Performance analysis of the decode-and-forward relay-based RF-FSO communication system in the presence of pointing errors

This study focuses on the analysis of a decode-and-forward relay-based asymmetric radio frequency-free space optical (RF-FSO) communication system. These types of communication systems are of very high speed, secure, and cost-effective. Such systems can be used to provide the last-mile access to many household users and can provide temporary network access during disasters and link failures. In the communication model analysed, the RF path is considered as Rayleigh fading, and the FSO path is considered as Malaga (${\cal M}$M)-distributed turbulence fading with the pointing error. Two types of detection schemes consisting of intensity modulation/direct detection and heterodyne detection are considered at the receiver for the analysis. For this cooperative communication system, novel mathematical expressions for the cumulative distribution function, probability density function, and moment generating function of the end-to-end signal-to-noise ratio are derived. With the aid of these statistical characteristics, new closed mathematical formulations are obtained for outage probability and the average bit error rate for different binary and M-ary modulation approaches.