Channel Charting in Smart Radio Environments

TL;DR

This paper presents a novel approach using static electromagnetic skins to improve device localization accuracy in urban environments through channel charting, significantly reducing errors and enhancing reliability in challenging NLoS conditions.

Contribution

It introduces a rigorous optimization framework for EMS phase profile design to enhance channel dissimilarity and spatial fingerprinting for device localization.

Findings

Reduced 90th-percentile localization error from over 60 m to less than 25 m.

Significant improvement in trustworthiness and continuity of localization.

First to exploit Smart Radio Environment with static EMS for channel charting enhancement.

Abstract

This paper introduces the use of static electromagnetic skins (EMSs) to enable robust device localization via channel charting (CC) in realistic urban environments. We develop a rigorous optimization framework that leverages EMS to enhance channel dissimilarity and spatial fingerprinting, formulating EMS phase profile design as a codebook-based problem targeting the upper quantiles of key embedding metric, localization error, trustworthiness, and continuity. Through 3D ray-traced simulations of a representative city scenario, we demonstrate that optimized EMS configurations, in addition to significant improvement of the average positioning error, reduce the 90th-percentile localization error from over 60 m (no EMS) to less than 25 m, while drastically improving trustworthiness and continuity. To the best of our knowledge, this is the first work to exploit Smart Radio Environment (SRE) with static EMS for enhancing CC, achieving substantial gains in localization performance under challenging None-Line-of-Sight (NLoS) conditions.