The Role of Integrity Monitoring in Connected and Automated Vehicles: Current State-of-Practice and Future Directions

Positioning integrity refers to the trust in the performance of a navigation system. Accurate and reliable position information is needed to meet the requirements of connected and Automated Vehicle (CAV) applications, particularly in safety-critical scenarios. Receiver Autonomous Integrity Monitoring (RAIM) and its variants have been widely studied for Global Navigation Satellite System (GNSS)-based vehicle positioning, often fused with kinematic (e.g., Odometry) and perception sensors (e.g., camera). However, integrity monitoring (IM) for cooperative positioning solutions leveraging Vehicle-to-Everything (V2X) communication has received comparatively limited attention. This paper reviews existing research in the field of positioning IM and identifies various research gaps. Particular attention has been placed on identifying research that highlights cooperative IM methods. It also examines key automotive safety standards and public V2X datasets to map current research priorities and uncover critical gaps. Finally, the paper outlines promising future directions, highlighting research topics aimed at advancing and benchmarking positioning integrity.