This letter studies secure communications in a full-duplex relay (FDR) network when an eavesdropper overhears communications between legitimate parties. In a FDR network, both the amplify-and-forward relay and the destination operate in full-duplex for the purpose of achieving a higher secrecy rate and/or improving security. In particular, the destination is capable of receiving the relayed signal and simultaneously emitting a cooperative jamming signal. This work is motivated by an intriguing question: how much residual self-interference (SI) in a FDR network is allowed to achieve a superiority of secrecy performance over conventional half-duplex relay (HDR) networks? To answer the question, the secrecy outage probability (SOP) of the FDR network is derived as a function of residual SI. The analytic results enable us to compare the SOPs of existing HDR networks and the FDR network at various levels of residual SI. In addition, this work allows one to opportunistically select either FD or HD, which leads to a significant performance improvement.

中文翻译：

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在残余自干扰下与全双工中继网络进行安全通信

这封信研究了当窃听者偷听合法方之间的通信时全双工中继 (FDR) 网络中的安全通信。在 FDR 网络中，为了实现更高的保密率和/或提高安全性，放大转发中继和目的地都以全双工方式运行。特别地，目的地能够接收中继信号并同时发射协同干扰信号。这项工作的动机是一个有趣的问题：允许 FDR 网络中多少残余自干扰 (SI) 实现优于传统半双工中继 (HDR) 网络的保密性能？为了回答这个问题，FDR 网络的保密中断概率 (SOP) 被推导出为剩余 SI 的函数。分析结果使我们能够比较现有 HDR 网络和 FDR 网络在各种残余 SI 水平下的 SOP。此外，这项工作允许人们机会性地选择 FD 或 HD，从而显着提高性能。