System and method of locating a mobile terminal within the service area of a cellular telecommunication system
First Claim
1. A method of locating a mobile terminal in an unsynchronized cellular telecommunication system having a plurality of unsynchronized base stations and associated cells, said mobile terminal being served by one of said plurality of base stations, said method comprising the steps of:
- identifying a plurality of candidate handoff cells having sufficient signal strength to maintain a call with said mobile terminal;
forcing sequential handoffs of said mobile terminal from said serving cell to said plurality of candidate handoff cells having sufficient signal strength to maintain a call;
measuring signal strength and propagation delay between the mobile terminal and each unsynchronized base station associated with each of said plurality of candidate handoff cells and between the mobile terminal and said serving base station;
calculating a distance between the mobile terminal and each unsynchronized base station associated with each of said plurality of candidate handoff cells and between the mobile terminal and said serving base station;
defining a plurality of arcs of possible locations of said mobile terminal, said arcs being centered on said serving base station and each unsynchronized base station associated with each of said plurality of candidate handoff cells; and
calculating an intersection point of said plurality of arcs of possible locations, said intersection point defining the location of said mobile station.
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Accused Products
Abstract
A mobile terminal locator for locating a mobile terminal in a cellular telecommunication system having a plurality of base stations and associated cells. The mobile terminal locator identifies a plurality of candidate handoff cells having sufficient signal strength to maintain a call with the mobile terminal, and forces sequential handoffs of the mobile terminal from its serving cell to the plurality of candidate handoff cells. The locator then measures signal strength and propagation delay between the mobile terminal and each base station associated with each of the plurality of candidate handoff cells and between the mobile terminal and the serving base station. Either the signal strength, the propagation delay, or both are then used to calculate a distance between the mobile terminal and each base station associated with each of the plurality of candidate handoff cells and between the mobile terminal and its serving base station. From the calculated distances, a plurality of arcs of possible locations of said mobile terminal are then defined, the arcs being centered on the serving base station and each base station associated with each of the plurality of candidate handoff cells. Finally, the mobile terminal locator calculates an intersection point of the plurality of arcs of possible locations, the intersection point defining the location of the mobile station. The locator may operate in cellular telecommunication systems with or without synchronized timing reference signals from the base stations.
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Citations
17 Claims
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1. A method of locating a mobile terminal in an unsynchronized cellular telecommunication system having a plurality of unsynchronized base stations and associated cells, said mobile terminal being served by one of said plurality of base stations, said method comprising the steps of:
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identifying a plurality of candidate handoff cells having sufficient signal strength to maintain a call with said mobile terminal; forcing sequential handoffs of said mobile terminal from said serving cell to said plurality of candidate handoff cells having sufficient signal strength to maintain a call; measuring signal strength and propagation delay between the mobile terminal and each unsynchronized base station associated with each of said plurality of candidate handoff cells and between the mobile terminal and said serving base station; calculating a distance between the mobile terminal and each unsynchronized base station associated with each of said plurality of candidate handoff cells and between the mobile terminal and said serving base station; defining a plurality of arcs of possible locations of said mobile terminal, said arcs being centered on said serving base station and each unsynchronized base station associated with each of said plurality of candidate handoff cells; and calculating an intersection point of said plurality of arcs of possible locations, said intersection point defining the location of said mobile station. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A mobile terminal locator for locating a mobile terminal in an unsynchronized cellular telecommunication system having a plurality of unsynchronized base stations and associated cells, said mobile terminal being served by one of said plurality of base stations, said mobile terminal locator comprising:
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means for identifying a plurality of candidate handoff cells having sufficient signal strength to maintain a call with said mobile terminal; means for forcing sequential handoffs of said mobile terminal from said serving cell to said plurality of candidate handoff cells having sufficient signal strength to maintain a call; means for measuring signal strength and propagation delay between the mobile terminal and each unsynchronized base station associated with each of said plurality of candidate handoff cells and between the mobile terminal and said serving base station; means for calculating a distance between the mobile terminal and each unsynchronized base station associated with each of said plurality of candidate handoff cells and between the mobile terminal and said serving base station; means for defining a plurality of arcs of possible locations of said mobile terminal, said arcs being centered on said serving base station and each unsynchronized base station associated with each of said plurality of candidate handoff cells; and means for calculating an intersection point of said plurality of arcs of possible locations, said intersection point defining the location of said mobile station. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification