Various techniques of vehicle to roadside communication have been presented together with examples of propagation problems. For road traffic informations, Radio Data System/Traffic Message Channel (RDS/TMC) is a rapidly growing technique since each braodcast transmitter covers a wide area. For more specific application such as road guidance and automatic debiting system, a short range dedicated link is needed and it is usually achieved in the centimetric or millimetric (or infrared) band by means of beacons put on a pole above the road or on the side and planar antennas inside the vehicle. Other systems which have been described, such as the Global System of Mobile Communication (GSM), are until now, only used for telecommunication purposes, but this technique can be also used in the future for telecommunication and road traffic applications.
Abstract