This work deals with the secrecy performance analysis of a dual-hop RF-FSO DF relaying network composed of a source, a relay, a destination, and an eavesdropper. We assume the eavesdropper is located close to the destination and overhears the relay's transmitted optical signal. The RF and FSO links undergo ($\alpha$-$\kappa$-$\mu$)-shadowed fading and unified M\'alaga turbulence with pointing error. The secrecy performance of the mixed system is studied by deriving closed-form analytical expressions of secure outage probability (SOP), strictly positive secrecy capacity (SPSC), and intercept probability (IP). Besides, we also derive the asymptotic SOP, SPSC, and IP upon utilizing the unfolding of Meijer's G function where the electrical SNR of the FSO link tends to infinity. Finally, the Monte-Carlo simulation is performed to corroborate the analytical expressions. Our results illustrate that fading, shadowing, detection techniques (i.e., heterodyne detection (HD) and intensity modulation and direct detection (IM/DD)), atmospheric turbulence, and pointing error significantly affect the secrecy performance. In addition, better performance is obtained exploiting the HD technique at the destination relative to IM/DD technique.

中文翻译：

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混合($α$-$κ$-$μ$)-阴影和马拉加湍流模型的拦截概率和安全中断分析

这项工作涉及由源、中继、目的地和窃听者组成的双跳 RF-FSO DF 中继网络的保密性能分析。我们假设窃听者位于目的地附近并偷听中继传输的光信号。RF 和 FSO 链路经历 ($\alpha$-$\kappa$-$\mu$)-阴影衰落和统一的 M\'alaga 湍流与指向错误。通过导出安全中断概率 (SOP)、严格正保密容量 (SPSC) 和拦截概率 (IP) 的封闭式解析表达式来研究混合系统的保密性能。此外，我们还利用 Meijer G 函数的展开推导出渐近 SOP、SPSC 和 IP，其中 FSO 链路的电 SNR 趋于无穷大。最后，执行蒙特卡罗模拟以证实解析表达式。我们的结果表明，衰落、阴影、检测技术（即外差检测（HD）和强度调制和直接检测（IM/DD））、大气湍流和指向误差显着影响保密性能。此外，相对于 IM/DD 技术，在目的地利用 HD 技术可以获得更好的性能。