Patent ID: 8494709

Claim:
An on-vehicle communication device mounted on a first vehicle and wirelessly communicating with at least one second vehicle other than said first vehicle, comprising: a transmitter/receiver configured to obtain a first communication channel utilization rate indicating a time rate at which a radio wave field intensity of a predetermined level or more in said first vehicle is received and to receive from said second vehicle, second vehicle information regarding running of said second vehicle and a second communication channel utilization rate indicating a time rate at which a radio wave field intensity of a predetermined level or more in said second vehicle is received; and communication control means controlling a first vehicle transmission cycle and first vehicle transmission power when data is transmitted from said transmitter/receiver, wherein said communication control means controls said first vehicle transmission cycle based on said first communication channel utilization rate and said second communication channel utilization rate to increase the first transmission cycle if said first channel communication rate is equal to or higher than a certain level and to decrease said first transmission cycle if said first channel communication rate is equal to or lower than a second level and within a certain range, so as to converge on a target communication channel utilization rate.