Land-based wireless communications system having a scanned directional antenna

• US 5,701,583 A
• Filed: 05/25/1995
• Issued: 12/23/1997
• Est. Priority Date: 11/17/1992
• Status: Expired due to Term

• Current Assignee: SBC Technology Resources, Inc. (AT&T, Inc.)
• Original Assignee: Southwestern Bell Technology Resources, Inc. (AT&T, Inc.)
• Inventors: Rainer, Brian Keith, Harbin, Steven Anthony
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): BANKS HAROLD, MARSHA DENISE
• Application Number:
  US08/450,403
• Time in Patent Office: 943 Days
• Field of Search: 455/33.1, 455/33.3, 455/54.1, 455/54.2, 455/56.1, 455/62-63, 455/67.1, 455/67.3, 455/276.2, 455/277.1, 455/277.2, 455/278.1, 455/133, 455/161.2 , 455/161.1, 455/161.3, 342/360, 342/367, 342/374, 379/58-60, 379/63, 343/703, 340/825.44
• US Class Current: 455/25
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H04B 7/24 for communication between two or more posts wireless communication networks H04W
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

A radio communication system is disclosed which comprises a base station for transmitting and receiving signals to and from one or more remote stations. The base station is provided with at least one receive antenna coupled to a base station receiver. The receive antenna is provided with a directional pattern in a horizontal plane and a mechanism for steering the directional pattern azimuthly, until such time as a synchronization signal transmitted by a remote station located within the coverage area is received by the base station receiver. Upon detection of the synchronization signal, scanning of the receive antenna'"'"'s pattern is stopped until such time as message information can be obtained from the remote station and forwarded to a particular destination requested by the remote station. Upon receiving the information, the base station will resume scanning of the antenna, and the information will be forwarded to its requested destination.

Claims

1. A radio communications system comprising:

a plurality of base stations for transmitting and receiving signals to and from one or more remote stations, said one or more remote stations being within a near line-of-sight of at least one of said plurality of base stations, each of said plurality of base stations comprising at least one receive antenna coupled to a base station receiver, said at least one receive antenna having a directional pattern in a horizontal plane and means for steering said directional pattern to sequentially scan from one azimuthal position to another azimuthal position;

means for filtering a signal received at said at least one receive antenna;

means for processing said received signal after filtering by said filtering means;

means for detecting a signal strength of said received signal; and

means for controlling said steering means, said controlling means comprising means for instructing said steering means to stop, and without further scanning, instructing said at least one receive antenna to receive said received signal at an azimuthal position where said detecting means detects said signal strength of said received signal to be is above a predetermined threshold value.

2. The radio communications system according to claim 1, wherein said means for controlling said steering means comprises means for controlling scanning of said directional pattern as a function of the signal strength of said received signal.

3. The radio communications system according to claim 1, further comprising said one or more remote stations, wherein predetermined remote stations each comprise means for transmitting an identifying signal pattern and message information within a frequency band monitored by said base station receiver.

4. The radio communications system according to claim 3, wherein said transmitting means of said remote stations further comprises means for phrasing said message information to include an origination address, a destination address, a message, and error correction information, wherein all of said message information is transmitted subsequent to transmission of said identifying signal pattern.

5. The radio communications system according to claim 3, wherein said processing means comprises means for decoding information which is included in said received signals.

6. The radio communications system according to claim 5, wherein said decoding means comprises means for decoding said identifying signal pattern, said system further comprising:

means for determining if said identifying signal pattern has been correctly decoded; and

means for decoding remaining portions of said received signal and forwarding a corresponding message to a network, if it is determined by said determining means that said identifying signal pattern has been correctly decoded;

said means for controlling said steering means further comprising means for instructing said steering means to move said directional pattern from one azimuthal position to another if said identifying signal pattern has not been correctly decoded.

7. The radio communications system according to claim 5, wherein said means for controlling said steering means comprises:

means for determining if said received signal strength, detected by said detecting means, is greater than said predetermined threshold value; and

means for instructing said steering means to move said directional pattern from one azimuthal position to another if said received signal strength is not greater than said predetermined threshold value.

8. The radio communications system according to claim 7, wherein said threshold value comprises a signal level which is substantially higher than an expected background noise level.

9. The radio communications system according to claim 1, wherein said at least one receive antenna comprises an array of collinear antennas.

10. The radio communications system according to claim 1, wherein said radio communications system comprises a microcellular communications network.

11. The radio communications system according to claim 1, wherein said radio communications system comprises a wireless data network.

12. The radio communications system according to claim 1, wherein said radio communications system comprises an answer back paging system.

13. The radio communications system according to claim 1, said system further comprising a network control center connected to said base station and connected to a telecommunications switching network.

14. The radio communications system according to claim 1, wherein each of said remote stations comprises a transmitter which transmits signals having an effective isotropic radiated power of less than 4 watts.

15. The radio communications system according to claim 1, wherein each of said remote stations comprises a transmitter which transmits signals having an effective isotropic radiated power of less than 2 watts.

16. The radio communications system according to claim 1, wherein said directional pattern comprises a half power beam width in the azimuthal plane of less than 30 degrees and a half power beam width in the elevation plane of less than 30 degrees.

