SFPF：用于异常无线设备检测的空频极化指纹
SFPF: Spatio-Frequency Polarization Fingerprint for Anomalous Wireless Device Detection
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中文总结 AI 辅助
针对硬件替换导致的异常无线设备难以检测问题，提出空频极化指纹（SFPF），联合多频率与多方向极化响应，相比传统PF和RFF显著提升检测性能。
中文摘要 AI 辅助
对已部署的无线设备进行定期检查是必要的，因为未经授权的硬件替换可能保留通信功能、凭据和逻辑身份，使得异常设备难以被检测。此类检查在受控测量条件下进行，以验证每个设备与其注册的硬件状态保持一致。当替换硬件与合法硬件非常相似时，传统的射频指纹（RFF）可能无法提供足够的区分度，而在单一观测方向构建的极化指纹（PF）可能遗漏空间非均匀的极化变化。本文提出了空频极化指纹（SFPF），它联合表示多个频率和观测方向上的复杂极化响应；传统PF是其固定方向的切片。我们从硬件相关的模态激励、方向性远场辐射和极化投影推导出SFPF的形成过程。一阶灵敏度分析表明，对相同硬件变化的响应随频率和方向而变化，这促使了联合空频采集。电磁仿真证实了非均匀的空频灵敏度，并表明在相同观测预算下，SFPF相比PF在归一化距离、Fisher分数和类间/类内比上分别提高了17.7%、45.8%和11.3%。实验表明，SFPF在0–20 dB范围内始终优于RFF和PF。在15–20 dB下，SFPF的异常设备F1分数达到87.3–90.4%，AUROC值达到85.4–95.5%。
英文摘要
Periodic inspection of deployed wireless devices is necessary because unauthorized hardware replacement may preserve communication functions, credentials, and logical identity, making anomalous devices difficult to detect. Such inspections are conducted under controlled measurement conditions to verify that each device remains consistent with its enrolled hardware state. Conventional radio-frequency fingerprint (RFF) may provide insufficient separation when replacement hardware closely resembles legitimate hardware, while a polarization fingerprint (PF) constructed at one observation direction may miss spatially nonuniform polarization changes. This paper proposes the spatio-frequency polarization fingerprint (SFPF), which jointly represents complex polarization responses over multiple frequencies and observation directions; conventional PF is its fixed-direction slice. We derive SFPF formation from hardware-dependent modal excitation, directional far-field radiation, and polarization projection. A first-order sensitivity analysis shows that the response to the same hardware change varies with both frequency and direction, motivating joint spatio-frequency acquisition. Electromagnetic simulations confirm the nonuniform spatio-frequency sensitivity and show that, under the same observation budget, SFPF improves normalized distance, Fisher score, and the inter-/intra-class ratio over PF by 17.7%, 45.8%, and 11.3%, respectively. Experiments show that SFPF consistently outperforms RFF and PF over 0--20~dB. At 15--20~dB, SFPF achieves anomalous-device F1 scores of 87.3--90.4% and AUROC values of 85.4--95.5%.
