High gain antenna systems for cellular use

• US 5,684,491 A
• Filed: 01/27/1995
• Issued: 11/04/1997
• Est. Priority Date: 01/27/1995
• Status: Expired due to Fees

• Current Assignee: PHAZAR Corp. (QAR Industries, Inc.)
• Original Assignee: Hazeltine Corporation (BAE Systems Plc)
• Inventors: Lopez, Alfred R., Pedersen, John F., Newman, Edward M., Schay, Gary A.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US08/379,820
• Time in Patent Office: 1,012 Days
• Field of Search: 342/374, 342/81, 342/154, 342/372, 342/354, 455/277.1, 455/277.2, 455/33.1, 455/33.3
• US Class Current: 342/374
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

In a cellular type communication system a sector antenna 12 provides coverage of a sector with a relatively low receive gain. A multi-beam antenna 20 covers the same sector with a plurality of narrower beams 21'"'"', 22'"'"', 23'"'"' and 24'"'"' providing higher gain. A multi-beam antenna system 10 provides higher gain operation by selecting the one of the narrower beams 21'"'"', 22'"'"', 23'"'"' or 24'"'"' currently providing best reception of a signal transmitted by a user and coupling that selected beam to a system receiver 18. Beam selection is accomplished by sequentially coupling each narrow beam to a microprocessor based control unit 40 and storing samples of user signals as received in each narrow beam on a continuing repetitive basis. The stored samples are then analyzed in order to select the beam currently providing best reception. If, based on analysis of subsequent samples, a different one of beams 21'"'"', 22'"'"', 23'"'"' or 24'"'"' provides best reception (because of user movement or changing transmission conditions) that different beam is coupled to the system receiver 18. Spaced diversity reception is achieved by providing a second multi-beam antenna 20a and enabling the system receiver 18 to choose either of two, or both, inputs. Fail/safe operation is provided by coupling the sector antenna 12 to the system receiver 18 in the absence of coupling of a superior narrow beam signal.

Claims

1. A multi-beam antenna system, suitable for use in a communication system including a sector antenna having a beamwidth providing sector coverage, a transmitter, and a receiver system for receiving user signals from a user located in said sector, comprising:

multi-beam first antenna means for providing a plurality of first antenna beams which are narrower than said sector and collectively cover at least a portion of said sector;

a plurality of beam ports, each arranged for coupling first antenna beam signals received in one of said first antenna beams;

multicoupler means, coupled to each of said beam ports, for making first antenna beam signals received in each said first antenna beam available at a plurality of parallel ports;

a plurality of switching means, each coupled to each of said beam ports via said parallel ports and having a switch output port and each responsive to selection signals, for selectively providing any one of said first antenna beam signals at a first switch output port coupled to said receiver system and any one of said first antenna beam signals at a second switch output port; and

controller means, coupled to said second switch output port of said switching means, (a) for providing selection signals to said switching means to cause first antenna beam signals received in different ones of said first antenna beams to be sequentially provided at said second switch output port, (b) for analyzing said sequentially provided beam signals and selecting, on a predetermined basis, first antenna beam signals received in one of said first antenna beams, and (c) for providing selection signals to said switching means to cause said selected first antenna beam signals to be coupled to said receiver system via said first switch output port to enable reception of said user signals.

2. A multi-beam antenna system as in claim 1, wherein said predetermined basis comprises one of the following, the best signal to spurious signal ratio and the highest signal amplitude, for signals received from an identified user of said communication signal.

3. A multi-beam antenna system as in claim 1, wherein said controller means continues said analyzing of sequentially provided first antenna beam signals and selecting of first antenna beam signals received in one of said first antenna beams, said controller means arranged for responding to changes in signal reception by causing selected first antenna beam signals received in a different one of said first antenna beams to be coupled to said receiver system when said first antenna beam signals in said different beam are selected on said predetermined basis.

4. A multi-beam antenna system as in claim 1, wherein said plurality of beam ports includes a beam port arranged for coupling sector beam signals received by said sector antenna, said sector beam signals being selectively provided at said first and second switch output ports in the same manner as said first antenna beam signals, and wherein said controller means is arranged for providing selection signals to said switching means to cause said sector beam signals to be coupled to said receiver system in the absence of any first antenna beam signals being coupled to said receiver system.

5. A multi-beam antenna system as in claim 1, wherein said receive antenna system additionally includes, in laterally spaced relation to said first antenna means, multi-beam second antenna means similar to said first antenna means, with associated beam ports, multicoupler means and switching means with first and second switch output ports, as provided with reference to said first antenna means, and wherein:

said controller means, additionally coupled to said second switch output port of said switching means associated with said second antenna means, is additionally arranged (a) for providing selection signals to said switching means of said second antenna means to cause second antenna beam signals received in different ones of the second antenna beams of said second antenna means to be sequentially provided at said second switch output port of said second antenna means, (b) for analyzing said sequentially provided second antenna beam signals and selecting, on a predetermined basis, one of said second antenna beam signals, and (c) for providing selection signals to said switching means to cause said selected second antenna beam signals to also be coupled to said receiver system;

said receiver system thereby enabled to receive said user signal from said user from at least one of said laterally spaced multi-beam first and second antenna means.

