Beyond PKI: Enhanced Authentication in Vehicular Networks via MIMO

In the scope of vehicular communication networks (V2X), the nature of exchanged safety/warning messages renders itself highly location dependent as it is usually for incident reporting. Vehicles are required to periodically exchange beacon messages that include speed, time and GPS location information. Reported position information must be accurate and authentic. To mitigate the potential risk of location spoofing/falsifying attack, this project presents the dual use of a multi-antenna roadside unit (RSU) as a radar as well as a wireless transceiver. The radar capabilities we integrated into the RSU enabled us to utilize the Angle of Arrival (AoA) estimation as a physical layer authentication scheme for cross verification of the reported location information. As a part of the development, we first evaluated the basic limits of AoA estimation in our system. The problem of deciding whether the received signal is originated from the claimed GPS location is formulated as a two sided hypotheses testing problem whose solution is given by Wald test statistics. Next, we built a hardware implementation of our system using software defined radios and demonstrated the operation of our system on real field experiments. This experience showed us that, the keystone for obtaining reliable AoA measurements is the accurate characterization of the array response vector. Our hardware measurements showed that, unlike idealized models, hardware imperfections leave the actual array response vector in a highly unstructured form. To address this problem, we introduce the method for obtaining the actual array response vector empirically which led to an accurate and stable AoA measurements.