MIMO Interference Channels Assisted by Reconfigurable Intelligent Surfaces: Mutual Coupling Aware Sum-Rate Optimization Based on a Mutual Impedance Channel Model

We study a multi-user multiple-input multiple-output interference network in the presence of multiple reconfigurable intelligent surfaces (RISs). The entire system is described by using circuit-based model for transmitters, receivers, and RISs. This obtained leveraging electromagnetic tool mutual impedances, which accounts signal propagation coupling among closely-spaced scattering elements. An iterative provably convergent optimization algorithm that maximizes sum-rate RIS-assisted channels introduced. Numerical results show enhanced if RIS elements accounted at stage.