Robust physical layer authentication using inherent properties of channel impulse response

We propose a robust physical layer authentication scheme for wireless communications based on a hypothesis testing of the inherent properties of channel impulse response (CIR) in a time-varying multipath environment. In this paper, the variation between two consecutive CIRs from a transmitter of interest is monitored at the receiver to distinguish the identities of transmitters for authentication purpose. To improve the authentication performance, we develop a new test statistic based on the difference between noise-mitigated CIRs, to minimize the impact of noise and interference from the wireless environment. To achieve this goal, a signal-to-noise ratio (SNR) dependent threshold is derived to eliminate the excessive noise in the estimated CIRs prior to the determination of CIR difference. An adaptive threshold for authentication decision is also developed by statistically evaluating the CIR variation between the legitimate transmitter and the receiver. The theoretical False Alarm Rate (FAR) and Probability of Detection (PD) are analyzed to evaluate the performance and robustness of the proposed authentication technique. Additionally, an orthogonal frequency division multiplexing (OFDM) system is employed to validate the proposed scheme and the related theoretical analysis.