SIC-Free Rate-Splitting Multiple Access: Constellation Constrained Sum-Rate Optimization
Sibo Zhang, Bruno Clerckx, David Vargas · 2024
Rate-Splitting Multiple Access (RSMA) has been recognized as a potential multiple access technique for future wireless communication systems. Recent research shows that it is possible to preserve the superiority of RSMA without using Successive Interference Cancellation (SIC) receivers. In practical systems, SIC-free receivers can be more attractive than SIC receivers due to its low complexity. In this paper, we evaluate the theoretical limits of RSMA with and without SIC receivers under finite constellations. We first derive the constellation constrained sum-rate expressions for RSMA. We then design a projected subgradient ascent algorithm to perform sum-rate optimization by designing the precoders. Numerical results show that, under optimized precoders, SIC-free RSMA leads to minor losses in sum-rate in comparison to RSMA with SIC receivers.