Reconfigurable Intelligent Surface Optimization for Uplink Sparse Code Multiple Access

The reconfigurable intelligent surface (RIS)-assisted sparse code multiple access (RIS-SCMA) is an attractive scheme for future wireless networks. In this letter, the first time, RIS phase shifts of uplink RIS-SCMA system are optimized based on alternate optimization (AO) technique to improve received signal-to-noise ratio (SNR) a discrete set shifts. model formulated utilize AO algorithm. For further reduction in computational complexity, low-complexity (LC-AO) algorithm proposed. complexity analysis two proposed algorithms performed. Monte Carlo simulations and show that significantly SNR compared non-optimized scenario. LC-AO provides same as algorithm, with significant complexity. Moreover, deployment RISs investigated.