UAV-relay placement with unknown user locations and channel parameters

This work investigates the problem of optimal placement of an UAV that provides communication services by acting as a flying wireless relay between a fixed base station (BS) and ground users. The proposed approach builds on the knowledge of the terrain topology where the network is deployed and aims at finding the optimal position of the UAV that maximizes the throughput in the max-min sense. Different from prior works, we do not assume any prior knowledge on user locations and the underlying wireless channel pathloss parameters. We first jointly estimate the user location and the pathloss parameters from the measurements collected by the UAV, and then use them to find the optimal relay position. When it comes to the optimal placement, an iterative algorithm is provided which iterates between the planar UAV placement and altitude optimization by exploiting the 3D city map information.