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Li B.,Beijing University of Posts and Telecommunications | Li Y.,Key Laboratory of Universal Wireless Communications | Wang S.,Key Laboratory of Universal Wireless Communications
Proceedings of 2016 4th IEEE International Conference on Cloud Computing and Intelligence Systems, CCIS 2016 | Year: 2016

The Internet of Things (IoT) is the most important trend of network service in future; therefore, the variety of IoT is developed rapidly. The AllJoyn is an emerging technology with many features, which have accelerated the Internet of Things coming to life. In this paper, the key workflows of centralized gateway are proposed based on the AllJoyn technology including equipment registration, user registration and user assignments, device linkage modes switch, the security mechanism of device linkage, multiple gateways scenarios. All the proposed workflows make the AllJoyn service more useful and convenient to smart home field. © 2016 IEEE.


Li X.,Beijing University of Posts and Telecommunications | Li X.,Key Laboratory of Universal Wireless Communications | Lv D.,Tianjin University of Technology | Chen K.,Tianjin University of Technology
Journal of Non-Crystalline Solids | Year: 2012

This paper reports effects of graphite additive on dielectric properties and microwave absorption performances of zinc-containing foam glasses. Changes of pore structure of porous glass are analyzed. One-dimensional zinc oxide crystal whiskers on walls of foam glass are observed. With the graphite additive increases, both real (ε′) and imaginary (ε″) parts of complex permittivity increase from ∼ 3.25 and ∼ 0.2 to ∼ 7.5 and ∼ 2.8, respectively. Microwave reflection loss of porous glass was calculated based on the permittivity in the range of 8.2-12.4 GHz(X-band). Reflection loss of foam glass decreases as graphite additive and the sample with 2.0 wt% graphite additive achieve reflection loss less than - 10 dB in whole X-band with thickness ranging from 2.3 to 3.5 mm. Linear relation between reduction of reflectivity and increase of graphite content is achieved. The results show that changing foaming agent additive is an efficient way to design dielectric and microwave absorption properties of foam glass. Foam glass with 1.0 wt% graphite additive may find application in photocatalytic degradation of many environmental pollutants due to its considerable zinc oxide whiskers. © 2012 Elsevier B.V. All rights reserved.


Peng-Ren D.,Beijing University of Posts and Telecommunications | Can Z.,Key Laboratory of Universal Wireless Communications
Proceedings of the 2014 9th International Conference on Communications and Networking in China, CHINACOM 2014 | Year: 2015

Cloud radio access network (C-RAN) is a next generation wireless access network architecture. In this architecture, common public radio interface (CPRI) links are widely used to transmit baseband signals. Currently, one of the great technical challenges for the C-RAN architecture is the soaring CPRI bandwidth required for data transmission between remote radio unit (RRU) and baseband unit (BBU). In this paper, we propose a novel compression method that exploits the temporal and spectral features of baseband signals, which can achieve high compression ratio (3.56x) and low latency (3.4usec) with limited impact on end-to-end communication performance (error vector magnitude <1.89%). We use a combination of reducing signal sampling, digital automatic gain control, Lloyd-Max quantization and cyclic prefix replacement to compress LTE uplink and downlink signals. Upon verifying the feasibility and validity of the algorithm, we implement the design with field programmable gate array (FPGA) resources. © 2014 IEEE.


Du G.,Key Laboratory of Universal Wireless Communications | Zou W.,Beijing University of Posts and Telecommunications | Zhou Z.,Nanjing Southeast University
Lecture Notes in Electrical Engineering | Year: 2016

This paper explores multifrequency channel interference alignment (IA) system with single data stream transmit for each user. This paper first proves that aM frequency independent fading channels and 2M − 2 users IA system will have only single optimal IA solution when the transmit signal power reduce to 0. Then based on this idea, and by derivation of the sum rate gradient function, this paper proposes gradient ascend with power increase method to search interference alignment solution. At last, the numerical simulation results show that the proposed method will obtain a better network sum rate performance than the classical maximum signal to interference plus noise (Max-SINR) algorithm and minimum interference leakage (Min-IL) algorithm. © Springer-Verlag Berlin Heidelberg 2016.


