2013

This paper presents that the extra passband with two transmission zeros can be obtained by adding shunt open stubs to the asymmetric half-wavelength resonators structure. By using this method, a fourth or even higher passband with good selectivity and compact size can be obtained. Dual-band, tri-band and quad-band bandpass filters are demonstrated by using this method. The measured bandwidth is 80/180 MHz for the dual-band, 60/180/180 MHz for the tri-band and 130/360/170/70 MHz for the quad-band filter, respectively. The measured insertion loss for the dual-band, tri-band and quad-band filter is less than 2.7 dB, 2.5 dB and 2.9 dB at the center frequency. All the simulated results and the measured results agree well.


Zhang X.,Beijing University of Posts and Telecommunications | Yan Z.,Beijing University of Posts and Telecommunications | Gao Y.,Queen Mary, University of London | Wang W.,Beijing University of Posts and Telecommunications
IEEE Wireless Communications Letters | Year: 2013

Relay selection is an effective way to achieve considerable performance gains in cognitive relay networks (CRN). In practice, the best relay may not always be selected, thus the study of the small Nth best relay selection will be very beneficial for CRN design. In this paper, performance analysis for underlay cognitive decode-and-forward relay networks with the small Nth best-relay selection scheme is studied over independent and identically distributed (i.i.d.) Rayleigh fading channels. Closed-form expression for the exact outage probability is derived, which can be used to evaluate the impact of the relay selection scheme, the number of relays, the interference power constraint and the transmit power limit on the outage performance. The theoretical analysis is validated by Monte-Carlo simulations. The results show that both the relay selection scheme and the number of relays have great impact on the outage performance of cognitive relay networks. © 2013 IEEE.


Niu X.,Beijing University of Posts and Telecommunications
Metallurgical and Mining Industry | Year: 2015

To improve the predictive accuracy of network traffic, as for the training sample selection, this paper proposes a FCM-LSSVM for training sample selection. Firstly, fuzzy-means clustering algorithm is used to make cluster analysis of network filling data to eliminate the isolated sample points in it and to build training set of LSSVM, and then the training set is input to the LSSVM for learning. Furthermore, Artificial Bee Colony is used to optimize model parameters, and finally, network traffic forecasting model is established, and the simulation experiment is employed to test the performance of the model. Simulation results show that compared to other network traffic forecasting models, FCM-LSSVM not only improves the prediction accuracy of network traffic, and increases modeling speed, getting more desirable forecasted results of network traffic.


Li X.,Beijing University of Posts and Telecommunications | Ji X.,Beijing University of Posts and Telecommunications
IEEE Microwave and Wireless Components Letters | Year: 2014

Two novel, compact, and highly frequency selective ultra-wideband (UWB) bandpass filters (BPFs) based on an improved model are presented in this letter. The improved model contains four short-circuited stubs connected by transmission lines. A cross-coupling between the first and last short-circuited stubs is introduced to obtain new pairs of transmission zeros on both sides of the passband. The relationship between the coupling factor and the position of the transmission zeros was analyzed and good agreement was obtained between the analysis and model simulation results. Based on the model, two UWB BPFs are designed with 51% (3.1 to 5.2) GHz and 108% (3 to 10) GHz relative bandwidth and small size of 15 mm×15 mm and 19 mm×14 mm, respectively. The insertion loss of the (3.1 to 5.2) GHz filter is less than 0.4 dB in passband and the other one is less than 3 dB. The simulation and measurement results agree well. © 2001-2012 IEEE.


Haibo L.,Harbin Institute of Technology | Wu Y.,Beijing University of Posts and Telecommunications | Peng B.,Dongguan City Leading electronic Technology Co.
Procedia Engineering | Year: 2011

This paper proposes a new localization algorithm THFL (Two-Hop Focus Localization) for wireless sensor network (WSN). This algorithm focuses the localization area of nodes in WSN by using the anchor nodes communicating directly and two-hop with unknown nodes. The advantage of this algorithm is that no additional hardware is needed, and the localization accuracy of classic range-free localization is improved obviously. From the simulation of this algorithm, we get the expected results. © 2011 Published by Elsevier Ltd.


Xu P.,Beijing University of Posts and Telecommunications | Tian H.P.,Beijing University of Posts and Telecommunications | Ji Y.F.,Beijing University of Posts and Telecommunications
Journal of the Optical Society of America B: Optical Physics | Year: 2010

In this paper, a fractal structure is introduced into a one-dimensional (1D) photonic crystal to design a new structure of photonic crystal. We create three typical fractal photonic crystals: the Cantor-like fractal photonic crystal (CLFPC), golden-section fractal photonic crystal (GSFPC), and Fibonacci fractal photonic crystal (FFPC). The transmission spectra of CLFPCs, GSFPCs, and FFPCs are simulated and analyzed. The calculation result shows that the transmission spectrum and the group velocity of a CLFPC are self-similar and in accord with the self-similarity in structure, and the peak numbers in the transmission spectra of the GSFPC and FFPC also follow the principals of special fractal structures. © 2010 Optical Society of America.


Kou X.,Beijing University of Posts and Telecommunications | Wen Q.,Beijing University of Posts and Telecommunications
Proceedings - 2011 4th IEEE International Conference on Broadband Network and Multimedia Technology, IC-BNMT 2011 | Year: 2011

In this paper, the traditional intrusion detection system based on computer is applied to Android platform. Taking into account the performance and storage capacity of smart phone, we proposed a light weight intrusion detection model based on Android - LIDS which changes the traditional passive antivirus to active defense. The Snort intrusion detection technology is used on mobile phones and the key pattern matching algorithm of Snort is improved. © 2011 IEEE.


Wang L.,Beijing University of Posts and Telecommunications | Stuber G.L.,Georgia Institute of Technology
IEEE Network | Year: 2016

D2D communications has attracted substantial research attention recently due to its potential for improving spectrum and energy efficiency within existing cellular infrastructures. This work investigates methods for matching a DUE link (or links) to CUE to form spectrum sharing partners. The objective is to maximize various sum performance metrics (reward) of all D2D links and CUEs after successful pairing under individual power constraints. In our approach, a set of DUE candidates for each CUE uplink for a requisite SINR level is first identified, which allows us to form a bi-partite graph linking CUEs with their candidate DUE links for spectrum sharing. Classic algorithms, such as the Hopcroft-Karp, Gale-Shapley, and Kuhn-Munkres algorithms, are investigated for maximizing different performance metrics (reward) of all spectrum sharing CUEs and D2D links. Their performance is compared tp a low-complexity fairness-based algorithm that can deliver solid sum rate performance without high complexity. © 1986-2012 IEEE.


Li J.,Beijing University of Posts and Telecommunications | Du J.,Beijing University of Posts and Telecommunications
2010 2nd Pacific-Asia Conference on Circuits, Communications and System, PACCS 2010 | Year: 2010

This paper has a thorough study on panoramic image, an important application of virtual reality technology, and proposes a feature based method of generating a panorama. Descriptions of solutions and algorithms for each step were given in details, including Harris corner detection algorithm, RANSAC algorithm, Levenberg-Marquardt algorithm and so on. Some improvements of the algorithm were proposed in order to resolve the deficiencies. The experimental results were given at the end of the paper. It shows that the panoramic generated by this method is complete, clear, and no obvious distortion, and the methods adopted in the system are appropriate and practical. © 2010 IEEE.


Wang S.,Beijing University of Posts and Telecommunications | Zhu X.,China Mobile | Yang F.,Beijing University of Posts and Telecommunications
International Journal of Web and Grid Services | Year: 2014

In this paper, we propose an efficient QoS management approach for QoS-aware web service composition. In the approach, we classify web services according to theirs similarity and then design a QoS tree to manage the QoS the classified web services. Besides, by querying the managed QoS, we propose a QoS-aware web service composition via a particle swarm optimisation algorithm to perform fast web service composition. Experimental results based on two kinds of dataset show our proposed approach outperforms other schemes in terms of query cost, computation time and optimality. © Copyright 2014 Inderscience Enterprises Ltd.


Yao B.Z.,Beijing University of Posts and Telecommunications | Nie B.X.,University of California at Los Angeles | Liu Z.,Microsoft | Zhu S.-C.,University of California at Los Angeles
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2014

This paper presents animated pose templates (APTs) for detecting short-term, long-term, and contextual actions from cluttered scenes in videos. Each pose template consists of two components: 1) a shape template with deformable parts represented in an And-node whose appearances are represented by the Histogram of Oriented Gradient (HOG) features, and 2) a motion template specifying the motion of the parts by the Histogram of Optical-Flows (HOF) features. A shape template may have more than one motion template represented by an Or-node. Therefore, each action is defined as a mixture (Or-node) of pose templates in an And-Or tree structure. While this pose template is suitable for detecting short-term action snippets in two to five frames, we extend it in two ways: 1) For long-term actions, we animate the pose templates by adding temporal constraints in a Hidden Markov Model (HMM), and 2) for contextual actions, we treat contextual objects as additional parts of the pose templates and add constraints that encode spatial correlations between parts. To train the model, we manually annotate part locations on several keyframes of each video and cluster them into pose templates using EM. This leaves the unknown parameters for our learning algorithm in two groups: 1) latent variables for the unannotated frames including pose-IDs and part locations, 2) model parameters shared by all training samples such as weights for HOG and HOF features, canonical part locations of each pose, coefficients penalizing pose-transition and part-deformation. To learn these parameters, we introduce a semi-supervised structural SVM algorithm that iterates between two steps: 1) learning (updating) model parameters using labeled data by solving a structural SVM optimization, and 2) imputing missing variables (i.e., detecting actions on unlabeled frames) with parameters learned from the previous step and progressively accepting high-score frames as newly labeled examples. This algorithm belongs to a family of optimization methods known as the Concave-Convex Procedure (CCCP) that converge to a local optimal solution. The inference algorithm consists of two components: 1) Detecting top candidates for the pose templates, and 2) computing the sequence of pose templates. Both are done by dynamic programming or, more precisely, beam search. In experiments, we demonstrate that this method is capable of discovering salient poses of actions as well as interactions with contextual objects. We test our method on several public action data sets and a challenging outdoor contextual action data set collected by ourselves. The results show that our model achieves comparable or better performance compared to state-of-the-art methods. © 2014 IEEE.


Li X.,Fudan University | Yu J.,Fudan University | Yu J.,ZTE Corporation | Dong Z.,Zte United States Inc. | And 3 more authors.
Optics Letters | Year: 2013

We experimentally investigate the interference in multiple-input multiple-output (MIMO) wireless transmission by adjusting the relative locations of horn antennas (HAs) in a 100 GHz optical wireless integration system, which can deliver a 50 Gb/s polarization-division-multiplexing quadrature-phase-shift- keying signal over 80 km single-mode fiber-28 and a 2 × 2 MIMO wireless link. For the parallel 2 × 2 MIMO wireless link, each receiver HA can only get wireless power from the corresponding transmitter HA, while for the crossover ones, the receiver HA can get wireless power from two transmitter HAs. At the wireless receiver, polarization demultiplexing is realized by the constant modulus algorithm (CMA) in the digital-signal-processing part. Compared to the parallel case, wireless interference causes about 2 dB optical signal-to-noise ratio penalty at a bit-error ratio (BER) of 3.8 × 10 -3 for the crossover cases if similar CMA taps are employed. The increase in CMA tap length can reduce wireless interference and improve BER performance. Furthermore, more CMA taps should be adopted to overcome the severe wireless interference when two pairs of transmitter and receiver HAs have different wireless distances. © 2013 Optical Society of America.


