Trajectory Optimization and Power Allocation for UAV Alternate Relay Communications

To improve the spectrum efficiency of the Unmanned Aerial Vehicle (UAV) relaying communication systems, a UAV alternate relay scheme is proposed, where two UAV relays alternately forward information from the source to the destination. To coordinate the interference amon g the two relaying data links, UAV trajectory and transmit power are investigated to maximize the end-to-end throughput of the UAV alternate relay system. The considered optimization problem is subject to the height, maneuver and collision avoidance constraints of the UAVs and the average and peak transmit power constraints of the source and UAV relays, which is non-convex and difficult to obtain the optimal solution. Nevertheless, an efficient iterative algorithm based on the alternating maximization and successive convex optimization techniques is proposed to obtain a suboptimal solution. Simulation results verify the effectiveness of the proposed algorithm.