Xu W.,Beijing University of Posts and Telecommunications | Xu W.,University of Alberta | Zhang J.,Key Laboratory of Universal Wireless Communications | Zhang P.,Key Laboratory of Universal Wireless Communications | Tellambura C.,University of Alberta
IEEE Communications Letters | Year: 2012

In the presence of the primary user's interference, the outage probability of a dual-hop decode-and-forward (DF) cognitive relay network (CRN) over Rayleigh fading channels is investigated. We first derive the exact expression for the outage probability, using which the impact of different system parameters on the outage performance is presented in the asymptotic regimes. In addition, the asymptotic outage probability is also derived in the high signal-to-noise ratio (SNR) regime. © 1997-2012 IEEE.


Xu W.,Beijing University of Posts and Telecommunications | Zhang J.,Key Laboratory of Universal Wireless Communications | Zhang P.,Key Laboratory of Universal Wireless Communications
IEEE Transactions on Vehicular Technology | Year: 2012

The exact asymptotic symbol error rate (SER) for cognitive ratio systems with maximum ratio combining (MRC) considered by Li is derived, which circumvents the precondition requirement in the derivation made by Li. Monte Carlo simulations validate the theoretical analysis. © 1967-2012 IEEE.


Xu W.,Beijing University of Posts and Telecommunications | Zhang J.,Key Laboratory of Universal Wireless Communications | Zhang P.,Key Laboratory of Universal Wireless Communications
IEEE Communications Letters | Year: 2011

In this letter, we investigate the outage performance of a two-hop fixed-gain relay system in the presence of multiple unequal-power Rayleigh interference at both relay and destination. The closed-form expression for the outage probability is derived. We also show that the equal-power interference at the relay and destination leads to the worst outage performance. © 2011 IEEE.


Lei L.,Beijing Jiaotong University | Zhong Z.,Beijing Jiaotong University | Zheng K.,Beijing University of Posts and Telecommunications | Chen J.,Beijing University of Posts and Telecommunications | And 3 more authors.
IEEE Wireless Communications | Year: 2013

Mobile cloud computing (MCC) is an appealing paradigm enabling users to enjoy the vast computation power and abundant network services ubiquitously with the support of remote cloud. However, the wireless networks and mobile devices have to face many challenges due to the limited radio resources, battery power and communications capabilities, which may significantly impede the improvement of service qualities. Heterogeneous Network (HetNet), which has multiple types of low power radio access nodes in addition to the traditional macrocell nodes in a wireless network, is widely accepted as a promising way to satisfy the unrelenting traffic demand. In this article, we first introduce the framework of HetNet for MCC, identifying the main functional blocks. Then, the current state of the art techniques for each functional block are briefly surveyed, and the challenges for supporting MCC applications in HetNet under our proposed framework are discussed. We also envision the future for MCC in HetNet before drawing the conclusion. © 2013 IEEE.


Liu H.,Key Laboratory of Universal Wireless Communications | Hu Z.,Key Laboratory of Universal Wireless Communications | Haddadi H.,Queen Mary, University of London | Tian H.,Key Laboratory of Universal Wireless Communications
EPL | Year: 2013

Link prediction has been widely used to extract missing information, identify spurious interactions, evaluate network evolving mechanisms, and so on. In this context, similarity-based algorithms have become the mainstream. However, most of them take into account the contributions of each common neighbor equally to the connection likelihood of two nodes. This paper proposes a model for link prediction, which is based on the node centrality of common neighbors. Three node centralities are discussed: degree, closeness and betweenness centrality. In our model, each common neighbor plays a different role to the node connection likelihood according to their centralities. Moreover, the weak-tie theory is considered for improving the prediction accuracy. Finally, extensive experiments on five real-world networks show that the proposed model can outperform the Common Neighbor (CN) algorithm and gives competitively good prediction of or even better than Adamic-Adar (AA) index and Resource Allocation (RA) index. © Copyright EPLA, 2013.


Wang Y.,Key Laboratory of Universal Wireless Communications | Zhang J.,Key Laboratory of Universal Wireless Communications | Zhang P.,Key Laboratory of Universal Wireless Communications
IEEE Communications Letters | Year: 2013

This letter addresses the joint subcarrier and power allocation problem in downlink multiuser OFDM cooperative networks. The sum of the logarithmic per user time-averaged bits-per-Joule is maximized. The optimization problem is decomposed into two subproblems. First, the solution for the subcarrier allocation considering the proportional fairness is obtained. Second, an alternating power allocation (PA) scheme with separate transmit power constraints at the source and relays is derived under frequency selective fading channels. Then the complexity of the proposed scheme is analyzed. Finally, numerical results present the convergence, energy efficiency and outage probability performance of the proposed scheme. © 2013 IEEE.

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