解码转发中继选择系统的安全性能分析

Security performance analysis of DF relay selection systems

本文研究源节点与中继节点发送的信号均能被窃听时,多中继自适应解码转发(decode-andforward,DF)系统的安全性能.根据信道状态信息是否可知,分析最优中继选择(optimal relay selection,ORS)、传统中继选择(conventional relay selection,CRS)和多中继选择(multiple relays selection,MRS)3种方案的安全性能,推导出3种方案安全中断概率的解析表达式.通过渐进性能分析,得到了3种方案的安全分集增益和安全分集阶数.仿真结果验证了理论研究的正确性,并分析得到不同参数对系统安全性能的影响.结果表明多中继场景中,ORS方案对系统的安全性能提升最为明显,3种方案的安全分集阶数相同且均与中继个数有关,窃听信道参数只对系统安全分集增益有影响.最后,给出了系统最佳功率分配方法.

In this work, we investigate the security performance of adaptive decode-and-forward cooperative networks when the signals transmitted from source and relay would be wiretapped. Based on whether the channel state information（CSI） of the wiretap link is available or not, optimal relay selection（ORS）, conventional relay selection（CRS）, and multiple relays selection（MRS） schemes are considered, and the exact closed-form expressions for security outage probability（SOP） are derived. Besides, we obtain the closed-form expressions for the secrecy diversity order and secrecy array gain of the three different selection schemes through asymptotic analysis. Simulations are presented to validate the accuracy of our proposed analytical results and illustrate that ORS is the best scheme. Furthermore, asymptotic analysis reveals that the secrecy diversity order of each scheme is the same and closely related to the number of relays. The impact of the wiretap channels is only reflected in the secrecy array gain. Finally, we determine the optimal power allocation between the source and relay.