UAV Placement and Resource Allocation for Multi-hop UAV Assisted Backhaul System

Unmanned aerial vehicle (UAV) is widely deployed to assist wireless user access for providing low latency and high-reliability service. In this paper, we consider a communication scenario where ground user is far away from ground base station and focus on the multi-hop UAV assisted backhaul system. In particular, we aim to maximize the end-to-end throughput with full consideration of two different resource allocation schemes, namely orthogonal frequency (OF) scheme and power control (PC) scheme. The optimal UAV placement is derived in the OF scheme and an iterative algorithm is proposed to jointly optimize the UAV placement and transmit power in the PC scheme. Numerical results show that an additional UAV will bring about 19% performance gain for long-distance communication in both schemes, but when the distance exceeds 1.2 km, the PC scheme performs better than the OF scheme.