The inherent properties of channel impulse response (CIR), which are considered as location-specific characteristics of the physical link, have been exploited for the authentication purpose at the physical layer in the wireless communications. Unfortunately, the reliability of CIR-based physical layer authentication is challenged by the noise present in the CIR estimates, the rapid channel variation induced by the mobility of terminals, and the weak authentication decision by exploiting single CIR difference under the hypothesis testing. In this paper, three CIR-based authentication schemes are proposed to enhance the authentication reliability. Specifically, the noise components of the CIR estimates are mitigated in order to derive an adaptive threshold to form the authentication decision. Additionally, because of the rapid variation of the fading channel, channel prediction technique is employed to predict future CIR, and which is exploited to derive the CIR difference for the authentication analysis. Furthermore, to form the final decision in the authentication process, multiple CIR differences are observed by the receiver in a long range based on the channel predictor. In order to optimize the number of CIR differences, an optimization algorithm is developed by minimizing the total error rate under a false alarm constraint. Finally, the false alarm rate and the probability of detection are theoretically derived for performance evaluation, and the performance of proposed schemes is compared with that of a traditional channel-based authentication method using computer simulation. Copyright © 2014 John Wiley & Sons, Ltd.