Unified Performance Analysis for UAV-Based FSO Communication Systems

Relay-based free-space optical (FSO) communication systems effectively counter the degradation caused by turbulence-induced atmospheric scintillation. Traditional ground-based relays are stationary, which can complicate achieving their optimal deployment. Unmanned aerial vehicles (UAVs), due to their dynamic mobility and flexibility, introduce novel solutions for FSO relay systems. This research examines a UAV-based FSO system that employs a dual-hop decode-and-forward mechanism, incorporating several sources at the transmission side. The performance analysis of this system is expanded by integrating the Malaga (M), Gamma-Gamma (GG), and Fisher–Snedecor (F) distributions, which depict atmospheric turbulence, and considering the effects of atmospheric losses, pointing errors, and angle-of-arrival fluctuations. Deriving the probability density function (PDF) and cumulative distribution function (CDF) for these factors, we establish a practical expression for the PDF of the overall channel gain. Subsequent derivations of exact and asymptotic analytical expressions for the outage probability enable the assessment of the influence of these factors on system performance. Numerical validations underscore the accuracy of our theoretical models, verifying their effectiveness in evaluating the outage performance of the UAV-based FSO system with multiple sources.