6. A multi-beam antenna system as in claim 5, suitable for use with a communication system additionally including a second sector antenna laterally spaced from said sector antenna previously recited, wherein in said receive antenna system said plurality of beam ports includes beam ports arranged for coupling sector beam signals received by each said sector antenna, said sector beam signals being selectively provided respectively at said switch output ports of said first and second antenna means in the same manner as said first and second antenna beam signals;

and wherein said controller means is additionally arranged for providing selection signals to said switching means to cause said sector beam signals to be coupled to said receiver system in the respective absence of first or second antenna beam signals being coupled to said receiver system.

7. A multi-beam antenna system as in claim 5, wherein said predetermined basis comprises one of the following, the best signal to spurious signal ratio and the highest signal amplitude, for signals received from an identified user of said communication signal.

8. A multi-beam antenna system as in claim 1, suitable for use with a communication system including a second receiver system responsive to signals of a second frequency different from a frequency to which the first receiver system previously referenced is responsive, said receive antenna system additionally comprising a third switch output port, coupled to said second receiver system, to which any one of said first antenna beam signals is selectively coupled;

and wherein said controller means is additionally arranged for operation with signals of said second frequency to cause selected first antenna beam signals at said second frequency to be analyzed, selected and coupled to said second receiver system in the same manner as provided with reference to beam signals coupled to said first receiver system.

9. A multi-beam antenna system as in claim 1, additionally comprising synchronization means including:

coupling means for coupling a sample of signals transmitted by said transmitter; and

sync signal means for deriving a receive antenna system synchronizing signal from said sample of transmitted signals for use by said controller means.

10. A multi-beam antenna system as in claim 1, additionally comprising:

transmitter switching means, coupled between said transmitter and said multi-beam first antenna means, for coupling signals from said transmitter for transmission via said one of said first antenna beams identified in subparagraph (b) in reference to said controller means.

11. A multi-beam antenna system as in claim 10, wherein said transmitter switching means are responsive to selection signals provided by said controller means pursuant to subparagraph (c) in reference to said controller means.

12. A multi-beam antenna system as in claim 10, wherein said transmitter switching means are coupled to said multi-beam first antenna means via a duplexer.

13. A multi-beam antenna system as in claim 1, wherein said sector antenna is omnidirective in azimuth and said multi-beam first antenna means provides four first antenna beams each covering 90 degrees in azimuth and collectively covering 360 degrees in azimuth.

14. A multi-beam antenna system as in claim 13, wherein said sector antenna is one of a vertical dipole antenna and a vertical monopole antenna.

15. A multi-beam antenna system, for receiving user signals from a user located in an azimuth sector and providing said user signals to a receiver, comprising:

a sector antenna providing a sector beam for coverage in said sector with a first gain;

antenna means for providing a plurality of narrow beams, each narrower than said sector beam and providing higher gain;

a plurality of beam ports, each for providing signals received in one of said sector and narrow beams;

controller means, coupled to each of said beam ports and responsive to a user identification provided via said sector beam, for analyzing narrow beam signals received in each of said narrow beams with respect to presence of said user signals from said user, for selecting one of said narrow beam signals on a predetermined basis, and for causing said selected narrow band signals to be coupled to an output port to enable coupling to a receiver for processing of said user signal.

16. A multi-beam antenna system, for receiving user signals from a user located in an azimuth sector and providing said user signals to a receiver, comprising:

antenna means for providing a plurality of narrow beams, each narrower than said azimuth sector;

a plurality of beam ports, each for providing signals received in one of said narrow beams;

controller means, coupled to each of said beam ports, for sequentially analyzing, on a continuing basis, signals received in each of said narrow beams with respect to presence of said user signals from said user, for selecting signals in one of said narrow beams on a predetermined basis, for causing said selected signals to be coupled to an output port to enable coupling to a receiver for processing of said user signal and for subsequently causing signals in a different one of said narrow beams to be coupled to said output port when said sequential analysis results in selection of signals in said different one of said narrow beams on said predetermined basis.

17. A multi-beam antenna system as in claim 16, wherein said predetermined basis comprises one of the following, the best signal to spurious signal ratio and the highest signal amplitude, for signals received from said user.

18. A multi-beam antenna system as in claim 16, additionally including, in laterally spaced relation to said antenna means, second antenna means with associated beam ports as provided with reference to said first-recited antenna means, and wherein:

said controller means, additionally coupled to each of said beam ports associated with said second antenna means, is additionally arranged for sequentially analyzing, on a continuing basis, signals received in each of the narrow beams of said second antenna means with respect to presence of said user signals from said user, for selecting signals in one of said narrow beams of said second antenna means on said predetermined basis, for causing said selected second antenna signals to be coupled to a second output port, and for subsequently causing signals in a different one of said narrow beams of said second antenna means to be coupled to said second output port when said sequential analysis results in selection of signals in said different second antenna beam to be selected on said predetermined basis;

said receiver thereby enabled to receive said user signals from at least one of said laterally spaced antenna means.

