DOP analysis using AIS R-MODE stations combined with GNSS satellites into the Venice Lagoon

The concept of safety and security of shipping is an object of great attention from the maritime community. In this context, the knowledge of resilient position, navigation, and time (PNT) information about a ship is a fundamental requirement for a safe navigation and for avoiding accidents, especially in high-risk areas such as, channels, waterways, and Lagoons. About that, international organizations motivate the development of new on-board and land systems that can support or replace those currently in use to obtain more accurate information. In this context, a terrestrial positioning system called AIS Ranging Mode, which utilizes already existing maritime radio infrastructure, can be developed to support and integrate the GNSS (Global Navigation Satellite System), to date the main source of PNT information. As accuracy is the key for a positioning system, this paper investigates the position error due to observation geometry. In particular, in the current work, the potential performances of an integrated positioning system GPS-AIS R-Mode based on AIS shore-based station in Venice Lagoon, are verified in terms of dilution of position (DOP), showing evident improvements.