We consider a two-way relay network where the Amplify-and-Forward (AF) protocol is adopted by all relays in this paper.The network consists of two multi-antenna source nodes and multiple distributed single-antenna rel...We consider a two-way relay network where the Amplify-and-Forward (AF) protocol is adopted by all relays in this paper.The network consists of two multi-antenna source nodes and multiple distributed single-antenna relays.Two opportunistic relaying schemes are proposed to efficiently utilize the antennas of the source nodes and the relay nodes.In the first scheme,the best relay is selected out by a max-min-max criterion before transmitting.After that,at each source,only the antenna with the largest channel gain between itself and the best relay is activated to transmit and receive signals with full power.In the second scheme,assisted by the best relay which is selected by the typical max-min criterion,both source nodes use all their antennas to exchange data,and match filter beamforming techniques are employed at both source nodes.Further analyses show that all schemes can achieve the full diversity order,and the conclusions are not only mathematically demonstrated but numerically illustrated.System performance comparisons are carried out by numerical methods in terms of rate sum and outage probability,respectively.The beamforming assisted scheme can be found to be superior to the antenna selection scheme when accurate Channel State Information (CSI) is available at the transmitters.Otherwise,the latter is very suitable.展开更多
To gain the tradeoff between lower sidelobe and higher power amplifiers efficiency,a transmitting beam shaping scheme with limited amplitude weight values for satellite active phased array antenna is presented. The sc...To gain the tradeoff between lower sidelobe and higher power amplifiers efficiency,a transmitting beam shaping scheme with limited amplitude weight values for satellite active phased array antenna is presented. The scheme is implemented by a dual coding genetic algorithm(GA). Phase and amplitude of array weight vectors for beam shaping are encoded by real coding and finite length binary coding,respectively,which,maintaining accuracy of results,reduces the amplitude dynamic range and improves the efficiency of power amplifiers. The presented algorithm,compared with complex-coded GA,increases the convergence rate due to the search space's decrease. In order to overcome the prematurity and obtain better global optimization or quasi-global optimization,a new dual coding GA based on "species diversity retention" strategy and adaptive crossover and mutation probability are presented.展开更多
Network coding (NC), which works in the network layer, is an effective technology to improve the network throughput, by allowing the relay to encode the information from different users and ensuring the destination to...Network coding (NC), which works in the network layer, is an effective technology to improve the network throughput, by allowing the relay to encode the information from different users and ensuring the destination to retrieve the desired information. Employing network coding technique in a cooperative network can improve the network performance further. In this paper, we introduce analog network coding (ANC) to a simple two-user cooperative diversity network, which adopts amplify-and-forward (AF) mode and all nodes use multiple antennas. The impact of the number of antenna on the system achievable rate is investigated. And the bit error rate (BER) performances of the traditional relay cooperative network and the cooperative network based on analog network coding under different propagation conditions are discussed. The simulation results show that the performance of the traditional cooperative network has improved significantly due to the employ of network coding.展开更多
论文研究了存在信道估计误差及天线相关条件下,上行多用户MIMO中继系统的预编码问题,目标是提升系统的误比特率性能。针对基于放大转发中继技术的上行多用户MIMO中继系统,考虑源-中继和中继-目的端信道中存在的信道估计误差及天线相关,...论文研究了存在信道估计误差及天线相关条件下,上行多用户MIMO中继系统的预编码问题,目标是提升系统的误比特率性能。针对基于放大转发中继技术的上行多用户MIMO中继系统,考虑源-中继和中继-目的端信道中存在的信道估计误差及天线相关,提出一种基于不完全信道状态信息(Channel State Information,CSI)的预编码设计方案。首先根据最小均方误差(Minimum Mean-Squared Error,MMSE)准则设计代价函数,以发射端和中继端最大功率为约束条件,通过理论推导求得中继端和发射端的线性预编码矩阵,最后采用迭代下降法得到接收端处理矩阵的闭式解。数值仿真结果表明,在存在信道估计误差和天线相关的条件下,与现有算法相比,所提算法能有效降低系统的误比特率。展开更多
基金supported by the National Natural Science Foundation of China under Grant No.60902092
文摘We consider a two-way relay network where the Amplify-and-Forward (AF) protocol is adopted by all relays in this paper.The network consists of two multi-antenna source nodes and multiple distributed single-antenna relays.Two opportunistic relaying schemes are proposed to efficiently utilize the antennas of the source nodes and the relay nodes.In the first scheme,the best relay is selected out by a max-min-max criterion before transmitting.After that,at each source,only the antenna with the largest channel gain between itself and the best relay is activated to transmit and receive signals with full power.In the second scheme,assisted by the best relay which is selected by the typical max-min criterion,both source nodes use all their antennas to exchange data,and match filter beamforming techniques are employed at both source nodes.Further analyses show that all schemes can achieve the full diversity order,and the conclusions are not only mathematically demonstrated but numerically illustrated.System performance comparisons are carried out by numerical methods in terms of rate sum and outage probability,respectively.The beamforming assisted scheme can be found to be superior to the antenna selection scheme when accurate Channel State Information (CSI) is available at the transmitters.Otherwise,the latter is very suitable.
基金The project supported by National Natural Science Foundation of China (No. 60572095)Research Foundation for Doctors of ZZULI
文摘To gain the tradeoff between lower sidelobe and higher power amplifiers efficiency,a transmitting beam shaping scheme with limited amplitude weight values for satellite active phased array antenna is presented. The scheme is implemented by a dual coding genetic algorithm(GA). Phase and amplitude of array weight vectors for beam shaping are encoded by real coding and finite length binary coding,respectively,which,maintaining accuracy of results,reduces the amplitude dynamic range and improves the efficiency of power amplifiers. The presented algorithm,compared with complex-coded GA,increases the convergence rate due to the search space's decrease. In order to overcome the prematurity and obtain better global optimization or quasi-global optimization,a new dual coding GA based on "species diversity retention" strategy and adaptive crossover and mutation probability are presented.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 60872016)
文摘Network coding (NC), which works in the network layer, is an effective technology to improve the network throughput, by allowing the relay to encode the information from different users and ensuring the destination to retrieve the desired information. Employing network coding technique in a cooperative network can improve the network performance further. In this paper, we introduce analog network coding (ANC) to a simple two-user cooperative diversity network, which adopts amplify-and-forward (AF) mode and all nodes use multiple antennas. The impact of the number of antenna on the system achievable rate is investigated. And the bit error rate (BER) performances of the traditional relay cooperative network and the cooperative network based on analog network coding under different propagation conditions are discussed. The simulation results show that the performance of the traditional cooperative network has improved significantly due to the employ of network coding.
文摘论文研究了存在信道估计误差及天线相关条件下,上行多用户MIMO中继系统的预编码问题,目标是提升系统的误比特率性能。针对基于放大转发中继技术的上行多用户MIMO中继系统,考虑源-中继和中继-目的端信道中存在的信道估计误差及天线相关,提出一种基于不完全信道状态信息(Channel State Information,CSI)的预编码设计方案。首先根据最小均方误差(Minimum Mean-Squared Error,MMSE)准则设计代价函数,以发射端和中继端最大功率为约束条件,通过理论推导求得中继端和发射端的线性预编码矩阵,最后采用迭代下降法得到接收端处理矩阵的闭式解。数值仿真结果表明,在存在信道估计误差和天线相关的条件下,与现有算法相比,所提算法能有效降低系统的误比特率。
