User Pairing and Power Allocation for Downlink Non-Orthogonal Multiple Access

Non-orthogonal multiple access (NOMA) technology has been widely studied due to its principle to superpose multiple users in the power domain at the transmitter and apply successive interference cancellation (SIC) at receivers. Taking advantage of NOMA, more than one user are served simultaneously by a base station (BS) with the same radio resource. In this paper, we study the NOMA in downlink of the multi-user system where the sort-based user paring and power allocation are deployed in order to reduce the interference and maximize the system capacity. The simulation results demonstrate that the proposed sort-based user pairing schemes greatly improve the performances of both error probability and spectral efficiency.