协作发射分集系统及其误码性能分析

协作分集（cooperative diversity）技术通过使网络中各单天线用户共享彼此天线，形成虚拟的多天线阵列来实现发射或接收分集，并结合一定的编码方式，可以有效地提高系统性能。多载波码分多址（MC-CDMA，multi．carder code division multiple access）技术将数据调制到各个子载波上发送，可以有效地抵抗信道频率选择性衰落的影响。由此提出了无线网络中频率选择性衰落信道环境下的一种基于分布式空时分组码（DSTBC，distributed space tim eblock code）和MC-CDMA的协作发射分集方案，建立了协作用户间的误码表示模型，基于该模型推导了在协作条件下整个系统误码性能的理论表达式。分析了协作用户间的平均解码差错概率对系统误码性能的影响，并给出了仿真结果。结果表明，本系统相对于未编码的MC-CDMA系统获得了明显的性能增益，同时仿真也较好地验证了理论结果。

BER performance analysis of a cooperative transmit diversity system

A novel cooperative diversity system combined with distributed space-time block code and multi-carrier code division multiple access(DSTBC-MC-CDMA) techniques was proposed,which works well in multi-user wireless net-works with single-antenna users in frequency selective fading channels.And an analytical model was established to simulate the symbol decoding error between interusers,based on which,a close form expression for theoretical bit error rate(BER) performance of the system was derived.Then the simulation was done to versify the analytic results above,and the simulation also shows that the BER performance of DSTBC-MC-CDMA outgoes non-cooperative MC-CDMA with distinctive gains.Furthermore,the simulation results coincide with the theoretical results well.