A framework on the performance analysis of relay-assisted FSO transmission systems

Abstract

In this work, we tend to analyze the performance of dual-hop relayed free-space optical (FSO) transmission systems. To do this, the FSO links are modeled as the Double Generalized Gamma (DGG) distribution with generalized pointing error impairment and under both heterodyne detection (HD) and intensity modulation with direct detection (IM/DD) methods. Using amplify-and-forward (AF) fixed-gain relaying as well as channel state information (CSI)-assisted AF relaying along with decode-and-forward (DF) relaying, we derive closed-form expressions for the outage probability (OP), the average bit error rate (BER) and the ergodic capacity (EC) in terms of the bivariate Fox-H function. Additionally, we analyze high signal-to-noise-ratio (SNR) behavior of the OP and formerly we derive the diversity order of the considered system. To asses the accuracy of the obtained results, numerical and Monte-Carlo simulation results are provided. Based on the high SNR analysis, we further provide a diversity gain analysis and discuss the bottlenecks in the dual-hop FSO systems.