Code-aided non-orthogonal multiple access in downlink multiuser MIMO system
Conventional downlink non-orthogonal multiple access (NOMA) uses the power domain for multiple access and applies successive interference cancellation (SIC) to mitigate intra-cluster interference. It requires sophisticated user terminals (UTs) clustering, moreover, imperfect SIC results in error pro...
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Published in | Journal of the Franklin Institute Vol. 356; no. 12; pp. 6778 - 6792 |
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Main Author | |
Format | Journal Article |
Language | English |
Published |
Elmsford
Elsevier Ltd
01.08.2019
Elsevier Science Ltd |
Subjects | |
Online Access | Get full text |
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Summary: | Conventional downlink non-orthogonal multiple access (NOMA) uses the power domain for multiple access and applies successive interference cancellation (SIC) to mitigate intra-cluster interference. It requires sophisticated user terminals (UTs) clustering, moreover, imperfect SIC results in error propagation that severely degrades system capacity. In this paper, a novel code-aided multiuser multiple-input multiple-output NOMA (MIMONOMA) framework for downlink transmission is proposed. Since the total number of UTs in a cell is in general more than the number of transmit antennas at the base station (BS), purely zero-forcing (ZF) downlink beamforming is unable to mitigate multiuser interference (MUI). We first propose a simple grouping algorithm that separate all UTs in a cell into several clusters, with cluster number less than or equal to BS antennas. ZF-based multiuser beamforming is then employed to remove the inter-cluster interference. To mitigate the intra-cluster interference, we propose to modulate the downlink data for each UT within the same cluster by orthogonal codes, thereby, instead of SIC, matched-filtering can be employed at each UT for interference suppression. Computer simulation results quantify the capacity gain of the proposed coded-aided MIMONOMA method over conventional MIMONOMA schemes. |
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ISSN: | 0016-0032 1879-2693 0016-0032 |
DOI: | 10.1016/j.jfranklin.2019.06.003 |