Tag-based Physical-Layer Authentication (PLA) has attracted significant attention in recent years due to its low complexity, high security, and low latency. Traditional tag-based PLA schemes typically estimate tags by decoding the message and then subtracting the estimation of the message from the received signal. However, these approaches suffer from two main limitations. First, decoding errors introduce message interference that degrades authentication performance. Second, the analytical complexity of decoding errors leads to sub-optimal threshold settings, thereby limiting detection probability. To address these limitations, this paper proposes a Tag-Based Challenge-Response (TBCR) scheme and a Series Cancellation Authentication (SCA) scheme. Specifically, in the TBCR scheme, the tags are superimposed on a forwarded challenge signal, enabling the receiver to estimate tags by removing the known challenge signal rather than relying on decoding. However, the challenge-response mechanism introduces extra noise. Here, we propose the SCA scheme without the noise interference, where both the series signal generation and cancellation modules are well-designed to generate authentication signals and estimate tags, respectively. Furthermore, we derive the closed-form expressions to evaluate the robustness and security of both proposed schemes. Notably, on one hand, the optimal threshold and detection probability are derived, which theoretically reveal that the SCA scheme always achieves the ideal detection performance, while the TBCR scheme does so in the absence of noise at Alice. On the other hand, the TBCR scheme provides enhanced security at high Signal-to-Noise Ratio (SNR) regions with fewer keys. Theoretical analysis and simulation demonstrate that both proposed schemes significantly outperform the benchmarks in detection probability with reduced time complexity.

翻译：基于标签的物理层认证因其低复杂度、高安全性和低时延特性，近年来受到广泛关注。传统基于标签的物理层认证方案通常通过解码消息来估计标签，随后从接收信号中减去消息的估计值。然而，这类方法存在两大局限：首先，解码误差会引入消息干扰，导致认证性能下降；其次，解码误差的分析复杂性导致阈值设置次优，从而限制了检测概率。为解决这些问题，本文提出标签-挑战-响应（TBCR）方案与串行消去认证（SCA）方案。具体而言，TBCR方案将标签叠加于转发的挑战信号上，使接收端能够通过移除已知挑战信号而非依赖解码来估计标签。但挑战-响应机制会引入额外噪声。为此，我们进一步提出无噪声干扰的SCA方案，通过精心设计的串行信号生成模块与消去模块分别实现认证信号生成与标签估计。此外，我们推导了两种方案的鲁棒性与安全性闭式表达式。值得注意的是，一方面，我们推导了最优阈值与检测概率，从理论上揭示SCA方案始终能实现理想检测性能，而TBCR方案仅在Alice端无噪声时达到该性能；另一方面，TBCR方案可在高信噪比区域以更少的密钥提供增强安全性。理论分析与仿真表明，两种所提方案在检测概率上显著优于基准方案，且时间复杂度更低。