Movable body communication system

• US 5,963,149 A
• Filed: 05/01/1996
• Issued: 10/05/1999
• Est. Priority Date: 05/02/1995
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Nagura, Michinaga, Yoshida, Ichiro, Okada, Rokuro
• Primary Examiner(s): TONG, NINA C
• Application Number:
  US08/639,525
• Time in Patent Office: 1,252 Days
• Field of Search: 340/928, 340/932.2, 340/933, 340/991, 340/825.31, 342/51, 342/42, 342/44, 235/384, 235/380, 235/379
• US Class Current: 340/933
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: G08G 1/017 identifying vehicles G08G1/015, G08G1/054 take precedence

Abstract

A response unit located on a vehicle performs transmission operations for transmitting signals including a pilot response signal responsive to receipt of a pilot signal from a fixed transceiver. The transceiver uses a highly directive transmission antenna to transmit a beam-shaped signal containing a pilot signal to a communication zone set with respect to a lane along which the vehicle travels. The fixed transceiver also performs data transmission/reception operations with the response unit when it receives a pilot response signal therefrom. The beam-shaped signal is set to have a radiation area smaller than the area of the communication zone and is electronically scanned within the communication zone in a direction orthogonal to the movement direction of the vehicle by a scanner in the transceiver. The scan patterns of beams from transceivers corresponding to adjacent lanes are synchronized so that the scan areas of signals from adjacent transmission antennas do not overlap.

Claims

1. A movable body communication system having at least one transceiver, disposed with respect to at least one movement path of a movable body, for transmitting a transmit signal to said movable body and receiving a response signal transmitted from said movable body responsive to said transmit signal to thereby perform data transmission/reception with said movable body within a time period during a single scan of a communication zone, said transmit signal being transmitted in a beam-shaped pattern having a cross-sectional radiation area smaller than the area of the communication zone, said at least one transceiver comprising:

an antenna for performing transmission of said transmit signal and reception of said response signal; and

scanning means for scanning said transmit signal transmitted from said antenna in a direction orthogonal to said at least one movement path of said movable body through a plurality of movement path portions, and for specifying said movable body for data exchange between said transceiver and said movable body in an identified one of said plurality of movement path portions, identification of said movable body and said data exchange occurring while said movable body is within the same communication zone.

2. A movable communication system as set forth in claim 1, wherein:

said at least one transceiver includes a plurality of transceivers each having an antenna for performing transmission of said transmit signal and reception of said response signal, and scanning means for scanning said transmit signal transmitted from said antenna in a direction orthogonal to said at least one movement path of said movable body;

said at least one movement path includes a plurality of vehicle movement paths parallel to one another;

said plurality of transceivers are disposed in correspondence with said plurality of vehicle movement paths; and

each of said scanning means in said plurality of transceivers scans its respective signal in a predetermined pattern, said predetermined pattern of ones of said scanning means in said transceivers corresponding to adjacent travel paths being synchronized so that the communication zone of transmit signals radiated from transmission antennas in transceivers corresponding to adjacent travel paths do not overlap.

3. A movable body communication system as set forth in claim 1, wherein said at least one transceiver is for radiating a beam-shaped signal of millimetric waves from said transmission antenna.

4. A movable body communication system as set forth in claim 1, wherein said at least one transceiver is for performing communications with a plurality of movable bodies in a communication zone so that until communications with a response unit of a first movable body in said communication zone with which it has started to communicate initially are completed, communications with a response unit of another movable body in said communication zone are not performed.

5. A movable body communication system as set forth in claim 1, wherein said at least one transceiver is for performing communications with a plurality of movable bodies in a communication zone so that communication operations with said plurality of said movable bodies in said communication zone are performed alternately on step-by-step basis.

6. A movable body communication system as set forth in claim 1, wherein said antenna is an array antenna including patch antennas.

7. A movable body communication system as set forth in claim 1, wherein said movable body is equipped with a response unit for transmitting a response signal to said at least one transceiver and receiving a transmit signal therefrom.

8. A movable body communication system as set forth in claim 7, wherein said transceiver is for transmitting a pilot signal to wake up said response unit.

9. A movable body communication system as set forth in claim 8, wherein said transceiver is further for transmitting a first unmodulated carrier signal after transmitting said pilot signal.

10. A movable body communication system as set forth in claim 9, wherein said response unit is for waking up when it receives said pilot signal.

