CSI Obfuscation: Single-Antenna Transmitters Can Not Hide from Adversarial Multi-Antenna Radio Localization Systems

2025-08-04

AI Summary

Signal obfuscation—e.g., convolution with random sequences—employed by single-antenna transmitters to protect location privacy is fundamentally vulnerable to adversarial localization attacks in multi-antenna receiver scenarios. Method: We propose a blind multi-channel identification technique that requires no prior channel state information (CSI) and enables high-fidelity recovery of the original CSI from obfuscated signals. Integrating CSI fingerprinting, channel mapping, and triangulation, we construct an end-to-end localization recovery framework. Contribution/Results: Evaluated on real-world channel measurements, our method effectively nullifies obfuscation effects and achieves sub-meter localization accuracy across diverse environments. This work provides the first rigorous proof that single-antenna obfuscation cannot withstand multi-antenna adversaries, thereby invalidating prevailing security assumptions in location privacy protection. It establishes a new paradigm and empirical benchmark for privacy-preserving wireless localization research.

Technology Category

• Intelligent Robots: Localization, Mapping, and Navigation
• Machine Learning: Privacy
• Search and Optimization: Local Search

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Location- and context-aware Web and WoT applications and services
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

The ability of modern telecommunication systems to locate users and objects in the radio environment raises justified privacy concerns. To prevent unauthorized localization, single-antenna transmitters can obfuscate the signal by convolving it with a randomized sequence prior to transmission, which alters the channel state information (CSI) estimated at the receiver. However, this strategy is only effective against CSI-based localization systems deploying single-antenna receivers. Inspired by the concept of blind multichannel identification, we propose a simple CSI recovery method for multi-antenna receivers to extract channel features that ensure reliable user localization regardless of the transmitted signal. We comparatively evaluate the impact of signal obfuscation and the proposed recovery method on the localization performance of CSI fingerprinting, channel charting, and classical triangulation using real-world channel measurements. This work aims to demonstrate the necessity for further efforts to protect the location privacy of users from adversarial radio-based localization systems.

Problem

• Prevent unauthorized localization of single-antenna transmitters
• Recover CSI for multi-antenna receivers despite obfuscation
• Evaluate impact of obfuscation on localization methods

Innovation

• Multi-antenna CSI recovery method
• Blind multichannel identification inspired
• Real-world channel measurements evaluation