Abstract: In order to suppress the self-interference between active reconfigurable intelligent surface (RIS) components and further improve the system capacity, a joint optimization scheme for active RIS topology and precoding design is proposed. Under the maximum power constraints of base station and active RIS, the optimization problem is established based on the criterion of maximum weighted sum-rate (WSR). In order to solve the non-convex problem, the problem is decomposed into two subproblems, active RIS topology and precoding design. The subproblems are transformed and iteratively optimized by using adaptive tabu search, Lagrange multiplier method and binary search algorithm, and an approximate suboptimal solution for the non-convex problem is obtained. The simulation results show that the WSR of the proposed scheme is 3.75 bit·s^-1·Hz^-1 higher than that of the conventional scheme under ideal conditions. In the case of self-interference, the WSR of the proposed scheme only decreases by 0.46% compared with that of the ideal scheme versus 1.6% drop in the conventional scheme, demonstrating that the proposed scheme can effectively mitigate the self-interference between active elements.

Key words: wireless communication, active reconfigurable intelligent surface, weighted summation rate, self-interference suppression, topological structure design