Use of drone base stations for the optimization of capacityand coverage in new generation wireless networks

Recent technological advances enable the use of Unmanned Aerial Vehicles (UAV) or commonly known as drones in many civilian and military applications. Drones provide low-cost and efficient solutions to the problems arise in diverse applications such as surveillance, search and rescue, delivery of goods and communication. Research activities on the use of drones in wireless communication have substantially grown as it is understood that it could play an important role to satisfy the high data rate demand and service quality of users in beyond 5G networks. Drone based applications in military communication also motivates and triggers research activities. One of the most important research problems that needs to be addressed is how to deploy drone base stations (DBS) in 3 Dimensional (3D) space. In this thesis work, we model the DBSs deployment problem with respect to user capacities taking into account practical considerations for various scenarios and propose novel methods to determine the positions of DBSs. First, we investigate the problem of linear and logarithmic capacity maximization and propose a computationally low-cost method that determines the required number of DBSs and their positions. For a scenario, where users are not uniformly distributed and has a dense user region, the joint optimization of DBSs positions and DBS-user associations is proposed. We investigate the use of DBSs in a tactical network and design a method which estimates the positions of users and place DBSs considering the probability of DBSs being hit. In another case, taking into account the lower reliability of a drone compared to that of a radio system and the probability of DBS shoot down we propose novel methods in order to increase network performance during repositioning of DBSs. As the defined problems are not convex, we utilize metaheuristics and identify the one with the highest solution accuracy.