Systems Engineering and Electronics ›› 2020, Vol. 42 ›› Issue (8): 1857-1864.doi: 10.3969/j.issn.1001-506X.2020.08.28

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Decoding scheme of SCMA system based on conditional probability selection update

Kai SHAO1,2(), Juanhong ZHOU1,2(), Yan LIANG1,2(), Jin DENG1,2()   

  1. 1. School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
    2. Chongqing Key Laboratory of Mobile Communications Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
  • Received:2019-11-20 Online:2020-07-25 Published:2020-07-27
  • Supported by:
    重庆市科技委员会项目(cstc2017shmsA130115)

Abstract:

Sparse code multiple access (SCMA) is a new non-orthogonal multiple access scheme for the fifth generation mobile communication system. The message passing algorithm (MPA) adopted by the receiver has redundant calculations during the iterative update process, so the complexity is too high. To solve this problem, the Monte Carlo method is first used to statistically analyze the conditional probability density function value of the received signal, and it is found that with the change of the signal to noise ratio, the conditional probability density function value shows a certain statistical phenomenon. Then based on the statistical results, a conditional probability selection update MPA (CPSU-MPA) is proposed. The algorithm selects a conditional probability density function value with a certain proportion to update, and at the same time discards and compensates external information that does not participate in the update. Simulation results show that the proposed algorithm can effectively reduce the decoding complexity, and the sacrifice of bit error rate performance is small.

Key words: non-orthogonal multiple access, sparse code multiple access (SCMA), message passing algorithm, conditional probability

CLC Number: 

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