Wang C.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications | Jiao R.-Z.,Beijing University of Posts and Telecommunications | Jin G.-S.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2013

Here we investigate a physical implementation of the universal quantum controlled phase (CPHASE) gate operation on photonic qubits by using nitrogen vacancy (N-V) centers and microcavity resonators. The quantum CPHASE gate can be achieved by sending the photons through the microcavity and interacting with the N-V center. The proposed scheme can be further used for scalable quantum computation. We show that this technique provides us a deterministic source of cluster state generation on photonic qubits. In this scheme, only single photons and single N-V center are required and the proposed schemes are feasible with the current experimental technology. © 2013 Optical Society of America.


Yang Y.-H.,Beijing University of Posts and Telecommunications | Yang Y.-H.,Henan Polytechnic University | Gao F.,Beijing University of Posts and Telecommunications | Tian G.-J.,Beijing University of Posts and Telecommunications | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

In this Brief Report, we study the distinguishability of three-qubit quantum states by local operations and classical communication. We first determine α(S5)=4 and also show a necessary condition for local distinguishability of three-qubit quantum states. Applying the characterization of orthogonal product states, we obtain two methods to discriminate mixed states with some constraints. © 2013 American Physical Society.


Qi X.,Beijing University of Posts and Telecommunications | Xiao R.,Microsoft | Li C.-G.,Beijing University of Posts and Telecommunications | Qiao Y.,CAS Shenzhen Institutes of Advanced Technology | And 2 more authors.
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2014

Designing effective features is a fundamental problem in computer vision. However, it is usually difficult to achieve a great tradeoff between discriminative power and robustness. Previous works shown that spatial co-occurrence can boost the discriminative power of features. However the current existing co-occurrence features are taking few considerations to the robustness and hence suffering from sensitivity to geometric and photometric variations. In this work, we study the Transform Invariance (TI) of co-occurrence features. Concretely we formally introduce a Pairwise Transform Invariance (PTI) principle, and then propose a novel Pairwise Rotation Invariant Co-occurrence Local Binary Pattern (PRICoLBP) feature, and further extend it to incorporate multi-scale, multi-orientation, and multi-channel information. Different from other LBP variants, PRICoLBP can not only capture the spatial context co-occurrence information effectively, but also possess rotation invariance. We evaluate PRICoLBP comprehensively on nine benchmark data sets from five different perspectives, e.g., encoding strategy, rotation invariance, the number of templates, speed, and discriminative power compared to other LBP variants. Furthermore we apply PRICoLBP to six different but related applications - texture, material, flower, leaf, food, and scene classification, and demonstrate that PRICoLBP is efficient, effective, and of a well-balanced tradeoff between the discriminative power and robustness. © 1979-2012 IEEE.


Cui Y.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Yin F.,Beijing University of Posts and Telecommunications | Dai J.,East China Research Institute of Electronic Engineering | And 3 more authors.
Optics Express | Year: 2013

An intermodulation distortion suppression method based on the optical carrier band processing is demonstrated. A systematic analysis of the main optical spectrum contributors for the third-order intermodulation distortion in the nonlinear system is presented. Theoretical analysis shows that the third-order intermodulation distortion terms can cancel each other if a proper phase shifting is imposed to the optical carrier band. We experimentally demonstrate the approach with a two-tone test and a suppression of about 33 dB in the third-order intermodulation distortion is obtained. Experimental results show that an overall fundamental to thirdorder intermodulation distortion ratio of up to 64 dB is achieved and the link dynamic range is improved by 14.7 dB, compared with the conventional link without the proposed optical carrier band processing. ©2013 Optical Society of America.


Wu Z.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Yin F.,Beijing University of Posts and Telecommunications | Xu K.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Letters | Year: 2013

We propose and demonstrate a phase stabilization method for transfer and downconvert radio frequency (RF) signal from remote antenna to center station via a radio-over-fiber (ROF) link. Different from previous phaselocking- loop-based schemes, we post-correct any phase fluctuation bymixing during the downconversion process at the center station. A rapid and endless operation is predicted. The ROF technique transfers the received RF signal directly, which will reduce the electronic complexity at the antenna end. The proposed scheme is experimentally demonstrated, with a phase fluctuation compression factor of about 200. The theory and performance are also discussed. © 2013 Optical Society of America.


Zhang J.-L.,Beijing University of Posts and Telecommunications | Guo F.-Z.,Beijing University of Posts and Telecommunications | Gao F.,Beijing University of Posts and Telecommunications | Liu B.,Beijing University of Posts and Telecommunications | Wen Q.-Y.,Beijing University of Posts and Telecommunications
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

Based on the fundamental concept of quantum counterfactuality, we propose a protocol to achieve quantum private database queries, which is a theoretical study of how counterfactuality can be employed beyond counterfactual quantum key distribution (QKD). By adding crucial detecting apparatus to the device of QKD, the privacy of both the distrustful user and the database owner can be guaranteed. Furthermore, the proposed private-database-query protocol makes full use of the low efficiency in the counterfactual QKD, and by adjusting the relevant parameters, the protocol obtains excellent flexibility and extensibility. © 2013 American Physical Society.


Wang C.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications | Zhang R.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2011

We theoretically investigate an entanglement purification protocol with photon and electron hybrid entangled state resorting to quantum-dot spin and microcavity coupled system. The present system is used to construct the parity check gate which allows a quantum nonde-molition measurement on the spin parity. The cavity-spin coupled system provides a novel experimental platform of quantum information processing with photon and solid qubit. © 2011 Optical Society of America.


Li J.,Beijing University of Posts and Telecommunications | Zhang Y.-C.,Beijing University of Posts and Telecommunications | Yu S.,Beijing University of Posts and Telecommunications | Jiang T.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Letters | Year: 2013

A method to realize a highly linear microwave photonics link is proposed based on the dual-drive dual-parallel Mach-Zehnder modulator (MZM). The scheme theoretically eliminates third-order intermodulation distortion (IMD3) completely by taking all the sidebands in the optical spectrum that cause IMD3 into consideration. Without digital linearization and other optical processors, the method utilizes simple electrical signal phase control. Microwave signals are symmetrically single sideband modulated in the two MZMs. IMD3 suppression of approximately 30 dB is experimentally demonstrated, and the spurious-free dynamic range is improved by 12 dB · Hz2/3. © 2013 Optical Society of America.


A simple signal-to-signal beat interference cancellation receiver based on balanced detection (ICRBD) with an interleaver, a 2 × 2 three-decibel optical coupler, and a balanced photodiode pair is proposed for a single-sideband optical orthogonal frequency division multiplexing (SSB-OOFDM) signal with a reduced guard band (GB). Simulation demonstration of the ICRBD for a 40 Gbit/s 16-QAM SSB-OOFDM signal with a reduced GB was achieved successfully. © 2013 Optical Society of America.


Yan J.-Y.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2013

The theoretical model for the metal-insulator-semiconductor nanowires is established and the optical properties are investigated. The linear absorption of the hybrid excitons, formed due to the exciton-plasmon interaction, shows obvious red shift on the magnitude of several meVs. The mechanism of the red shift is found to be the joint action of the increased excitonic binding energy attributed to the indirect Coulomb interaction and the decreased effective bandgap caused by the additional self-energy potential. The conclusion is also supported by the evolution of the absorption spectra with the adjustable structural parameters. © 2013 Optical Society of America.


Liu L.,KDDI R and D Laboratories Inc. | Tsuritani T.,KDDI R and D Laboratories Inc. | Morita I.,KDDI R and D Laboratories Inc. | Guo H.,Beijing University of Posts and Telecommunications | Wu J.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2011

OpenFlow, as an open-source protocol for network virtualization, is also widely regarded as a promising control plane technique for heterogeneous networks. But the utilization of the OpenFlow protocol to control a wavelength switched optical network has not been investigated. In this paper, for the first time, we experimentally present a proof-of-concept demonstration of OpenFlow-based wavelength path control for lightpath provisioning in transparent optical networks. We propose two different approaches (sequential and delayed approaches) for lightpath setup and two different approaches (active and passive approaches) for lightpath release by using the OpenFlow protocol. The overall feasibility of these approaches is experimentally validated and the network performances are quantitatively evaluated. More importantly, all the proposed methodologies are demonstrated and evaluated on a real transparent optical network testbed with both OpenFlow-based control plane and data plane, which allows their feasibility and effectiveness to be verified, and valuable insights of the proposed solutions to be obtained for deploying into real OpenFlow controlled optical networks. © 2011 Optical Society of America.


Chen X.,University of Melbourne | Li A.,University of Melbourne | Li A.,Center for Energy Efficient Telecommunications | Gao G.,University of Melbourne | And 4 more authors.
Optics Express | Year: 2011

In this paper we experimentally demonstrate transmission performance of optical DFT-spread OFDM systems in comparison with conventional OFDM systems. A 440.8-Gb/s superchannel consisting of 8 x 55.1-Gb/s densely-spaced DFT-S OFDM signal is successfully received after 1120-km transmission with a spectral efficiency of 3.5 b/s/Hz. It is shown that DFT-S OFDM can achieve an improvement of 1 dB in Q factor and 1 dB in launch power over conventional OFDM. Additionally, unique word aided phase estimation algorithm is proposed and demonstrated enabling extremely long OFDM symbol transmission. © 2011 Optical Society of America.


Liu B.,Beijing University of Posts and Telecommunications | Zhang L.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications | Liu L.,Huawei
Optics Letters | Year: 2013

A dynamic wavelength-division-multiplexing/time-division-multiplexing hybrid access network with energy and data synchronized transmission is proposed to support flexible resource allocation. Dynamic scheduling of wavelength with different split ratio nodes is realized by the control model at the optical distribution network (ODN). All-optical amplification of the optical data signal and energy supply are also incorporated in the ODN. A proof-of-concept experiment is implemented to verify the feasibility of the proposal. © 2013 Optical Society of America.


Wang T.-Y.,Luoyang Normal University | Wen Q.-Y.,Beijing University of Posts and Telecommunications
Optics Communications | Year: 2011

In the comment, we show that the attack [G. Gao, Opt. Commun. 43 (2010) 902], which claims to be able to eavesdrop all the transmitted secret message of the improved three-party quantum secret sharing protocol [S. Lin, et al., Opt. Commun. 281 (2008) 4553], is invalid in the sense that it introduces 25% error rate. © 2011 Elsevier B.V. All rights reserved.


