  Accurate and robust localization is crucial for supporting high-level driving
automation and safety. Modern localization solutions rely on various sensors,
among which GPS has been and will continue to be essential. However, GPS can be
vulnerable to malicious attacks and GPS spoofing has been identified as a high
threat. With transportation infrastructure becoming increasingly important in
supporting emerging vehicle technologies and systems, this study explores the
potential of applying infrastructure data for defending against GPS spoofing.
We propose an infrastructure-enabled framework using roadside units as an
independent, secured data source. A real-time detector, based on the Isolation
Forest, is constructed to detect GPS spoofing. Once spoofing is detected, GPS
measurements are isolated, and the potentially compromised location estimator
is corrected using secure infrastructure data. We test the proposed method
using both simulation and real-world data and show its effectiveness in
defending against various GPS spoofing attacks, including stealthy attacks that
are proposed to fail the production-grade autonomous driving systems.
