Abstract This paper analyzes the physical layer secrecy (PLS) performance of a hybrid free space optical and radio frequency (FSO/RF) communication system under a modified selection combining scheme. The transmission scheme takes into account secrecy performance as well as diversity gain and ease of implementation. The effects of FSO link, namely the FSO atmospheric turbulence and the FSO receiver pointing error, are included in the analysis while the power amplifier (PA) inefficiency for the RF transmission is considered to have more realistic understandings on the system performance. The exact analytical expressions for the performance indicators including the average secrecy capacity (ASC) and secrecy outage probability (SOP) of the investigated mixed FSO/RF system are derived. The asymptotic SOP analysis reveals useful insights into the performance of the investigated mixed system. Analytical and simulation results are presented to evaluate the PLS performance of the proposed mixed system as well as to compare the performance of other hybrid systems with different setups.

中文翻译：

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具有并行 FSO 通信链路的射频回程系统的保密增强

摘要 本文分析了一种改进的选择合并方案下混合自由空间光和射频（FSO/RF）通信系统的物理层保密（PLS）性能。传输方案考虑了保密性能以及分集增益和易于实施。FSO 链路的影响，即 FSO 大气湍流和 FSO 接收机指向误差，都包含在分析中，而射频传输的功率放大器 (PA) 效率低下被认为对系统性能有更现实的理解。推导出了所研究混合FSO/RF系统的平均保密容量（ASC）和保密中断概率（SOP）等性能指标的精确解析表达式。渐近 SOP 分析揭示了对所研究混合系统性能的有用见解。分析和仿真结果用于评估所提出的混合系统的 PLS 性能以及比较具有不同设置的其他混合系统的性能。