We consider a reconfigurable intelligent surface (RIS) assisted multiple-input multiple-output (MIMO) system in the presence of scattering objects. The MIMO transmitter and receiver, the RIS, and the scattering objects are modeled as mutually coupled thin wires connected to load impedances. We introduce a novel numerical algorithm for optimizing the tunable loads connected to the RIS, which does not utilize the Neumann series approximation. The algorithm is provably convergent, has polynomial complexity with the number of RIS elements, and outperforms the most relevant benchmark algorithms while requiring fewer iterations and converging in a shorter time.

翻译：我们考虑存在散射体情况下可重构智能表面（RIS）辅助的多输入多输出（MIMO）系统。MIMO发射端与接收端、RIS及散射体均建模为连接负载阻抗的互耦细导线。我们提出一种新型数值算法，用于优化连接至RIS的可调负载，该算法不采用诺伊曼级数近似。该算法具有可证明的收敛性，计算复杂度随RIS单元数量呈多项式增长，且在所需迭代次数更少、收敛时间更短的前提下，性能优于最相关的基准算法。