Method and apparatus for determining location of a subscriber device in a wireless cellular communications system
First Claim
1. A method for determining a location of a subscriber device in a wireless cellular communications system, comprising the steps of:
- providing a subscriber device having a cellular digital data receiver system with a cellular digital data receiver therein;
transmitting cellular digital data signals to the subscriber device from at least three different cellular cell site transmitters at different but known locations, each data signal containing a time-synchronized synchronization signal, the time-synchronized synchronization signals of the at least three different cellular cell site transmitters being transmitted at the same time or being displaced in time from each other by a known time displacement;
informing the subscriber device of location data representing a location of each of the at least three cellular cell site transmitters;
determining a time of arrival of each of the time-synchronized synchronization signals with respect to an internal clock of the cellular digital data receiver system; and
obtaining the location of the subscriber device from the location data and the times of arrival of the time-synchronized synchronization signals relative to the internal clock.
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Accused Products
Abstract
The location of a subscriber device in a wireless cellular communications system is established by transmitting digital data signals to a cellular digital data receiver of the subscriber device from at least three different cellular cell site transmitters at known locations. Each data signal has a time-synchronized synchronization signal, preferably synchronized through the time signals of the global positioning system. The time of arrival of each of the time-synchronized synchronization signals is determined with respect to an internal clock of the receiver. The location of the subscriber device is established from the locations of the cell sites and the times of arrival of the synchronization signals relative to the internal clock.
237 Citations
24 Claims
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1. A method for determining a location of a subscriber device in a wireless cellular communications system, comprising the steps of:
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providing a subscriber device having a cellular digital data receiver system with a cellular digital data receiver therein; transmitting cellular digital data signals to the subscriber device from at least three different cellular cell site transmitters at different but known locations, each data signal containing a time-synchronized synchronization signal, the time-synchronized synchronization signals of the at least three different cellular cell site transmitters being transmitted at the same time or being displaced in time from each other by a known time displacement; informing the subscriber device of location data representing a location of each of the at least three cellular cell site transmitters; determining a time of arrival of each of the time-synchronized synchronization signals with respect to an internal clock of the cellular digital data receiver system; and obtaining the location of the subscriber device from the location data and the times of arrival of the time-synchronized synchronization signals relative to the internal clock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for determining a location of a subscriber device in a wireless cellular communications system, comprising:
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at least three cellular cell site transmitters, each of the cellular cell site transmitters including means for providing a timing signal synchronized to a common time standard, the common time standard being a time standard that is the same for each of the cellular cell site transmitters, and means for transmitting a cellular digital data signal having a time-synchronized synchronization signal synchronized to the timing signal; a subscriber device having a cellular digital data receiver operable to receive the cellular digital data signal transmitted by the cellular cell site transmitters, means for determining a time of arrival of each of the time-synchronized synchronization signals relative to the internal clock; means for determining the location of the cellular cell site transmitters; and means for obtaining the location of the subscriber device from the locations of the cellular cell site transmitters and the time of arrival of the time-synchronized synchronization signal at each of the at least three cellular cell site transmitters relative to the internal clock. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus for determining a location of a subscriber device in a wireless cellular communications system, the apparatus comprising the subscriber device having
a cellular digital data receiver operable to receive cellular digital data signals transmitted by at least three cellular cell site transmitters, each of the cellular digital data signals including a time-synchronized synchronization signal synchronized to a common time standard, the common time standard being a time standard that is the same for each of the cellular cell site transmitters,; -
an internal clock; means for determining a time of arrival of each of the time-synchronized synchronization signals relative to the internal clock; and means for obtaining the location of the subscriber device relative to the at least three cellular cell site transmitters from the times of arrival of the time-synchronized synchronization signals relative to the internal clock. - View Dependent Claims (21, 22, 23, 24)
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Specification