Power Minimization for Movable Antenna Enhanced Downlink NOMA

Abstract

Movable antenna (MA) has emerged as a promising technology for next-generation wireless communications, owing to its remarkable capability to dynamically reconfigure wireless channels through antenna movement. Non-orthogonal multiple access (NOMA) is also recognized as one of the key enabling technologies for future communication networks. In this letter, we investigate a downlink NOMA system empowered by MA, which is used to adjust channel strength of NOMA users. The aim is to minimize total transmit power of base station (BS) through jointly optimizing power allocation and antenna position. To simplify the optimization problem, the relation between each user’s required power and MA position is first derived in closed-form solution. Subsequently, a multi-directional descent (MDD) algorithm is invoked to determine locally optimal MA position for the non-convex problem. Simulation results demonstrate that the proposed MA-enhanced NOMA scheme outperforms both the fixed-position antenna (FPA) system and the traditional orthogonal multiple access (OMA) system significantly.