Vehicle communication system and method providing high responsivity to multiple polling units

• US 5,708,972 A
• Filed: 02/12/1996
• Issued: 01/13/1998
• Est. Priority Date: 02/17/1995
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Matsumoto, Manabu
• Primary Examiner(s): Pham, Chi H.
• Application Number:
  US08/600,024
• Time in Patent Office: 701 Days
• Field of Search: 455/33.4, 455/54.1, 455/103, 455/296, 455/89, 455/56.1, 340/825.08, 340/825.31, 340/825.54, 340/901, 340/905, 340/505, 342/50, 342/51
• US Class Current: 455/517
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G

Abstract

To enable communications between a vehicle-installed device and an antenna unit even when the vehicle-installed device passes through an area where neighboring communication areas overlap each other, a toll collection point of a multiple-lane express road is provided with a gantry having antenna units provided corresponding to the lanes. The antenna units are controlled so that neighboring units alternately transmit signals. The antenna units transmit signals according to a predetermined cycle and transmit an unmodulated carrier wave. Upon receiving a signal, a vehicle-installed device generates a response signal by using a control circuit and transmits a signal by reflection, fixes a communication party for further communications and assumes a status of waiting for an interrogation signal. If the vehicle-installed device receives pilot signals repeatedly from a single antenna unit, the device determines that the communications have failed, and cancels the fixation of communication party and invalidates the party to become able to communicate with other antenna units. The vehicle-installed device will communicate with one of the antenna units without a failure even if the device passes through an overlapping area, thus performing tolling processing without a failure.

Claims

1. A vehicle communication system comprising:

a plurality of antenna units provided corresponding to a plurality of communication areas for transmitting pilot signals at predetermined different timings and for transmitting interrogation signals in accordance with the transmission cycle for the pilot signals when receiving a pilot response signal;

a road-installed device for setting different timings of transmitting at least one of pilot signals and interrogation signals for at least those of the plurality of antenna units whose communication areas neighbor and overlap each other to cause those antenna units to operate in accordance with said different timings, and for identifying a vehicle passing through one of said communication areas on the basis of a signal received; and

a vehicle-installed device provided in a vehicle for transmitting a pilot response signal when receiving a pilot signal from one of the antenna units and for, when receiving an interrogation signal from the same antenna unit, transmitting an interrogation response signal in response to the interrogation signal received, so as to perform communications;

wherein said vehicle-installed device includes communication control means for, when receiving a pilot signal from an antenna unit after transmitting a pilot response signal to the same antenna unit, performing control to invalidate the communications with the antenna unit and to accept a pilot signal from another antenna unit.

2. A vehicle communication system according to claim 1, wherein said communication control means is further for, when it receives no interrogation signal from an antenna unit within a predetermined length of time after transmitting a response signal for a pilot signal or an interrogation signal from the same antenna unit, invalidating the communications with the antenna unit and accepting a pilot signal from another antenna unit.

3. A communication unit comprising:

receiving means for receiving communication signals;

response signal transmitting means for transmitting response signals responsive to said communication signals received by said receiving means; and

response signal prohibition means for, after said response signal transmitting means transmits a response signal responsive to reception by said receiving means of a first communication signal from a given transmitter, prohibiting said response signal transmitting means from transmitting subsequent response signals to said given transmitter when said receiving means receives a second communication signal from said given transmitter.

4. The communication unit of claim 3, further comprising communication party fixing means for establishing said given transmitter as a fixed communication party responsive to reception of said first communication signal by said receiving means and preventing said response signal transmitting means from transmitting response signals responsive to communication signals from other transmitters.

5. The communication unit of claim 4, wherein said communication party fixing means is further for cancelling said given transmitter as said fixed communication party after a predetermined period of time to permit said response signal transmitting means to respond to communication signals from other transmitters.

6. The communication unit of claim 3, further comprising:

a wait time timer initiated responsive to transmission of said response signal to measure a wait time period;

wherein said response signal prohibition means is further for preventing said response signal transmitting means from transmitting response signals to said given transmitter when said wait time timer measures said wait time period.

