Error Performance Analysis of FSO Links with Equal Gain Diversity Receivers over Double Generalized Gamma Fading Channels

TL;DR

This paper analyzes the error performance of free space optical links with diversity receivers over atmospheric turbulence modeled by the Double Generalized Gamma distribution, deriving new bounds and asymptotic expressions.

Contribution

It introduces a closed-form upper bound for the sum of Double GG distributed variables and develops a novel union upper bound for BER in FSO systems with diversity.

Findings

Derived a closed-form upper bound for the sum of Double GG RVs.

Developed a new union upper bound for average BER.

Provided asymptotic expressions evaluated with Meijer's G-functions.

Abstract

Free space optical (FSO) communication has been receiving increasing attention in recent years with its ability to achieve ultra-high data rates over unlicensed optical spectrum. A major performance limiting factor in FSO systems is atmospheric turbulence which severely degrades the system performance. To address this issue, multiple transmit and/or receive apertures can be employed, and the performance can be improved via diversity gain. In this paper, we investigate the bit error rate (BER) performance of FSO systems with transmit diversity or receive diversity with equal gain combining (EGC) over atmospheric turbulence channels described by the Double Generalized Gamma (Double GG) distribution. The Double GG distribution, recently proposed, generalizes many existing turbulence models in a closed-form expression and covers all turbulence conditions. Since the distribution function of a sum of Double GG random variables (RVs) appears in BER expression, we first derive a closed-form upper bound for the distribution of the sum of Double GG distributed RVs. A novel union upper bound for the average BER as well as corresponding asymptotic expression is then derived and evaluated in terms of Meijer's G-functions.