User selection and power schedule for downlink non-orthogonal multiple access (NOMA) system

As a promising multiple access techniques for 5th generation (5G) wireless systems, non-orthogonal multiple access (NOMA) has received many attentions recently. In this paper, we study the NOMA based downlink multi-user beamforming system, where the base station (BS) tries to transmit information to multiple user clusters and each beam serves one user cluster compromising of two users simultaneously. User selection algorithm is proposed to reduce the interference and improve the system information rate. Moreover, we also provide the user power schedule scheme to guarantee the advantage of the proposed NOMA downlink multi-user beamforming system. Simulation results show that the proposed user selection algorithm and the power schedule scheme can improve the sum-rate of NOMA based downlink multi-user system.