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.

中文翻译：

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可重构智能表面辅助上行链路稀疏代码多址接入

可重构智能表面授权通信 (RIS) 和稀疏代码多路访问 (SCMA) 是未来无线网络的有希望的候选者。前者增强了传输环境，而后者提供了高频谱效率传输。这封信首次提出了一种RIS辅助上行SCMA（SCMA-RIS）方案，以提高传统SCMA频谱效率。消息传递算法 (MPA) 被利用和修改来解码 SCMA-RIS 传输的信号。此外，提出了一种用于 SCMA-RIS 方案的低复杂度解码器，以显着降低 MPA 解码复杂度并提高传统 SCMA 的误码率性能。介绍了蒙特卡罗模拟和复杂性分析，它们支持了这些发现。