基于最优波束成型的中继增强型无线通信系统的性能分析

Performance Analysis of Optimal Beamforming in Relay-enhanced Wireless Communication Systems

考虑一对多天线的信源信宿通过一个单天线的放大前传(AF)中继辅助通信的两跳半双工无线网络。假设通信终端完全获知信道状态信息(CSI)。该文提出了该中继系统的最优波束成型方案,然后对采用此方案时的系统接收信噪比作高SNR下的统计特性分析,推导出瑞利平衰落信道下系统的遍历容量上界和平均误符号率(ASEP)的闭合表达式,并得出相应的分集度和阵列增益。理论分析结果显示了系统性能与天线数和发射功率的确切关系,并且在高SNR时不同的调制方式不影响分集度,只改变阵列增益。蒙特卡罗(MonteCarlo)数值仿真结果验证了理论分析的正确性。

This paper investigates the Multiple-Input Multiple-Output （MIMO） wireless communication assisted by an Amplify-and-Forward （AF） relay with single antenna in a two-hop and half-duplex relaying network.The system model is under the assumption of the perfect Channel State Information （CSI） at all the terminals.An optimum beamforming scheme is presented for this AF relaying system to maximize the received Signal-to-Noise Ratio （SNR）.The statistics of the output SNR in this scheme is characterized at high SNR over Rayleigh fading channels.Based on the statistical results,the explicit closed-form expressions are derived for the upper bound on the ergodic capacity,the Average Symbol Error Probability （ASEP）,the diversity order and the array gain of this system.It is proved from the expressions that the system performance is dominated by the number of the antennas and the transmitting power.It is also shown that various modulation modes have no impact on the diversity gain but influence the array gain especially in high SNR.The theoretical analysis is validated through comparison with Monte Carlo simulations.