US6084546A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Location determination in wireless communication systems using velocity information
Assignee: WIRELESS LOCATION TECHNOLOGIES Inc
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Filing: 1998-12-04
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Granted: 2000-07-04
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Expires: 2018-12-04
Abstract
Abstract A method for improving the accuracy of signal signature determinations in wireless location finding systems advantageously uses transmitter velocity estimates to accurately and reliably determine in real time a present signal covariance matrix for a transmitter. In a preferred embodiment of the invention, a method for determining a likely location of a transmitter in a wireless transmitter location finding system comprises coherently measuring transmitter signals received at an antenna array, and calculating a current signal covariance matrix from the measured transmitter signals. The method further comprises calculating an average covariance matrix by forming a linear combination of the current signal covariance matrix with past average covariance matrices. The coefficients of the linear combination are selected such that the average covariance matrix is derived primarily from covariance matrices measured over a range of recent transmitter locations within a predetermined distance D from the present location. This distance D preferably corresponds to a spatial span of calibrated signatures. In a preferred embodiment, this condition is satisfied by selecting the coefficients in dependence upon the distance D and an estimated current velocity of the transmitter. The method also includes determining a likely current transmitter location by measuring a similarity between the average covariance matrix and a set of calibrated covariance matrices corresponding to calibrated transmitter locations.
Inventors
- 👤 Mati Wax
- 👤 Sriram Jayaraman
- 👤 Oliver Hilsenrath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:38
CPC Classifications
G; G01; G01C; G01C21/00; G01C21/26; G01S; G01S1/00; G01S1/02; G01S1/022; G01S1/026; G01S5/00; G01S5/02; G01S5/0205; G01S5/021; G01S5/0218; H; H04; H04L; H04L67/00; H04L67/01; H04L67/04; H04L67/50; H04L67/51; H04L67/52; H04L67/535; H04W; H04W4/00; H04W4/02; H04W4/023; H04W4/024; H04W4/029; H04W4/20; H04W64/00; H04L69/00; H04L69/30; H04L69/32; H04L69/322; H04L69/329
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
105 words
In a system for wireless transmitter location finding, a method for determining a likely location of a transmitter, the method comprising: coherently measuring transmitter signals received at an antenna array; calculating a current signal covariance matrix from the coherently measured transmitter signals; calculating an average covariance matrix by forming a linear combination of the current signal covariance matrix with past covariance matrices, wherein coefficients of the linear combination depend on an estimated current velocity of the transmitter; and determining a likely current transmitter location by measuring a similarity between the average covariance matrix and a set of calibrated covariance matrices corresponding to calibrated transmitter locations.
Claim 2
Dependent Claim
105 words
In a system for wireless transmitter location finding, a method for determining a likely location of a transmitter, the method comprising: coherently measuring transmitter signals received at an antenna array; calculating a current signal covariance matrix from the coherently measured transmitter signals; calculating an average covariance matrix by forming a linear combination of the current signal covariance matrix with past covariance matrices, wherein coefficients of the linear combination depend on an estimated current velocity of the transmitter; and determining a likely current transmitter location by measuring a similarity between the average covariance matrix and a set of calibrated covariance matrices corresponding to calibrated transmitter locations.
Claim 3
Dependent Claim
56 words
The method of claim 1 wherein the average covariance matrix is calculated such that a zero estimated velocity corresponds to a majority contribution of the past average covariance matrices to the average covariance matrix, while a large estimated current velocity corresponds to a majority contribution of the current signal covariance matrix to the average covariance matrix.
Claim 4
Dependent Claim
52 words
The method of claim 1 wherein the average covariance matrix is calculated such that the average covariance matrix is derived primarily from covariance matrices measured over a range of recent transmitter locations within a predetermined distance D from a present location, where D corresponds to a spatial span between calibrated signature locations.
