Physical Layer Authentication Based on Nonlinear Kalman Filter for V2X Communication

Authentication is an important guarantee for vehicle to everything (V2X) commercial deployment. Currently, V2X security often use identity authentication schemes based on public key infrastructure (PKI). These schemes need to transmit certificates and signatures when sending safety-related information such as basic safety messages (BSMs), which need to occupy extra bandwidth and reduce the available channel capacity. So, V2X communication efficiency will be seriously affected in traffic congestion. In this paper, we propose a V2X authentication model based on physical layer characteristics. Then we use the Kalman filter to refine the iterative model and threshold model. The iterative model mainly realizes the priori and posteriori estimation of the current time based on the physical layer characteristics of the previous time, which provides the basis for the entire authentication process. The threshold model analyzes the mathematical characteristics of the priori estimation, and gives the calculation method of the authentication threshold. Since the conventional Kalman filter can only be used for linear discrete system, we use extended Kalman filter and unscented Kalman filter to extend the characteristics used for authentication to non-linearity. At the same time, iterative model and threshold model are improved according to these two algorithms. In terms of security and performance, we compare the proposed schemes with the conventional V2X authentication scheme and physical layer authentication scheme, and the effects of these schemes are analyzed by experiment. We select three characteristics for simulation: received signal strength indication (RSSI), the distance between the two vehicles, and the relative speed between the two vehicles. Then we analyze the process and effect of these two filters, and the factors that affect the threshold. Through experiments, the proposed authentication schemes can effectively take the responsibility of identity authentication in the V2X environment, and have high security level and low overhead, which can reduce the consumption of communication resources by security.