7. The communication unit of claim 6, further comprising communication party fixing means for establishing said given transmitter as a fixed communication party responsive to reception of said first communication signal by said receiving means and preventing said response signal transmitting means from transmitting response signals responsive to communication signals from other transmitters.

8. The communication unit of claim 3, wherein said communication unit is a vehicle-mounted unit in a toll-charging system.

9. A communication unit comprising:

receiving means for receiving communication signals;

response signal transmitting means for transmitting response signals responsive to said communication signals received by said receiving means;

communication party fixing means for establishing a given transmitter transmitting a first communication signal as a fixed communication party responsive to reception of said communication signal by said receiving means and preventing said response signal transmitting means from transmitting response signals responsive to communication signals from other transmitters; and

communication party cancellation means for cancelling said given transmitter as said fixed communication party responsive to reception by said receiving means of a second communication signal from said given transmitter.

10. The communication system of claim 9, wherein said communication party cancellation means is further for cancelling said given transmitter as said fixed communication party after a predetermined period of time.

11. The communication system of claim 9, further comprising response signal prohibition means for, after said response signal transmitting means transmits a response signal responsive to reception by said receiving means of said first communication signal from said given transmitter, prohibiting said response signal transmitting means from transmitting subsequent response signals to said given transmitter when said receiving means receives said second communication signal from said given transmitter.

12. The communication system of claim 9, further comprising:

a wait time timer initiated responsive to transmission of said response signals to measure a wait time period;

wherein said communication party cancellation means is further for cancelling said given transmitter as said fixed communication party when said wait time timer measures said wait time period.

13. The communication system of claim 12, further comprising response signal prohibition means for, after said response signal transmitting means transmits a response signal responsive to reception by said receiving means of said first communication signal from said given transmitter, prohibiting said response signal transmitting means from transmitting subsequent response signals to said given transmitter when said receiving means receives said second communication signal from said given transmitter.

14. The communication unit of claim 9, wherein said communication unit is a vehicle-mounted unit in a toll-charging system.

15. A method of communicating with a communications unit, said method comprising the steps of:

receiving communication signals from said communications unit;

transmitting response signals responsive to said received communication signals; and

after transmitting a response signal responsive to reception of a first communication signal from said communications unit, prohibiting transmission of subsequent response signals to said communications unit upon reception of a second communication signal from said communications unit.

16. The method of claim 15, further comprising the steps of:

establishing said communications unit as a fixed communication party responsive to reception of said first communication signal; and

preventing transmission of response signals responsive to communication signals from other communications units.

17. The method of claim 15, further comprising the steps of:

timing a wait time period responsive to transmission of said response signal; and

preventing transmission of response signals to said communication unit when said wait time period elapses.

18. The method of claim 17, further comprising the steps of:

establishing said communications unit as a fixed communication party responsive to reception of said first communication signal; and

preventing transmission of response signals responsive to communication signals from other communications units.

19. The communication unit of claim 15, wherein said communication party fixing means is further for cancelling said given transmitter as said fixed communication party after a predetermined period of time to permit said response signal transmitting means to respond to communication signals from other transmitters.

20. A method of communicating with a communications unit, said method comprising the steps of:

receiving communication signals from said communications unit;

transmitting response signals responsive to said received communication signals;

establishing said communications unit as a fixed communication party responsive to reception of a first communication signal from said communications unit and preventing transmission of response signals responsive to communication signals from other communications units; and

cancelling said communications unit as said fixed communication party responsive to reception of a second communication signal from said communications unit.

21. The method of claim 20, further comprising the steps of:

after transmission of a response signal responsive to reception of a first communication signal from said communications unit, prohibiting transmission of subsequent response signals to said communications unit upon reception of said second communication signal from said communications unit.

22. The method of claim 20, further comprising the steps of:

initiating timing of a wait time period responsive to transmission of said response signals; and

cancelling said communications unit as said fixed communication party when said wait time period elapses.

23. The method of claim 22, further comprising the steps of:

after transmission of a response signal responsive to reception of a first communication signal from said communications unit, prohibiting transmission of subsequent response signals to said given transmitter upon reception of said second communication signal from said communications unit.