Performance Analysis of DF-Based Satellite and UAV Relay Networks

In this paper, we investigate the performance of downlink transmission in a satellite and unmanned aerial vehicle (UAV) relay network. Specifically, given that the UAV equipped with multiple antennas adopts decoded-and-forward (DF) protocol, we propose three transmission schemes to satisfy the quality-of-service requirement of a terrestrial user, including direct transmission, cooperative transmission and joint transmission. Then, assuming that satellite-UAV link follows shadowed-Rician fading while the UAV-user link obeys Nakagami-m distribution, we derive the closed-form expression for outage probability (OP) of the considered system with different schemes. Based on the derived OP expressions, we further analyze the energy efficiency (EE) of the system. Finally, the simulations results verify the correctness of the theoretical analysis, and the influence of UAV antenna number on the performance in terms of OP and EE is revealed.