19. A multi-beam antenna system as in claim 16, wherein said controller means comprises:

a receiver responsive to said signals received in each of said narrow beams for sequentially translating said user signals present in each of said narrow beams to a video signal format;

an analog to digital converter, coupled to said receiver, for converting said video signal format user signals to digital form;

a buffer memory, coupled to said analog to digital converter, for storing samples of said user signals present in each of said narrow beams; and

processor means, coupled to said buffer memory, for analyzing said stored samples and selecting, on said predetermined basis, signals received in one of said narrow beams.

20. A multi-beam antenna system as in claim 19, wherein said processor means additionally causes signals received in said selected one of said narrow beams to be coupled to said output port.

21. A multi-beam antenna system as in claim 16, additionally comprising:

a transmitter; and

transmitter switching means, coupled between said transmitter and said antenna means, for coupling signals from said transmitter for transmission via said one of said narrow beams as selected on said predetermined basis and subsequently for transmission via said different one of said narrow beams pursuant to said sequential analysis.

22. A multi-beam antenna system as in claim 21, wherein said transmitter switching means are responsive to selection signals provided by said controller means based upon said sequential analysis.

23. A multi-beam antenna system as in claim 21, wherein said transmitter switching means are coupled to said antenna means via a duplexer.

24. A method for receiving cellular communication signals from a user located in an azimuth sector by use of an antenna beam narrower than said sector, comprising the steps of:

(a) identifying a user signal by use of sector beam signals received in a sector beam providing antenna beam coverage of said sector;

(b) providing a first plurality of narrow beams, each providing antenna beam coverage narrower than said sector and collectively providing coverage of at least a portion of said sector;

(c) analyzing narrow beam signals received in each of said narrow beams with respect to the presence of said user signal;

(d) selecting, on a predetermined basis, one of said narrow beam signals; and

(e) coupling said selected narrow beam signal to an output port to enable coupling to a receiver to provide said user signal with higher gain than provided by said sector beam.

25. A method for receiving cellular communication signals as in claim 24, wherein said narrow beam signals are analyzed in step (c) on a continuing sequential basis.

26. A method for receiving cellular communication signals as in claim 24, additionally comprising repetition of steps (c), (d) and (e) to monitor changing reception conditions resulting in selection of a different one of said narrow beam signals and coupling of said different narrow beam signal to said output port.

27. A method for receiving cellular communication signals as in claim 24, wherein steps (d) and (e) comprise:

(d) selecting, on a predetermined basis, one signal from the following group of signals, said narrow beam and said sector beam signals; and

(e) coupling said selected beam signals to an output port to enable coupling to a receiver for processing of said user signal.

28. A method for receiving cellular communication signals as in claim 24, additionally comprising the steps of:

(f) providing a second plurality of narrow beams originating from positions laterally spaced from the originating positions of said first plurality of narrow beams, said second plurality of beams having characteristics similar to said first plurality of beams;

(g) repeating steps (c), (d) and (e) with respect to the narrow beams of said second plurality of narrow beams to analyze, select and couple a second selected narrow beam signal to a second output port; and

(h) coupling a receiver system to said first and second output ports for use of at least one of said selected narrow beam signals to provide said user signal.

29. A method for receiving cellular communication signals as in claim 24, wherein said narrow beam signal is selected in step (d) on the basis of one of the following, the best signal to spurious signal ratio and the highest user signal amplitude.

30. A beam selection method, usable in a communication system wherein a user signal may initially be received in different ones of a plurality of available time slots, comprising the steps of:

(a) providing a plurality of contiguous antenna beams;

(b) receiving an initial signal from a user in a first time slot of a repetitive series of time slots;

(c) determining the antenna beam which provided the strongest reception of said initial signal;

(d) assigning the antenna beam determined in step (c) for reception of subsequent signals from said user in all available time slots within a time period;

(e) providing a relative count for each antenna beam of occurrences of strongest reception of signals from said user in available time slots within said time period; and

(f) selecting for reception of signals from said user the antenna beam for which said step (e) relative count is the highest.

31. A beam selection method as in claim 30, wherein step (a) additionally comprises providing a sector antenna beam providing azimuth coverage nominally the same as said plurality of contiguous beams, and wherein steps (c) through (f) are implemented only if said initial signal received in step (b) has an amplitude less than a predetermined level.

32. A beam selection method as in claim 30, wherein in step (b) said user is a cellular communication user and said initial signal is a randomly timed request for access to use of said system.

33. A beam selection method as in claim 30, wherein in step (b) each time slot is nominally 15 milliseconds long and is included in a series of time slots repeated nominally every 90 milliseconds, and said step (d) time period is a period nominally up to 10 seconds long.

34. A beam selection method as in claim 30, wherein in step (e) an occurrence of strongest reception by a particular beam results in increasing the count of a counter for that beam.

35. A beam selection method as in claim 34, wherein in step (e) the counts of counters for beams other than said particular beam are decreased when they do not provide occurrences of strongest reception of signals from said user.

36. A beam selection method as in claim 30, wherein in step (f) said selecting occurs at the end of said time period.