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

摘要

Free space optical (FSO) communication has been receiving increasingattention in recent years with its ability to achieve ultra-high data ratesover unlicensed optical spectrum. A major performance limiting factor in FSOsystems is atmospheric turbulence which severely degrades the systemperformance. To address this issue, multiple transmit and/or receive aperturescan be employed, and the performance can be improved via diversity gain. Inthis paper, we investigate the bit error rate (BER) performance of FSO systemswith 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 andcovers all turbulence conditions. Since the distribution function of a sum ofDouble GG random variables (RVs) appears in BER expression, we first derive aclosed-form upper bound for the distribution of the sum of Double GGdistributed RVs. A novel union upper bound for the average BER as well ascorresponding asymptotic expression is then derived and evaluated in terms ofMeijer's G-functions.