Proposal of Combination of NOMA and Beamforming Methods for Downlink Multi-users systems

In this paper, a downlink multi-users (MUs) system, where the MUs are clustered into several clusters based on the located regions, is taken into consideration. A combination of beamforming and no-orthogonal multiple access (NOMA) methods is proposed and the base station (BS) communicates instantaneously with all users in multiple clusters by the proposed method. The close-form expressions of outage probability and ergodic capacity are derived to evaluate our proposed method. The derived analytical results are verified by Monte Carlo simulations and the proposed method is compared with conventional orthogonal multiple access (OMA) method. The results indicate that our proposed method can improve the performance of downlink MUs systems more than the OMA method.