LOW-COMPLEXITY MPA FOR MULTI-USER DETECTION BASED ON MAXIMAL LOG AND MINIMAL THRESHOLD

Abstract

Sparse code multiple access (SCMA) is a distinct sort of non-orthogonal multiple access technology employed in 5G mobile communications. This present technology algorithm holds a traditional message passing algorithm (MPA) that is more complex and has a slower convergence speed. The threshold- based MPA is met with a huge bit error rate (BER) at low threshold values. In SCMA technology, maximal-logarithm MPA (Max-Log-MPA) approximations are used that do not ensure data reliability or data loss, thus leading to poor detection. To address these issues, in this paper, we propose a lowcomplexity MPA for multi-user detection based on maximal log and minimal threshold values. The proposed work integrates both the minimal-logarithm threshold MPA (TMax-Log-MPA) and serial maximal-logarithm MPA (SMax-Log-MPA) to minimize BERs and computational complexity, which reduces the processing time. Both user node and resource node messages are updated simultaneously by initially setting the minimum threshold value to enhance the stability of the user node in TMax-Log-MPA. The exponentials in Max-Log-MPA are replaced with the sum of the maximum values in SMax-Log-MPA. The BER and computational-complexity reduction-ratio performances of the proposed algorithm were obtained through simulations and the results were compared with the traditional MPA.