Frozen-Tag-Based Physical-Layer Authentication Against User Interference

2026-04-07

AI Summary

This work addresses the security limitations of existing physical-layer authentication schemes, which suffer from insufficient protection due to direct embedding of raw authentication tags and vulnerability to inter-user interference. The paper introduces a novel framework that, for the first time, leverages the concept of frozen bits from polar codes for physical-layer authentication: anchor information is treated as information bits while the original tag serves as frozen bits to generate the authentication tag. This approach effectively suppresses interference and conceals the original tag at the receiver, achieving both robustness and covertness. Theoretical analysis and simulations demonstrate that the proposed scheme significantly enhances detection performance for legitimate users while substantially degrading an eavesdropper’s ability to estimate the original tag, thereby improving overall system robustness and security.

Abstract

Tag-based physical layer authentication (PLA) has garnered significant attention due to its low complexity and enhanced security. However, existing PLA schemes encounter two challenges. First, unintended user interference, which overlaps with the authentication signal, corrupts the tag and degrades authentication performance. Second, the vulnerability introduced by direct embedding of the raw tag exposes the tag to the adversary and degrades the security. To address these challenges, this paper proposes a novel frozen-tag-based PLA framework. Different from typical schemes that directly embed the uncoded tag into the signal, a well-designed frozen tag is inserted for authentication, where the frozen tag is generated based on the concept of polar codes with the anchor information as information bits and raw tags as frozen bits. Accordingly, the proposed PLA framework offers two principal advantages. First, the authentication performance is improved since the legitimate receiver can decode the frozen tag and mitigate unintended user interference. Second, the authentication process becomes indecipherable to the illegitimate receiver due to the concealment of the raw tags. Furthermore, we conduct a comprehensive analysis of the proposed framework in terms of robustness, security, and compatibility. Theoretical analysis and simulation demonstrate that the proposed frozen-tag-based PLA framework not only enhances the detection performance but also significantly degrades Eve's capability to estimate the raw tags.

Problem

• physical-layer authentication
• user interference
• tag security
• authentication performance
• adversarial exposure

Innovation

• frozen-tag
• physical-layer authentication
• polar codes
• user interference mitigation
• security enhancement