Wireless Communications with Reconfigurable Intelligent Surface: Path Loss Modeling and Experimental Measurement

TL;DR

This paper develops and validates free-space path loss models for RIS-assisted wireless communications through simulations and experimental measurements, highlighting the impact of RIS size, placement, and electromagnetic properties.

Contribution

It introduces new path loss models for RIS-assisted communications and validates them with real-world measurements, advancing understanding of RIS effects in wireless systems.

Findings

Models accurately predict path loss based on RIS parameters

Experimental results match simulation predictions

Guidelines for RIS deployment in wireless networks

Abstract

Reconfigurable intelligent surfaces (RISs) comprised of tunable unit cells have recently drawn significant attention due to their superior capability in manipulating electromagnetic waves. In particular, RIS-assisted wireless communications have the great potential to achieve significant performance improvement and coverage enhancement in a cost-effective and energy-efficient manner, by properly programming the reflection coefficients of the unit cells of RISs. In this paper, free-space path loss models for RIS-assisted wireless communications are developed for different scenarios by studying the physics and electromagnetic nature of RISs. The proposed models, which are first validated through extensive simulation results, reveal the relationships between the free-space path loss of RIS-assisted wireless communications and the distances from the transmitter/receiver to the RIS, the size of the RIS, the near-field/far-field effects of the RIS, and the radiation patterns of antennas and unit cells. In addition, three fabricated RISs (metasurfaces) are utilized to further corroborate the theoretical findings through experimental measurements conducted in a microwave anechoic chamber. The measurement results match well with the modeling results, thus validating the proposed free-space path loss models for RIS, which may pave the way for further theoretical studies and practical applications in this field.