Peng M.,Beijing University of Posts and Telecommunications | Li Y.,Beijing University of Posts and Telecommunications | Quek T.Q.S.,Singapore University of Technology and Design | Quek T.Q.S.,Institute for Infocomm Research | Wang C.,Inter Digital Communications
IEEE Transactions on Wireless Communications | Year: 2014

Using Device-to-device (D2D) communications in a cellular network is an economical and effective approach to increase the transmission data rate and extend the coverage. Nevertheless, the D2D underlaid cellular network is challenging due to the presence of inter-tier and intra-tier interferences. With necessarily lower antenna heights in D2D communication links, the fading channels are likely to contain strong line-of-sight components, which are different from the Rayleigh fading distribution in conventional two-tier heterogeneous networks. In this paper, we derive the success probability, spatial average rate, and area spectral efficiency performances for both cellular users and D2D users by taking into account the different channel propagations that they experience. Specifically, we employ stochastic geometry as an analysis framework to derive closed-form expressions for above performance metrics. Furthermore, to reduce cross-tier interferences and improve system performances, we propose a centralized opportunistic access control scheme as well as a mode selection mechanism. According to the analysis and simulations, we obtain interesting tradeoffs that depend on the effect of the channel propagation parameter, user node density, and the spectrum occupation ratio on the different performance metrics. This work highlights the importance of incorporating the suitable channel propagation model into the system design and analysis to obtain the realistic results and conclusions. © 2002-2012 IEEE.


Li M.,University of Arizona | Li M.,Beijing University of Posts and Telecommunications | Cvijetic M.,University of Arizona | Takashima Y.,University of Arizona | Yu Z.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

We have evaluated the channel capacity of OAM-based FSO link under a strong atmospheric turbulence regime when adaptive optics (AO) are employed to correct the wavefront phase distortions of OAM modes. The turbulence is emulated by the Monte-Carlo phase screen method, which is validated by comparison with the theoretical phase structure function. Based on that, a closed-loop AO system with the capability of real-time correction is designed and validated. The simulation results show that the phase distortions of OAM modes induced by turbulence can be significantly compensated by the real-time correction of the properly designed AO. Furthermore, the crosstalk across channels is reduced drastically, while a substantial enhancement of channel capacity can be obtained when AO is deployed. © 2014 Optical Society of America.


Zhang L.,Beijing University of Posts and Telecommunications | Liu B.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications | Wang Y.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

A 10 × 70.4Gb/s dynamic filter bank multi-band carrier-less amplitude/phase modulation (FBMB/CAP) passive optical network (PON) with remote energy supply and single side-band (SSB) modulation is proposed in this paper. The dynamic wavelength scheduling with different split ratios can be realized at the optical distribution network based on the remote energy supply. The multi-granularity bandwidth allocation of CAP bands is performed by the filter bank. 10 × 6 band FBMB/CAP-16 downstream signals varying from 4Gb/s to 19.2Gb/s per band is demonstrated with 480 potential users. The system penalty due to dynamic scheduling is also investigated in the experiment. © 2014 Optical Society of America


Yang H.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications | Zhao Y.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications | And 6 more authors.
Optics Express | Year: 2014

Data center interconnection with elastic optical networks is a promising scenario to meet the high burstiness and high-bandwidth requirements of data center services. We previously implemented enhanced software defined networking over elastic optical network for data center application [Opt. Express 21, 26990 (2013)]. On the basis of it, this study extends to consider the time-aware data center service scheduling with elastic service time and service bandwidth according to the various time sensitivity requirements. A novel time-aware enhanced software defined networking (TeSDN) architecture for elastic data center optical interconnection has been proposed in this paper, by introducing a timeaware resources scheduling (TaRS) scheme. The TeSDN can accommodate the data center services with required QoS considering the time dimensionality, and enhance cross stratum optimization of application and elastic optical network stratums resources based on spectrum elasticity, application elasticity and time elasticity. The overall feasibility and efficiency of the proposed architecture is experimentally verified on our OpenFlow-based testbed. The performance of TaRS scheme under heavy traffic load scenario is also quantitatively evaluated based on TeSDN architecture in terms of blocking probability and resource occupation rate. © 2014 Optical Society of America.


Li J.,Beijing University of Posts and Telecommunications | Zhang X.,Beijing University of Posts and Telecommunications | Tian F.,Beijing University of Posts and Telecommunications | Xi L.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2011

The generation of stable and high-quality single-sideband (SSB) multi-carrier source based on recirculating frequency shifter (RFS) is analyzed theoretically and realized experimentally. The impact factors originated from the modulator intrinsic imperfections, deviation from the right operation bias voltage, as well as the unbalanced amplitude and phase of the radio frequency (RF) drive signals, have different influences on the output spectrum of the transfer function, which is the decisive factor in generating the high-quality multi-carrier output. Based on the theoretical analysis, the stable and high-quality 50-tone output was successfully realized. The experiments under some implementation imperfections have also been carried out. The imperfect and low-quality output results are in good agreement with the theoretical analysis. © 2011 Optical Society of America.


Liu L.,Beijing University of Posts and Telecommunications | Zhang X.,Texas A&M University | Ma H.,Beijing University of Posts and Telecommunications
IEEE Sensors Journal | Year: 2013

Deriving the critical density to achieve region coverage for random sensor deployment is a fundamentally important problem in the area of Internet of Things (IoT). Most of the existing works on sensor coverage mainly concentrate on the full coverage models, which ensure that all points in the deployment region are covered at the expense of high complexity and cost. In contrast, many applications of IoT focus on the exposure-path prevention, which does not require full coverage sensor deployment, and instead it only needs the partial coverage, because the exposure paths are prevented as long as no moving objects or phenomena can go through a deployment region without being detected. Finally, we focus on the partial coverage by applying the percolation theory to solve the exposure path problem for the network of sensors in IoT. Most of the existing percolation-based schemes apply the continuum-percolation theory, which, however, suffers from the loose lower and upper bounds on the critical density. To overcome this problem, we propose a bond-percolation theory based scheme by mapping the exposure path problem into a bond percolation model. Using this model, we derive the critical densities for both omnidirectional sensor networks and directional sensor networks under random sensor deployment where sensors are deployed according to a two-dimensional Poisson process. The rigorous modeling/analyses and extensive simulations show that our proposed scheme can yield much tighter upper and lower bounds on the critical densities as compared with those generated by continuum-percolation. © 2001-2012 IEEE.


Liang X.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Yin F.,Beijing University of Posts and Telecommunications | Li J.,Beijing University of Posts and Telecommunications | Xu K.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

We propose and demonstrate a novel scheme to effectively suppress the cross modulation distortion (XMD) and the third-order inter-modulation distortion (IMD3) which exist in wide-band, multi-carrier analog photonic link (APL) system. Such nonlinearities, which are caused by the out-of-band and in-band signals, respectively, constrain the link's performance severely. Instead of building an extra nonlinear path in hardware, the XMD and IMD3 compensation information is extracted from the received distorted signal, and both distortions are then suppressed by digitally multiplying the distorted signal with the compensation information. After compensation in the digital domain, the down-converted XMD and IMD3 distortions are experimentally suppressed with 33 dB and 25 dB, respectively, resulting in an improved upper limit for the SFDR. ©2014 Optical Society of America


Yang Z.,Beijing University of Posts and Telecommunications | Hong X.,Beijing University of Posts and Telecommunications | Guo H.,Beijing University of Posts and Telecommunications | Wu J.,Beijing University of Posts and Telecommunications | Lin J.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

We propose and demonstrate a distributed Brillouin fiber sensor using Stokes and anti-Stokes differential pulse pair based on doublesideband probe wave, in which the two sidebands of probe wave are used to balance the power of two pump pulses. The spatial resolution is determined by the slightly width difference of the two balanced pulses, without Brillouin gain spectrum broadening. The pulses perform gain-loss process in optical field before the probe signal being detected, without any postprocessing or extra measurement time. The proposed technique can achieve high spatial resolution, natural Brillouin gain spectrum linewidth, normal measurement time and long sensing range simultaneously. © 2014 Optical Society of America.


Hu H.,Technical University of Denmark | Kong D.,Technical University of Denmark | Kong D.,Beijing University of Posts and Telecommunications | Palushani E.,Technical University of Denmark | And 3 more authors.
Optics Express | Year: 2014

We have demonstrated the generation of a 320 Gb/s Nyquist-OTDM signal by rectangular filtering on an RZ-OTDM signal with the filter bandwidth (320 GHz) equal to the baud rate (320 Gbaud) and the reception of such a Nyquist-OTDM signal using polarization-insensitive time-domain optical Fourier transformation (TD-OFT) followed by passive filtering. After the time-to-frequency mapping in the TD-OFT, the Nyquist-OTDM signal with its characteristic sinc-shaped time-domain trace is converted into an orthogonal frequency division multiplexing (OFDM) signal with sinc-shaped spectra for each subcarrier. The subcarrier frequency spacing of the converted OFDM signal is designed to be larger than the transform-limited case, here 10 times greater than the symbol rate of each subcarrier. Therefore, only passive filtering is needed to extract the subcarriers of the converted OFDM signal. In addition, a polarization diversity scheme is used in the four-wave mixing (FWM) based TD-OFT, and less than 0.5 dB polarization sensitivity is demonstrated in the OTDM receiver. ©2013 Optical Society of America.


Palushani E.,Technical University of Denmark | Mulvad H.C.H.,Technical University of Denmark | Kong D.,Technical University of Denmark | Kong D.,Beijing University of Posts and Telecommunications | And 3 more authors.
Optics Express | Year: 2014

We propose a simple OFDM receiver allowing for the use of standard WDM receivers to receive spectrally advanced OFDM signals. We propose to spectrally magnify the optical-OFDM super-channels using a spectral telescope consisting of two time-lenses, which enables reduced inter-carrier-interference in subcarrier detection by simple band-pass filtering. A demonstration on an emulated 100 Gbit/s DPSK optical-OFDM channel shows improved sensitivities after 4-times spectral magnification. ©2013 Optical Society of America.


Ma J.,Beijing University of Posts and Telecommunications
Optics Express | Year: 2014

The paper has theoretically evaluated a signal-signal beat interference (SSBI) cancellation receiver with the balanced detection (ICRBD) for single sideband optical orthogonal frequency division multiplexing (SSB-OOFDM) signal, which has an improved spectral efficiency (SE) by reducing the guard band (GB) between the OOFDM signal and the optical carrier. The influences of the parameters of the interleaver (IL), the optical coupler (OC), and the balanced photodiodes (BPD) as well as the connecting optical/electrical paths in the ICRBD on the received OFDM signal performance are studied in detail. The theoretical results show that the received OFDM signal and noise power are dependent on the parameters of the devices and their deviation away from the ideal value degrades the performance greatly. Based on the simulation system, the 40Gb/s 16QAM SSB-OOFDM signal with 5GHz GB is converted to the OFDM signal by the ICRBD with the suppressed SSBI. It is observed that (1) the received OFDM signal is insensitive to the deviation of the coupling coefficient of the 3dB OC; (2) the received signal suffers little degradation from the filter outline of the IL if an IL with the bandwidth over 13GHz and 6- or higher-order Gaussian filter is used; (3) the polarization deviation and phase shift between the OOFDM signal and the optical carrier caused by the optical paths between IL and OC have smaller influence on the EVM of the received signal; and (4) although the ICRBD is immune to the polarization deviation of the two recombined SSB-OOFDM signals, the relative time delay between the two optical/electrical paths from the OC to the BPD degrades the received signal seriously. By tuning the time delay in optical or electrical domain to reduce the total relative time delay within 10ps, the EVM maintains below 20%. The simulation results agree well with the theoretical analysis and catch an insight on the mechanism of the ICRBD. © 2014 Optical Society of America.


