Rotary-Wing UAV Enabled Wireless Network: Trajectory Design and Resource Allocation

This paper studies a wireless communication system with a rotary-wing unmanned aerial vehicle (UAV) dispatched to communicate with multiple ground nodes (GNs). With limited on-board energy available at the UAV, we aim to maximize the weighted minimum of the communication throughput of the GNs, by jointly designing the UAV trajectory and communication resource allocation. The formulated problem is difficult to be directly solved, as it is non-convex and involves infinitely many variables over time. To tackle this problem, we first propose a simple fly-hover-communicate protocol, where the UAV successively visits a set of hovering locations and at each of them communicates with one corresponding GN. By leveraging the classic travelling salesman problem (TSP) and convex optimization techniques, we propose an efficient algorithm to optimize the hovering locations and durations, as well as the flying trajectory connecting these hovering locations. To further improve the performance, we consider the general scenario where the UAV also communicates while flying, and under a given UAV path, we find the optimal time allocation by solving a linear programming (LP) problem. Numerical results show the significant performance gains of the proposed designs over benchmark schemes.