Millimeter-wave communicating-radars for enhanced vehicle-to-vehicle communications

To be effective, safety relevant applications based on wireless communications between vehicles need a minimum rate of vehicles equipped with communication devices. Although this minimum rate of vehicles could be relatively low, it is still difficult to obtain starting from a nonequipped vehicles situation. However, Long and short range radars are becoming very popular these days for cruise control, obstacle detection, parking assistance and pre-crash sensing. These radars are active sensors that produce significant radiofrequency power in wide allocated frequency bands. They also integrate a sensitive receiver. To accelerate the vehicle-to-vehicle communications penetration rate, this paper evaluates the possibility of enhancing vehicle-to-vehicle communications by using communicating-radars working at millimeter-wave. Current allocated frequencies for both vehicle-to-vehicle communication and radars are presented. Short-range and long-range radar radiofrequency parameters are analyzed to verify that existing automotive radar radio standards are consistent with communication. At grazing angles above the road, the characteristics of the communicating-radar propagation channel are theoretically and experimentally studied and compared to a more conventional 5.9 GHz channel. An analysis of Ultra Wide Band radio communication providing simultaneous access to vehicles in the same communication area is presented. Lastly, relevant architectures for communicating-radars are discussed.