Placement Optimization of Multiple UAV Base Stations

Due to recent technological advancements in the area of unmanned aerial systems, equipping an unmanned aerial vehicle (UAV) with a base station (BS) has been proposed to augment terrestrial base stations and to enhance the performance of 5G and beyond-5G networks. In this paper, we investigate the 3D placement problem for multiple UAV-BSs that maximizes the number of covered users with the same as well as with different quality-of-service (QoS) requirements. First, we present a mathematical formulation of the multiple UAV-BS placement problem, and show that it is a non-convex optimization problem. Then, we propose two heuristic algorithms, and we show that for users with the same as well as with different QoS requirements, the proposed algorithms outperform the Linear Approximation (LA) state-of the-art algorithm in terms of the average number of covered users and execution time, and achieve near optimal performance. Finally, a tradeoff between the two heuristic algorithms in terms of the average number of covered users and their execution time is presented.