Patent ID: 8754788

Claim:
A communication device, which is mounted on a vehicle or installed at a roadside, and which performs inter-vehicle communication between in-vehicle communication devices mounted to vehicles, or which performs road-to-vehicle communication between an in-vehicle communication device and a road-side communication device installed at the roadside, comprising: an in-vehicle radio section which performs radio communication with the other communication device; a surrounding communication device information table which stores other communication device position information received from the other communication device and a time of the position information; a transmission destination determining section which controls a storage content of the surrounding communication device information table, and which, when receiving transmission destination position or area information representing a position or area of a transmission destination communication device, determines, on the basis of the transmission destination position or area information and of the storage content of the surrounding communication device information table, a communication device with which communication is to be performed, and then returns a determination result as a transmission destination setting signal; and an in-vehicle communication control section which transmits one's own device position information at every predetermined period from the in-vehicle radio section, which, when receiving the position information from the other communication device, stores the received position information in the surrounding communication device information table via the transmission destination determining section together with the reception time of the position information, and which when performing communication with a communication device whose position or area is designated, outputs the transmission destination position or area information to the transmission destination determining section, and performs, via the in-vehicle radio section, communication with the communication device designated by the subsequently transmitted transmission destination setting signal, wherein the radio communication channel used in a radio signal for transmitting and receiving a data information is different from the radio communication channel for transmitting and receiving the device position information, wherein when selecting a relay communication device from communication devices which are a latest to be set and registered in the surrounding communication device information table, the transmission destination determining section sets the communication device arranged at the roadside to have a higher priority for the relay communication device than the in-vehicle communication device.