UWB rapid-bit-exchange system for distance bounding

Distance bounding protocols enable one device (the verifier) to securely establish an upper bound on its distance to another device (the prover). These protocols can be used for secure location verification and detection of relay attacks, even in presence of strong attackers. The rapid-bit-exchange is the core of distance bounding protocols---the verifier sends single bit challenges, which the prover is expected to answer with minimal and stable processing delay. Based on the measured round trip time of flight, the verifier calculates its upper bound to the prover. Although several aspects of distance bounding implementations have been discussed in the past, no full implementation of a wireless distance bounding system has been presented so far. In this work, we present the first full realization of a rapid bit exchange system for distance bounding. Our system consists of an Ultra-Wideband (UWB) ranging radio and of an efficient digital processing implemented on an Field-Programmable-Gate-Array (FPGA) board; it achieves a ranging accuracy of 7:5 cm and a short processing delay at the prover (< 100 ns). This minimal processing delay is the lowest reported so far for provers that demodulate the challenge before responding.