Xinchao Z.,Beijing University of Posts and Telecommunications
Applied Soft Computing Journal | Year: 2011

As we know, simulated annealing algorithm with large neighborhoods has greater probability of arriving at a global optimum than a small one has, if the other conditions, i.e., the initial configuration, initial temperature and temperature decreasing rate, are the same. However, the large neighborhood is not always beneficial, such as when the distance between the global optimum and the current solution is smaller than the step size. Therefore a simulated annealing algorithm with adaptive neighborhood is proposed in this paper. The adaptive non-uniform mutation operation borrowed from evolutionary algorithm is incorporated into simulated annealing for new solution generation. The neighborhood size reduces in probability with the progress of algorithm. It nearly covers the whole search space in the initial stage of algorithm in the sense of probability. The search engine only searches a very local neighborhood at the later stage of algorithm. Why to hybridize non-uniform mutation with simulated annealing is also analyzed and demonstrated. The numerical experiments show that the hybridization can greatly enhance the performance and the reliability of simulated annealing algorithm. Further experiments are made for benchmarks with expanding search domains. Satisfiable results are obtained again even if the variable bounds are enlarged to 1000 times. Theoretical analysis and simulation experiments illustrate the consistent excellent performance and the possible application of nonu-SA algorithm. © 2010 Elsevier B.V. All rights reserved.


Zhao B.,Beijing University of Posts and Telecommunications | Chen X.,Beijing University of Posts and Telecommunications
Proceedings - 2011 3rd International Conference on Communications and Mobile Computing, CMC 2011 | Year: 2011

The paper has proposed a novel OFDMA PON architecture that can reach 40Gbps over 20Km standard single-mode fiber (SSMF). Simulation results show that the architecture can support upstream dynamic bandwidth allocation. Receiver sensitivity at BER © 2011 IEEE.


Li Y.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications | Huang Y.,Beijing University of Posts and Telecommunications
IEEE Photonics Technology Letters | Year: 2013

A versatile any point bias control scheme for the Mach-Zehnder modulator is proposed. The ratio of first-order harmonic and average output power was used as feedback signal. We also demonstrate its effectiveness with simulations and experiments. This technique has been shown to be independent of optical input power to the modulator. The results show that this is an effective bias control technique suitable for a variety of modulation formats. The penalty for locking is small and it is 0.5 dB in OSNR penalty. The system BER performance has been observed for 72 h without degradation. © 1989-2012 IEEE.


Yang D.,State Key Laboratory of Information Photonics and Optical Communications | Yang D.,Beijing University of Posts and Telecommunications | Tian H.,State Key Laboratory of Information Photonics and Optical Communications | Tian H.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Express | Year: 2011

We present nanoscale photonic crystal sensor arrays (NPhCSAs) on monolithic substrates. The NPhCSAs can be used as an opto-fluidic architecture for performing highly parallel, label-free detection of biochemical interactions in aqueous environments. The architecture consists of arrays of lattice-shifted resonant cavities side-coupled to a single PhC waveguide. Each resonant cavity has slightly different cavity spacing and is shown to independently shift its resonant peak (a single and narrow drop) in response to the changes in refractive index. The extinction ratio of welldefined single drop exceeds 20 dB. With three-dimensional finite-difference time-domain (3D-FDTD) technique, we demonstrate that the refractive index sensitivity of 115.60 nmRIU (refractive index unit) is achieved and a refractive index detection limit is approximately of 8.65 × 10∼5 for this device. In addition, the sensitivity can be adjusted from 84.39 nmRIU to 161.25 nmRIU by changing the number of functionalized holes. © 2011 Optical Society of America.


Zuo Y.,Beijing University of Posts and Telecommunications | Xiao H.,Beijing University of Posts and Telecommunications | Wu J.,Beijing University of Posts and Telecommunications | Li W.,Beijing University of Posts and Telecommunications | Lin J.,Beijing University of Posts and Telecommunications
Optics Letters | Year: 2013

Non-line-of-sight ultraviolet propagation models have been developed for both coplanar and noncoplanar geometries. Based on an exact integral-form single-scatter model, this Letter proposes an approximate closed-form model for tractable analysis applicable to noncoplanar geometries with a narrow transmitter beam or receiver field of view. Numerical results on path loss are presented for various system geometries. These results are verified with the integral-form model and a previous approximate model, showing our model agrees well with the former and outperforms the latter. © 2013 Optical Society of America.


Gao G.,Beijing University of Posts and Telecommunications | Zhang J.,Beijing University of Posts and Telecommunications | Gu W.,Beijing University of Posts and Telecommunications
IEEE Photonics Technology Letters | Year: 2013

We derive an analytical expression for the transmission performance of intra-channel nonlinearity compensated and dispersion unmanaged orthogonal frequency-divison multiplexing (OFDM) systems using practical digital back propagation (DBP) with span-length step size. The analytical expression is verified by numerical simulations with evaluation inaccuracy less than 0.4 dB for 1000-km 16-QAM modulated polarization division multiplexed-OFDM transmissions. Using the derived theory, the dependence of performance and optimum nonlinear compensation coefficient on system parameters is identified. The limitation of processing bandwidth on the performance improvement using practical intra-channel DBP is also investigated. Analytical results show that for achieving 1-dB improvement on maximum Q2 factor, the processing signal bandwidth of span-length step size DBP should be within 55 GHz for 2000-km SSMF transmissions over 62.5-km spans. © 1989-2012 IEEE.


Zhang L.,Beijing University of Posts and Telecommunications | Liu B.,Beijing University of Posts and Telecommunications | Xin X.,Beijing University of Posts and Telecommunications | Wang Y.,Beijing University of Posts and Telecommunications
IEEE Photonics Technology Letters | Year: 2013

A novel multi-amplitude minimum shift keying (MAMSK) orthogonal frequency division multiplexing (OFDM) signal is proposed for 60-GHz radio-over-fiber (RoF) access system. It can increase the tolerance toward frequency offset of an OFDM signal due to the faster roll-off side-lobe. In the experiment, a 3.21-Gb/s 2AMSK-OFDM signal is transmitted over 22 km single mode fiber (SMF) and 5 m air link successfully. Compared with a conventional 8QAM-OFDM signal, the signal-to-interference ratio (SIR) of 2AMSK-OFDM is improved by 11.5 dB at a frequency offset of 0.15. The performance is improved by 1.7 dB under a normalized frequency offset (FO) of 0.2. © 2013 IEEE.


Wu T.,Beijing University of Posts and Telecommunications | Liu Y.,Beijing University of Posts and Telecommunications | Yu Z.,Beijing University of Posts and Telecommunications | Peng Y.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Express | Year: 2014

A surface plasmon polaritons (SPPs) refractive index sensor which consists of two metal-insulator-metal (MIM) waveguides coupled to each other by a ring resonator is proposed. The transmission properties are numerically simulated by finite element method. The sensing characteristics of such structure are systematically analyzed by investigating the transmission spectrum. The results indicate that there exist three resonance peaks in the transmission spectrum, and all of which have a linear relationship with the refractive index of the material under sensing. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity as high as 3460nmRIU-1. Furthermore, this structure can also be used as a temperature sensor with temperature sensitivity of 1.36nm/°C. This work paves the way toward sensitive nanometer scale refractive index sensor and temperature sensor for design and application. © 2014 Optical Society of America.


Ding Z.,Newcastle University | Peng M.,Beijing University of Posts and Telecommunications | Chen H.-H.,National Cheng Kung University
IEEE Transactions on Communications | Year: 2012

In this paper, we consider a secrecy relaying communication scenario where all nodes are equipped with multiple antennas. An eavesdropper has the access to the global channel state information (CSI), and all the other nodes only know the CSI not associated with the eavesdropper. A new secrecy transmission protocol is proposed, where the concept of interference alignment is combined with cooperative jamming to ensure that artificial noise from transmitters can be aligned at the destination, but not at the eavesdropper due to the randomness of wireless channels. Analytical results, such as ergodic secrecy rate and outage probability, are developed, from which more insightful understanding of the proposed protocol, such as multiplexing and diversity gains, can be obtained. A few special cases, where outage probability cannot be decreased to zero regardless of SNR, are also discussed. Simulation results are provided to demonstrate the performance of the proposed secrecy transmission protocol. © 2012 IEEE.


Xia J.,Beijing University of Posts and Telecommunications
Telecommunications Policy | Year: 2012

The Special Issue of Telecommunications Policy 36, 2012, presents research papers on China's telecommunications industry in the era of 3G and beyond, reviewing various aspects such as market, technology and institutions. The development and adoption of the domestic-mint 3GTD-SCDMA standard and technology catching-up are the main theme of the paper by Xudong Gao and Jianxin Liu. Based on extensive primary data collection, Gao and Liu ask what are the key factors and underlying mechanisms affecting catching-up through technology standard development in the Chinese case by looking at the catching-up process as a complex co-evolution process between firm strategy and government policy in solving the challenges of late-comer disadvantages. The paper by Jiang Yu,Yue Zhang and Ping Gao shifts focus by following closely the development and evolution of mobile broadband infrastructure(WBI) in China that spans the eras of 2G, 3G and beyond.


Han J.-T.,Beijing University of Posts and Telecommunications
Environment, Energy and Sustainable Development - Proceedings of the 2013 International Conference on Frontier of Energy and Environment Engineering, ICFEEE 2013 | Year: 2014

Online shopping is becoming to be more and more as the express industry has developed rapidly. But the alliance that price is agreed by several courier firms appears sometimes as the price competition occurs. This paper discusses the problem of the price completion of the service homogeneity provided by courier service online market under the condition of complete information. The courier pricing competition game among several market agents is designed based on Bertrand model. It is proved that the price alliance is unstable. Some rationalization proposals are presented. © 2014 Taylor & Francis Group, London.


We analyzed the different biological processes and occurrence numbers between low expression inhibited PTHLH downstream-mediated aging gene ontology (GO) network of no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection) and the corresponding high expression (fold change ≥2) inhibited GO network of human hepatocellular carcinoma (HCC). Inhibited PTHLH downstream-mediated aging network consisted of aging, branched chain family amino acid biosynthesis, cellular metabolism, cholesterol biosynthesis, coupled to cyclic nucleotide second messenger, cytolysis, 'de novo' GDP-l-fucose biosynthesis, detection of mechanical stimulus, glucose homeostasis, G-protein signaling, leukocyte adhesion, iron-sulfur cluster assembly, JAK-STAT cascade, Notch signaling pathway, nucleotide-sugar metabolism, peptidyl-tyrosine sulfation, protein amino acid N-linked glycosylation, protein amino acid phosphorylation, response to drug, rRNA processing, translational initiation, ubiquitin-dependent protein catabolism, homophilic cell adhesion in no-tumor hepatitis/cirrhotic tissues. We proposed inhibited PTHLH downstream leukocyte adhesion-mediated protein amino acid N-linked glycosylation coupling Notch and JAK-STAT cascade to iron-sulfur cluster assembly-induced aging network. Our hypothesis was verified by the same inhibited PTHLH downstream-mediated aging GO network in no-tumor hepatitis/cirrhotic tissues with the corresponding activated GO network of HCC, or the different with the corresponding activated GO network of no-tumor hepatitis/cirrhotic tissues. Inhibited PTHLH downstream leukocyte adhesion-mediated protein amino acid N-linked glycosylation coupling Notch and JAK-STAT cascade to iron-sulfur cluster assembly-induced aging network included TSTA3, ALK, CIAO1, NOTCH3 in no-tumor hepatitis/cirrhotic tissues from the GEO data set using gene regulatory network inference method and our programming.


