Positioning Performance of VDES R-Mode

Global navigation satellite systems (GNSSs) have become an essential part of maritime navigation, in particular for collision avoidance and vessel traffic management. The dependence on GNSSs creates vulnerability for maritime shipping. Driven by this vulnerability, the desire for a backup system for maritime navigation has been emerging. The VHF data exchange system (VDES) standard provides communication capabilities for maritime applications. VDES is currently being revised at the ITU-R Working Party 5B and foreseen to be finalized as early as 2022. As part of this revision, VDES will be extended by ranging and navigation functionalities, called R-Mode, as backup for maritime navigation. In this paper we evaluate the positioning performance of VDES R-Mode. For VDES R-mode performance evaluation, we derive estimation theory bounds for the distance and velocity estimation and introduce a Kalman filter which we use for position and velocity tracking. For validation of the positioning performance of VDES R-mode, we describe an experiment we conducted at Lake Ammer, southwest of Munich. Results obtained from this experiment show that VDES R-Mode achieves a positioning accuracy of 10 m, therefore providing an appropriate backup solution for maritime navigation.