Path-optimization method for UAV-aided relay broadcast communication system

Abstract

Unmanned aerial vehicle (UAV) relay technology is an important means of long-distance wireless communication. In this paper, we address a broadcast communication system using a fixed-wing UAV as a relay platform between a base station (BS) and a cluster of mobile-task UAVs. To improve the system performance, especially to ensure the quality of service (QoS) of high-priority task UAVs, the path-optimization method for the relay UAV is investigated.We first present the system and signal model of the UAV-aided relay broadcast communication system and derive the approximate expression of the ergodic capacity of the single link. Then, considering the different demands of the task UAVs, we propose a relay UAV path-optimization method based on the criterion of maximizing the weighted sum-ergodic capacity of each link. After that, the mathematical expressions of accurate outage probability and closed-form ergodic capacity of the relay links are derived to quantify the system performance. Finally, we give the optimal path of the relay UAV in two simulation scenarios and provide the effects of the task UAVs’ priority and maximal heading angle of relay UAV on optimal path of relay UAV and communication performance of links using the proposed method. The computer simulation results demonstrate the validity of the proposed method and the performance analysis expressions. Our work can provide a useful reference for UAV relay broadcast communication system design.