Secrecy Performance Analysis of RIS-Aided Wireless Systems over Correlated Extended α-η-F Composite Fading Channels

Abstract

In this paper, the secrecy of the physical layer of an reconfigurable intelligent surface (RIS)-assisted wireless communications system over extended α-η-F composite fading channels is analyzed. The extended α-η-F composite fading model is introduced in this work as a generalization of the versatile extended η-F and α-μ distributions. Accordingly, this model encompasses as special cases most of the generalized fading distributions, such as extended α-η-μ, extended η-F, and α-η-F. To this effect, the probability density functions (PDFs) of a single random variable (RV) and product of two non-identically distributed variates of extended α-η-F composite fading model are provided first. Thereafter, we derive mathematically tractable expressions of the average secrecy capacity (ASC), secure outage probability (SOP), lower bound of SOP (SOPL), and effective secrecy throughput (EST) of RIS-assisted wireless communications system over correlated extended α-η-F composite fading channels. In addition, the asymptotic expressions of the ASC, SOP, and SOPL at high average SNR regime are also presented to explain the impact of both the number of the RIS elements and fading parameters on the secrecy performance metrics. The validity of our analytical results is confirmed through Monte Carlo (MC) simulations as well as a comparison with some special cases of the extended α-η-F composite fading channels.