Reconfigurable Intelligent Surface-Assisted Uplink Sparse Code Multiple Access

TL;DR

This paper introduces a novel RIS-assisted uplink SCMA scheme that enhances spectral efficiency and reduces decoding complexity, leveraging a modified message passing algorithm and low-complexity decoding techniques.

Contribution

It is the first to integrate reconfigurable intelligent surfaces with uplink SCMA, proposing a new scheme with improved performance and reduced decoding complexity.

Findings

Enhanced spectral efficiency with RIS-assisted uplink SCMA

Reduced decoding complexity using a low-complexity decoder

Improved bit error rate performance over conventional SCMA

Abstract

Reconfigurable intelligent surface-empowered communication (RIS) and sparse code multiple access (SCMA) are promising candidates for future generations of wireless networks. The former enhances the transmission environments, whereas the latter provides a high spectral efficiency transmission. This letter proposes, for the first time, an RIS-assisted uplink SCMA (SCMA-RIS) scheme to improve the conventional SCMA spectrum efficiency. The message passing algorithm (MPA) is utilized and modified to decode the SCMA-RIS transmitted signals. Moreover, a low-complexity decoder for the SCMA-RIS scheme is proposed to significantly reduce the MPA decoding complexity and improve the bit error rate performance of the conventional SCMA. Monte-Carlo simulations and complexity analysis are presented, which support the findings.