Patent ID: 9560213
Date: 2017-01-31
CPC Classifications: G07B,H04M,H04W

Claim:
1. A communication system, comprising: an on-board unit; a first communication device performing communications with the on-board unit for a first service; and a second communication device performing communications with the on-board unit for a second service, wherein, in communications for both of the first and second services, each communication slot includes one control channel in which broadcasting is performed and at least one service channel in which a transmission to a specific destination is performed, wherein communications in the control channels of the communications for the first service are performed at a first frequency, wherein communications in the service channels of the communications for the first service are performed at a second frequency which is different from the first frequency, wherein communications in the control channels of the communications for the second service are performed at a third frequency which is different from both of the first and second frequencies, wherein, with respect to communications in the service channels of the communications for the second service, one reception-only service channel in which the on-board unit only performs a reception operation is provided for a plurality of the service channels and communications in the reception-only service channel is performed at the first frequency, whereas communications in the remaining service channels are performed at a fourth frequency which is different from all of the first, second and third frequencies, and wherein, when a communication for the second service is performed, the on-board unit performs switching to a communication for the first service in response to detection of reception in the reception-only service channel of a radio signal transmitted from the first communication device in the control channel of the communication for the first service.