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Yang P.,China Academy of Telecommunications Research | Yang P.,Chongqing University of Posts and Telecommunications | Li X.,Chongqing University of Posts and Telecommunications | Liu D.,Chongqing University of Posts and Telecommunications
Xi'an Dianzi Keji Daxue Xuebao/Journal of Xidian University | Year: 2015

We present a packet scheduling algorithm to improve the performance of video traffic. By considering the number of packet loss and packet delay in the buffer, the priority of each user can be adjusted dynamically to reduce the packet loss rate and maximize the system throughput. The results show that, compared with the current typical packet scheduling algorithm, the proposed algorithm can significantly improve the packet loss rate, fairness, throughput and other performance. ©, 2015, Science Press. All right reserved. Source


Huang Q.,Beijing University of Posts and Telecommunications | Liu X.,China Academy of Telecommunications Research | Yang H.,Beijing University of Posts and Telecommunications
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2011

This paper studies the optimal power control which can maximize the information-theoretical sum rate of the uplink of multi-cell, multi-user cellular systems equipped with successive interference cancelation (SIC). One important property for the optimal power control is presented: for the optimal power allocation, there will be at least one user transmitting at peak power in the system, and at most one user transmitting at part of the peak power in each cell. With this property, the peak throughput for multi-cell, multi-user cellular systems can be approached by simulated annealing algorithm. System level simulations show that the gain of SIC highly depends on the distribution of users. When users distribute uniformly in multi-cell cellular system, the gain of SIC is not obvious. © 2011 IEEE. Source


Zhu X.,Beijing University of Posts and Telecommunications | Li W.,Beijing University of Posts and Telecommunications | Feng C.,Beijing University of Posts and Telecommunications | Wang H.,China Academy of Telecommunications Research
Proceedings of 2nd International Conference on Computer Science and Network Technology, ICCSNT 2012 | Year: 2012

Carrier aggregation (CA) is one of the most distinct techniques of Long Term Evolution-Advanced (LTE-Advanced) system because of its capability to support wide bandwidth while guaranteeing backward compatibility. In this paper, adjacent channel interference at user equipment (UE) in LTE-A system with CA is investigated. Due to the characteristics of orthogonal frequency division multiplexing (OFDM), slight variation of the frequency spacing between component carriers (CCs) and the adjacent channel interferer (ACI) results in different interference levels. This paper analyzed the impact of frequency spacing between CA signal and the ACI on the interference level. Moreover, utilizing the frequency response model of the Chebyshev filter, the relationship between the interference-resistance capability of LTE/LTE-A UE and the bandwidth of the receiver filter is studied. With the practical LTE-A system parameters, link level simulation results and the theoretical analysis match pretty well, and the analysis provide some guidelines for the UE design and standardization study of LTE-A. © 2012 IEEE. Source


Huang Q.,Beijing University of Posts and Telecommunications | Liu X.,China Academy of Telecommunications Research | Yang H.,Beijing University of Posts and Telecommunications
IEEE Vehicular Technology Conference | Year: 2012

This paper studies the uplink information-theoretical sum capacity of single cell, multi-user cellular systems with minimum SINR constraint. The uplink of single cell multiuser systems is interference limited. If one user increases its transmission power, it will bring more interference to other users. Therefore, power control should be used to balance all users' transmission power. To achieve the maximum system capacity, the optimal power allocation schedules users according to their link gains, which will lead to unfair problem. In order to avoid this problem, a QoS constraint in the form of minimum SINR constraint could be introduced. In previous works, some properties of the optimal allocation under this constraint have been found. However, it is still difficult to get the optimal power allocation. In this paper, we have found some new mathematical properties of the optimal power allocation, and based on these properties, the algorithm for getting the optimal power allocation is proposed. Numerical results are also presented to show the effects of minimum SINR constraint on system capacity. © 2012 IEEE. Source


Huang Q.,Beijing University of Posts and Telecommunications | Liu X.,China Academy of Telecommunications Research | Yang H.,Beijing University of Posts and Telecommunications
2012 International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2012 | Year: 2012

This paper investigates the information-theoretical capacity of the Max-SNR multi-user diversity system with quantized channel state information(CSI) under slow fading channels. General optimal quantization problems under the condition with or without transmit power control are derived. Numerical results show that the capacity with 4 bits optimal quantization is almost enough to approach that of infinite quantization. For fewer quantization bits, both the capacity loss due to quantization and the gain of power control increase with the number of system users. © 2012 IEEE. Source

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