RIS-Aided Positioning Under Adverse Conditions: Interference from Unauthorized RIS

TL;DR

This paper investigates how unauthorized reconfigurable intelligent surfaces (RIS) can interfere with positioning systems, analyzing their impact on accuracy and exploring strategies to mitigate such threats.

Contribution

It introduces a theoretical framework for understanding unauthorized RIS interference and evaluates codebook design strategies to enhance system robustness.

Findings

High channel gain unauthorized RIS significantly degrades positioning accuracy.

Directional beamforming codebooks are more effective for unauthorized RIS interference.

Simulation confirms the impact of similar delay paths on localization performance.

Abstract

Positioning technology, which aims to determine the geometric information of a device in a global coordinate, is a key component in integrated sensing and communication systems. In addition to traditional active anchor-based positioning systems, reconfigurable intelligent surfaces (RIS) have shown great potential for enhancing system performance. However, their ability to manipulate electromagnetic waves and ease of deployment pose potential risks, as unauthorized RIS may be intentionally introduced to jeopardize the positioning service. Such an unauthorized RIS can cause unexpected interference in the original localization system, distorting the transmitted signals, and leading to degraded positioning accuracy. In this work, we investigate the scenario of RIS-aided positioning in the presence of interference from an unauthorized RIS. Theoretical lower bounds are employed to analyze the impact of unauthorized RIS on channel parameter estimation and positioning accuracy. Several codebook design strategies for unauthorized RIS are evaluated, and various system arrangements are discussed. The simulation results show that an unauthorized RIS path with a high channel gain or a delay similar to that of legitimate RIS paths leads to poor positioning performance. Furthermore, unauthorized RIS generates more effective interference when using directional beamforming codebooks compared to random codebooks.