High Precision Relative Positioning and Slot Management for ad-hoc Networks as Examples for Traffic Applications of Galileo

For the new European satellite navigation system Galileo many new applications are envisaged using the enhanced features with the reliability and accuracy of the system. Most applications focus on the transport area where new approaches are dealing with increased traffic and road safety using Advanced Driver Assistance Systems (ADAS). The paper shows how this can be realised by means of procedures for a high precise relative positioning of vehicles vs. other vehicles or infrastructure (e.g. fixed obstacles). For that Galileo based technologies can primary be used being supplemented by additional onboard sensors. The acquired positioning raw data (satellite pseudo ranges, speed, acceleration, etc.), being subject of the same ionospheric interferences within a short range, will be exchanged with other vehicles where special algorithms can calculate the precise distances or velocities finally creating a virtual image of a vehicles surrounding with an extended visual horizon. For the information exchange high amounts of data have to be transferred on dedicated frequencies with standardised procedures. The paper shows that future data communication for that high dynamic radio data traffic with permanent changing link partners needs highly enhanced protocols and access procedures (ad-hoc networks) where each participant gets a precise allocated time slot for transmitting own data. The synchronisation of such transmissions needs then a high accurate common time base which can be provided by the onboard Galileo receiver with services of guaranteed reliability and availability.