Intelligent Omni-Surface Aided Rate Splitting Multiple Access

This letter proposes a new coupled phase-shift intelligent omni-surface (IOS) aided rate splitting multiple access (RSMA) transmission framework. Specifically, the base station (BS) splits user messages into common and private parts and precodes the common stream carefully to exploit the operation of IOS aided communication for spectral efficiency improvement. A resource allocation problem to maximize the minimum rate among users is formulated, where the beamforming vector at the BS, the IOS coefficients, and the rate allocation are jointly optimized while satisfying the users' quality of service requirements and successive interference cancellation constraint. An efficient alternating optimization algorithm is then developed to solve the non-convex resource allocation problem and obtain the stationary point solution. Numerical results show that our proposed IOS aided RSMA transmission framework achieves a significant spectral efficiency improvement compared with other baseline schemes.