Outage Probability Analysis of Variable and Fixed Gain Relay-Assisted Dual-Hop RF-FSO Links Using Space–time Block Code Users

In this paper, we have implemented an analytical study on a relay-assisted dual-hop system using fixed and variable gains for the radio-frequency (RF) and free-space optical communication (FSO). RF and FSO links are realized using the Rayleigh and Malaga distribution functions. Simulation results shows that pointing errors become severe, system performance deteriorates, and conjointly that the RF users exploiting space–time block coding (STBC) will enhance the performance of the end-to-end system. Outage probability of the end-to-end communication link operated with the STBC using the variable and fixed gain system implemented and plotted with respect to average SNR. From the obtained results, fixed gain relay-based communication link performs better efficient than the variable gain relay system.