UC Irvine

Autonomous vehicles are promised to share the road, sea, and sky alongside human-operated vehicles. Full autonomy requires an accurate and tamper-proof navigation system that operates robustly in all settings. To meet this requirement, vehicles must fuse redundant position information from various sources. The state of the art is to fuse position information from a suite of diverse and complementary onboard sensors (e.g., a global navigation satellite system (GNSS) receiver provides stable absolute position information and an inertial measurement unit (IMU) and other dead reckoning (DR) sensors provide short-term accurate DR-type information). Relying on GNSS alone to provide absolute positioning poses an alarming vulnerability: GNSS signals could become unavailable or unreliable in deep urban canyons or locations experiencing a malicious attack (e.g., jamming or spoofing). After prolonged GNSS signal unavailability, the position solution degrades to unsafe levels as error-corrupted DR-type information is integrated without correction from an absolute positioning source. Recently, ambient radio frequency signals of opportunity (SOPs), such as AM/FM, cellular, digital television, and low Earth orbit (LEO) satellites, have emerged as an effective backup or alternative source of absolute positioning information in the absence of GNSS signals.