Efficient Computation of Scattered Fields from Reconfigurable Intelligent Surfaces for Propagation Modeling

Abstract

<p>Most existing path loss models for radio links enabled by reconfigurable intelligence surfaces (RISs) have been derived by assuming that each unit cell of these surfaces scatters incident waves individually. However, unit cells are mutually coupled and scatter collectively, as expressed by the complex radar cross-section (CRCS) of the surface. The CRCS can be computed by full-wave analysis, but this analysis has to be repeated for each of the many states of the RIS, requiring excessive resources. We present an approximate method to efficiently compute the CRCS of an RIS at any state, without repeated full-wave simulations. Our method accounts for the mutual coupling of unit cells and allows us to estimate the scattered fields in the main scattering direction of the RIS, at an accuracy that is comparable to full-wave analysis. Integrating this method with ray-tracing enables the modeling of wireless propagation in realistic, RIS-enabled communication channels over multiple RIS states. </p>