Non-Orthogonal Multiple Access Using Intra-Beam Superposition Coding and SIC in Base Station Cooperative MIMO Cellular Downlink

Nobuhide NONAKA  Yoshihisa KISHIYAMA  Kenichi HIGUCHI  

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B   No.8   pp.1651-1659
Publication Date: 2015/08/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.1651
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
non-orthogonal multiple access,  superposition coding,  successive interference cancellation,  downlink,  MIMO,  base station cooperation,  

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Summary: 
This paper extends our previously proposed non-orthogonal multiple access (NOMA) scheme to the base station (BS) cooperative multiple-input multiple-output (MIMO) cellular downlink for future radio access. The proposed NOMA scheme employs intra-beam superposition coding of a multiuser signal at the transmitter and the spatial filtering of inter-beam interference followed by the intra-beam successive interference canceller (SIC) at the user terminal receiver. The intra-beam SIC cancels out the inter-user interference within a beam. This configuration achieves reduced overhead for the downlink reference signaling for channel estimation at the user terminal in the case of non-orthogonal user multiplexing and enables the use of the SIC receiver in the MIMO downlink. The transmitter beamforming (precoding) matrix is controlled based on open loop-type random beamforming using a block-diagonalized beamforming matrix, which is very efficient in terms of the amount of feedback information from the user terminal. Simulation results show that the proposed NOMA scheme with block-diagonalized random beamforming in BS cooperative multiuser MIMO and the intra-beam SIC achieves better system-level throughput than orthogonal multiple access (OMA), which is assumed in LTE-Advanced. We also show that BS cooperative operation along with the proposed NOMA further enhances the cell-edge user throughput gain which implies better user fairness and universal connectivity.