Joint User Scheduling, Trajectory, Beamforming and Power Allocation for Millimeter-Wave Full-Duplex UAV Relay

With small size, low cost and high mobility, unmanned aerial vehicles (UAVs) are playing an increasingly important role in all areas of modern society. In this paper, a full-duplex (FD) UAV equipped with a large antenna array is investigated as a relay base station (BS) to provide services to multiple ground users (GUs) using millimeter-wave (mmWave). Specifically, we propose a joint optimization problem based on user scheduling, UAV flight trajectory, beamforming and UAV transmit power to maximize the average transmission rate of the overall system. As the problem described is highly coupled and non-convex, making it difficult to solve, we propose an iterative algorithm based on the block coordinate descent (BCD) technique and the successive convex approximation (SCA) techniques to obtain an approximate optimal solution. Simulation results show that the proposed algorithm is able to converge with a small number of iterations and can significantly improve the system throughput.