Method for estimating a location of a mobile unit based on at least two fixed transceivers
First Claim
1. In a wireless communication system comprising a fixed infrastructure in wireless communication with a mobile unit, the fixed infrastructure further comprising at least two fixed transceivers, a method for estimating a location of the mobile unit, the method comprising steps of:
- receiving, by the mobile unit, signals transmitted by each of the at least two fixed transceivers to produce received signals, each of the received signals including a time of transmission indication generated by a respective one of the at least two fixed transceivers relative to a common time base;
determining, by the mobile unit, a time of reception indication relative to the common time base for each of the received signals, wherein the common time base is provided by a continuously corrected local oscillator;
for each of the received signals, determining a pseudo-range based on the respective time of transmission and time of reception indications; and
determining a weighted least squares solution using the pseudo-ranges to estimate the location of the mobile unit.
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Accused Products
Abstract
Signals comprising time of transmission indications relative to a common time base (302) are transmitted by at least two fixed transceivers (110-116). When the signals are received by a mobile unit (160), a time of reception indication relative to the common time base is calculated for each signal. Pseudo-ranges are calculated based on the time of transmission and time of reception indications, and a WLS solution location estimate is calculated based on the pseudo-ranges. Essentially the same procedure may be performed on signals transmitted by the mobile unit. Given the common time base between the fixed transceivers and the mobile unit, only two or more signals are required to determine the location estimate. Where GPS receivers are used to supply the common time base, location determinations can still be made when a GPS solution is unavailable.
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Citations
15 Claims
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1. In a wireless communication system comprising a fixed infrastructure in wireless communication with a mobile unit, the fixed infrastructure further comprising at least two fixed transceivers, a method for estimating a location of the mobile unit, the method comprising steps of:
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receiving, by the mobile unit, signals transmitted by each of the at least two fixed transceivers to produce received signals, each of the received signals including a time of transmission indication generated by a respective one of the at least two fixed transceivers relative to a common time base; determining, by the mobile unit, a time of reception indication relative to the common time base for each of the received signals, wherein the common time base is provided by a continuously corrected local oscillator; for each of the received signals, determining a pseudo-range based on the respective time of transmission and time of reception indications; and determining a weighted least squares solution using the pseudo-ranges to estimate the location of the mobile unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a wireless communication system comprising a fixed infrastructure in wireless communication with a mobile unit, the fixed infrastructure further comprising at least two fixed transceivers in communication with a location processor, a method for estimating a location of the mobile unit, the method comprising steps of:
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receiving, by each of the at least two transceivers, a signal sent by the mobile unit to produce received signals, wherein each of the received signals includes a time of transmission indication generated by the mobile unit based on a local oscillator synchronized relative to a common time base; determining, by each of the at least two transceivers, a time of reception indication relative to the common time base for a corresponding one of the received signals; for each of the received signals, determining a pseudo-range based on the respective time of transmission and time of reception indications; and determining, by the location processor, a weighted least squares solution using the pseudo-ranges to estimate the location of the mobile unit. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification