We investigate the physical-layer security performance for a wireless-powered relaying mixed free-space optical-radio frequency (FSO-RF) system. In this system, a source transmits optical information to a relay (R), which decodes the received signal with a decode-and-forward protocol, converts it into an RF signal, and forwards it to a destination in the presence of an eavesdropper. Furthermore, we also assume that R has no extra power supply, and it only relies on harvesting energy from a power beacon to forward the information. Assuming that the FSO and all of the RF channels experience gamma-gamma and Rayleigh fading, the closed-form analytical expressions for secrecy outage probability and the probability of strictly positive secrecy capacity are derived. In addition, the effects of atmospheric turbulence, pointing errors, and detection techniques on the system performance are analyzed. Finally, we perform Monte Carlo simulations to verify the accuracy of the derived expressions.

中文翻译：

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无线供电中继FSO-RF系统保密分析

我们研究了无线供电中继混合自由空间光射频 (FSO-RF) 系统的物理层安全性能。在该系统中，源将光信息传输到中继 (R)，中继 (R) 使用解码转发协议对接收到的信号进行解码，将其转换为 RF 信号，然后在窃听者存在的情况下将其转发到目的地。此外，我们还假设 R 没有额外的电源，它仅依靠从电源信标中获取能量来转发信息。假设FSO 和所有RF 信道都经历伽马-伽马和瑞利衰落，则推导出保密中断概率和严格正保密容量概率的闭式解析表达式。此外，大气湍流、指向误差、并对系统性能的检测技术进行了分析。最后，我们执行蒙特卡罗模拟来验证导出表达式的准确性。