Cellular communications with scheduled handoffs
First Claim
1. In a cellular communication system wherein a satellite projects a plurality of cells that move with respect to the earth, a method of handing-off subscriber unit communications between cells comprising the steps of:
- determining a location of a subscriber unit in a first cell;
scheduling, in response to said determining step, a second cell in which said subscriber unit may reside in the future and upcoming timing corresponding to when said subscriber unit may reside in said second cell;
receiving said second cell and said upcoming timing at said subscriber unit; and
transferring communications with said subscriber unit to said second cell, upon occurrence of said upcoming timing as determined by said subscriber unit, in accordance with said scheduling step.
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Accused Products
Abstract
A cellular communications network includes satellites which project cells toward the earth. The satellites and cells move relative to the earth. When a call is being set up to a subscriber unit, data describing the subscriber unit'"'"'s location are sent to a switching office of the network. The switching office generates a schedule which forecasts when movement of the cells will cause the subscriber unit to cross cell boundaries. During an ongoing call, the subscriber unit 5 determines when scheduled boundary crossings occur. So long as an adequate signal is present in a scheduled cell and network capacity exists in the scheduled cell to handle the call, the call will be handed off to the scheduled cell. The subscriber unit also monitors signal strengths to determine when a traffic channel'"'"'s signal is getting weak and when an alternate cell'"'"'s signal is stronger.
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Citations
32 Claims
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1. In a cellular communication system wherein a satellite projects a plurality of cells that move with respect to the earth, a method of handing-off subscriber unit communications between cells comprising the steps of:
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determining a location of a subscriber unit in a first cell; scheduling, in response to said determining step, a second cell in which said subscriber unit may reside in the future and upcoming timing corresponding to when said subscriber unit may reside in said second cell; receiving said second cell and said upcoming timing at said subscriber unit; and transferring communications with said subscriber unit to said second cell, upon occurrence of said upcoming timing as determined by said subscriber unit, in accordance with said scheduling step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating a subscriber unit in accordance with a cellular communication system wherein a satellite projects a plurality of cells which move over the earth, said method comprising the steps of:
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receiving, through a first one of said cells, a schedule that associates timing data with a channel identity, said channel identity being associated with a second one of said cells; monitoring real time to determine when a time described by said timing data from said schedule occurs; and upon occurrence of said time described by said timing data, transferring communications from said first cell to said second cell in response to said monitoring step. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A cellular communications system with scheduled handoffs comprising:
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a plurality of satellites orbiting so as to move with respect to the earth, said satellites collectively projecting a plurality of cells toward the earth; a subscriber unit in data communication with one of said satellites through a first one of said cells, said subscriber unit including a position location receiver for providing data describing a location for said subscriber unit; a scheduler, responsive to said position location receiver, for generating a schedule which associates a channel used in a second cell of said plurality of cells with timing data that describe when said subscriber unit may reside in said second cell, said schedule being sent to said subscriber unit for use in handoff decisions; and means, coupled to said scheduler, for transferring communications for said subscriber unit to said second cell, upon occurrence of said timing data as determined by said subscriber unit in accordance with said schedule. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A subscriber unit which undergoes scheduled handoffs and which operates in accordance with a cellular communications system wherein satellite projects a plurality of moving cells, said subscriber unit comprising:
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a schedule receiver for receiving, via communications conducted in a first cell of said plurality of moving cells, a schedule that associates timing data with a channel identity, said channel identity being associated with a second cell of said plurality of moving cells; a timer, coupled to said schedule receiver, for monitoring real time to determine when a time described by said timing data from said schedule occurs; and means, coupled to said timer, for transferring communications from said first cell to said second cell upon occurrence of said timing data in accordance with said schedule. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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Specification