US6876859B2
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for estimating TDOA and FDOA in a wireless location system
Assignee: Qualcomm Inc
•
Filing: 2001-07-18
•
Granted: 2005-04-05
•
Expires: 2021-07-18
Abstract
Abstract A method, used in locating a mobile transmitter, includes providing a set of cross-correlation values, wherein each cross-correlation value is associated with a corresponding TDOA and/or FDOA estimate and is produced by cross-correlating a reference signal with a cooperating signal. The reference signal comprises a copy of a signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal comprises a copy of the same signal as received at a second antenna. The method further includes determining a most likely range of TDOA and/or FDOA estimates, and then identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and/or FDOA estimates. The TDOA and/or FDOA value corresponding to the optimal cross-correlation value is then employed in calculating the location of the mobile transmitter.
Inventors
- 👤 Robert J. Anderson
- 👤 Alan E. E. Rogers
- 👤 Louis A. Stilp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:08
CPC Classifications
H; H04; H04W; H04W64/00; G; G01; G01S; G01S5/00; G01S5/02; G01S5/06; G01S5/10; G01S1/00; G01S1/02; G01S1/022; G01S1/026
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
134 words
A method used in locating a mobile transmitter for improving a time difference of arrival (TDOA) estimate produced by cross-correlating a reference signal with a cooperating signal, using either a time-domain cross-correlation or frequency-domain cross-spectrum process, wherein the reference signal is a copy of a first signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal is a copy of the first signal transmitted by the mobile transmitter as received at a second antenna, comprising the steps of: a. determining a most likely range of TDOA estimates; b. searching the cross-correlation results only within the most likely range of TDOA estimates; and c. estimating the TDOA to be the value within the most likely range that is associated with an optimal value of the magnitude of the cross-correlation.
Claim 2
Independent Claim
134 words
A method used in locating a mobile transmitter for improving a time difference of arrival (TDOA) estimate produced by cross-correlating a reference signal with a cooperating signal, using either a time-domain cross-correlation or frequency-domain cross-spectrum process, wherein the reference signal is a copy of a first signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal is a copy of the first signal transmitted by the mobile transmitter as received at a second antenna, comprising the steps of: a. determining a most likely range of TDOA estimates; b. searching the cross-correlation results only within the most likely range of TDOA estimates; and c. estimating the TDOA to be the value within the most likely range that is associated with an optimal value of the magnitude of the cross-correlation.
Claim 3
Dependent Claim
52 words
A method as recited in claim 1 , wherein the most likely range of TDOA estimates is limited to time values associated with the distance between the first antenna at which the reference signal was received and the second antenna at which the cooperating signal was received, plus a predetermined error value.
Claim 4
Dependent Claim
34 words
A method as recited in claim 1 , wherein the most likely range of TDOA estimates is determined as corresponding to only an area in which the mobile transmitter is known to be located.
Claim 5
Dependent Claim
26 words
A method as recited in claim 1 , wherein the optimal value is the highest magnitude peak of the time-domain cross-correlation or equivalent frequency-domain cross-spectrum process.
Claim 6
Dependent Claim
52 words
A method as recited in claim 1 , wherein the optimal value is the earliest point in time when the magnitude of the time-domain cross-correlation or equivalent frequency-domain cross spectrum process is no less than a predetermined proportion of the highest magnitude peak of the time-domain cross-correlation or equivalent frequency-domain cross-spectrum process.
Claim 7
Dependent Claim
42 words
A method as recited in claim 1 , wherein the optimal value is the earliest point in time when the magnitude of the time-domain cross-correlation or equivalent frequency-domain cross-spectrum process is no less than a predetermined proportion of the average noise level.
Claim 8
Dependent Claim
38 words
A method as recited in claim 1 , wherein the mostly like range of TDOA estimates is further limited so as to correspond to an area within a predetermined distance from the first antenna receiving the reference signal.
