Antenna beam boundary detector for preliminary handoff determination
First Claim
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1. An antenna beam boundary detector for a cellular radiotelephone system employing a plurality of cells, comprising:
- a first antenna receiving a first radio signal from a first geographic area of radio coverage defined by a beam boundary;
a second antenna receiving a second radio signal geographic area of radio coverage including at least part of said first geographic area, said second radio signal having a high correlation to said first radio signal at said first and second antennas;
means for comparing a magnitude of said first radio signal with a magnitude of said second radio signal; and
means, responsive to said means for comparing, for generating an output signal when a predetermined magnitude relationship exists between said first radio signal magnitude and said second radio signal magnitude thereby detecting said beam boundary.
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Abstract
An antenna beam boundary detector for a sectorized cellular system is disclosed. The difference in signal level received by a main directional antenna and a broad beamwidth antenna is determined by detecting a modulator signal locally impressed on the signal received by the broad beamwidth antenna. The signal level difference factor is the directional antenna beam boundary when the two antennas are correlated. Interferometer effects are cancelled by detecting both amplitude and phase modulation of the locally impressed modulation.
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Citations
36 Claims
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1. An antenna beam boundary detector for a cellular radiotelephone system employing a plurality of cells, comprising:
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a first antenna receiving a first radio signal from a first geographic area of radio coverage defined by a beam boundary; a second antenna receiving a second radio signal geographic area of radio coverage including at least part of said first geographic area, said second radio signal having a high correlation to said first radio signal at said first and second antennas; means for comparing a magnitude of said first radio signal with a magnitude of said second radio signal; and means, responsive to said means for comparing, for generating an output signal when a predetermined magnitude relationship exists between said first radio signal magnitude and said second radio signal magnitude thereby detecting said beam boundary. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A cellular radiotelephone system antenna beam boundary handoff detector for sectorized cells, comprising:
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at least one directional antenna receiving a first radio signal from a first geographic area of radio coverage defined by a beam boundary; a broad beam antenna receiving a second radio signal from a second geographic area of radio coverage including at least part of said first geographic area, said second radio signal having a high correlation to said first radio signal at said first and second antennas; means for comparing a magnitude of said first radio signal with a magnitude of said second radio signal; and means, responsive to said means for comparing, for generating an output signal when said second radio signal magnitude exceeds a predetermined proportion of said first radio signal magnitude thereby determining said beam boundary. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. An antenna beam boundary detector for a cellular radiotelephone system employing a plurality of cells, comprising:
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an antenna array further comprising a first antenna and a second antenna, one of said antennas disposed a predetermined vertical distance above the other, said first antenna adapted to receive a first radio signal from a first geographic area of radio coverage defined by a beam boundary and said second antenna adapted to receive a second radio signal from a second geographic area of radio coverage including at least part of said first geographic area, said second radio signal having a high correlation to said first radio signal at said first and second antennas; means for modulating said second radio signal with a local modulating signal; means for shifting the phase of said modulated second radio signal; means for combining said modulated and phase shifted second radio signal and said first radio signal; means for phase and amplitude demodulating said combined first and second radio signals to recover said local modulating signal; means for detecting a recovered amplitude of said local modulating signal from said means for phase and amplitude demodulating; and means for comparing said detected amplitude to a predetermined threshold.
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27. A method of detecting an antenna beam boundary in a cellular radiotelephone system employing a plurality of cells, comprising the steps of:
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receiving a first radio signal on a first antenna having a first geographic area of radio coverage defined by a beam boundary; receiving a second radio signal on a second antenna having a second geographic area of radio coverage including at least part of said first geographic area, said second radio signal having a high correlation to said first radio signal at said first and second antennas; comparing a magnitude of said first radio signal with a magnitude of said second radio signal; and generating an output signal in response to said comparing step when a predetermined magnitude relationship exists between said first radio signal magnitude and said second radio signal magnitude thereby detecting said beam boundary. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification