On the Performance of RF-FSO System Over Rayleigh and Kappa-Mu/Inverse Gaussian Fading Environment

In this paper, we investigate a decode-and-forward cooperative communication based radio frequency (RF)-free space optical (FSO) system. An asymmetric environment is considered where source to relay channel is subjected to Rayleigh fading and relay to destination path is assumed to follow κ-μ/Inverse Gaussian (IG) distribution. The analytical framework proposed is based on a versatile κ-μ/IG model which includes one-sided Gaussian/IG, Rice (Nakagami-n)/IG, Nakagami-m/IG and Rayleigh/IG distributions as special cases. The expressions for moment generating function (MGF) and its special case are derived for this mixed RF and FSO network. The MGF is further utilized to derive the expression of end-to-end ergodic channel capacity for the RF-FSO communication system. Thereafter, end-to-end bit error rate is determined for BPSK, QPSK, DPSK and NCFSK modulation schemes. In addition, we have also derived analytical and asymptotic expressions of MGF and outage probability of the proposed RF-FSO system. Furthermore, we have also investigated the diversity gain and coding gain of the considered RF-FSO system.