Claim 9
Dependent Claim
38 words
A method as recited in claim 1 , wherein the mostly like range of TDOA estimates is further limited so as to correspond to an area within a predetermined distance from the second antenna receiving the cooperating signal.
Claim 10
Independent Claim
22 words
A method as recited in claims 7 or 8 , wherein the predetermined distance is determined using a round trip delay measurement.
Claim 11
Independent Claim
31 words
A method as recited in claims 7 or 8 , wherein the predetermined distance is determined by measuring the received power of the mobile phone at the first and second antennas.
Claim 12
Independent Claim
161 words
A method used in locating a mobile transmitter for improving a time difference of arrival (TDOA) estimate produced by cross-correlating a reference signal with a cooperating signal, using either a time-domain cross-correlation or equivalent frequency-domain cross-spectrum process, wherein either process requires the simultaneous solution of both frequency difference of arrival (FDOA) and TDOA, wherein the reference signal is a copy of a first signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal is a copy of the first signal transmitted by the mobile transmitter as received at a second antenna, comprising the steps of: a. determining a most likely range of FDOA estimates; b. determining a most likely range of TDOA estimates; c. searching the cross-correlation results only within the most likely range of TDOA and FDOA estimates; d. estimating the TDOA to be the value within the most likely range that is associated with an optimal value of the magnitude of the cross-correlation.
Claim 13
Independent Claim
161 words
A method used in locating a mobile transmitter for improving a time difference of arrival (TDOA) estimate produced by cross-correlating a reference signal with a cooperating signal, using either a time-domain cross-correlation or equivalent frequency-domain cross-spectrum process, wherein either process requires the simultaneous solution of both frequency difference of arrival (FDOA) and TDOA, wherein the reference signal is a copy of a first signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal is a copy of the first signal transmitted by the mobile transmitter as received at a second antenna, comprising the steps of: a. determining a most likely range of FDOA estimates; b. determining a most likely range of TDOA estimates; c. searching the cross-correlation results only within the most likely range of TDOA and FDOA estimates; d. estimating the TDOA to be the value within the most likely range that is associated with an optimal value of the magnitude of the cross-correlation.
Claim 14
Dependent Claim
31 words
A method as recited in claim 11 , wherein the most likely range of FDOA estimates is limited to the frequency values associated with a stationary or nearly stationary mobile transmitter.
Claim 15
Dependent Claim
54 words
A method as recited in claim 11 or 12 , wherein the most likely range of TDOA estimates is limited to time values associated with the distance between the first antenna at which the reference signal was received and the second antenna at which the cooperating signal was received, plus a predetermined error value.
Claim 16
Dependent Claim
29 words
A method as recited in claim 11 or 12 , wherein the optimal value is the highest magnitude peak of the time-domain cross-correlation or equivalent frequency-domain cross spectrum process.
Claim 17
Dependent Claim
55 words
A method as recited in claim 11 or 12 , wherein the optimal value is the earliest point in time when the magnitude of the time-domain cross-correlation or equivalent frequency-domain cross spectrum process is no less than a predetermined proportion of the highest magnitude peak of the time-domain cross-correlation or equivalent frequency-domain cross spectrum process.
Claim 18
Dependent Claim
45 words
A method as recited in claim 11 or 12 , wherein the optimal value is the earliest point in time when the magnitude of the time-domain cross-correlation or equivalent frequency-domain cross spectrum process is no less than a predetermined proportion of the average noise level.
Claim 19
Dependent Claim
38 words
A method as recited in claim 12 , wherein the mostly like range of TDOA estimates is further limited so as to correspond to an area within a predetermined distance from the first antenna receiving the reference signal.
Claim 20
Dependent Claim
38 words
A method as recited in claim 12 , wherein the mostly like range of TDOA estimates is further limited so as to correspond to an area within a predetermined distance from the second antenna receiving the cooperating signal.
Claim 21
Independent Claim
22 words
A method as recited in claims 17 or 18 , wherein the predetermined distance is determined using a round trip delay measurement.