Claim 5
Dependent Claim
69 words
The method of claim 3 wherein the average covariance matrix R t .sbsb.n is calculated from past covariance matrices R t .sbsb.m, . . . , R t .sbsb.n by evaluating an equation substantially equivalent to ##EQU8## where D m =v t .sbsb.m Δt m + . . . +v t .sbsb.n Δt n , and where m is selected such that D m is approximately equal to D.
Claim 6
Dependent Claim
56 words
The method of claim 1 wherein the average covariance matrix R t .sbsb.n is calculated by evaluating an equation substantially equivalent to R.sub.t.sbsb.n =λ.sub.t.sbsb.n R.sub.t.sbsb.n-1 +(1-λ.sub.t.sbsb.n) R.sub.t.sbsb.n, where R t .sbsb.n-1 is a prior average covariance matrix, and where λ t .sbsb.n is a coefficient selected in dependence upon the estimated current velocity of the transmitter.
Claim 7
Independent Claim
120 words
An apparatus for wireless transmitter location finding comprising: a multichannel receiver for coherently measuring signals received at an antenna array from a transmitter; and a signal processor in electrical communication with the multichannel receiver for estimating a location of the transmitter, wherein the signal processor: calculates a current signal covariance matrix from the coherently measured transmitter signals; calculates an average covariance matrix by forming a linear combination of the current signal covariance matrix with past covariance matrices, wherein coefficients of the linear combination depend on an estimated current velocity of the transmitter; and determines a likely current transmitter location by measuring a similarity between the average covariance matrix and a set of calibrated covariance matrices corresponding to calibrated transmitter locations.
Claim 8
Independent Claim
120 words
An apparatus for wireless transmitter location finding comprising: a multichannel receiver for coherently measuring signals received at an antenna array from a transmitter; and a signal processor in electrical communication with the multichannel receiver for estimating a location of the transmitter, wherein the signal processor: calculates a current signal covariance matrix from the coherently measured transmitter signals; calculates an average covariance matrix by forming a linear combination of the current signal covariance matrix with past covariance matrices, wherein coefficients of the linear combination depend on an estimated current velocity of the transmitter; and determines a likely current transmitter location by measuring a similarity between the average covariance matrix and a set of calibrated covariance matrices corresponding to calibrated transmitter locations.
Claim 9
Dependent Claim
58 words
The apparatus of claim 6 wherein the signal processor calculates the average covariance matrix such that a zero estimated velocity corresponds to a majority contribution of the past average covariance matrices to the average covariance matrix, while a large estimated current velocity corresponds to a majority contribution of the current signal covariance matrix to the average covariance matrix.
Claim 10
Dependent Claim
54 words
The apparatus of claim 6 wherein the signal processor calculates the average covariance matrix such that the average covariance matrix is derived primarily from covariance matrices measured over a range of recent transmitter locations within a predetermined distance D from a present location, where D corresponds to a spatial span between calibrated signature locations.
Claim 11
Dependent Claim
71 words
The apparatus of claim 8 wherein the signal processor calculates the average covariance matrix R t .sbsb.n from past covariance matrices R t .sbsb.m, . . . , R t .sbsb.n by evaluating an equation substantially equivalent to ##EQU9## where D m =v t .sbsb.m Δt m + . . . +v t .sbsb.n Δt n , and where m is selected such that D m is approximately equal to D.
Claim 12
Dependent Claim
58 words
The apparatus of claim 6 wherein the signal processor calculates the average covariance matrix R t .sbsb.n by evaluating an equation substantially equivalent to R.sub.t.sbsb.n =λ.sub.t.sbsb.n R.sub.t.sbsb.n-1 +(1-λ.sub.t.sbsb.n) R.sub.t.sbsb.n, where R t .sbsb.n-1 is a prior average covariance matrix, and where λ t .sbsb.n is a coefficient selected in dependence upon the estimated current velocity of the transmitter.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-07-04 | 2004-01-03 | 2004-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-07-04 | 2008-01-03 | 2008-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-07-04 | 2012-01-03 | 2012-07-04 | $7700.00 | Window Closed / Lapsed |