Physical Layer Group Authentication in mMTC Networks with NOMA

Due to energy- and computation-efficiency, physical layer authentication has been acknowledged as a powerful approach in verifying the identity of mobile terminals, especially in the massive machine type communication (mMTC) scenario with resource-constraint terminals. In existing literatures, most of works arc mainly focused on point-to-point verification, where only one terminal can be authenticated at a time. In this paper, we propose a novel physical layer group authentication mechanism exploiting the benefits of non-orthogonal multiple-access (NOMA) and the irreversibility of hash operation. The proposed mechanism is especially suitable for group authentication of multiple terminals in the mMTC networks with massive connections to one access point. In the authentication procedure, challenge-response signals are multiplied with upper layer keys with hash operations and then exchanged at the physical layer. Binary hypothesis test is employed to verify multiple terminals. Missing rate and false alarm rate are investigated to evaluate the performance of the proposed authentication mechanism. Signal to noise ratio(SNR) is the ratio of the power of total transmission signal and noise. The proposed scheme can achieve a missing rate of 0.8% with the false alarm rate below 1% under the SNR of 25dB.