On the performance of differential cooperative DF-FSO network utilizing PL approximation

Abstract

In this paper, we analyze differential binary modulation for decode-and-forward (DF) based cooperative free space optical (FSO) network utilizing piecewise linear (PL) approximation and Gamma-Gamma (GG) fading links. We adopt subcarrier intensity modulation (SIM) scheme and a single relay for transmitting the binary phase shift keying (BPSK) modulated data over the FSO channels. The PL decoder considers the possibility of erroneous relaying and performs almost similar to optimal maximum likelihood (ML) decoder. For the considered differential DF-FSO cooperative network, we analytically derive exact expression for average bit error rate (BER) and outage probability. Moreover, we also obtain analytical diversity order from the derived closed form expression of outage probability. The impact of different power allocation schemes on BER is determined by utilizing power allocation factor.