Physical Layer Security Analysis of Hybrid FSO/RF Systems in SAGIN With Channel Imperfection and Interference

作者：Xin Li, Yongjun Li, Xinkang Song, Jianjia Li, Shanghong Zhao · 发表于：IEEE Transactions on Aerospace and Electronic Systems · 年份：2025 · DOI：10.1109/taes.2025.3576315 · 被引用次数：4 · 研究领域：Optical Wireless Communication Technologies

Physical layer security (PLS) of satellite-air-ground integrated network (SAGIN) has become an increasingly concerned issue in 5G and beyond-5G networks. In this paper, we propose an analytical framework for PLS in hybrid free-space optical (FSO) and radio frequency (RF) systems based on SAGIN, where the eavesdroppers on both FSO and RF links are considered. Specifically, we consider channel state information (CSI) imperfections in the FSO link and malicious interference in the RF link. A hard-switching based relay scheme is designed to further improve the PLS of FSO-FSO/RF dual-hop relay links. System performance is evaluated in terms of secrecy outage probability (SOP), secrecy throughput (ST), and strict positive secrecy capacity (SPSC). Asymptotic SOP analysis in the high signal-to-noise ratio (SNR) regime is conducted to provide further engineering insights. Numerical results reveal that imperfect CSI induces a PLS performance bottleneck in hybrid FSO-FSO/RF relay links. The proposed scheme achieves an SOP improvement exceeding 2.5 dB and enhances system ST by 16.2% compared to conventional FSO-RF relay scheme.