Performance Analysis of Dual-Hop UAV-Assisted FSO Communication System with DF Protocol

Relay-assisted free-space optical (FSO) communication has been an effective means of mitigating the fading affect caused by atmospheric turbulence. In addition, the emergence of unmanned aerial vehicles (UAVs) has further extended the coverage of relay-assisted FSO communication systems, owing to their mobility and flexibility. In this paper, we analyze the performance of a UAV-assisted dual-hop FSO relay communication system in which the combined effects of attenuation loss, at-mospheric turbulence (following the Málaga and gamma-gamma distributions), and pointing errors caused by UAV fluctuations are considered. Closed-form expressions for the outage probability and average bit error rate (BER) of the system are derived. It is found that the atmospheric turbulence, the position deviation of the UAV, the link length of the source-to-UAV link, and the system modulation scheme have significant effects on the system performance. Finally, we find that a system with coherent binary phase-shift keying yields the best average BER performance.