China Academy of Telecommunications Research

Beijing, China

China Academy of Telecommunications Research

Beijing, China
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Yang P.,China Academy of Telecommunications Research | Yang P.,Chongqing University of Posts and Telecommunications | Liu D.,Chongqing University of Posts and Telecommunications | Zhang Y.,China Academy of Telecommunications Research
International Journal of Antennas and Propagation | Year: 2014

Different from the traditional configuration of hierarchical cellular, we introduce the joint base-station multi-antenna multi-beam and channel assignment scheme for hierarchical cellular in this paper. The proposed scheme is based on multi-beam base-station antenna splitting in the elevation-radiating plane, and a dynamic channel allocation scheme by combining the adaptive antenna technologies. Simulation results showthat the proposed configuration of the hierarchical cellular can enhance the spectral efficiency remarkably. Copyright © 2014 Peng Yang et al.


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.


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.


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.


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.


Yang P.,China Academy of Telecommunications Research | Yang P.,Chongqing University of Posts and Telecommunications | Liu D.,Chongqing University of Posts and Telecommunications | Zhang Y.,China Academy of Telecommunications Research
2014 2nd International Conference on Systems and Informatics, ICSAI 2014 | Year: 2015

The limited network resources can be utilized effectively through the network coding method in Intermittent Connectivity Wireless Networks, but the number of coding nodes should be dynamically adjusted according to network status. To effectively improve the network resources utilization, a dynamical coding method is proposed. According to the estimated results of current network status, the number of required coding nodes can be determined with the distributed manner. Furthermore, in order to achieve reliable data forwarding with the lower overhead, the social property and available resources are considered during coding nodes selection. Results show that the connection opportunities between nodes can be exploited by our mechanism; moreover, the utilization of network resources can be optimized dramatically. © 2014 IEEE.


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.


Guo L.,Beijing University of Posts and Telecommunications | Guo L.,China Academy of Telecommunications Research | Sun C.,China Academy of Telecommunications Research | An X.,China Academy of Telecommunications Research | And 2 more authors.
2013 7th European Conference on Antennas and Propagation, EuCAP 2013 | Year: 2013

In the over the air (OTA) test for the multi-antenna devices, the validation of the multi-input multi-output (MIMO) channel model is critical which ensures that the device is tested under the desired channel environment. In this paper, we perform the validation for some of the key parameters in the MIMO channel, such as the power delay profile and the Doppler spectrum spread, within a multi-probe anechoic chamber. The measured results of these parameters correspond well with the theoretical values, which show that the channel environment in the chamber is qualified for the OTA test of multi-antenna devices. © 2013 EurAAP.


Yang P.,Chongqing University of Posts and Telecommunications | Yang P.,China Academy of Telecommunications Research | Liu D.,Chongqing University of Posts and Telecommunications | Wang R.-Y.,Chongqing University of Posts and Telecommunications | Yan J.-J.,Chongqing University of Posts and Telecommunications
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2015

In opportunistic networks, the node energy is limited and hard to recharge, and the energy consumption has a determinant impact on the network lifetime and performance. To solve the problem that socially popular nodes may quickly deplete their energy resources and consequently not participate in the routing process, the node activity and residual-energy are exploited to evaluate the comprehensive forwarding ability, and then an node residual energy balanced routing mechanism (NREB) for opportunistic networks is introduced. The NREB saves energy by rationally choosing the next-hop node to avoid unnecessary forwarding, which can also balance the network overhead. Simulation results show that the proposed mechanism can ensure the delivery ratio while balancing the energy consumption between nodes and thus to prolong the network lifetime. ©, 2015, Chinese Institute of Electronics. All right reserved.


Zhao S.,Beijing University of Posts and Telecommunications | Zhu X.,Beijing University of Posts and Telecommunications | Wang H.,China Academy of Telecommunications Research | Wu L.,University of Technology, Sydney
2013 International Conference on Wireless Communications and Signal Processing, WCSP 2013 | Year: 2013

The Orthogonal Frequency Division Multiplexing (OFDM) based system is highly sensitive to Radio Frequency (RF) impairments including phase noise and IQ imbalance at the receiver and High Power Amplifier (HPA) nonlinearity at the transmitter. In this paper, the theoretical characterization of the joint effects of these RF impairments on the performance of the OFDM system with QPSK and 16QAM modulations are presented. The theoretical models for the three RF impairments are derived individually and jointly. Furthermore, the Bit Error Rate (BER) as a function of the RF impairments parameters is formulated for the OFDM system over AWGN channels. The results indicate that phase noise, IQ imbalance and HPA nonlinearity strengthen each other when they are jointly evaluated. The average BER performance is inversely proportional to the RF impairments, and there exists a BER error floor when RF impairments are high. The close matching of the work presented in this paper with previous works confirm the validity of the proposed theoretical approach. © 2013 IEEE.

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