An Electromagnetic Analysis of the Impact of Random Scattering and RISs on the Shannon Capacity of MIMO Communication Systems

The channel capacity of a multiple-input-multiple-output (MIMO) system is a critical metric for assessing its potential information transmission ability. Accurately assessing the impact of spatial environments and potential capacity embedded in electromagnetic (EM) space is of great significance. Conventional capacity analyses often lean on statistical models or channel approximations, which frequently encounter challenges in adapting to swift advancements in near-field and high-frequency applications. In addition, they tend to overlook accurate EM effects. From a rigorous EM perspective, we evaluate the scatterer effects on channel capacity in two distinct types of scatter-MIMO systems based on effective EM methodologies. The scatterers are initially distributed randomly across diverse spatial ranges, and macroscopic data are generated through a stochastic Monte Carlo simulation approach. Moreover, this article extends its investigation to an EM model applied to assess capacity in the presence of reconfigureable intelligent surfaces (RISs), and its impact on capacity has also been assessed. The proposed EM information strategy and macroscopic conclusions presented in this work provide a universal framework for accurately assessing and designing MIMO channels by accounting for the impact of environment random scatter and RIS distributions.