Privacy Preservation in Delay-Based Localization Systems: Artificial Noise or Artificial Multipath?

TL;DR

This work tackles privacy leakage in delay-based localization by showing that an end user can degrade unauthorized localization at eavesdropping base stations through pilot manipulation. It develops and compares two privacy-preserving strategies, Artificial Noise (AN) and Artificial Multipath (AM), and leverages the misspecified Cramér-Rao bound (MCRB) to quantify the impact of model mismatch on delay and location estimation by adversaries. The results demonstrate that pilot manipulation can substantially reduce unauthorized localization accuracy with minimal disruption to legitimate localization, with AM and AN performing differently depending on the scenario. The study provides guidance for selecting privacy-preserving techniques in 5G/6G systems and highlights the need for scenario-aware strategy choice and extensions to angle- and scene-aware localization.

Abstract

Localization plays an increasingly pivotal role in 5G/6G systems, enabling various applications. This paper focuses on the privacy concerns associated with delay-based localization, where unauthorized base stations attempt to infer the location of the end user. We propose a method to disrupt localization at unauthorized nodes by injecting artificial components into the pilot signal, exploiting model mismatches inherent in these nodes. Specifically, we investigate the effectiveness of two techniques, namely artificial multipath (AM) and artificial noise (AN), in mitigating location leakage. By leveraging the misspecified Cramér-Rao bound framework, we evaluate the impact of these techniques on unauthorized localization performance. Our results demonstrate that pilot manipulation significantly degrades the accuracy of unauthorized localization while minimally affecting legitimate localization. Moreover, we find that the superiority of AM over AN varies depending on the specific scenario.

Figures (5)

• Figure 1: Illustration of location leakage in a delay-based localization system (e.g., TDOA with 3 anchors, or TOA with 2 anchors up to an ambiguity). Alice modifies the uplink pilot to avoid being localized by the Eves.
• Figure 2: Location LB versus number of am for various power allocation coefficients.
• Figure 3: Heat map for localization LB versus $\beta_1$ and $\tilde{\delta}_1$.
• Figure 4: Localization error bounds (crb, mcrb, and lb) and bias under am and an, versus $\beta_1$ or $\tilde{\beta}$, for $\delta_1=1/W$.
• Figure 5: Localization error bounds (crb, mcrb, and lb) and bias under am and an for $\delta_1=1/W$, versus (a) Transmit power $P$ when $\beta_1=10\text{ dB}$. (b) Transmit power $P$ when $\beta_1=30\text{ dB}$.

Theorems & Definitions (1)

• Remark 1