Wei W.,Beijing University of Posts and Telecommunications | Liu Y.,Nankai University | Zhang X.,Beijing University of Posts and Telecommunications | Wang Z.,Nankai University | Ren X.,Beijing University of Posts and Telecommunications
Applied Physics Letters | Year: 2014

Evanescent-wave pumped room-temperature single-mode GaAs/AlGaAs core-shell nanowire lasers are proposed and demonstrated. The nanowires are axially excited by evanescent wave outside a microfiber with a diameter about 10μm via a ns-pulse laser. The lasing emission with a low effective threshold less than 90 nJ is achieved at 868.62 nm along with a linewidth of ∼1.8 nm. Moreover, multiple lasing lines in a wavelength range from 852.56 nm to 882.48 nm are observed. The mechanism of diverse lasing wavelengths is revealed. Furthermore, the proposed GaAs/AlGaAs nanowire laser has advantages such as simple structure, easy to operate, and controllable lasing wavelength, tending to be practical in optical communications and integrated photonic circuits. © 2014 AIP Publishing LLC.


Wang P.,Wuhan University of Technology | Wang J.,Wuhan University of Technology | Wang X.,Wuhan University of Technology | Yu H.,Wuhan University of Technology | And 3 more authors.
Applied Catalysis B: Environmental | Year: 2013

The addition of reduced graphene oxide (rGO) in the TiO2 has been demonstrated to be one of the effective methods to improve the photocatalytic performance of TiO2 photocatalyst. Despite tremendous efforts, developing facile and green synthetic method of TiO2-rGO nanocomposites still remains a great challenge. In this study, a one-step green hydrothermal method for the fabrication of easily recycled TiO2-rGO composites, based on the initial formation of strong-coupling TiO2-GO nanocomposite and the subsequent in situ reduction of GO to rGO during hydrothermal treatment, was developed in the pure water without using any reductant and surfactant. It is found that the TiO2 nanoparticles with a clean surface and a good dispersion are highly required for the formation of the easy-recycling TiO2-rGO composite photocatalyst. Photocatalytic experimental results indicated that compared with the high-efficiency P25 TiO2 precursor, the photocatalytic performance could be obviously improved (about 23%) for the decomposition of phenol after coupling 1-wt% rGO. The enhanced photocatalytic performance can be attributed the cooperation effect of the effective separation of charge carriers via rGO cocatalyst, the enrichment of phenol molecular on the rGO, and the strong coupling interaction between TiO2 nanoparticles and rGO nanosheets. Considering its completely green and facile preparation and recyclable feature from an aqueous solution, the present TiO2-rGO nanocomposite photocatalyst can be regards as one of the ideal photocatalysts for various potential applications. © 2012 Elsevier B.V.


Xia N.,Dalian University of Technology | Qiu T.-S.,Dalian University of Technology | Li J.-C.,State Radio Monitoring Center | Li S.-F.,Beijing University of Posts and Telecommunications
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2013

A nonlinear filtering algorithm is proposed based on the Kalman filter and the particle filter. The method can provide significant performance for dynamic nonlinear system which is consist of linear state equation and nonlinear measurement equation. Firstly, the particle filter is utilized for initial estimation of the state variables, and then the Kalman filter is performed. The Cramer-Rao Bound is derived for the nonlinear model. Computation complexity analysis and numerical simulations demonstrate that the proposed algorithm has the same complexity as the standard particle filter, but the estimation accuracy is higher than the standard particle filter and the extended Kalman filter. The estimation error is even lower than the Cramer-Rao Bound of the system model.


Ren X.-M.,Beijing University of Posts and Telecommunications
Beijing Youdian Daxue Xuebao/Journal of Beijing University of Posts and Telecommunications | Year: 2015

Based on the bivergentum theory, the law of universal gravitation is extended to the hypothesis of full-cosmic-scope (FCS) universal interaction force, which involves not only the attractive forces but also the repulsive forces and applies to the microscopic, the meso-scopic and the macroscopic regimes, and the formula of FCS universal interaction force is established. The basic principle is that the wave property of a real physical object with the FCS quantization variable hB as its measure decreases from its maximum (hB=h) to its minimum (hB=hΔ) and correspondingly the particle property of the object increases from its minimum to its maximum when the bivergentum argument Bm of the object varies from 0 to ∞. The main points include (1) the law of universal gravitation is rigorously valid for a pair of real physical objects when the particle properties of both objects reach their common upper limit. (2) In general cases, the property of the universal interaction force (attractive or repulsive) between a pair of real physical objects is related to their FCS quantization variables hB1, hB2 and the distance r between them. (3) There exists a critical distance rc related to the spatial extension dimensions S1 and S2 of the two objects' wave functions (determined by hB1 and hB2). The reversal of the property of the universal interaction force happens at the point r=rc, i.e. the force manifests itself as an attractive force when r>rc and as a repulsive force when r


Liao Q.-Z.,Beijing University of Posts and Telecommunications
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2015

Like dual quaternion, double quaternion can be used in mathematic modeling of spatial mechanisms. The advantages of fast computing and robustness can be used in some special applications. So far, international journals have published some papers introducing this method, however, these methods need special mathematic knowledge and are not easy to understand. Based on the matrix method, the homogeneous transformation matrix can be divided into rotation and translation parts, and then the two parts are transformed into Hamilton operator. Double quaternion is then derived. By using the double quaternion, a small error will be introduced into the results, however, it can be controlled by the program. Another advantage is that it needs less multiply computing. A numerical example is given to verify the method, and this method can be easily understood. © 2015, Beijing University of Technology. All right reserved.


Ding S.,China University of Mining and Technology | Ding S.,Beijing University of Posts and Telecommunications | Qi B.,China University of Mining and Technology
Artificial Intelligence Review | Year: 2012

Granular support vector machine (GSVM) is a new learning model based on Granular Computing and Statistical Learning Theory. Compared with the traditional SVM, GSVM improves the generalization ability and learning efficiency to a large extent. This paper mainly reviews the research progress of GSVM. Firstly, it analyzes the basic theory and the algorithm thought of GSVM, then tracking describes the research progress of GSVM including the learning model and specific applications in recent years, finally points out the research and development prospects. © 2011 Springer Science+Business Media B.V.


Sun Y.,Beijing University of Posts and Telecommunications | Luo H.,Beijing University of Posts and Telecommunications | Das S.K.,University of Texas at Arlington
IEEE Transactions on Dependable and Secure Computing | Year: 2012

For wireless multimedia sensor networks (WMSNs) deployed in noisy and unattended environments, it is necessary to establish a comprehensive framework that protects the accuracy of the gathered multimedia information. In this paper, we jointly consider data aggregation, information trust, and fault tolerance to enhance the correctness and trustworthiness of collected information. Based on the multilayer aggregation architecture of WMSNs, we design a trust-based framework for data aggregation with fault tolerance with a goal to reduce the impact of erroneous data and provide measurable trustworthiness for aggregated results. By extracting statistical characteristics from different sources and extending Josang's trust model, we propose how to compute self-data trust opinion, peer node trust opinion, and peer data trust opinion. According to the trust transfer and trust combination rules designed in our framework, we derive the trust opinion of the sink node on the final aggregated result. In particular, this framework can evaluate both discrete data and continuous media streams in WMSNs through a uniform mechanism. Results obtained from both simulation study and experiments on a real WMSN testbed demonstrate the validity and efficiency of our framework, which can significantly improve the quality of multimedia information as well as more precisely evaluate the trustworthiness of collected information. © 2012 IEEE.


Huang Z.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
Chinese Optics Letters | Year: 2013

A room division multiplexing (RDM)-based hybrid visible light communication (VLC) network for realizing indoor broadband communication within a multi-room house is presented. The downlink information is transmitted by light-emitting diode lamps, whereas the uplink information is transmitted through WiFi. RDM is introduced to improve the VLC network throughput; in addition, the associated signaling localization and active handoff mechanisms are designed for implementation. The experimental platform demonstrates the effectiveness of the proposed hybrid architecture, along with the RDM and active handoff mechanisms. © 2013 Chinese Optics Letters.


Yan K.-F.,Beijing University of Posts and Telecommunications
Advanced Materials Research | Year: 2013

With the development of digital information technology, speech coding enhances its development rapidly and plays an important role. Especially the speech coding algorithm, which has low bit rate and high quality, provides qualified multimedia services based on limited channel width. The paper studies the application of DSP technology of TMS320VC5509 in data speech coding algorithm, the overall plan of coding design, AIC23 interface design and coding algorithm. Based on these studies, it explores the optimization of coding algorithm and analyzes algorithm according to optimization results. © (2013) Trans Tech Publications, Switzerland.


Tao X.,Beijing University of Posts and Telecommunications | Xu X.,Beijing University of Posts and Telecommunications | Cui Q.,Beijing University of Posts and Telecommunications
IEEE Communications Magazine | Year: 2012

Cooperative communications have recently been migrated to one of state-of-the-art features of 3GPP LTE-Advanced (LTE-A). Cooperative communications fundamentally change the abstraction of a wireless link and offer significant potential advantages for wireless communication networks. This article visits cooperative techniques, such as relay, distributed antennas systems (DAS), multicell coordination, Group Cell, Coordinated Multiple Point transmission and reception (CoMP), those turn the traditional cellular system into a cooperative system. In particular, we propose several joint processing policies to demonstrate the Group Cell (CoMP) concept. Results of a trial network implementation and a performance evaluation of the concept are also reported. © 2012 IEEE.


Wen J.-R.,Beijing University of Posts and Telecommunications | Wu M.-Q.,Beijing University of Posts and Telecommunications | Su J.-F.,Hebei University of Science and Technology
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2012

Cyber-physical system (CPS) represents a system which tightly integrates computation, communication and physical processes. Perception, communication, and computing capabilities are embedded into the physical device, in order to realize distributed sensing, reliable data transfer, intelligent information processing, real-time feedback and control. This paper summarizes the basic concepts and characteristics of CPS firstly, and then gives a systemic review of recent progress on some key technologies, such as architecture, middleware system, real-time feature, security and privacy, and also puts forward some related research ideas. Some prototype systems and practical examples are also described to show the advantages of CPS. Finally, CPS is compared with wireless sensor network (WSN), the internet of things (IOT), networked control systems (NCSs), and some existing deficiencies are summarized, and the future research directions of CPS are proposed. Copyright © 2012 Acta Automatica Sinica. All rights reserved.


