On the Ergodic Capacity of Ground-To-UAV Free-Space Optical Communications

Recently, free-space optical (FSO)communications have gained an increased popularity for data transfer between unmanned aerial vehicles (UAVs). Despite providing large unlicensed bandwidth, the channel capacity of UAV-based FSO links is negatively affected by atmospheric turbulence-induced fading, pointing error due to the position and orientation deviations of hovering UAVs along with link interruption probability due to the joint effects of angle-of-arrival (AOA)fluctuation and receiver field-of-view (FOV)limitation. For a better understanding of UAV-based FSO systems, it is important to study the capacity of such channels, which is the main goal of this paper. To this aim, we first derive the closed-form expression for ergodic capacity of ground-to-UAV link in terms of well-known elementary functions. Then, we characterize the influence of different system parameters on the ergodic capacity of UAV channels.