Subscriber unit, a cellular communication system and a method for determining a location therefor
First Claim
1. A subscriber unit for a cellular communication system comprising:
- first location determining means operable to determine a first location estimate of the subscriber unit in response to signals transmitted from a plurality of satellites and satellite information related to the plurality of satellites;
means for receiving the satellite information;
second location determining means operable to determine a second location estimate based on information associated with the cellular communication system; and
an update controller operable to determine an update time of the satellite information in response to the second location estimate.
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Accused Products
Abstract
A subscriber unit (103) for a cellular communication system (100) comprises a first location processor (117) which determines a location estimate from signals transmitted from satellites (105) and from satellite information related to the satellites (105). The satellites (105) may be Global Positioning System (GPS) satellites. The subscriber unit (103) also comprises a receiver (115) which receives the satellite information, and further comprises a second location processor (111) which determines location estimates based on uplink or downlink transmissions in the cellular communication system (100). An update controller (121) determines an update time for the satellite information in response to the location estimates of the second location processor (111). Accordingly, the update operation may be optimised for the specific movement of the subscriber unit (103) without requiring satellite based location estimates. This may improve location determination accuracy, time to first fix and may reduce power consumption.
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Citations
20 Claims
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1. A subscriber unit for a cellular communication system comprising:
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first location determining means operable to determine a first location estimate of the subscriber unit in response to signals transmitted from a plurality of satellites and satellite information related to the plurality of satellites;
means for receiving the satellite information;
second location determining means operable to determine a second location estimate based on information associated with the cellular communication system; and
an update controller operable to determine an update time of the satellite information in response to the second location estimate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A cellular communication system comprising:
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first location determining means operable to determine a first location estimate of the subscriber unit in response to signals transmitted from a plurality of satellites and satellite information related to the plurality of satellites;
means for receiving the satellite information;
second location determining means operable to determine a second location estimate of the subscriber unit in response to radio signals between the subscriber unit and a plurality of base station of the cellular communication system; and
an update controller operable to determine an update time of the satellite information in response to the second location estimate.
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20. A method of determining a location in a subscriber unit for a cellular communication system comprising the steps of
determining a first location estimate based on information associated with the cellular communication system; -
determining an update time for updating satellite information related to a plurality of satellites in response to the first location estimate;
receiving the satellite information at the update time; and
determining a location estimate of the subscriber unit in response to signals transmitted from a plurality of satellites and the satellite information.
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Specification