Patent ID: 7342509

Claim:
An in-vehicle radio apparatus comprising: a transmission unit for transmitting a radio signal by using a spread spectrum method; a first approach determination unit for determining that a vehicle has entered a first distance from an intersection; and an allocation unit for allocating a spread code corresponding to an approach direction of the vehicle to the intersection as a spread code used for transmission by the transmission unit based on determination by the first approach determination unit, wherein the allocation unit specifies the spread code corresponding to the approach direction of the vehicle to the intersection based on a traveling direction of the vehicle, and correspondence data between approach directions to a particular intersection and spread codes, wherein in the correspondence data, a spread code in a particular approach direction to a particular intersection corresponds to a transmission end position of transmission with the spread code, and wherein the in-vehicle radio apparatus further comprises a transmission termination control unit for, when the transmission unit transmits a radio signal with a spread code allocated by the allocation unit regarding an approach direction to an intersection, terminating transmission with the spread code by the transmission unit based on passage of the vehicle across a transmission end position corresponding to the spread code for the approach direction to the intersection of the correspondence data.