A Low-Complexity and Fast Convergence Message Passing Receiver Based on Partial Codeword Transmission for SCMA Systems

Xuewan ZHANG  Wenping GE  Xiong WU  Wenli DAI  

IEICE TRANSACTIONS on Communications   Vol.E101-B   No.11   pp.2259-2266
Publication Date: 2018/11/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2017EBP3420
Type of Manuscript: PAPER
Category: Transmission Systems and Transmission Equipment for Communications
sparse code multiple access (SCMA),  message passing algorithm (MPA),  probability density function (PDF),  Monte Carlo method,  

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Sparse code multiple access (SCMA) based on the message passing algorithm (MPA) for multiuser detection is a competitive non-orthogonal multiple access technique for fifth-generation wireless communication networks Among the existing multiuser detection schemes for uplink (UP) SCMA systems, the serial MPA (S-MPA) scheme, where messages are updated sequentially, generally converges faster than the conventional MPA (C-MPA) scheme, where all messages are updated in a parallel manner. In this paper, the optimization of message scheduling in the S-MPA scheme is proposed. Firstly, some statistical results for the probability density function (PDF) of the received signal are obtained at various signal-to-noise ratios (SNR) by using the Monte Carlo method. Then, based on the non-orthogonal property of SCMA, the data mapping relationship between resource nodes and user nodes is comprehensively analyzed. A partial codeword transmission of S-MPA (PCTS-MPA) with threshold decision scheme of PDF is proposed and verified. Simulations show that the proposed PCTS-MPA not only reduces the complexity of MPA without changing the bit error ratio (BER), but also has a faster convergence than S-MPA, especially at high SNR values.