相关瑞利信道下差分空时检测协同分集方案

A Cooperative Diversity Scheme Based on Differential Space-Time Codes for Correlated Rayleigh Channels

本文提出了一种采用分布式差分空时分组编码和检测的协同分集方案,在不需要信道状态信息(CSI)的情况下可以实现满分集和全速率发射,并推导了相关瑞利信道下该方案误码率(BER)性能上限的解析表达式。传统的差分空时分组编码对整个码块进行差分,而协同分集下的任何一个协同用户进行差分编码时都不知道整个码块的信息。本文所提出的差分BPSK调制方案,通过将两协同用户的信息分别被调制到相互正交的实轴和虚轴上,从而将码块的联合差分转化为各用户独立差分。分析了在协同用户间不同的信道状态信息(CSI)和协同用户到接收用户不同的CSI情况下本文所提出发射方案的性能。仿真结果表明本文所提出的方案获得了明显的分集增益,同时也较好的吻合了理论分析的结果。

In this paper,a novel cooperative diversity protocol with distributed differential space-time block coding is presented which can achieve full diversity with full rate with no need of channel state information （CSI）. A close form expression for bit error rate （BER） of the proposed scheme is derived for temporal correlated Rayleigh channels without considering the decoding errors between interusers. In traditional differential space-time block coding scheme, difference is done on each whole block. As to distributed cooperative diversity scheme, traditional difference is not practical for the perfect information of the block is unknown to each user when to be differential encoded. In the proposed differential modulation scheme ,the information of the two cooperative users is modulated to orthogonal real axes and image axes. This degrades joint block difference to independent difference, which makes the full rate transmission possible. The proposed transmission scheme is analyzed for different channels of interusers and channels from cooperative users to destination. Nu- merical results show that the proposed scheme gets distinct diversity gain and coincides with the analytical results well.