Performance Analysis of a Mixed RF-FSO Aided Cognitive Radio Network

This paper analyzes outage performance in a dual-hop system that uses a combination of free-space-optical (FSO) and radio-frequency (RF) transmission system, within a cognitive radio (CR) framework exploring non-orthogonal multiple access (NOMA) principles. The Gamma-Gamma (GG) distribution suit-able for atmospheric turbulence conditions ranging from moder-ate to severe, is utilized to model the source-relay FSO channel. On the other hand, the relay-to-user links are characterized using the Rayleigh channel model. The outage performances of far user and near user are evaluated and corresponding closed-form expressions are derived, which involves the Meijer G-function. Further, asymptotic expressions for the outage probability are provided for the high SNR regime of the FSO link.