Open Access

ARTICLE

Uplink SCMA Codebook Reuse Transmission and Reception Scheme

by Xiaohong Ji¹, Junjun Du¹, Guoqing Jia^1,*, Weidong Fang^2,3

1 Qinghai Nationalities University, Xining, 810007, China
2 Science and Technology on Micro-System Laboratory, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 201800, China
3 University of Chinese Academy of Sciences, Beijing, 100049, China

* Corresponding Author: Guoqing Jia. Email:

Intelligent Automation & Soft Computing 2021, 27(1), 221-231. https://doi.org/10.32604/iasc.2021.013145

Received 27 July 2020; Accepted 20 September 2020; Issue published 07 January 2021

Abstract

Sparse code multiple access (SCMA) is a new non-orthogonal multiple access scheme suitable for 5G communication, which can effectively improve spectrum efficiency and support massive connections. Multiple users in the SCMA system realize the sharing of the same time-frequency resources by mapping data into codewords of a special code book (Code Book, CB). A typical SCMA system increases the spectrum utilization to 150%. In order to further improve the system spectrum utilization and increase the number of user connections, this paper proposes an uplink SCMA codebook reuse transmission and reception scheme (CB-Reuse-SCMA), which reuse a codebook to multiple users. The base station allocates β users to each codebook at the same time, so that β users use the same codebook to transmit uplink information. On the receiver of the base station, an improved Logarithmic Message Passing Algorithm (Log-MPA) is designed for multi-user detection, so that the base station can correctly detect the data of β users who reuse the same codebook. Simulation results show that at the time β = 2, the proposed scheme increased the spectrum utilization to 300%; at the time β = 3, the proposed scheme increased the spectrum utilization to 450%. Compared with the traditional SCMA scheme where the user has an exclusive codebook, the proposed scheme improves the spectrum utilization to β × 150% through codebook reuse at the expense of a small amount of SNR gain, which improves the throughput and user connection by β times number.

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Keywords

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