Trajectory Optimization and Resource Allocation for Multi-User OFDMA UAV Relay Networks

In this paper, we consider a single-cell multi-user orthogonal frequency division multiple access (OFDMA) network with one unmanned aerial vehicle (UAV), which works as an amplify-and-forward relay to improve the quality-of-service (QoS) of the user equipments (UEs) in the cell edge. Aiming to improve the throughput while guaranteeing user fairness, we formulate a joint mode selection, subchannel allocation, trajectory optimization, and power allocation problem, which is NP-hard. To solve the problem efficiently, we first decompose it into three subproblems, i.e., mode selection and subchannel allocation, trajectory optimization, and power allocation. Then we propose a joint mode selection and subchannel allocation, trajectory optimization, and power allocation (JMS-T-P) algorithm where these subproblems are solved iteratively. Simulation results show that the JMS- T-P algorithm outperforms the random algorithm and the cellular scheme.