GNSS User Authentication Schemes for Location – based Selective Broadcasting

In this work an application derived from GNSS positioning service is presented. The problem of making available to maritime users (boats or ships) traffic data in the neighbouring of a vehicle in order to gather a virtual radar-like picture of the situation with a simply GNSS-receiver/radio-modem device is described. The paper focuses on possible tech-niques to limit the content of a received broadcast traffic message only to that part of the traffic related to the user position. This constraint can be caused by security issues and authority restrictions. This aim is pursued assuming the presence of a ground monitoring and broadcasting station (local element), not provided with directional beam antennas, that only uses ciphering processing schemes based on satellite positioning related observables.