Physical-layer Authentication with Watermarked Preamble for Internet of Things.

Physical-layer authentication (PLA) can provide lightweight security solutions for the next-generation Internet of Things (IoT) networks. This paper adopts and modifies the spreading code authentication techniques initially designed for the Global Navigation Satellite System to apply PLA to narrowband IoT networks. In particular, the chip values of the PHY-layer preamble are replaced by a message-generated tag at the transmitter. At the receiver, two kinds of test statistics, crosscorrelation and double-correlation values, are computed to decide the authenticity of a received signal. Also, the closed-form expressions of the corresponding optimal thresholds for the hypothesis tests are explicitly derived. Afterward, the single-frame authentication schemes are extended to multi-frame authentication, where several frames are jointly authenticated. Simulation results of the proposed schemes, along with the prototype validation of the double-correlation scheme based on the GNU Radio/USRP SDR platform, corroborate the effectiveness of the PLA strategies.