Performance Analysis of Hybrid FSO/RF Transmission for DF Relaying System

Abstract

In this paper, we propose a novel switching scheme for hybrid free-space optical (FSO)/radio frequency (RF) system considering decode-and-forward (DF) relaying in a dual-hop (DH) scenario. For such a scenario, when direct link between source and destination exists, selection combining (SC) scheme is assumed at the destination. Specifically, the system transmits over FSO channel as long as the instantaneous signal-to-noise ratio (SNR) at the FSO receiver is greater than the threshold SNR. If it falls below the threshold, then the system switches its transmission over RF channel. Moreover, log-normal and Nakagami- m distributions are used to characterize FSO and RF links, respectively. The exact theoretical expressions for cumulative distribution function (CDF), probability density function (PDF) and outage probability are derived in closed-form and validated by Monte-Carlo simulations. Additionally, by using MATLAB integration function, the evaluation of average bit error rate (BER) is performed. Finally, to confirm the efficiency of the proposed switching scheme, the performance of the hybrid FSO/RF system is compared with the performance of the FSO system.