Microwave radio coverage for vehicle-to-vehicle and in-vehicle communication.

For a few years, autonomous intelligent cruise control (AICC) systems as well as anticollision radars have been developed and are currently sold by manufacturers [Grac 1999]. These systems are working at microwave frequencies. As an example, CEPT (European Post and Telecommunication Conference) has allocated frequency bands at 5.8 GHz for dedicated short-range communication (DSRC), at 63 GHz for vehicle-to-vehicle communication and at 76 GHz for anticollision sensors. DSRC and AICC equipment are readily available now. However, in the same time very few vehicle-to-vehicle communication systems have been commercially developed and are currently on the bench. More recently new standards have emerged in the telecommunication industry. These standards develop an open global specification that enables mobile devices to access and interact with information and services instantly. These mobile devices are for example cellular phones, personal digital assistants, satellite positioning systems. Among these emerging standards, Bluetooth is a candidate operating into the 2.45 GHz band [Blue 2001]. Local Area Network (LAN) working at 64 GHz is also a candidate, higher in frequency. From the Intelligent Transport System (ITS) point of view, in-vehicle communication as well as vehicle-to-vehicle communication are a major concern. Thus, these emerging standards can probably offer an effective way of communicating inside the vehicle or between vehicles. In order to explore this opportunity, this paper analyzes the microwave radio coverage of these systems applied to in-vehicle communication and then to vehicle-to-vehicle communication. In the first section, the authors describe simulation and experimental results of in-car radio coverage using the Bluetooth radio frequency (RF) channel. The simulation, as well as broadband experimental measurements explore different transmitter-receiver locations inside a car. In the second part, vehicle-to-vehicle communication is analyzed. The concept of the electronic preview mirror [Hedd 2000] is used to experiment a Bluetooth link in a vehicle-to-vehicle communication scenario. This scenario is compared to the one using an AICC extended sensor. Because of the broad scope of this paper, only significant results can be presented among all the available ones.