Physical Layer Security in RIS-assisted Networks in Fisher-Snedecor Composite Fading

In this study, we investigate the physical layer security (PLS) of a reconfigurable intelligent surface (RIS) enabled system over generalized fading channels. The RIS concept is becoming an essential technology for the achievement of smart radio environments, where large number of passive, miniature cells, are designed to influence incident signal. Key benefits have been demonstrated for RIS-assisted PLS purposes, due to the flexibility of simultaneously enhancing or suppressing signal beams to different users. Due to the potential of such RIS-assisted systems as reported in the literature, we study a system with a RIS-based access point for transmission, at the source node. The system is modelled with reference to a receiver transmitter pair in the presence of an eavesdropper. The Fisher-Snedecor model is adopted to analyse the composite fading and shadowing channel. Expressions are derived for the average secrecy capacity and secrecy outage probability of the network. The derived expressions can be adopted for the PLS analysis of RIS-assisted networks for several common distributions such as Rayleigh, Nakagami-m and the one-sided Gaussian distributions. The results were validated using Monte-Carlo simulations. The results indicate the clear secrecy benefit of employing a RIS-enabled access point for various fading and shadowing conditions.