17. The radio communications system according to claim 1, wherein said directional pattern comprises a half power beam width in the azimuthal plane of less than 6 degrees and a half power beam width in the elevation plane of less than 8 degrees.

18. The radio communications system according to claim 1, wherein said at least one receive antenna comprises a plurality of distinct antennas, each of said distinct antennas comprising means for scanning a directional beam azimuthly across a range equal to a fraction of 360 degrees, said distinct antennas being arranged so that the total area scanned by said distinct antennas equals 360 degrees.

19. The radio communications system according to claim 1, further comprising a plurality of base stations, a portion of said plurality of base stations comprising receivers and corresponding scanned base station receive antennas which share a common frequency channel, and means for synchronizing the scanning of said base station receive antennas which share said common frequency channel.

20. The radio communications system according to claim 1, wherein each of said remote stations comprises an omnidirectional antenna coupled to a transmitter and a receiver, for transmitting and receiving signals to and from said base station.

21. The radio communications system according to claim 1, wherein said base station comprises an omnidirectional transmit antenna.

22. A method for communicating, comprising:

operating a plurality of base stations to transmit and receive signals to and from one or more remote stations, said one or more remote stations being within a near line-of-sight of at least one of said plurality of base stations, said method comprising steering at least one receive antenna, coupled to a receiver of each of said base stations, to sequentially scan from one azimuthal position to another azimuthal position, wherein said at least one receive antenna has a directional pattern in a horizontal plane;

filtering a signal received at said at least one receive antenna;

processing said received signal after said filtering;

monitoring a signal strength of said received signal; and

controlling said steering, said controlling comprising instructing said steering to stop, and without further scanning, controlling said at least one receive antenna to receive said received signal at an azimuthal position where it is detected that said signal strength of said received signal at said azimuthal position is above a predetermined threshold value.

23. The method for communicating according to claim 22, further comprising controlling steering of said directional pattern as a function of the signal strength of said received signal.

24. The method for communicating according to claim 22, further comprising operating selected ones of said remote stations to transmit an identifying signal pattern and message information within a frequency band monitored by said base station receiver.

25. The method for communicating according to claim 24, further comprising operating said selected ones of said remote stations to phrase said message information to include an origination address, a destination address, a message, and error correction information, so that all of said message information is transmitted subsequent to transmission of said identifying signal pattern.

26. The method for communicating according to claim 24, wherein said processing comprises decoding information which is included in said received signal.

27. The method for communicating according to claim 26, wherein said decoding comprises decoding said identifying signal pattern, said method further comprising:

determining if said identifying signal pattern has been correctly decoded;

decoding remaining portions of said received signal and forwarding a corresponding message to a network, if it is determined, during said determining, that said identifying signal pattern has been correctly decoded; and

controlling said steering to move said directional pattern from one azimuthal position to another if said identifying signal pattern has not been correctly decoded.

28. The method for communicating according to claim 26, further comprising:

determining if received signal strength is greater than said predetermined threshold value; and

instructing said steering to move said directional pattern from one azimuthal position to another if said received signal strength is not greater than said predetermined threshold value.

29. The method for communicating according to claim 28, wherein said predetermined threshold value comprises a signal level which is substantially higher than an expected background noise level.

30. The method for communicating according to claim 22, wherein said at least one receive antenna comprises an array of collinear antennas.

31. The method for communicating according to claim 22, wherein said method utilizes a microcellular communications network.

32. The method for communicating according to claim 22, wherein said method utilizes a wireless data network.

33. The method for communicating according to claim 22, wherein said method utilizes an answer back paging system.

34. The method for communicating according to claim 22, further comprising operating a network control center which is connected to said base station and is connected to a telecommunications switching network.

35. The method for communicating according to claim 22, wherein each of said remote stations comprises a transmitter which transmits signals having an effective isotropic radiated power of less than 4 watts.

36. The method for communicating according to claim 22, wherein each of said remote stations comprises a transmitter which transmits signals having an effective isotropic radiated power of less than 2 watts.

37. The method for communicating according to claim 22, wherein said directional pattern comprises a half power beam width in the azimuthal plane of less than 30 degrees, and a half power beam width in the elevation plane of less than 30 degrees.

38. The method for communicating according to claim 22, wherein said directional pattern comprises a half power beam width in the azimuthal plane of less than 6 degrees, and a half power beam width in the elevation plane of less than 8 degrees.

39. The method for communicating according to claim 22, wherein said at least one receive antenna comprises a plurality of distinct antennas, said scanning comprising scanning a directional beam of each of said distinct antennas azimuthly across a range equal to a fraction of 360 degrees, said distinct antennas being arranged so that the total area scanned by said distinct antennas equals 360 degrees.

40. The method for communicating according to claim 22, further comprising:

operating a plurality of base stations, a portion of said plurality of base stations comprising receivers and corresponding scanned base station receive antennas which share a common frequency channel; and

synchronizing the scanning of said base station receive antennas which share said common frequency channel.

41. The method for communicating according to claim 22, wherein each of said remote stations comprises an omnidirectional antenna coupled to a transmitter and a receiver, for transmitting and receiving signals to and from said base station.

42. The method for communicating according to claim 22, wherein said base station comprises an omnidirectional transmit antenna.