A weighted-beam-superposition method for mmWave massive MIMO-NOMA systems

Abstract

Millimeter wave (mmWave) massive multiple input multiple output (MIMO) and non-orthogonal multiple access (NOMA) are recognized as key technologies in the forthcoming beyond the fifth-generation (B5G) and the sixth-generation (6G) wireless networks. In this paper, we propose a multi-beam MIMO NOMA scheme where each beam is augmented by weighted beam superposition to focus the beam in a manner targeted at each user. This method exploits the full array of antennas within each beam to maximize the gain of each beam. To guarantee fairness for the weak user (lower channel gain) in each group, we use a method of power allocation, which satisfies the weak user with a minimum demanded for the quality of service (QoS). To improve further the sum rate when the QoS of the weak users is satisfied, the coefficient of strong users are set to the largest value. In system simulations, we compare the performance of differnet multi beam schemes, together with a single beam scheme, and a Time Division Multiple Access (TDMA) scheme at different levels of the signal noise ratio (SNR). Based on the simulation results, the proposed method significantly increases system sum rate.