Mixed FSO/RF SIMO SWIPT Decode-and-Forward Relaying Systems

This article focuses on a dual-hop simultaneous wireless information and power transfer (SWIPT) single-input-multiple-output (SIMO) system having one free-space optical (FSO) link followed by one radio frequency (RF) link. We assume that RF source conveys secure information to the FSO receiver through an intermediate relay equipped with multiple antenna, which exploits the decode-and-forward relaying technique. The FSO link endures pointing error and atmospheric turbulence, which is modeled as Gamma-Gamma distribution, and RF link suffers from Fisher-Snedecor F fading. We investigate the consequences of number of antennas, pointing error, atmospheric turbulence, detection technology, electrical signal-to-noise ratio of FSO link, and energy harvesting on the performance of proposed SIMO mixed FSO/RF SWIPT framework. More specifically, we derive the unified analytical expressions for statistical channel characteristics such as probability density function, moments, amount of fading, outage probability, and ergodic capacity. Based on these results, physical layer security analysis is carried out, and the analytical expressions for secure outage probability and strictly positive secrecy capacity are derived.