Propagation Modeling for RIS-Enabled Channels Based on Ray-Tracing and the Equivalence Principle

We propose a method to model wave propagation in realistic reconfigurable intelligent surface (RIS)-enabled communication channels. Based on full-wave simulation and the equivalence principle, an RIS is equivalent to a surface current source with electric and magnetic current densities. Next, this equivalent source is integrated into ray-tracing to derive the RIS propagation model. This method combines the accuracy of full-wave analysis with the efficiency of ray-tracing, and provides a rigorous way to analyze realistic RIS-enabled channels. A case study of modeling a simple scenario demonstrates that the accuracy of this method is comparable with full-wave analysis across the near-field and far-field regions of the RIS.