窃听双向协作网络机会中继选择方案的保密性能分析

Secrecy performance analysis of opportunistic relay selection for the wiretap two-way cooperative networks

对于多中继、窃听双向协作网络,研究使用机会中继选择和模拟网络编码技术来增强窃听系统物理层安全性。具体地,窃听双向协作网络的通信过程共3个时隙。第1和第2时隙,两信源分别发送消息到中继节点;第3时隙,根据最大最小中继选择方案,选取一个成功解码两信源消息的中继节点。使用模拟网络编码技术将两信源消息混合,把混合消息广播给两信源。分析了最大最小中继选择方案,推导出该方案保密中断概率的闭式表达式。对最大最小中继选择方案进行渐近分析,并求得该方案的保密分集阶数等于中继节点的个数。仿真结果表明,最大最小中继选择方案的保密中断概率随中继节点数增加而迅速减小。

For multi-relay and eavesdropping two-way cooperative networks, opportunistic relay selection and analog network coding technology are studied to enhance the physical layer security of eavesdropping system. The communication between the two sources of the wiretap two-way cooperative relay network consists of three phases. In the first/second phase, a source transmits a message to the relays. In the third phase, the max-min opportunistic relay selection scheme is proposed to mitigate the eavesdropping attacks. Specifically, a relay who can successfully decode the source messages is selected. Then, the selected relay combines the obtained source messages with each other by the analog network coding, and broadcasts the mixed message to the sources. We analyze the secrecy performance of the max-min relay selection scheme, and derive closed-form expression of the secrecy outage probability for proposed relay selection. To gain further insight into the secrecy performance of the max-min relay selection scheme, we conduct an asymptotic analysis of the considered opportunistic relay selection and show that the secrecy diversity order of the max-min relay selection scheme is equal to the number of relays. Numerical results indicate that the secrecy outage probability can be significantly decreased by increasing the number of relays.