Time filter

Source Type

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.

Wang T.,State Radio Monitoring Center | Huang B.,State Radio Monitoring Center | Wang Y.,Beijing University of Posts and Telecommunications
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2013

Cellular structures are to be enhanced by heterogeneous deployments. One type of such deployments is to add outdoor pico evolved NodeBs (PeNBs), formulating a hierarchical cell structure with macro eNBs (MeNBs). The cell selection in such system is facing challenges, including problems of coverage and cross interference. One method is called cell range expansion (RE), typically in which a common fixed bias value is added to the users' receiving signal power from PeNBs to adjust their coverage. However, it might not be appropriate to use the same bias for all the PeNBs. This paper focus on the specific bias design. By defining the interfered region, it proposes a mechanism to obtain the average interference suffered by each PeNB. The interference is from MeNBs with sector antennas and other randomly located PeNBs. In the discussion, it is further pointed out that its implementation follows a self-organized manner, with sustainable signalling overhead. Simulation results show that the proposed method achieves much better cell edge performances than those with fixed bias values. © 2013 IEEE.

Mei Y.,Beijing Jiaotong University | Liu L.,Georgia Institute of Technology | Pu X.,State Radio Monitoring Center | Sivathanu S.,Georgia Institute of Technology | Dong X.,Xi'an University of Science and Technology
IEEE Transactions on Services Computing | Year: 2013

Server consolidation and application consolidation through virtualization are key performance optimizations in cloud-based service delivery industry. In this paper, we argue that it is important for both cloud consumers and cloud providers to understand the various factors that may have significant impact on the performance of applications running in a virtualized cloud. This paper presents an extensive performance study of network I/O workloads in a virtualized cloud environment. We first show that current implementation of virtual machine monitor (VMM) does not provide sufficient performance isolation to guarantee the effectiveness of resource sharing across multiple virtual machine instances (VMs) running on a single physical host machine, especially when applications running on neighboring VMs are competing for computing and communication resources. Then we study a set of representative workloads in cloud-based data centers, which compete for either CPU or network I/O resources, and present the detailed analysis on different factors that can impact the throughput performance and resource sharing effectiveness. For example, we analyze the cost and the benefit of running idle VM instances on a physical host where some applications are hosted concurrently. We also present an in-depth discussion on the performance impact of colocating applications that compete for either CPU or network I/O resources. Finally, we analyze the impact of different CPU resource scheduling strategies and different workload rates on the performance of applications running on different VMs hosted by the same physical machine. © 2013 IEEE.

Chang L.,State Radio Monitoring Center | Ye Li G.,Georgia Institute of Technology | Li J.,State Radio Monitoring Center
IEEE Transactions on Vehicular Technology | Year: 2016

Estimation of signal-to-noise ratio (SNR) plays an important role in many fields of communications. This paper addresses the SNR estimation of multiple phase-shift keying (MPSK) signals in Nakagami-m fading channels. A family of SNR estimators with closed-form expressions is developed based on the relationship among different orders of moments. Compared with the existing algorithms, the estimator, which exploits theminimum order of moments, exhibits the best performance in general. We also propose a joint estimation algorithm for SNR and the fading factor when it is unknown. Simulation results verify the feasibility and superiority of the proposed algorithms. © 2015 IEEE.

Li R.,State Radio Monitoring Center | Li J.,Center for Monitoring Research
2014 2nd International Conference on Systems and Informatics, ICSAI 2014 | Year: 2015

