How to Extend 3D GBSM to RIS Cascade Channel with Non-ideal Phase Modulation?

TL;DR

This paper introduces a 3D geometry-based stochastic model for RIS cascade channels that accounts for non-ideal phase modulation, improving the accuracy of channel characterization in next-generation wireless systems.

Contribution

It extends the traditional Tx-Rx channel model to include RIS cascade channels with non-ideal phase modulation, following a 3GPP framework.

Findings

Model accurately reflects angle and polarization dependence.

Differences between ideal and non-ideal phase models are significant.

Simulation results validate the proposed model's effectiveness.

Abstract

Reconfigurable intelligent surface (RIS) is envisioned as a promising technology for next-generation wireless communications. Its deployment introduces a RIS cascade link between the transmitter (Tx) and receiver (Rx), which makes its channel model significantly different from the Tx-Rx direct link. In this letter, a RIS cascade channel modeling method based on a 3D geometry-based stochastic model (GBSM) is proposed. The model follows a 3GPP standardized modeling framework and extends the traditional Tx-Rx channel to Tx-RIS-Rx cascade channel. In the modeling process, we consider the non-ideal phase modulation of the RIS element, so as to accurately characterize the dependence of its phase modulation on the incoming wave angle. The differences between the proposed cascade channel model and the channel model with ideal phase modulation are investigated. The simulation results show that the proposed model can better reflect the dependence of RIS on angle and polarization.