Radiotelephone system incorporating two thresholds for handoff
First Claim
1. A radiotelephone system requiring a communication transfer from a source base-site to a selected one target base-site, comprising:
- means for providing a first threshold and a second threshold each associated with the source base-site;
means for obtaining a first signal quality value of a signal received by the source base-site;
means for obtaining a second signal quality value of said signal received by at least the selected one target base-site;
means for sending a communication transfer request to at least the selected one target base-site when said first signal quality value is less than said first threshold;
means, at the selected target base-site and coupled to said means for sending, for responding to the source base-site when said second signal quality value is greater than said first signal quality value; and
means, coupled to said means for responding, for transferring communication from the source base-site to the selected one target base-site when said first signal level quality value is less than said second threshold.
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Abstract
A digital radiotelephone system requiring a transfer of communication from a source base-site (200) in a source cell (100) to a selected one target base-site in a target cell. A source base-site (200) in the source cell (100) provides a first and a second threshold and measures the received signal strength of a mobile unit (225) communicating to the source base-site (200). When the measured signal strength at the source base-site (200) falls below the first threshold, the source base-site (200) initiates a handoff to target base-sites located by the mobile unit (225). The target base-sites measure the received signal strength of the mobile unit (225) and a target base-site is selected. The source base-site (200) is notified of the selected target base-site and hands off communication of the mobile unit (225) to the selected target base-site when the previously measured signal strength at the source base-site (200) falls below the second threshold.
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Citations
14 Claims
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1. A radiotelephone system requiring a communication transfer from a source base-site to a selected one target base-site, comprising:
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means for providing a first threshold and a second threshold each associated with the source base-site; means for obtaining a first signal quality value of a signal received by the source base-site; means for obtaining a second signal quality value of said signal received by at least the selected one target base-site; means for sending a communication transfer request to at least the selected one target base-site when said first signal quality value is less than said first threshold; means, at the selected target base-site and coupled to said means for sending, for responding to the source base-site when said second signal quality value is greater than said first signal quality value; and means, coupled to said means for responding, for transferring communication from the source base-site to the selected one target base-site when said first signal level quality value is less than said second threshold. - View Dependent Claims (2, 3, 4, 5)
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6. A radiotelephone system having a mobile unit communicating to a source base-site, the mobile unit requiring a transfer of communication from the source base-site to a selected one target base-site, the radiotelephone system comprising:
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means for providing a first threshold and a second threshold each associated with the source base-site; means, at the source base-site, for obtaining a first signal quality value of the mobile unit communicating with the source base-site; means, at the source base-site, for receiving information from the mobile unit; means, at at least the selected one target base-site, for obtaining a second signal quality value of the mobile unit communicating with the source base-site; means, coupled to said means for obtaining a first signal quality value, for providing a hysteresis value correlating the physical locations of the source base-site and at least the selected one target base-site; means for comparing said first signal quality value to said first threshold and for comparing said first signal quality value to said second threshold; means, coupled to said means for receiving, for sending said first signal quality value to at least the selected one target base-site when said first signal quality value is less than said first threshold; means, at at least the selected one target base-site, for responding to the source base-site when said second signal quality value is greater than said first signal quality value plus said hysteresis value; and means, coupled to said means for responding, for transferring communication from the source base-site to the selected one target base-site when said first signal quality value is less than said second threshold. - View Dependent Claims (7)
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8. A method of communication transfer from a source base-site to a selected one target base-site in a radiotelephone system comprising the steps of:
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providing a first threshold and a second threshold each associated with the source base-site; obtaining a first signal quality value of a signal received by the source base-site; obtaining a second signal quality value of said signal received by at least the selected one target base-site; sending a communication transfer request when said first signal quality value is less than said first threshold; responding to the source base-site when said second signal quality value is greater than said first signal quality value; and transferring communication from the source base-site to the selected one target base-site when said first signal level quality value is less than said second threshold. - View Dependent Claims (9, 10, 11, 12)
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13. A method of communication transfer in radiotelephone system having a mobile unit communicating to a source base-site, the mobile unit requiring a transfer of communication from the source base-site to a selected one target base-site, the method comprising the steps of:
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providing a first threshold and a second threshold each associated with the source base-site; obtaining, at the source base-site, a first signal quality value of the mobile unit communicating with the source base-site; receiving, at the source base-site, information from the mobile unit; obtaining, at at least the selected one target base-site, a second signal quality value of the mobile unit communicating with the source base-site; providing a hysteresis value correlating the physical locations of the source base-site and at least the selected one target base-site; comparing said first signal quality value to said first threshold and comparing said first signal quality value to said second threshold; sending said first signal quality value to at least the selected one target base-site when said first signal quality value is less than said first threshold; responding to the source base-site when said second signal quality value is greater than said first signal quality value plus said hysteresis value; and transferring communication from the source base-site to the selected one target base-site when said first signal quality value is less than said second threshold. - View Dependent Claims (14)
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Specification