Efficient Localization with Base Station-Integrated Beyond Diagonal RIS

TL;DR

This paper proposes a novel BD-RIS-based passive beamforming method at the base station for high-accuracy localization, outperforming traditional RISs and approaching active antenna array performance in future communication systems.

Contribution

It introduces the use of beyond diagonal RISs for passive localization, demonstrating enhanced control and accuracy over conventional RISs through comprehensive analysis.

Findings

BD-RIS achieves near active array localization performance

CRLB analysis confirms improved localization bounds

BD-RIS outperforms diagonal RISs in various scenarios

Abstract

This paper introduces a novel approach to efficient localization in next-generation communication systems through a base station (BS)-enabled passive beamforming utilizing beyond diagonal reconfigurable intelligent surfaces (BD-RISs). Unlike conventional diagonal RISs (D-RISs), which suffer from limited beamforming capability, a BD-RIS provides enhanced control over both phase and amplitude, significantly improving localization accuracy. By conducting a comprehensive Cram\'er-Rao lower bound (CRLB) analysis across various system parameters in both near-field and far-field scenarios, we establish the BD-RIS structure as a competitive alternative to traditional active antenna arrays. Our results reveal that BD-RISs achieve near active antenna arrays performance in localization precision, overcoming the limitations of D-RISs and underscoring its potential for high-accuracy positioning in future communication networks. This work envisions the use of BD-RIS for enabling passive beamforming-based localization, setting the stage for more efficient and scalable localization strategies in sixth-generation networks and beyond.