Power Allocation, UAV Position, and User Pairing Optimization in Coordinated NOMA Systems for Mobile Edge Computing Support.

Abstract

This paper investigates a coordinated non-orthogonal multiple access (NOMA) system employing an unmanned aerial vehicle (UAV) as a relay in a mobile edge computing (MEC) environment. In the proposed model, the ground base station (GBS) is equipped with MEC capability to serve near users with high data transmission demand, while the UAV assists far users that do not have a reliable direct link to the GBS. Based on a two-phase transmission model and successive interference cancellation (SIC) at both the UAV and the GBS, the paper formulates a problem of maximizing the total system data rate under constraints on transmit power, UAV altitude, and minimum data-rate requirements. To solve the problem, user pairing is performed based on distance, power allocation is optimized using numerical gradient descent (NGD), and UAV altitude is optimized using particle swarm optimization (PSO). Simulation results show that the proposed solution improves transmission performance, especially for far users, while enhancing the overall system data rate.