Wang S.,Beijing University of Posts and Telecommunications | Sun Q.,Beijing University of Posts and Telecommunications | Yang F.,Beijing University of Posts and Telecommunications
IET Software | Year: 2012

Quality of service (QoS) is critical for service customers to select suitable web services for business applications in open web environment. However, since QoS are often influenced by several factors, traditional approaches are not very efficient and effective in measuring QoS of web service. The authors introduce in this study a novel QoS measure approach to efficiently measure QoS of web service for web service selection. The core of this approach is to take the three factors, that is, service providers, the context of customers and historical statistics into QoS measure. The experimental results demonstrate that the proposed approach is efficient and effective in measuring QoS of web service. © 2012 The Institution of Engineering and Technology.


Zhao X.,Orange S.A. | Zhao X.,Yahoo! | Dong Y.,Beijing University of Posts and Telecommunications
IEEE Transactions on Audio, Speech and Language Processing | Year: 2012

Joint factor analysis (JFA) is a recently developed method to model speaker and session variability in Gaussian Mixture Models (GMMs). In this paper, both batch and sequential Bayesian analysis of JFA models are evaluated for robust speaker recognition. Various sources of uncertainties in JFA models, from latent speaker and channel factors to Gaussian mixture indicator variables, are examined from a Bayesian perspective. By integrating over all these latent factors, we could better account for the sources of variability in speaker enrollment and verification processes than considering only point estimates; through this study, we could also analyze and identify the contribution of these various underlying model uncertainties to the final speaker verification performance. However, as all latent variables in JFA GMM become correlated with each other given observed data, it becomes practically intractable to do Bayesian analysis in closed analytic form. Hence, an alternative approach based on variational Bayes is developed in this paper to explore Bayesian JFA models in an approximate yet efficient way. In this method, fully correlated a posteriori distribution is approximated by a variational distribution of factored form to facilitate inference; and a lower bound on model likelihood is also derived to construct detection scores. Experimental results on the 2008 NIST Speaker Recognition Evaluation (NIST SRE) show that these variational Bayesian JFA models could obtain significant performance improvements over JFA using point estimates, especially for the cases with limited enrollment and test data. For the 10-s task in the 2008 NIST SRE, the variational Bayesian JFA systems obtained relatively 9.4% EER and 11.5% DCF reductions compared to the baseline JFA system. This paper also shows the importance of taking into account the uncertainties in both speaker and channel factors, which is more effective than considering uncertainties in channel factors alone. © 2012 IEEE.


Gao J.,Huazhong Agricultural University | Du H.,Beijing University of Posts and Telecommunications
Procedia Engineering | Year: 2011

The embedded web technology is increasingly applied in precision agriculture. Based on ARM-Linux development environment, this paper constructs embedded web server and use it in acquisition and transmission of greenhouse information. The system could transmit the collected information effectively with benign stability and expansibility. Microprocessor S3C2440 based on ARM9 is used as the system processing unit, its rich resources can not only realize the system function, but also facilitate the system expansion in the future. Embedded web server Boa and embedded database management system (DBMS) SQLite are selected to construct the software system of web server. Common Gateway Interface (CGI) program is developed to implement dynamic web technology and the interaction with the users. Experiment results show that the working performance of the system is quite stable and can reach the design requirements in real-time data acquisition and remote control. Furthermore, the system has the characteristics of good expansibility, networking flexibility and low cost. © 2011 Published by Elsevier Ltd.


Liao Q.-Z.,Beijing University of Posts and Telecommunications
Beijing Youdian Daxue Xuebao/Journal of Beijing University of Posts and Telecommunications | Year: 2010

The problem discussed here is the research work of linkage mechanisms, which has relations with geometry. These works include planar and spatial mechanisms, series and parallel mechanisms, geometrical modeling of the mechanisms and equations solving. The kinematic analysis and synthesis of mechanisms are also discussed. Except traditional method, modern ones for solving these problems are outlined here. When computer is used, some special problems appear in the calculation and are also discussed.


Wang X.-Y.,Liaoning Normal University | Wang X.-Y.,Beijing University of Posts and Telecommunications | Bu J.,Liaoning Normal University
Digital Signal Processing: A Review Journal | Year: 2010

Automated segmentation of images has been considered an important intermediate processing task to extract semantic meaning from pixels. In general, the fuzzy c-means approach (FCM) is highly effective for image segmentation. But for the conventional FCM image segmentation algorithm, cluster assignment is based solely on the distribution of pixel attributes in the feature space, and the spatial distribution of pixels in an image is not taken into consideration. In this paper, we present a novel FCM image segmentation scheme by utilizing local contextual information and the high inter-pixel correlation inherent. Firstly, a local spatial similarity measure model is established, and the initial clustering center and initial membership are determined adaptively based on local spatial similarity measure model. Secondly, the fuzzy membership function is modified according to the high inter-pixel correlation inherent. Finally, the image is segmented by using the modified FCM algorithm. Experimental results showed the proposed method achieves competitive segmentation results compared to other FCM-based methods, and is in general faster. © 2009 Elsevier Inc. All rights reserved.


Zuo X.,Beijing University of Posts and Telecommunications | Zhang G.,CAS Institute of Microelectronics | Tan W.,IBM
IEEE Transactions on Automation Science and Engineering | Year: 2014

Public clouds provide Infrastructure as a Service (IaaS) to users who do not own sufficient compute resources. IaaS achieves the economy of scale by multiplexing, and therefore faces the challenge of scheduling tasks to meet the peak demand while preserving Quality-of-Service (QoS). Previous studies proposed proactive machine purchasing or cloud federation to resolve this problem. However, the former is not economic and the latter for now is hardly feasible in practice. In this paper, we propose a resource allocation framework in which an IaaS provider can outsource its tasks to External Clouds (ECs) when its own resources are not sufficient to meet the demand. This architecture does not require any formal inter-cloud agreement that is necessary for the cloud federation. The key issue is how to allocate users' tasks to maximize the profit of IaaS provider while guaranteeing QoS. This problem is formulated as an integer programming (IP) model, and solved by a self-adaptive learning particle swarm optimization (SLPSO)-based scheduling approach. In SLPSO, four updating strategies are used to adaptively update the velocity of each particle to ensure its diversity and robustness. Experiments show that, SLPSO can improve a cloud provider's profit by 0.25%-11.56% compared with standard PSO; and by 2.37%-16.71% for problems of nontrivial size compared with CPLEX under reasonable computation time. © 2004-2012 IEEE.


Li J.B.,Beijing University of Posts and Telecommunications
Advanced Materials Research | Year: 2014

With the Internet of Vehicles popular, many service providers can provide vehicle service (e.g. Web service, Application, Network access, etc.) for users. Then more and more vehicle services are published in Internet of Vehicles, and how to measure the quality of vehicle service (QoVS) become a very important issue. In this paper, we propose a QoVS prediction approach using eAutoregressive integrated moving average. Our approach can predict the QoVS of different vehicle services according their history data. In order to evaluate our proposed approach, we construct experiments and results show that our approach is very effective in internet of vehicles. © (2014) Trans Tech Publications, Switzerland.


Abdulla A.E.A.A.,Tohoku University | Nishiyama H.,Tohoku University | Yang J.,Beijing University of Posts and Telecommunications | Ansari N.,New Jersey Institute of Technology | Kato N.,Tohoku University
IEEE Transactions on Wireless Communications | Year: 2012

colorblack{Power-aware routing in Wireless Sensor Networks (WSNs) is designed to adequately prolong the lifetime of severely resource-constrained ad hoc wireless sensor nodes}. Recent research has identified the energy hole problem in single sink-based WSNs, a characteristic of the many-to-one (convergecast) traffic patterns. In this paper, we propose HYbrid Multi-hop routiNg (HYMN) algorithm, which is a hybrid of the two contemporary multi-hop routing algorithm architectures, namely, flat multi-hop routing that utilizes efficient transmission distances, and hierarchical multi-hop routing algorithms that capitalizes on data aggregation. We provide rigorous mathematical analysis for HYMNoptimize it and model its power consumption. In addition, through extensive simulations, we demonstrate the effective performance of HYMN in terms of superior connectivity. © 2012 IEEE.


Yin S.,Beijing University of Posts and Telecommunications | Chen D.,Hong Kong University of Science and Technology | Zhang Q.,Hong Kong University of Science and Technology | Liu M.,University of Michigan | Li S.,Beijing University of Posts and Telecommunications
IEEE Transactions on Mobile Computing | Year: 2012

Dynamic spectrum access has been a subject of extensive study in recent years. The increasing volume of literatures calls for a deeper understanding of the characteristics of current spectrum utilization. In this paper, we present a detailed spectrum measurement study, with data collected in the 20 MHz to 3 GHz spectrum band and at four locations concurrently in Guangdong province of China. We examine the statistics of the collected data, including channel vacancy statistics, channel utilization within each individual wireless service, and the spectral and spatial correlation of these measures. Main findings include that the channel vacancy durations follow an exponential-like distribution, but are not independently distributed over time, and that significant spectral and spatial correlations are found between channels of the same service. We then exploit such spectrum correlation to develop a 2D frequent pattern mining algorithm that can predict channel availability based on past observations with considerable accuracy. © 2012 IEEE.


Huang J.,Beijing University of Posts and Telecommunications | Liu Y.,Chongqing University of Posts and Telecommunications
Expert Systems with Applications | Year: 2010

Multicast routing is regarded as a critical component in networks especially the real-time applications become increasingly popular in recent years. This paper proposes a novel fast multi-objective evolutionary algorithm called MOEAQ for solving multicast routing problem (MRP) in MANET. The strengths and limitations of the well-known multicast model are analyzed firstly in this work. Specifically, the "Greedy" and "family competition" approach are integrated into MOEAQ to speed up the convergence and to maintain the diversity of population. The theoretical validations for the proposed method are presented to show its efficiency. After that, a CBT-based improved protocol is then proposed to simplify the MRP, and finally, the performance of MANET scaled from 20 to 200 nodes with different types of service is evaluated by OPNET, experimental results show that the proposed method is capable of achieving faster convergence and more preferable for multicast routing in MANET compared with other GA-based protocol well-known in the literature. © 2009.


Cai H.,Beijing University of Posts and Telecommunications
Chemical Engineering Transactions | Year: 2016

The paper investigates the problem of a distributed robust relay beamforming in one-way relay networks with imperfect channel state information. The aim is to maximize the SNR (signal-to-noise ratio) of the receiver with the constraint of the total transmits power of relays is less than a certain predefined threshold. Because the channel is imperfect and the objective function is fractional quadratic form, the optimal problem is a non-convex problem which is hard to be solved. We first change the fractional problem into a non-fractional one. Second, we consider the semi-definite programming (SDP) method efficiently by exploiting S-procedure theorem and relaxing the rank-one constrain to obtain the robust beamforming vector. The paper gives the schematic total algorithm too. Numerical results show that the proposed algorithm can solve the maximum problem with robust features efficiently and obtain satisfactory results. Copyright © 2016, AIDIC Servizi S.r.l.


