Performance analysis of mixed RF/FSO communication system with the presence of pointing error using the MGF-based approach

In this paper, we address a performance analysis of a dual-hop mixed communication system over both radio-frequency (RF) and free-space-optical (FSO) links with the presence of pointing error impairments. Our system model consists of two communication paths, and the receiver uses the MRC combining scheme to combine the received signals through these both links. The first optical link consists of a source (S) and a destination (D) nodes communicating through a relay node (R), which receives the incoming information-bearing signal and forwards it to the destination (i.e. detect-and-forward relaying (Det-F)). Both (S-R) and (R-D) hops are operating under FSO link subject to Málaga-M turbulence model with the presence of pointing error. The second link is a direct RF link, connecting the source (S) directly to the destination (D), and is assumed to be subject to Rayleigh fading channel. We present in this paper the exact closed-form expression of the moment-generating function (MGF) of the total end-to-end SNR. Based on this result, we derive successfully the average symbol error rate of our mixed RF/FSO communication system using the MGF-based approach, in terms of either univariate or bivariate Fox's H-Function. All these derived analytical results are validated through computer-based simulation.