Cascaded channel modeling and experimental validation for RIS assisted communication system

TL;DR

This paper develops a detailed RIS cascaded channel model based on GBSM, extending existing models to include small-scale multipath characteristics, and validates it through real-world measurements at 6.9 GHz.

Contribution

It introduces an extended convolution-based RIS channel model aligned with 3GPP standards, incorporating small-scale multipath features, and validates it with experimental data.

Findings

The model accurately reflects delay, angle, and power characteristics of RIS channels.

Experimental validation confirms the model's applicability in complex environments.

Provides a reliable basis for RIS system design and deployment.

Abstract

Reconfigurable Intelligent Surface (RIS) is considered as a promising technology for 6G due to its ability to actively modify the electromagnetic propagation environment. Accurate channel modeling is essential for the design and evaluation of RIS assisted communication systems. Most current research models the RIS channel as a cascade of Tx-RIS and RIS-Rx sub-channels. However, most validation efforts regarding this assumption focus on large-scale path loss. To further explore this, in this paper, we derive and extend a convolution expression of RIS cascaded channel model based on the previously proposed Geometry-based Stochastic Model (GBSM)-based RIS cascaded channels. This model follows the 3GPP standard framework and leverages parameters such as angles, delays, and path powers defined in the GBSM model to more accurately reflect the smallscale characteristics of RIS multipath cascades. To verify the accuracy of this model, we conduct measurements of the TxRIS-Rx channel, Tx-RIS, and RIS-Rx sub-channels in a factory environment at 6.9 GHz, using the measured data to demonstrate the models validity and applicability in real-world scenarios. Validation with measured data shows that the proposed model accurately describes the characteristics of the RIS cascaded channel in terms of delay, angle, and power in complex multipath environments, providing important references for the design and deployment of RIS systems.