Trusted Radionavigation via Two-Way Ranging

Wireless positioning systems based on passive ranging, such as Global Navigation Satellite Systems (GNSS), are very attractive and represent the most pragmatic and efficient solution to offer ranging capabilities to billions of users worldwide with medium earth orbit satellites. However, they are based on the fundamental assumption that the observed propagation delay relates to the geometric range. Rather than operating on the principles of time-of-arrival ranging, a two-way ranging (TWR) technique can form ranging estimates based on infrastructure interrogation, using cryptographic techniques asserting the validity of the channel estimates. This paper presents a system architecture and node design providing Secure Time Transfer (STT), Authenticated Ranging (AR), and Verifiable Multilateration (VM) involving two-way ranging. STT and AR functions are used as a source of trustworthy additional information supporting the GNSS receiver, which can exploit this information to extend its level of resilience against intentional attacks and unintentional interferences. This concept is further demonstrated into the security augmented GNSS receiver, along with an Inertial Measurement Unit (IMU). The implemented hardware and software solutions were validated in laboratory environment as well as in field tests. The field tests were conducted outdoors in static, pedestrian, and vehicular scenarios. The results proved that the implemented system using UWB can provide time accuracy in the order of a few microseconds, and distance accuracy of a few tens of centimeters with maximum distance around 40 meters. With Wi-Fi, the achievable time accuracy was a few tens of microseconds, and distance accuracy was a few meters with maximum distance around 500 meters.