Performance assessment of hybrid PPM–BPSK–SIM based FSO communication system using time and wavelength diversity under variant atmospheric turbulence

Abstract

In this paper, free space optical communication system employing a hybrid modulation technique called pulse position modulation–binary phase shift keying–subcarrier intensity modulation technique, is investigated using wavelength and time diversity, by considering log-normal and gamma–gamma probability density function as the channel-fading statistics under weak, moderate and strong turbulence. The analytical average bit error rate and closed form of expression of the proposed hybrid modulation scheme are derived. The outcomes of the simulation demonstrate the outstanding consistency of the derived closed form expression with those achieved by the Gauss–Hermite approximation and the Monte Carlo simulations.