Optimal UAV deployment in downlink non-orthogonal multiple access system: a two-user case

This paper investigates a unmanned aerial vehicle(UAV) deployment problem in a non-orthogonal multiple access(NOMA) system, where the UAV is deployed as an aerial mobile base station to transmit data to two ground users. An optimization problem is formulated by deploying the UAV for maximizing the sum rate of the two users. In order to solve the optimization problem, the feasible solution region is first reduced to a line segment between two users. Then, the optimization problem is simplified to a univariate problem, which can be solved by derivation under a certain situation, and the corresponding analytical solution is also provided.Moreover, a generalized algorithm, which considers 2 situations, is proposed to further determine the optimal UAV’s location. Specifically, four cases are discussed in the first situation. Extensive simulations are depicted to demonstrate effectiveness of the proposed algorithm and its superiority over the benchmarks in maximizing the two users’ sum rate.