Trajectory Optimization and Resource Allocation for UAV Relay-based Emergency Satellite Communication

Abstract

In emergency communication scenarios, to rapidly restore communication networks in disaster-stricken areas, it is necessary to utilize unmanned aerial vehicles (UAV) relays to assist satellite-to-ground communication systems. Nonetheless, the trajectory of the UAV impacts both the communication link from the UAV to the synchronous satellite and the wireless connection between the UAV and the users concurrently. In order to enhance the downlink spectrum efficiency for emergency communication, we aim to maximize the rates of the return link and access link by collectively optimizing user association, resource allocation, and the trajectory of the UAV. To address this challenge, we employ a continuous convex approximation approach that transforms the initial problem into four sub-problems, allowing us to derive locally optimal solutions. Subsequently, based on alternating optimization, we devise a joint optimization algorithm aimed at approximating the global optimal solution. Simulation outcomes affirm the effectiveness of this algorithm in improving user transmission rates within the satellite-ground network while upholding fairness in user service.