Backhaul-Constrained Resource Allocation and 3D Placement for UAV-Enabled Networks

Unmanned aerial vehicle (UAV)-base stations (BS) are envisioned to provide wireless access to areas where the existing wireless infrastructure is either not deployed, damaged or simply congested. In this paper, the problem of minimizing the transmit power of a UAV-BS, while serving users with their QoS requirements and accounting for the wireless backhaul limitation of the UAV, is investigated. To this end, an algorithm that finds the optimal bandwidth assignment in the backhaul link, the optimal 3D position of the UAV, as well as the transmit power distribution in the access and the backhaul links is proposed. Simulation results show that, using the proposed approach, the needed power is greatly reduced, when compared to a strategy that separates between the frequency band used in the access and the backhaul links. In addition, the performance enhancement of a UAV-enabled system over a traditional one in which the macro base station (MBS) directly serves users is shown.