UAV Trajectory, User Association and Power Control for Multi-UAV Solar-Powered Networks.

This paper investigates the design of multiple solar-powered wireless nodes that transmit data to unmanned aerial vehicles (UAVs). We address the problem of jointly optimizing UAV flight trajectories, UAV-node user association, and uplink power control over a finite time horizon, with the goal of maximizing the worst user rate while managing co-channel interference. The design problem is highly non-convex and requires future knowledge of both energy state information (ESI) and channel state information (CSI), which are difficult to predict in practice. To tackle these challenges, we propose an offline method based on convex optimization that only uses the average ESI and CSI, while accounting for both line-of-sight (LOS) and non-LOS (NLOS) channels. We solve the problem using successive convex approximation (SCA) and alternative optimization, by dividing it into three convex subproblems. Our computer simulations demonstrate the effectiveness of the proposed hybrid channel offline method, which outperforms existing offline methods that only consider LOS channels.