Method and apparatus for a portable communication device to identify its own location
First Claim
1. Apparatus for a portable communication device to locally identify its own location within a cellular telephone network comprising:
- a receiver for receiving a first pilot signal transmitted from a first base station and at least second and third pilot signals transmitted from at least second and third base stations;
a relative delay calculation unit coupled to the receiver for computing delays between an arrival time of the first pilot signal and arrival times of the second and third pilot signals; and
a processor coupled to the relative delay unit, said processor programmed to determine the location of the portable communication device.
6 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for a portable communication device, such as a mobile radio terminal in a CDMA network, to identify its geographic location. A communication network comprises multiple base stations which transmit pilot signals, where the pilot signals of one base station are offset from the pilot signals of other base stations by integral multiples of a substantially fixed duration. Associated sync channel messages are also transmitted from which the geographic location of the base stations may be extracted. A portable communication device identifies its location by calculating the delay between the arrival time of a pilot signal from a primary base station and the arrival times of pilot signals from at least two other base stations. For each pair of base stations corresponding to one of the calculated delays, the portable communication device initially specifies its location as being on a selected one of three curves. The current location of the portable communication device is identified based upon points of intersection of the selected curves. The identified location may be stored in, transmitted from, or displayed at the portable communication device.
71 Citations
19 Claims
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1. Apparatus for a portable communication device to locally identify its own location within a cellular telephone network comprising:
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a receiver for receiving a first pilot signal transmitted from a first base station and at least second and third pilot signals transmitted from at least second and third base stations; a relative delay calculation unit coupled to the receiver for computing delays between an arrival time of the first pilot signal and arrival times of the second and third pilot signals; and a processor coupled to the relative delay unit, said processor programmed to determine the location of the portable communication device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for a portable communication device to locally identify its own location within a cellular telephone network comprising the steps of:
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receiving pilot signals and locking onto a first pilot signal transmitted from a first base station; recording the time at which the first pilot signal is received; locking onto second and third pilot signals transmitted from a first base station; recording arrival times for the second and third pilot signals; computing a first delay between the arrival of the first and second signals and a second delay between the arrival of the first and third signals; and determining the location of the portable communication device based upon the first and second delays. - View Dependent Claims (16, 17, 18, 19)
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Specification