A DWT-Based PHY Key Generation Scheme for the Cross-Layer Security in IoT Networks

In this letter, a novel cross physical layer (PHY)/medium access control (MAC) layer security scheme is proposed, where PHY key generated based on channel information is introduced into the random access procedure to protect the security of wireless communications from the very outset. To ensure the accessing rate of legal user, high key generation rate (KGR) and low key disagreement rate (KDR) are critical. We first utilize instantaneous channel information of demodulation reference signal to rapidly generate key without frequently information exchanging in PHY. Then, to reduce the inconsistency of the generated PHY key caused by high-frequency noise, discrete wavelet transform is used to decrease the KDR. Furthermore, the theoretical KGR upper bound of the proposed scheme is derived from the aspect of information theory. Finally, the proposed scheme is verified in OpenAirInterface platform. Simulation results show that the proposed scheme has the high accessing rate of legal user and low-delay, which effectively protects the random access procedure from unauthorized user.