Precise relative ego-positioning by stand-alone RTK-GPS

Intelligent Transportation System (ITS) applications for integral and cooperative vehicle safety as well as some Advanced Driver Assistance Systems (ADASs) benefit from highly accurate positioning. Shared position data between dynamic traffic objects via Inter-Vehicle Communication (IVC) are the backbone for deriving vehicle trajectories. These can be used for assessing a situation's criticality in vehicle safety. However, with conventional Global Navigation Satellite System (GNSS) measurements, e.g. using Global Positioning System (GPS), the required accuracy cannot be achieved. There are known Cooperative Positioning (CP) methods like Differential GNSS (DGNSS) and Real-Time Kinematic (RTK) for enhanced positioning. Augmentation data are typically transmitted by a wireless communication link like cellular mobile communication. However, there exist dead spots where no correction data are available. For this reason, we introduce in this paper a method for stand-alone RTK by using own stored observations. Thereby, precise relative ego-positioning is possible during correction data interruption. The buffer time is varied in experiment and the error distribution is analyzed.