US6108558A
Expired / Lapsed
US
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Method for calculating a location of a remote Unit utilizing observed time difference (OTD) and real time difference (RTD) measurements.
Assignee: Google Technology Holdings LLC
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Filing: 1999-04-13
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Granted: 2000-08-22
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Expires: 2019-04-13
Abstract
Abstract Base stations (101, 103, and 105) transmit, and a remote unit (117) receives a radio frequency (RF) location signal. The remote unit (117) then computes an observed-time-difference (OTD) for each base station at particular time t1. Observed differences in received signal times, and are reported to a Mobile Location Center (MLC) (111). Additionally, a Real-Time-Difference receiver (115) receives an RF signal from two or more base stations. The Real Time Differences between the base stations (101, 103, and 105) are computed at a second time. These differences are also reported to the MLC (111). The MLC (111) computes an estimated RTD for the time period t 1 via standard curve fitting algorithms, or simple interpolating algorithms. A corrected Time Difference of Arrival (TDOA) as determined by the remote unit (117) is computed based on the OTD measurements and the estimated RTD measurements.
Inventors
- 👤 II Jan P. Vanderspool
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:00
CPC Classifications
H; H04; H04W; H04W64/00; G; G01; G01S; G01S5/00; G01S5/02; G01S5/10; H04B; H04B17/00; H04B17/30; H04B17/309; H04B17/364
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
113 words
A method for locating a remote unit within a communication system, the method comprising the steps of: receiving a plurality of measurements from a remote unit of Observed Time Differences (OTDs) for a plurality of base stations, wherein the plurality of OTD measurements were performed at a first time period; receiving a measurement of Real Time Differences (RTD) for the plurality of base stations performed at a second time period; calculating a predicted RTD for the plurality of base stations at the first time period; and calculating a location of the remote unit based on the OTD measurements and the predicted RTD for the plurality of base stations at the first time period.
Claim 2
Independent Claim
113 words
A method for locating a remote unit within a communication system, the method comprising the steps of: receiving a plurality of measurements from a remote unit of Observed Time Differences (OTDs) for a plurality of base stations, wherein the plurality of OTD measurements were performed at a first time period; receiving a measurement of Real Time Differences (RTD) for the plurality of base stations performed at a second time period; calculating a predicted RTD for the plurality of base stations at the first time period; and calculating a location of the remote unit based on the OTD measurements and the predicted RTD for the plurality of base stations at the first time period.
Claim 3
Dependent Claim
51 words
The method of claim 1 wherein the step of receiving the plurality of measurements from the remote unit comprises the step of receiving the plurality of measurements from the remote unit of OTDs for the plurality of base stations and a time period when the plurality of OTD measurements were performed.
Claim 4
Dependent Claim
51 words
The method of claim 1 wherein the step of receiving the plurality of measurements from the remote unit comprises the step of receiving the plurality of measurements from the remote unit of OTDs for the plurality of base stations and a frame number when the plurality of OTD measurements were performed.
Claim 5
Dependent Claim
40 words
The method of claim 1 wherein the step of receiving the measurement of RTD for the plurality of base stations comprises the step of receiving the measurement of RTD along with a time period that the RTD measurement was taken.
Claim 6
Dependent Claim
40 words
The method of claim 1 wherein the step of receiving the measurement of RTD for the plurality of base stations comprises the step of receiving the measurement of RTD along with a frame number that the RTD measurement was taken.
Claim 7
Dependent Claim
41 words
The method of claim 1 wherein the step of receiving the RTD data for the plurality of base stations comprises the step of receiving two or more raw RTD measurements along with frame numbers for when the RTD measurements were taken.
Claim 8
Dependent Claim
30 words
The method of claim 1 wherein the step of receiving the RTD data for the plurality of base stations comprises the step of receiving RTD data in curve fit form.
Claim 9
Independent Claim
123 words
A method for locating a remote unit within a communication system, the method comprising the steps of: receiving a request to locate the remote unit; sending a downlink location signal to the remote unit; performing a series of Observed Time Difference (OTD) measurements to obtain OTD data at a first time period; obtaining Real Time Difference (RTD) measurements for a plurality of base stations, wherein the RTD measurements are taken at a second time period; reporting the OTD and RTD measurements to a location center along with the first and the second time period; predicting an RDT measurement at the third time period based on the RTD measurements; and locating the remote unit based on the predicted RTD measurement and the OTD measurements.
Claim 10
Independent Claim
123 words
A method for locating a remote unit within a communication system, the method comprising the steps of: receiving a request to locate the remote unit; sending a downlink location signal to the remote unit; performing a series of Observed Time Difference (OTD) measurements to obtain OTD data at a first time period; obtaining Real Time Difference (RTD) measurements for a plurality of base stations, wherein the RTD measurements are taken at a second time period; reporting the OTD and RTD measurements to a location center along with the first and the second time period; predicting an RDT measurement at the third time period based on the RTD measurements; and locating the remote unit based on the predicted RTD measurement and the OTD measurements.
Claim 11
Dependent Claim
29 words
The method of claim 8 wherein the step of performing a series of OTD measurements comprises the step of performing a series of OTD measurements by the remote unit.
Claim 12
Dependent Claim
35 words
The method of claim 9 wherein the step of performing RTD measurements comprises the step of performing RTD measurements comprises the step of performing RTD measurements by a network element separated from the remote unit.
Claim 13
Dependent Claim
56 words
The method of claim 8 wherein the step of reporting the OTD and RTD measurements to the location center comprises the steps of: reporting, by the remote unit, the OTD measurement along with a first frame number; and reporting, by a network element separated from the remote unit, RTD measurements along with a second frame number.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2003-08-22 | 2004-02-21 | 2004-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-08-22 | 2008-02-21 | 2008-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-08-22 | 2012-02-21 | 2012-08-22 | $7700.00 | Window Closed / Lapsed |