协同通信系统中基于遍历容量的近似最优功率分配  

Approximately optimum power allocation based on ergodic capacity for cooperative communication systems

作　　者：林霏[1,2] 罗涛[1] 路安琼[1] 乐光新[1] 

机构地区：[1]北京邮电大学电信工程学院,北京100876 [2]山东轻工业学院电子信息与控制学院,山东济南250353

出　　处：《通信学报》2009年第6期26-32,共7页Journal on Communications

基　　金：国家自然科学基金资助项目(60872049,60871042);国家高技术研究发展(“863”计划)基金资助项目(2007AA10Z235);教育部留学归国人员教学、科研建设基金资助项目~~

摘　　要：传统半双工放大转发(AF)协同通信无论信道状态如何,总是采用协同通信模式,在一定程度上降低了系统自由度的利用率。基于此研究了"何时协同"与最优发送功率分配的问题。首先给出了AF系统的遍历容量表达式及其上界;然后以遍历容量上界为代价函数,提出一种适用于AF系统的近似最优功率分配方案(AOPA),通过比较源—目的端与中继—目的端的统计信道增益来判定是否需要采用协同通信模式;最后,还分析了在中继端按随机方向模型移动时AOPA方案的性能。理论分析和仿真结果表明,AOPA方案在系统容量和误码差错性能上均要优于等功率EPA方案。Conventional half-duplex amplify-and-forward （AF） method always adopted cooperative communications model regardless the fading state of the channel, which made insufficient use of the degrees of freedom of the system in a way. So, the problem about ＂when to cooperate＂ and the optimum allocation of transmitted power were discussed. An exact ergodic capacity formulation and corresponding upper bound were first derived for a two-user AF cooperative communications system. And then an approximately optimum power allocation scheme （AOPA） was proposed by making use of the upper bound as cost function. Whether the AOPA scheme adopting the cooperative model or not based on the comparison about the channel gains of source-to-destination with that of relay-to-destination. Finally, the system performances were analyzed with AOPA scheme when the relay moved in terms of the random direction model. Theoretical analysis and simulation results show that the AOPA outperforms the EPA scheme both in ergodic capacity and symbol-error-rate（SER） performance.

关 键 词：协同通信 功率分配 遍历容量 误码率 随机方向模型 

分 类 号：TN929.5[电子电信—通信与信息系统]