High density cellular mobile radio communications
First Claim
1. In a plural channel mobile communication system for serving mobile units from a plurality of cell sites each equipped with signal strength measuring apparatus and each having one or more antenna/channel groups, a method for transferring control of communications with a mobile unit from one antenna/channel group of one cell site to another antenna/channel group, comprising the steps of:
- storing in a local cell site data base at each of said cell sites a list of nearby cell sites and a list of candidate hand-off antenna/channel groups and associated signal strength thresholds;
ascertaining at said one cell site when the signal strength of said mobile unit drops below a prespecified threshold;
responsive to said signal strength ascertaining step, accessing the local cell site data base at said one cell site to obtain said list of nearby cell sites and transmitting a command to said signal strength measuring apparatus of said nearby cell sites to measure and report the signal strength of said mobile unit;
responsive to the receipt of said reports from said signal strength measuring apparatus, selecting from said accessed data base candidate list those antenna/channel groups associated with signal strength reports above said associated signal strength threshold.
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Accused Products
Abstract
In a cellular mobile telecommunication system, a method and apparatus for controlling the process of locating a mobile unit from the cell sites. When a mobile unit goes beyond the radio range of its associated controlling cell site, that cell site sends a message to nearby cell sites to measure and report the strength of the received signal from that mobile on each of their directional antennas and to report radio channel availability. These reports are returned to the controlling cell site which compares the received signal strength mesurements against stored thresholds. The controlling cell site generates and transmits to the mobile telecommunications switching office (MTSO) a hand-off request message including a list of candidate hand-off cell sites and directional antennas. The MTSO then selects an available channel associated with one of the candidate cell sites and antennas and generates a sequence of messages to hand-off communications control from the controlling cell site to a candidate cell site.
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Citations
27 Claims
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1. In a plural channel mobile communication system for serving mobile units from a plurality of cell sites each equipped with signal strength measuring apparatus and each having one or more antenna/channel groups, a method for transferring control of communications with a mobile unit from one antenna/channel group of one cell site to another antenna/channel group, comprising the steps of:
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storing in a local cell site data base at each of said cell sites a list of nearby cell sites and a list of candidate hand-off antenna/channel groups and associated signal strength thresholds; ascertaining at said one cell site when the signal strength of said mobile unit drops below a prespecified threshold; responsive to said signal strength ascertaining step, accessing the local cell site data base at said one cell site to obtain said list of nearby cell sites and transmitting a command to said signal strength measuring apparatus of said nearby cell sites to measure and report the signal strength of said mobile unit; responsive to the receipt of said reports from said signal strength measuring apparatus, selecting from said accessed data base candidate list those antenna/channel groups associated with signal strength reports above said associated signal strength threshold. - View Dependent Claims (2, 3, 4, 5)
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6. In a mobile communication system having a plurality of antenna/channel groups for serving mobile units from a plurality of cell sites connected to a telephone switching office and having signal strength measuring apparatus, means for transferring control of communications with a mobile unit from one of said antenna/channel groups at one of said cell sites to another antenna/channel group, comprising:
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means for storing a list of nearby cell sites in a data base local to said one of said cell sites; means for ascertaining at said one of said cell sites when the signal strength of said mobile unit drops below a predetermined value; means responsive to said ascertaining means for accessing said stored list to formulate a packetized message including an address directed to each of said nearby cell sites, said message including a command to said signal strength measuring apparatus to measure said signal strength of said mobile unit. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. In a mobile communication system for serving a multiplicity of mobile units from a plurality of cell sites each equipped with signal strength measuring apparatus and adapted to process mobile unit signal strength measurements to generate a message including a hand-off candidate list of cell sites and associated channel groups, a method for transferring control of communications with a mobile unit from one cell site to another, comprising the steps of:
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storing in a control data base state indicators specifying which channels are available for use at said cell sites; responsive to reception of said message including a hand-off candidate list, selecting one of said available channels associated with a member of said candidate list, using said control data base to determine availability; and transmitting a hand-off message sequence including the identification of said selected available channel. - View Dependent Claims (16)
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17. In a plural channel mobile communication system for serving mobile units from a plurality of cell sites each equipped with signal strength measuring apparatus and each having one or more antenna/channel groups, a method for transferring control of communications with a mobile unit from one antenna/channel group at one cell site to another antenna/channel group, comprising the steps of:
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storing in a local cell site data base at each of said cell sites first and second lists of nearby cell sites and first and second lists of candidate hand-off antenna/channel groups and associated primary and secondary signal strength thresholds; first ascertaining at said one cell site when the signal strength of said mobile unit drops below a primary prespecified threshold; responsive to said signal strength ascertaining step, accessing said local cell site data base to obtain said first list of nearby cell sites and transmitting a first command to said signal strength measuring apparatus of said nearby cell sites on said first list to measure and report the signal strength of said mobile unit; responsive to the receipt of said reports from said signal strength measuring apparatus of said nearby cell sites on said first list, selecting from said accessed data base first candidate list those antenna/channel groups associated with signal strength reports above said associated primary signal strength threshold; responsive to said first selecting step, if said first selecting step selects no antenna/channel groups, further ascertaining at said one cell site whether the signal strength of said mobile unit is below a secondary prespecified threshold; and responsive to said second ascertaining step, accessing said local cell site data base to obtain said second list of nearby cell sites and transmitting a second command to said signal strength measurement apparatus of said nearby cell sites on said second list to measure and report the signal strength of said mobile unit. - View Dependent Claims (18, 19)
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20. ln a plural channel mobile communication system for serving mobile units from a plurality of cell sites each equipped with signal strength measuring apparatus and each having one or more antenna/channel groups, a method for transferring control of communications with a mobile unit from one antenna/channel group at one cell site to another antenna/channel group, comprising the steps of:
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storing in a data base for said one cell site, first and second lists of nearby cell sites and first and second lists of candidate hand-off antenna/channel groups and associated primary and secondary signal strength thresholds; first ascertaining at said one cell site when the signal strength of said mobile unit drops below a primary prespecified threshold; responsive to said signal strength ascertaining step, accessing said data base for said one cell site to obtain said first list of nearby cell sites and transmitting a first command to said signal strength measuring apparatus of said nearby cell sites on said first list to measure and report the signal strength of said mobile unit; responsive to the receipt of said reports from said signal strength measuring apparatus of said nearby cell sites on said first list, selecting from said accessed data base first candidate list those antenna/channel groups associated with signal strength reports above said associated primary signal strength threshold; responsive to said first selecting step, if said first selecting step selects no antenna/channel groups, further ascertaining whether the signal strength of said mobile unit is below a secondary prespecified threshold; and responsive to said second ascertaining step, accessing said local cell site data base to obtain said second list of nearby cell sites and transmitting a second command to said signal strength measurement apparatus of said nearby cell sites on said second list to measure and report the signal strength of said mobile unit. - View Dependent Claims (21, 22, 23, 24)
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25. In a plural channel mobile communication system for serving mobile units from a plurality of cell sites each equipped with signal strength measuring apparatus and each having one or more antenna/channel groups, a method for transferring control of communications with a mobile unit from one antenna/channel group at one cell site to another antenna/channel group, comprising the steps of:
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storing in a local cell site data base at said one cell site a list of nearby cell sites; ascertaining at said one cell site when the signal strength of said mobile unit drops below a prespecified threshold; responsive to said signal strength ascertaining step, accessing said local cell site data base and generating a request to said nearby cell sites to measure and report the signal strength of said mobile unit. - View Dependent Claims (26, 27)
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Specification