With the rapid development of wireless technologies and rising demand for high speed multimedia applications, a variety of wireless communication networks have been deployed in the same geographic region to provide seamless services. The coexistence of these networks makes the electromagnetic spectrum environment extraordinary complex and irregular, thus bringing in great difficulty for spectrum monitoring. However, the existing monitoring mechanisms mainly concentrate on local monitoring issues, allowing individual stations to communicate and exchange data with each other to achieve ideal performance. In these mechanisms, the decision making of monitoring stations relies on the information transmitted by other stations. If the information is incorrect, the overall system performance will be affected. Moreover, the monitoring stations merely pay attention to a limited amount of data, with no consideration of massive data from global network, thus the decisions may be one-sidedness. To solve the global monitoring problem within time-varying environment and supervise the behavior of transmitting stations in an efficient way, a clouds based spectrum monitoring approach is proposed. The approach enables sensor nodes to directly transmit monitoring data to the clouds. And then it handles the multi-dimensional data with advanced cloud computing technique with great flexibility and extensibility. Simulation results show that the clouds based monitoring approach can greatly reduce the overhead of communication links than the traditional monitoring network. © 2014 IEEE.

Li M.,State Radio Monitoring Center | Wang D.,China Unicom
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

This paper mainly presents the indoor coverage performance and time delay comparison between IEEE 802.11g and IEEE 802.11 ah of wireless sensor node in Machine to Machine(M2M)network. Firstly, three key problems about the development of M2M network are proposed in order to bring out why IEEE chooses to release IEEE 802.11ah standard and its current situation and tendency. And also, we simply introduce the standard of IEEE 802.11g. Secondly, the paper illustrates the indoor coverage performance and time delay comparison of wireless sensor nodes according to different indoor path loss models respectively for Sub 1GHz and 2.4GHz ISM band. And numeral simulation results and simulation results are respectively offered to depict sensor nodes' coverage and the time delay. © 2014 Springer International Publishing Switzerland.

Wu Y.,State Radio Monitoring Center | Niu L.,State Radio Monitoring Center
2015 IEEE 6th International Symposium on Microwave, Antenna, Propagation, and EMC Technologies, MAPE 2015 | Year: 2015

First of all, this paper analyzes the short baseline interferometer direction finding and gets the shortcoming of this direction finding. As the following, the paper analyzes the long/short baseline direction finding and the direction finding based on L array. After, we give the analysis of the circular array interferometer direction finding and the theory of antenna array. At the end, we make a test of this direction finding. © 2015 IEEE.

Wu Y.,State Radio Monitoring Center | Huang W.,State Radio Monitoring Center
2015 IEEE 6th International Symposium on Microwave, Antenna, Propagation, and EMC Technologies, MAPE 2015 | Year: 2015

This paper makes a test of the near field of the unmanned aerial vehicle's (UAV) radiation at the semi-anechoic chamber and analyses the characteristic of the UAV's radiation and the band of the radiation. A electric short dipole charges' near field is simulated and analyzed. At last, this paper tests the UAV's near field at the open area test side, and obtains the distribution of magnetic field. The greatest distance of the radiation is obtained by analyzing the results. © 2015 IEEE.

Li M.M.,State Radio Monitoring Center | Yang W.H.,State Radio Monitoring Center
Applied Mechanics and Materials | Year: 2014

This paper mainly presents Access Point s' (APs') performance according to 802.11g standard. Our study illustrates the performance of one AP, including its coverage performance, load-carrying properties and fairness. Performance analyses are evaluated by simulation for a dense wireless network. Our contribution is that the simulation and test results can be the basis offered to network operators. © (2014) Trans Tech Publications, Switzerland.

Chuanan C.,State Radio Monitoring Center | Lulu L.,Sichuan Radio Monitoring Station
Proceedings - 2015 7th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2015 | Year: 2015

According to the current situation that the existing electromagnetic signal visualization can only be applied in part of the spacial scale of middle or low latitude on earth, this paper built a earth shell space grid model applied to describing the environment of terrestrial space through employing the method of QTM sphere octree subdivision to subdivide the three-dimensional space of earth shell space on account of the earth shell space grid theory. And the paper utilized model to improve the ray casting arithmetic based on GPU as it seeks to reduce the memory of the whole gradient and raise the draw efficiency effectively. Based on the foundation above, the paper implemented the calculation of electromagnetic signal's form, field intensity and visualization by approaching the circular cone to signal beam and applying the certain propagation forecasting methods, which has the practical application value. © 2015 IEEE.

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