Physics-Aware RIS Codebook Compilation for Near-Field Beam Focusing under Mutual Coupling and Specular Reflections

TL;DR

This paper presents MATCH, a physics-aware codebook compilation algorithm for RIS in near-field environments, explicitly modeling mutual coupling and reflections to improve beam focusing accuracy in wireless networks.

Contribution

The paper introduces a novel physics-based algorithm that accounts for mutual coupling and reflections, enhancing RIS configuration accuracy in near-field conditions.

Findings

MATCH effectively concentrates energy within the focal region.

Physics-consistent codebooks improve RIS performance in complex environments.

The approach is validated through full-wave simulations.

Abstract

Next-generation wireless networks are envisioned to achieve reliable, low-latency connectivity within environments characterized by strong multipath and severe channel variability. Programmable wireless environments (PWEs) address this challenge by enabling deterministic control of electromagnetic (EM) propagation through software-defined reconfigurable intelligent surfaces (RISs). However, effectively configuring RISs in real time remains a major bottleneck, particularly under near-field conditions where mutual coupling and specular reflections alter the intended response. To overcome this limitation, this paper introduces MATCH, a physics-based codebook compilation algorithm that explicitly accounts for the EM coupling among RIS unit cells and the reflective interactions with surrounding structures, ensuring that the resulting codebooks remain consistent with the physical characteristics of the environment. Finally, MATCH is evaluated under a full-wave simulation framework incorporating mutual coupling and secondary reflections, demonstrating its ability to concentrate scattered energy within the focal region, confirming that physics-consistent, codebook-based optimization constitutes an effective approach for practical and efficient RIS configuration.