Claim 22
Independent Claim
31 words
A method as recited in claims 17 or 18 , wherein the predetermined distance is determined by measuring the received power of the mobile phone at the first and second antennas.
Claim 23
Independent Claim
138 words
A method used in locating a mobile transmitter, comprising: a. providing a set of cross-correlation values, wherein each cross-correlation value is associated with a corresponding TDOA and FDOA estimate and is produced by cross-correlating a reference signal with a cooperating signal, the reference signal comprising a copy of a signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal comprising a copy of the signal transmitted by the mobile transmitter as received at a second antenna; b. determining a most likely range of TDOA and FDOA estimates; c. identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and/or FDOA estimates; and d. employing the TDOA and FDOA value corresponding to the optimal cross-correlation value in calculating the location of the mobile transmitter.
Claim 24
Independent Claim
138 words
A method used in locating a mobile transmitter, comprising: a. providing a set of cross-correlation values, wherein each cross-correlation value is associated with a corresponding TDOA and FDOA estimate and is produced by cross-correlating a reference signal with a cooperating signal, the reference signal comprising a copy of a signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal comprising a copy of the signal transmitted by the mobile transmitter as received at a second antenna; b. determining a most likely range of TDOA and FDOA estimates; c. identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and/or FDOA estimates; and d. employing the TDOA and FDOA value corresponding to the optimal cross-correlation value in calculating the location of the mobile transmitter.
Claim 25
Dependent Claim
16 words
A method as recited in claim 21 , wherein the cross-correlating comprises cross-correlating in the time-domain.
Claim 26
Dependent Claim
16 words
A method as recited in claim 21 , wherein the cross-correlating comprises cross-correlating in the frequency-domain.
Claim 27
Dependent Claim
29 words
A method as recited in claim 21 , wherein the most likely range of TDOA estimates is based upon a rough estimate of the location of the mobile transmitter.
Claim 28
Dependent Claim
29 words
A method as recited in claim 21 , wherein the most likely range of FDOA estimates is based upon a rough estimate of the speed of the mobile transmitter.
Claim 29
Dependent Claim
27 words
A method as recited in claim 24 , wherein the rough estimate is based at least in part on the distance between the first and second antennas.
Claim 30
Dependent Claim
20 words
A method as recited in claim 26 , wherein the rough estimate is further based on a predetermined error value.
Claim 31
Dependent Claim
27 words
A method as recited in claim 24 , wherein the rough estimate is based on an area in which the mobile transmitter is known to be located.
Claim 32
Dependent Claim
30 words
A method as recited in claim 21 , wherein the cross-correlation value having the largest peak magnitude within said subset of cross-correlation values is identified as the optimal cross-correlation value.
Claim 33
Dependent Claim
45 words
A method as recited in claim 21 , comprising identifying, as the optimal cross-correlation value, the value within said subset of cross-correlation values having the smallest associated TDOA estimate for which the magnitude is no less than a predetermined proportion of the largest peak magnitude.
Claim 34
Dependent Claim
45 words
A method as recited in claim 21 , comprising identifying, as the optimal cross-correlation value, the value within said subset of cross-correlation values having the smallest associated TDOA estimate for which the magnitude is no less than a predetermined proportion of an average noise level.
Claim 35
Dependent Claim
25 words
A method as recited in claim 24 , wherein the rough estimate is based on an area within a predetermined distance from the first antenna.
Claim 36
Dependent Claim
25 words
A method as recited in claim 24 , wherein the rough estimate is based on an area within a predetermined distance from the second antenna.
Claim 37
Independent Claim
22 words
A method as recited in claims 32 or 33 , wherein the predetermined distance is determined using a round trip delay measurement.
Claim 38
Independent Claim
31 words
A method as recited in claims 32 or 33 , wherein the predetermined distance is determined by measuring the received power of the mobile transmitter at the first and second antennas.