Zhong Y.-X.,Beijing University of Posts and Telecommunications
Beijing Youdian Daxue Xuebao/Journal of Beijing University of Posts and Telecommunications | Year: 2010

A completely new approach to artificial intelligence, named mechanism approach, was presented in the paper to cope with the advanced intelligence (AI) research. It was discovered that the core mechanism of intelligence formation is a series of conversions-the one from information to knowledge and the one from knowledge to intelligence (intelligent strategy), or more concisely information-knowledge-intelligence transform. It was also discovered that there is a system of knowledge ecology from experimental knowledge to regular knowledge and further to commonsense knowledge. To combine the mechanism approach and the ecology system of knowledge, it is discovered that the three existed schools of advanced intelligence theory (the structuralism, functionalism, and behaviorism) are unified within the framework of the mechanism approach. More interestingly, it can also be proved that the general form of mechanism approach is the information conversion which is an effective approach to advanced intelligence and as significant as that of material conversion and energy conversion in physics.


Jin Z.,Beijing University of Posts and Telecommunications | Wen Q.,Beijing University of Posts and Telecommunications | Du H.,Baoji University of Arts And Sciences
Computers and Electrical Engineering | Year: 2010

Recently, Yu et al. proposed the first identity-based signcryption scheme without random oracles and proved it was semantically secure in the standard model. However, in this paper we find that their scheme actually does not reach the semantic security as they claimed. To make up for this defect, we propose a rescue scheme and show our improvement is really secure in the standard model based on the intractability of the Decisional Bilinear Diffie-Hellman assumption. Crown Copyright © 2009.


Wang Z.,Beijing University of Posts and Telecommunications | Shuang K.,Beijing University of Posts and Telecommunications | Yang L.,Beijing University of Posts and Telecommunications | Yang F.,Beijing University of Posts and Telecommunications
Journal of Convergence Information Technology | Year: 2012

As the scale of cloud datacenter becomes larger and larger, the energy consumption and revenue enhancing of the cloud datacenter will grow rapidly. How to improve high-throughput computing resource allocation strategy was taken into account. High-throughput computing resource consolidation is an effective method to increase resource utilization and in turn reduces energy consumption and increases revenue acquisition. However, high-throughput computing resource consolidation may lead to several problems, such as the freeing up of resources that can sit idling yet still drawing power and the energy consumption of communication and revenue acquisition are ignored. Based on these considerations, this paper proposes a Particle Swarm Optimized Tabu search Mechanism, aiming to maximize resource utilization and explicitly taking into account both active and idle energy consumption in minimizing finish time. While fulfilling requirements and QoS of cloud datacenter, this proposed mechanism allows turning off the spare servers, thus reducing power consumption and increasing revenue enhancing overall datacenter. We conducted extensive experiments based on the platform of CloudSim. By comparing with traditional algorithms, we prove that proposed algorithm can save energy consumption reducing by 67.5% and increase revenue enhancing by 8.14 times averagely based on the consideration of communication and QoS of cloud datacenter in minimizing finish time.


Ding J.,Beijing University of Posts and Telecommunications | Huang Z.,Beijing University of Posts and Telecommunications | Ji Y.,Beijing University of Posts and Telecommunications
IEEE Communications Letters | Year: 2012

Inherent multipath diffuse channel characteristics inhibit visible light communications (VLC) system to provide uniform and satisfactory communication performance within the room domain. An evolutionary algorithm based optimization scheme is proposed to modify the optical intensity of LED transmitters for reducing the signal power fluctuation extent. Simulation results show that the proposed scheme can efficiently reduce the signal power dynamic range up to 26.5% while the SNR is still sufficient for keeping BER < 10 -6 (using OOK-NRZ modulation format). © 1997-2012 IEEE.


Peng M.,Beijing University of Posts and Telecommunications | Liang D.,Beijing University of Posts and Telecommunications | Wei Y.,Beijing University of Posts and Telecommunications | Li J.,Beijing University of Posts and Telecommunications | Chen H.-H.,National Cheng Kung University
IEEE Communications Magazine | Year: 2013

Self-organizing network, or SON, technology, which is able to minimize human intervention in networking processes, was proposed to reduce the operational costs for service providers in future wireless systems. As a cost-effective means to significantly enhance capacity, heterogeneous deployment has been defined in the 3GPP LTEAdvanced standard, where performance gains can be achieved through increasing node density with low-power nodes, such as pico, femto, and relay nodes. The SON has great potential for application in future LTE-Advanced heterogeneous networks, also called HetNets. In this article, state-of-the-art research on self-configuring and self-optimizing HetNets are surveyed, and their corresponding SON architectures are introduced. In particular, we discuss the issues of automatic physical cell identifier assignment and radio resource configuration in HetNets based on selfconfiguring SONs. As for self-optimizing SONs, we address the issues of optimization strategies and algorithms for mobility management and energy saving in HetNets. At the end of the article, we show a testbed designed for evaluating SON technology, with which the performance gain of SON algorithms is demonstrated. © 2013 IEEE.


Mao J.,Beijing University of Posts and Telecommunications | Gao J.,Beijing University of Posts and Telecommunications | Liu Y.,Beijing University of Posts and Telecommunications | Xie G.,Beijing University of Posts and Telecommunications | Li X.,Beijing University of Posts and Telecommunications
IEEE Transactions on Vehicular Technology | Year: 2012

This paper studies the power allocation problem for a cognitive radio (CR) multiple-input-multiple-output (MIMO) system under spectrum sharing with an existing primary radio network. In particular, the ergodic capacity maximization problem is studied in the Rayleigh fading cognitive MIMO channel under both the total transmit power constraint and a set of interference power constraints where each is applied at one of the primary receivers (PRs). This paper considers that the channel from primary transmitter (PT) to secondary receiver (SR), and the channel from secondary transmitter (ST) to SR are both in short-term fading due to the mobility of SR, whereas the channels from ST to PRs are in long-term fading. By using the Lagrangian dual method, the optimal transmit precoding matrix is derived, and some nearly optimal power allocation algorithms are proposed to maximize the bounds of secondary user ergodic capacity. Performance analysis and simulation results show that the proposed schemes can approach the comparative capacity of the optimal power allocation algorithm, which has perfect instant channel state information (CSI), particularly when the antenna number of the ST exceeds the total antenna number of PRs. © 2006 IEEE.


Mao J.,Beijing University of Posts and Telecommunications | Xie G.,Beijing University of Posts and Telecommunications | Gao J.,Beijing University of Posts and Telecommunications | Liu Y.,Beijing University of Posts and Telecommunications
IEEE Transactions on Wireless Communications | Year: 2013

Conventional designs of OFDM-based cognitive radio (CR) systems mainly focus on the system throughput. Since nowdays the energy efficiency (EE) of wireless systems becomes more and more important, this paper intends to improve the system throughput for unit-energy consumption in OFDM-based CR systems. The energy-efficient power allocation problem of OFDM-based CR systems is studied under the total power constraint, the interference power constraint and the rate constraint. Since the energy-efficient power allocation problem is non-convex, in order to find the optimal power allocation at each subcarrier, we propose a novel method named water-filling factors aided search (WFAS) to solve the EE optimization problems with multiple constraints. The global ε-optimality and the convergence of the proposed method are presented. The numerical results confirm the theoretical conclusions. The comparisons of the energy-efficient power allocation and the spectrum-efficient power allocation in OFDM-based CR systems are given under different constraints via numerical simulations as well. © 2002-2012 IEEE.


Liu W.-J.,Beijing University of Posts and Telecommunications | Lei M.,Beijing University of Posts and Telecommunications
Journal of Electromagnetic Waves and Applications | Year: 2013

An analytic study on soliton amplification in inhomogeneous optical fibers is presented in this paper. By use of the Hirota method, the bilinear forms for the nonlinear Schrödinger equation, which describes the soliton propagation in inhomogeneous optical fibers, are obtained. The analytic soliton solutions are derived with symbolic computation. According to the solution obtained, the solitons are amplified without the pedestals, and the technique permit high-quality amplification of solitons, which to our knowledge has not been reported before. The physical effects affecting soliton amplification are discussed. The gain of the amplifier, the soliton velocity and phase can be adjusted with two arbitrary parameters. The influences of group-velocity dispersion and Kerr nonlinearity on soliton amplification are studied. With the different values of group-velocity dispersion and Kerr nonlinearity, amplification of solitons in inhomogeneous optical fibers can be controlled. The results of this paper provide a simple and efficient approach to amplify solitons in the communication systems. © 2013 Taylor & Francis.


Wu K.,Beijing University of Posts and Telecommunications | Li C.,PLA Air Force Aviation University
Journal of Convergence Information Technology | Year: 2012

In order to solve the problems of system access authorization in trusted network, in view of the fuzziness of network environment, the randomness of user behavior and the subjectivity of historical experience, a secure authorization scheme based on the cloud model called CTAS is proposed. CTAS synthetically analyzes multiple trust characteristics and security threats of access in trusted network. The weights analysis method is used to extract the Security Degree of access. The cloud model is utilized to quantitatively construct the trusted benchmark cloud. The Security Level of access is qualitatively judged according to the Certainty Degree of the Security Degree attaching to the benchmark cloud. The access is authorized by the Security Level. Under the improved framework of Trusted Network Connect (TNC), the trust timeliness mechanism is presented to implement the reassessment of the Security Level for dynamically updating authorization. The experiments show that CTAS can timely and accurately accomplish system access authorization in TNC, effectively prevent and control security risks and threats, and provide better security, integrity and availability.


Zhang H.,Beijing University of Posts and Telecommunications | Zhao K.,Beijing University of Posts and Telecommunications | Song Y.-Z.,Queen Mary, University of London | Guo J.,Beijing University of Posts and Telecommunications
Neurocomputing | Year: 2013

With the increasing popularity of portable camera devices and embedded visual processing, text extraction from natural scene images has become a key problem that is deemed to change our everyday lives via novel applications such as augmented reality. Text extraction from natural scene images algorithms is generally composed of the following three stages: (i) detection and localization, (ii) text enhancement and segmentation and (iii) optical character recognition (OCR). The problem is challenging in nature due to variations in the font size and color, text alignment, illumination change and reflections. This paper aims to classify and assess the latest algorithms. More specifically, we draw attention to studies on the first two steps in the extraction process, since OCR is a well-studied area where powerful algorithms already exist. This paper offers to the researchers a link to public image database for the algorithm assessment of text extraction from natural scene images. © 2013 Elsevier B.V.


Peng M.,Princeton University | Peng M.,Beijing University of Posts and Telecommunications | Yan S.,Beijing University of Posts and Telecommunications | Poor H.V.,Princeton University
IEEE Wireless Communications Letters | Year: 2014

Characterizing user to remote radio head (RRH) association strategies in cloud radio access networks (C-RANs) is critical for performance optimization. In this letter, the single nearest and $N$-nearest RRH association strategies are presented, and the corresponding impact on the ergodic capacity of C-RANs is analyzed, where RRHs are distributed according to a stationary point process. Closed-form expressions for the ergodic capacity of the proposed RRH association strategies are derived. Simulation results demonstrate that the derived uplink closed-form capacity expressions are accurate. Furthermore, the analysis and simulation results show that the ergodic capacity gain is not linear with either the RRH density or the number of antennas per RRH. The ergodic capacity gain from the RRH density is larger than that from the number of antennas per RRH, which indicates that the association number of the RRH should not be bigger than 4 to balance the performance gain and the implementation cost. © 2012 IEEE.


