Communication between roadside beacons and vehicles is considered to be a crucial element of any future Integrated Road Transport Environment (IRTE). Automatic Debiting and beacon-based Interactive Route Guidance (IRG) system rely entirely on this type of short-range data communication. It can also be used for a wide range of other applications such as traffic information and fleet management. The objective of the DRIVE CAR GOES project is to study the integration of dynamic route guidance and traffic control systems. After an overview of the system architecture, the requirements of the vehicle/roadside are detailed. The proposed infrastructure is based on roadside infrared beacons and works in a multi-lane environment. The mode of operation of the infrared link is a two-way alternate with fixed time division multiplexing. The Vehicle/roadside communication is built on a 3 Layer architecture (1.2,7) called a "OSI-like" model. Two services are provided to the In Vehicle Units, a File Broadcast Service and a Message Handling Service. The File Broadcast Service offers multi-file transfer facilities and uses encryption to provide a paying service. At layer 2 the transparency is managed by HDLC bit stuffing, the error detection is based on 16 bits FCS, the error correction is achieved by cyclical repetition. The Message Handling Service offers an acknowledged datagram transfer on a Multi-point channel (n to 1). The user's privacy is respected by data encryption. The layer 2 provides an Acknowledge connectionless Service. Transparency error detection and error correction are based on HDLC standard. A slotted-Aloha method manages the conflicts on the multi-points channel. A mathematical model describes a method to optimize the main transmission parameters.
Samenvatting