When Movable Antenna Meets Downlink NOMA: Transmit Beamforming and Discrete Antenna Position Optimization

This paper investigates the joint optimization of transmit beamforming and discrete antenna positions for maximally improving the sum rate of movable antenna (MA) enhanced downlink non-orthogonal multiple access (NOMA) systems. As such an optimization problem belongs to a challenging mixed-integer nonlinear programming, we first develop an equivalent problem reformulation, with which we further propose a two-sided matching assisted optimization algorithm to jointly optimize the discrete antenna positions and transmit beamforming. Theoretical analysis demonstrates that the proposed algorithm always converges to a stable matching within polynomial complexity. Simulation results show that NOMA-MA using our proposed algorithm not only significantly outperforms the NOMA-MA using sequential optimization and the reconfigurable intelligent surface aided fixed position antenna (FPA) empowered NOMA, but also achieves a better performance gain over FPA than its orthogonal multiple access counterpart.