G5GIM: Integrity Monitoring for GNSS/5G Integrated Navigation of Urban Vehicles

Integrity monitoring (IM) for navigation systems is critical to ensure the safety of auto-driving vehicles. It refers to accurately raising alarms to a user when navigation positioning errors exceed the performance limitation. Although receiver autonomous IM (RAIM) methods have been widely applied for global navigation satellite system (GNSS) observations via a consistency checking algorithm, the integrity performance for auto-driving would suffer from a large degradation due to the low satellite visibility with signal occlusions and non-line-of-sight (NLOS) receptions in urban environments. To alleviate this problem, the fifth-generation (5G) communication signals are used as an auxiliary urban navigation source to increase the number of observations, and then, an IM method for the integration of GNSS/5G (G5GIM) is proposed to improve the integrity performance. Specifically, the positioning reference signals (PRSs) of the 5G system in urban canyons are modeled to enrich the observations of the vehicle navigation, followed by the horizontal protection level (HPL) estimation method and the fault detection algorithm for the integration of GNSS and 5G observations. Experimental results on the simulation and UrbanNav datasets show that the proposed G5GIM method significantly outperforms the existing GNSS RAIM method in terms of HPL reduction, fault detection rate, and positioning accuracy improvement.