LAUSR

Reconfigurable intelligent surfaces (RIS) aided multiple user interference mitigation with constant modulus constraint (CMC) is a key issue in the future 6G communication systems. Usually, the existing methods solve this problem either by relaxing the CMC with performance degrading or by relaxing the cost function with huge computational cost. To achieve a good trade-off between the performance and the complexity, a Fast Successive Upper-bound Minimization (FSUM) method is proposed. In the proposed method, the problem is first reformulated as a penalty quadratic function with CMC. Then, by efficiently finding the surrogate function, a FSUM algorithm is derived to obtain the solution. Compared with the existing methods, the proposed method can achieve 0.4 bits/Hz/s average sum-achievable rate gain enhancement.