UAV Deployment with Flexible Height Under SINR Constraint

This paper proposes using UAVs as auxiliary flying relays between IoT access points (APs) and terrestrial base stations/satellites. Specifically, we consider the 3D deployment of multiple UAVs above a given area of APs, aiming at providing efficient services to the APs while optimizing the overall performance of UAVs. In particular, we aim to minimize the number of required UAV flights when serving the APs within a demanded time, which is constrained by the total available power of UAVs, and maximize the total number of successfully served APs. For this, we propose an integer linear programming (ILP) model that can achieve the above goals by adjusting the UAV hovering heights in the appropriately selected coordinates. The proposed ILP model is evaluated when considering interference among the multiple UAVs and compared with the schemes based on fixed heights. The numerical results show that the proposed ILP model can automatically adjust the flying height of UAVs to reduce the flights when complying with the constraints of the signal-to-interference-noise ratio (SINR) threshold and the number of APs to be served.