A Novel Hybrid Physical-Layer Authentication Scheme for Multiuser Wireless Communication Systems

Guaranteeing decent secrecy levels in future wireless network generations has gained crucial importance due to the unprecedented increase in wireless connectivity worldwide. In this article, an enhanced hybrid channel/device-based physical-layer authentication (PLA) scheme is proposed. The channel state information (CSI) and device-dependent carrier frequency offset (CFO) are employed to discriminate various malign and benign devices in a wireless network. In particular, CSI-based hypothesis testing (HT) is applied initially on the received authentication requests of several unknown transmitters, relying on legitimate CSI values from previous transmissions to classify such nodes. Then, a second stage takes place using the CFO HT on either the interval containing misclassified legitimate or illegitimate nodes to improve the initial stage’s classification results. Approximate expressions for the authentication and detection probabilities are retrieved, whose tightness is endorsed by extensive Monte Carlo simulations. Results show that the proposed scheme enhances the single-attribute PLA performance (CSI- and CFO-based). Also, the authentication probability improves by the increase in the average legitimate signal-to-noise ratio (SNR) and lower nodes’ speed. In addition, the detection probability (DP) rises at high legitimate and intruder links SNRs, while it degrades for low SNR (i.e., noisy attributes observations). Finally, the more significant the difference between the actual malign and benign nodes’ CFOs, the better the DP.