Intelligent Reflecting Surfaces: Physics, Propagation, and Pathloss Modeling

TL;DR

This paper derives a physically accurate far-field pathloss model for intelligent reflecting surfaces, clarifying their beamforming capabilities and disproving a previously used pathloss model in the literature.

Contribution

It introduces a new far-field pathloss model based on physical optics and explains the joint beamforming behavior of surface elements, correcting prior misconceptions.

Findings

Derived the far-field pathloss using physical optics techniques.

Showed that surface elements act as diffuse scatterers but can beamform collectively.

Disproved a previously conjectured pathloss model.

Abstract

Intelligent reflecting surfaces can improve the communication between a source and a destination. The surface contains metamaterial that is configured to "reflect" the incident wave from the source towards the destination. Two incompatible pathloss models have been used in prior work. In this letter, we derive the far-field pathloss using physical optics techniques and explain why the surface consists of many elements that individually act as diffuse scatterers but can jointly beamform the signal in a desired direction with a certain beamwidth. We disprove one of the previously conjectured pathloss models.