Ris and rsma improve wireless network data rates despite practical limits
Sum Rate Maximization for Practical RIS-Enhanced Rate-Splitting Multiple Access Systems
Information Theory
Summary
Wireless networks in the future want to send data faster and more efficiently. A technology called RIS can help, but real devices have limitations that cause problems. The authors found a way to work around these limitations in RIS combined with another method called RSMA. Their solution boosts the total data rates significantly more than older methods, showing practical improvements for future 6G networks.
What this means in practice
- •For wireless network designers: Improve spectral efficiency in multiuser 6G systems by optimizing RIS with realistic hardware constraints using RSMA.
- •For satellite communication operators: Enhance satellite downlink data rates in multiuser scenarios by applying RIS optimization that considers amplitude-phase coupling effects.
Authors
Qian Zhang, Xuejun Cheng, Jiaming Shi, Yufei Zhao, Rugui Yao, Ye Fan
Abstract
Reconfigurable intelligent surfaces (RIS) combined with rate-splitting multiple access (RSMA) provide a promising solution for improving the spectral efficiency (SE) of sixth-generation (6G) communication systems. However, most existing studies neglect the practical coupling between the RIS phase shift and amplitude, which may cause phase-shift mismatch and significant performance loss. In this paper, we investigate the multiuser sum-rate maximization problem for practical RIS-enhanced RSMA systems considering amplitude-phase coupling. To address the resulting non-convex problem, an effective variable separation algorithm is proposed. The proposed algorithm is compatible with RIS reflecting optimization under the continuous phase shift or any amplitude-phase coupling relationship and can also be directly extended to practical RIS-enhanced NOMA and OMA systems. Simulation results demonstrate performance gain of over 190\% compared with the ideal-RIS-based benchmark, while the proposed RSMA scheme significantly outperforms the corresponding NOMA and OMA schemes.