Maximize-Minimum User Capacity for UBS and WiFi Systems by Optimizing UBS Position and User offloading

Abstract In recent years, Unmanned Aerial Vehicles (UAVs) communication has become very popular, with the characteristics of strong flexibility, Line-of-Sight (LoS) communication link capability, and low cost. In some disasters or remote areas, the ground base station (BS) is damaged. In some disasters or remote areas where ground base stations (BS) are damaged, using this method UAV-mounted BS (UBS) combined with ubiquitous WiFi can still continue to serve users and provide them with better communication services. In this paper, we combine UBS with WiFi to maximize the minimum user capacity in the system by optimizing the UBS location, user offloading and spectrum allocation. In this system, users are divided into WiFi subscribers (WSs) and cellular subscribers (CSs). WSs can only connect to WiFi Access Point (AP), and CSs are allowed to connect to both the UBS and APs or only UBS. This optimization problem is an NP-hard problem, and it is difficult to find the result directly. To solve this problem, we use the Block Coordinate Descent Algorithm (BCDA), which divides the total problem into three subproblems and solves them in alternating iterations. Finally, we compare the results obtained by the BCDA with the results obtained by the exhaustive algorithm. The comparison results show that the results of our proposed solution are close to those obtained by the exhaustive algorithm, and the complexity is much lower than that of the exhaustive algorithm.