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.

翻译：基于标签的物理层认证技术因其低复杂性和增强的安全性而备受关注。然而，现有物理层认证方案存在两个挑战。首先，与认证信号重叠的非预期用户干扰会破坏标签并降低认证性能。其次，原始标签直接嵌入带来的脆弱性会将该标签暴露给攻击者，从而降低安全性。针对这些挑战，本文提出一种新颖的基于冻结标签的物理层认证框架。与直接将未编码标签嵌入信号的典型方案不同，本方案将精心设计的冻结标签用于认证，该冻结标签基于极化码概念生成，其中锚信息作为信息位，原始标签作为冻结位。据此，所提出的物理层认证框架具有两大优势。首先，合法接收方能解码冻结标签并抑制非预期用户干扰，从而提升认证性能。其次，由于原始标签的隐匿性，非法接收方无法破解认证过程。此外，我们从鲁棒性、安全性和兼容性三方面对该框架进行了全面分析。理论分析与仿真结果表明，所提出的基于冻结标签的物理层认证框架不仅能增强检测性能，还能显著削弱窃听者对原始标签的估计能力。