11. A movable body communication system as set forth in claim 10, wherein said response unit is for modulating said first unmodulated carrier signal to obtain a modulated carrier signal and for transmitting said modulated carrier signal as a pilot response signal to said at least one transceiver.

12. A movable body communication system as set forth in claim 11, wherein said transceiver is for transmitting an interrogation signal to said response unit responsive to receipt of said pilot response signal.

13. A movable body communication system as set forth in claim 12, wherein said transceiver is for transmitting a second unmodulated carrier signal after it has transmitted said interrogation signal.

14. A movable body communication system as set forth in claim 13, wherein said response unit is for modulating said second unmodulated carrier signal to obtain a second modulated carrier signal when it has received said interrogation signal and for transmitting said second modulated carrier signal as an interrogation response signal to said transceiver.

15. A movable body communication system as set forth in claim 1, which is applied to an automatic toll collection system for a road.

16. A movable body communication system as set forth in claim 1, wherein said transmit signal transmitted from said antenna has a radiation width which is less than a movable body lane width.

17. A method of communicating comprising the steps of:

radiating a first communication signal from a first fixed station to a first portion in a plurality of portions of a first communication zone located in a path of travel of a mobile station, said first communication signal being radiated in a beam-shaped pattern having a cross sectional radiation area smaller than an area of the first communication zone;

moving an area of radiation of said first communication signal to a second portion, different from said first portion, in said plurality of portions of said first communication zone;

receiving said communication signal with said mobile station when said mobile station is within one of said plurality of portions radiated by said first communication signal; and

transmitting a communication response signal responsive to said first communication signal from said mobile station to said first fixed station in said one of said plurality of portions radiated by said first communication signal, wherein said radiating, moving receiving and transmitting steps cause said mobile station to be identified and data to be exchanged and said identification of said mobile station and said exchange of date occur within a time period during a single scan of said first communication zone while said movable station is within the said first communication zone.

18. The method of claim 17, wherein said plurality of portions collectively define said first communication zone.

19. The method of claim 17, wherein said moving step is performed in a direction orthogonal to said path of travel of said mobile station.

20. The method of claim 17, wherein said first communication signal is a pilot signal and said communication response signal is a pilot response signal.

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

radiating an interrogation signal from said first fixed station to one of said plurality of portions;

moving an area of radiation of said interrogation signal to a different one of said plurality of portions;

receiving said interrogation signal with said mobile station when said mobile station is within one of said plurality of portions radiated by said interrogation signal; and

transmitting an interrogation response signal responsive to said interrogation signal from said mobile station to said first fixed station;

receiving said interrogation response signal at said first fixed station.

22. The method of claim 21, further comprising the step of prohibiting communication between said first fixed station and other mobile stations during a time period between receipt of said pilot response signal by said first fixed station and receipt of said interrogation response signal by said first fixed station.

23. The method of claim 21, further comprising the step of performing communication between said first fixed station and at least one other mobile station during a time period between receipt of said pilot response signal by said first fixed station and receipt of said interrogation response signal by said first fixed station.

24. The method of claim 17, wherein said first communication signal is an interrogation signal and said response signal is an interrogation response signal.

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

radiating a second communication signal from a second fixed station to a first portion in a plurality of portions of a second communication zone located in a path of travel of a mobile station; and

moving an area of radiation of said second communication signal to a second portion, different from said first portion, in said plurality of portions of said second communication zone in synchronization with movement of said first communication signal so that an area of radiation of said first communication signal and an area of radiation of said second communication zone do not overlap.

26. The method of claim 17, wherein said moving step comprises scanning in a mobile station lane width direction.

27. A communication system including at least one transceiver that transmits a transceiver signal to a moving vehicle, and that receives a response signal from the moving vehicle that is responsive to the transceiver signal for data transmission/reception purposes within a time period during a single scan of a communication zone, said transceiver signal being transmitted in a beam-shaped pattern having a cross-sectional radiation area smaller than the area of the communication zone, the at least one transceiver comprising:

an antenna that transmits the transceiver signal, and that receives the response signal; and

a scanner that scans the transceiver signal transmitted from the antenna in a vehicle lane width direction through a plurality of vehicle lane width portions to specify said moving vehicle in one of said vehicle lane width portions for data exchange between said transceiver and said moving vehicle in said identified one of said plurality of vehicle lane width portions, identification of said moving vehicle and said data exchange occurring while said moving vehicle is within the same communication zone.