放大转发认知中继协作系统中继增益分配方案和性能分析

Relay Gain Allocation Scheme and Performance Analysis of Cognitive Relay Systems with Amplify-and-Forward Protocols

由于在传统的放大转发认知中继协作方案中,中继增益因子的分配只考虑了部分主、从系统参数,使得系统的能量效率较低、系统资源未被充分利用。为此,基于主系统传输速率约束和从系统终端接收信号平均误符号率最小准则,文章提出了一个新颖的中继增益最优化分配方案,获得了中继增益最优化精确解以及相应的上、下限封闭解析解;并基于获得的最优化中继增益,分析了系统的平均误符号率。结果表明,文章所获得的中继增益因子分配方案由于不仅考虑了从信源功率和从信源-中继链路增益,而且还综合考虑了中继-从信宿链路和主系统参数,可以实现系统资源的最优化配置,系统性能得到改善。

Due to the fact that in traditional relay gain allocation（ RGA） schemes only the partial system parameters are included,the energy efficiency of cognitive relay systems is very low. To improve the performance of amplify-and-forward（ AF） relay cooperation cognitive radio（ AF-R-CR）,a novel RGA scheme is proposed firstly,which is based on the capacity constraint of primary systems and the average symbol error ratio（ SER） minimization of secondary systems. Then,for the proposed RGA scheme,we obtain the exact optimization relay gain（ amplifier factor） as well as the corresponding lower and upper bounds that are given in closed-form expressions. Finally,based on the achieved optimization RGA scheme,the average SER of the considered AF-R-CR systems is derived. The derivations show clearly that in the proposed RGA the effect of the secondary source-relay links and the transmit power of the secondary source is considered,but also the one of the secondary relay-destination links and the parameters of primary systems. This yields the system resources exploited in an effective means,and the system performance improved greatly.