Unified Performance Analysis of Dual-Hop Radio Frequency/Free Space Optical System

Abstract

In this paper, the performance of the dual-hop radio frequency/free space optical (RF/FSO) system based on the amplify-and-forward relaying scheme is analyzed. The RF link is modeled by Nakagami-m distribution for the multipath fading channel which is a generalized distribution. The FSO link is characterized by Fisher-Snedecor fading distribution that is valid for all atmospheric turbulence conditions. Operating the intensity modulation direct detection scheme, the unified expression of the cumulative distribution function (CDF) is employed for the instantaneous end-to-end received electrical signal-to-noise ratio. By utilizing its CDF, a novel mathematical framework to drive the exact closed-form expressions of the outage probability and the average bit error rate with different modulation schemes are calculated for the considered system involving Meijer-G functions. Additionally, to get a deeper understanding, asymptotic expressions for the OP and ABER are also obtained in terms of basic elementary functions. The analytical and asymptotic expressions are simulated in MATLAB. The results revealed that increases in the severity of atmospheric turbulence profoundly degrade the system performance. Furthermore, the dual-hop RF/FSO system mitigates atmospheric turbulence effectively in contrast to the single FSO system.