Positioning

Abstract

Benefits of connectivity in Intelligent Transportation Systems (ITS), including safety and convenience, arise from information shared between connected vehicles, other connected traffic participants, and road infrastructure. An essential shared set of information includes position (location) and velocity. Position and velocity allow the connected device to know the presence and predict the behavior of other relevant traffic. Awareness is possible by relying solely on the exchanged data in absence of other sensors. This further enables an in-vehicle system to warn the human driver, or even automatically initiate corrective actions. Satellite-based positioning systems, including the American Global Positioning System (GPS) and also other such Global Navigation Satellite Systems (GNSS), provide globally referenced location and velocity that are often sufficiently accurate for many ITS applications. However, their performance suffers in obstructed skies. Integration of other positioning-relevant data through sensor fusion, such as that from inertial sensors, vision, and maps, improves positioning robustness across diverse environments. Application of advanced satellite-based positioning algorithms, such as Differential GPS (DGPS), Real-Time Kinematic (RTK), and Precise Point Positioning (PPP), to data received from ground reference stations, allows decimeter-level global positioning accuracy and improved integrity measures that further extend the scope of supported ITS applications. The Dedicated Short-Range Communications (DSRC) standards intend to address ITS applications. The standards provide for sharing of information such as basic position data, local high-definition map data, and GPS corrections.