Zhao D.,Beijing University of Posts and Telecommunications | Ma H.,Beijing University of Posts and Telecommunications | Liu L.,Beijing University of Posts and Telecommunications
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2012

Mobile sensors are a viable choice for providing monitoring service on a set of Points of Interest (PoIs) in a large sensing field. In some applications, each PoI should be covered periodically (sweep coverage), and the collected data should be delivered to the sink node timely (timely transmission), namely both the sensing and transmission delay constraints for each PoI should be satisfied, which we call as timely sweep coverage. We investigate how to optimize the movement path of one mobile sensor to satisfy the two delay constraints for each PoI, so that the required movement velocity for the mobile sensor is minimized. We consider two cases: 1) all PoIs are placed along a straight line (linear case), and 2) all PoIs are arbitrarily placed on a plane (general 2-D case). Under the linear case, the optimal algorithm is presented. Under the general 2-D case, we prove the problem is NP-hard, and two algorithms, STSP and ITSP, are presented. We prove that the approximation ratio of STSP depends on the ratio between the sensing and transmission delay constraints. The ITSP can improve the solution much especially when the two delay constraints differ greatly for each PoI. Extensive simulation results are provided to evaluate our algorithms. © 2012 IEEE.


Han B.,Beijing University of Posts and Telecommunications | Wang W.,Beijing University of Posts and Telecommunications | Peng M.,Beijing University of Posts and Telecommunications
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2012

This paper investigates optimal resource allocation in orthogonal frequency division multiplexing (OFDM) based multiple two-way relay systems operating with analog network coding (ANC) protocol. We formulate a joint optimization problem considering power allocation, relay selection and subcarrier paring to maximize the sum capacity under individual power constraints on each node. By applying dual method, an unified optimization framework is provided and the problem is solved efficiently. Based on this framework, we further propose three suboptimal algorithms. The complexity of optimal algorithm (ORA) and three suboptimal algorithms are evaluated, and the analysis results show that the complexity of ORA is only a polynomial function of the number of subcarriers and relay nodes. Simulation results demonstrate that the proposed ORA scheme yields substantial performance improvement over baseline scheme, and suboptimal algorithms can achieve a trade off between performance and complexity. © 2012 IEEE.


Wang H.,Beijing University of Posts and Telecommunications | Ren W.,Beijing University of Posts and Telecommunications | Cui Y.,Beijing University of Posts and Telecommunications
Procedia Engineering | Year: 2012

In order to overcome effects of complex environment and movement on node tracking, and improve tracking precision further, a rough-set neural network-based adaptive tracking algorithm named rough-set adaptive interactive multi-modulus (RSAIMM) was proposed in which tracking filter based on neural network was employed. When target moved between maneuvering and non-maneuvering, rough-set neural network output adaptive feature value automatically online, to adapt to the movement with adequately accurate system variance and maintain high precision tracking of target state. Simulation results showed that compared with traditional interactive multi-modulus (IMM) tracking algorithm, tracking precision of RSAIMM algorithm was improved by 23.15%. © 2011 Published by Elsevier Ltd.


Yang Y.-G.,Beijing University of Technology | Xia J.,Beijing University of Technology | Jia X.,Beijing University of Technology | Zhang H.,Beijing University of Posts and Telecommunications
Quantum Information Processing | Year: 2013

A novel gray-level image encryption/decryption scheme is proposed, which is based on quantum Fourier transform and double random-phase encoding technique. The biggest contribution of our work lies in that it is the first time that the double random-phase encoding technique is generalized to quantum scenarios. As the encryption keys, two phase coding operations are applied in the quantum image spatial domain and the Fourier transform domain respectively. Only applying the correct keys, the original image can be retrieved successfully. Because all operations in quantum computation must be invertible, decryption is the inverse of the encryption process. A detailed theoretical analysis is given to clarify its robustness, computational complexity and advantages over its classical counterparts. It paves the way for introducing more optical information processing techniques into quantum scenarios. © 2013 Springer Science+Business Media New York.


Hu S.Q.,Beijing University of Posts and Telecommunications
Advanced Materials Research | Year: 2014

With the development of cloud-based data centers, cloud-based system has been widely used in many kinds of enterprises. Human resource management is an important issue in enterprise management.In this paper, we proposed a cloud based system for human resource management. Under the help of our design, the performance of the human resource management system can be improved apparently. In order to illustrate its superiority, we use some experiment to evaluate the proposed system. The experimental results indicated that the cloudy-based system would consume less memory and cpu resources while it has faster connection speed. © (2014) Trans Tech Publications, Switzerland.


Yang Y.-G.,Beijing University of Technology | Yang Y.-G.,Xidian University | Xia J.,Beijing University of Technology | Jia X.,Beijing University of Technology | Zhang H.,Beijing University of Posts and Telecommunications
Quantum Information Processing | Year: 2013

As an important branch of quantum cryptography, quantum private comparison (QPC) has recently received a lot of attention. In this paper we study the security of previous QPC protocols with a semi-honest third party (TP) from the viewpoint of secure multi-party computation and show that the assumption of a semi-honest TP is unreasonable. Without the unreasonable assumption of a semi-honest TP, one can easily find that the QPC protocol (Tseng et al. in Quantum Inf Process, 2011, doi: 10.1007/s11128-011-0251-0) has an obvious security flaw. Some suggestions about the design of QPC protocols are also given. © 2012 Springer Science+Business Media, LLC.


Chen J.,Beijing University of Posts and Telecommunications | Liu X.,Beijing University of Posts and Telecommunications
International Journal of Advancements in Computing Technology | Year: 2012

Sensor localization is one of the supporting technologies in wireless sensor networks. The paper introduces the localization process of sensor nodes of DV-Hop algorithm. DV-Hop is one of the rangefree localization algorithms using hop-distance estimate. Based on the characteristic of using average hop-distance to calculate the distance between nodes in DV-Hop algorithm, in order to reduce error grey correlation method is used to estimate average hop-distance. Simulation under MATLAB indicates that the improved DV-Hop algorithm outperforms the original DV-Hop algorithm and can provide more accurate location estimation.


Zhang W.-W.,Beijing University of Posts and Telecommunications | Zhang W.-W.,CAS Institute of Software | Gao F.,Beijing University of Posts and Telecommunications | Liu B.,Beijing University of Posts and Telecommunications | And 2 more authors.
Quantum Information Processing | Year: 2013

We present a robust watermark strategy for quantum images. The watermark image is embedded into the fourier coefficients of the quantum carrier image, which will not affect the carrier image's visual effect. Before being embedded into the carrier image, the watermark image is preprocessed to be seemingly meaningless using quantum circuit, which further ensures the security of the watermark image. The properties of fourier transform ensure that the watermark embedded in the carrier image resists the unavoidable noise and cropping. © 2012 Springer Science+Business Media, LLC.


Wang C.,Beijing University of Posts and Telecommunications | Zhang R.,Beijing University of Posts and Telecommunications | Zhang Y.,Beijing University of Posts and Telecommunications | Ma H.-Q.,Beijing University of Posts and Telecommunications
Quantum Information Processing | Year: 2013

This paper presents an entanglement purification protocol of multipartite electronic spin entangled state resorting to quantum-dot (QD) spin and micro cavity coupled system. The QD and microcavity coupling system is used to construct parity check detectors which provides a novel experimental platform of quantum information processing with photon and solid qubit. In this proposed protocol, the mixed multi-electron entangled state ensemble can be purified efficiently. © 2012 Springer Science+Business Media, LLC.


Zheng Z.,Chinese University of Hong Kong | Zheng Z.,Beijing University of Posts and Telecommunications | Zhou T.C.,Chinese University of Hong Kong | Lyu M.R.,Chinese University of Hong Kong | And 2 more authors.
IEEE Transactions on Services Computing | Year: 2012

Cloud computing is becoming a mainstream aspect of information technology. More and more enterprises deploy their software systems in the cloud environment. The cloud applications are usually large scale and include a lot of distributed cloud components. Building highly reliable cloud applications is a challenging and critical research problem. To attack this challenge, we propose a component ranking framework, named FTCloud, for building fault-tolerant cloud applications. FTCloud includes two ranking algorithms. The first algorithm employs component invocation structures and invocation frequencies for making significant component ranking. The second ranking algorithm systematically fuses the system structure information as well as the application designers' wisdom to identify the significant components in a cloud application. After the component ranking phase, an algorithm is proposed to automatically determine an optimal fault-tolerance strategy for the significant cloud components. The experimental results show that by tolerating faults of a small part of the most significant components, the reliability of cloud applications can be greatly improved. © 2008-2012 IEEE.


Zhang W.-W.,Beijing University of Posts and Telecommunications | Zhang W.-W.,CAS Institute of Software | Zhang K.-J.,Beijing University of Posts and Telecommunications
Quantum Information Processing | Year: 2013

Recently, a quantum private comparison (QPC) protocol with a dishonest third party (TP) (Yang et al. in Quantum Inf Process, 2012. doi: 10.1007/s11128-012-0433-4) was proposed, which pointed out that the assumption of semi-honest third party (TP) is unreasonable. Here we find this protocol is not so secure as it was expected, and then we give some improvement strategies, which ensure that both players' secrets will not be leaked to anyone. We also discuss the assumption for TP in QPC protocls, which gives a constructive suggestions for the design of a new QPC protocol. © 2012 Springer Science+Business Media New York.


Zhang K.-J.,Beijing University of Posts and Telecommunications | Zhang K.-J.,CAS Institute of Software | Zhang W.-W.,Beijing University of Posts and Telecommunications | Li D.,Beijing University of Posts and Telecommunications
Quantum Information Processing | Year: 2013

As a feasible model for signing quantum messages, some cryptanalysis and improvement of arbitrated quantum signature (AQS) have received a great deal of attentions in recent years. However, in this paper we find the previous improvement is not suitable implemented in some typical AQS protocols in the sense that the receiver, Bob, can forge a valid signature under known message attack. We describe the forgery strategy and present some corresponding improved strategies to stand against the forgery attack by modifying the encryption algorithm, an important part of AQS. These works preserve the merits of AQS and lead some potential improvements of the security in quantum signature or other cryptography problems. © 2013 Springer Science+Business Media New York.


Quan Q.,Beijing University of Posts and Telecommunications
IEEJ Transactions on Electrical and Electronic Engineering | Year: 2014

A closed-form expression for the position dilution of precision (PDOP) in absolute-range-based two-dimensional (2-D) wireless location systems is derived. Then, using the closed-form expression, the observation space (OS) required for achieving the lowest PDOP of 2/√N is studied, where N is the number of measuring points. The OS is measured by central angle of a sector which covers all measuring points. The target is located at the vertex of the sector. It is shown that, for achieving the lowest PDOP of 2/√N, the OS is