Claim 39
Dependent Claim
79 words
A Wireless Location System (WLS) for locating a mobile transmitter, comprising: a. means for determining a most likely range of TDOA and FDOA estimates; and b. means for identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and FDOA estimates, said subset of cross-correlation values being contained within a set of cross-correlation values, wherein each cross-correlation value in the set is associated with a corresponding TDOA and FDOA estimate.
Claim 40
Dependent Claim
79 words
A Wireless Location System (WLS) for locating a mobile transmitter, comprising: a. means for determining a most likely range of TDOA and FDOA estimates; and b. means for identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and FDOA estimates, said subset of cross-correlation values being contained within a set of cross-correlation values, wherein each cross-correlation value in the set is associated with a corresponding TDOA and FDOA estimate.
Claim 41
Dependent Claim
37 words
A system as recited in claim 36 , wherein each value in said set of cross-correlation values and is representative of a cross-correlation, in the time or frequency domain, of a reference signal with a cooperating signal.
Claim 42
Dependent Claim
50 words
A system as recited in claim 37 , wherein the reference signal comprises a copy of a signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal comprises a copy of the signal transmitted by the mobile transmitter as received at a second antenna.
Claim 43
Dependent Claim
32 words
A system as recited in claim 36 , further comprising means for employing the TDOA and FDOA values corresponding to the optimal cross-correlation value in calculating the location of the mobile transmitter.
Claim 44
Independent Claim
80 words
A method for use in a Wireless Location System (WLS) for locating a mobile transmitter, comprising: a. determining a most likely range of TDOA and FDOA estimates; and b. identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and FDOA estimates, said subset of cross-correlation values being contained within a set of cross-correlation values, wherein each cross-correlation value in the set is associated with a corresponding TDOA and FDOA estimate.
Claim 45
Independent Claim
80 words
A method for use in a Wireless Location System (WLS) for locating a mobile transmitter, comprising: a. determining a most likely range of TDOA and FDOA estimates; and b. identifying an optimal cross-correlation value within a subset of cross-correlation values corresponding to the most likely range of TDOA and FDOA estimates, said subset of cross-correlation values being contained within a set of cross-correlation values, wherein each cross-correlation value in the set is associated with a corresponding TDOA and FDOA estimate.
Claim 46
Dependent Claim
37 words
A method as recited in claim 40 , wherein each value in said set of cross-correlation values and is representative of a cross-correlation, in the time or frequency domain, of a reference signal with a cooperating signal.
Claim 47
Dependent Claim
50 words
A system as recited in claim 41 , wherein the reference signal comprises a copy of a signal transmitted by the mobile transmitter as received at a first antenna and the cooperating signal comprises a copy of the signal transmitted by the mobile transmitter as received at a second antenna.
Claim 48
Dependent Claim
30 words
A system as recited in claim 40 , further comprising employing the TDOA and FDOA values corresponding to the optimal cross-correlation value in calculating the location of the mobile transmitter.
References Cited (Backward Citations)
US4888593A
Cited
US5265121A
Cited
US5208756A
Cited
US5327144A
Cited
US5608410A
Cited
US5570099A
Cited
US5874916A
Cited
US6047192A
Cited
US6546256B1
Cited
US6108555A
Cited
US6034635A
Cited
US5859612A
Cited
US6160758A
Cited
US6249252B1
Cited
GB2354129A
Cited
US6236365B1
Cited
US5890068A
Cited
US5936571A
Cited
US6381464B1
Cited
US6243587B1
Cited
US6522887B2
Cited
US6330452B1
Cited
US6246884B1
Cited
US6184829B1
Cited
US6172644B1
Cited
US6115599A
Cited
US6097336A
Cited
US6091362A
Cited
US6366240B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2008-04-04 | 2008-10-04 | 2009-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2012-04-04 | 2012-10-04 | 2013-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2016-04-04 | 2016-10-04 | 2017-04-05 | $7700.00 | Window Closed / Lapsed |