Channel Modeling and Accelerated Ray-Tracing Simulation for RIS-Assisted MIMO Systems

Reconfigurable intelligent surfaces (RIS) enable programmable control over spatial electromagnetic waves, creating adaptable and intelligent wireless environments. In a RIS-assisted system, a new channel is established between the transmitter (Tx) and receiver (Rx), specifically the cascaded Tx–RIS and RIS–Rx channels, which enhance the system’s overall efficiency and reliability. We propose an accelerated ray-tracing method and a new channel similarity index to quantify channel similarity based on the power delay profile and power angular spectrum for RIS-assisted massive multiple-input–multiple-output systems, which support end-to-end modeling of spherical wavefront propagation. The proposed acceleration algorithm achieves acceptable accuracy while significantly improving simulation efficiency.