Non-Orthogonal Multiple Access (NOMA) for Downlink Multiuser MIMO Systems: User Clustering, Beamforming, and Power Allocation

摘要

We investigate the application of non-orthogonal multiple access (NOMA) withsuccessive interference cancellation (SIC) in downlink multiuser multiple-inputmultiple-output (MIMO) cellular systems, where the total number of receiveantennas at user equipment (UE) ends in a cell is more than the number oftransmit antennas at the base station (BS). We first dynamically group the UEreceive antennas into a number of clusters equal to or more than the number ofBS transmit antennas. A single beamforming vector is then shared by all thereceive antennas in a cluster. We propose a linear beamforming technique inwhich all the receive antennas can significantly cancel the inter-clusterinterference. On the other hand, the receive antennas in each cluster arescheduled on power domain NOMA basis with SIC at the receiver ends. Forinter-cluster and intra-cluster power allocation, we provide dynamic powerallocation solutions with an objective to maximizing the overall cell capacity.An extensive performance evaluation is carried out for the proposed MIMO-NOMAsystem and the results are compared with those for conventional orthogonalmultiple access (OMA)-based MIMO systems and other existing MIMO-NOMAsolutions. The numerical results quantify the capacity gain of the proposedMIMO-NOMA model over MIMO-OMA and other existing MIMO-NOMA solutions.