MULTIPATH REJECTION USING COOPERATIVE GPS RECEIVERS

• US 20150323675A1
• Filed: 05/12/2015
• Published: 11/12/2015
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: LinQuest Corporation
• Original Assignee: LinQuest Corporation
• Inventors: Munoz, Michael, Wu, Shawkang, Mousavi, Faezeh
• Granted Patent: US 10,330,790 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/13 Receivers
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks

Abstract

Systems and methods are disclosed for improving the speed and accuracy of terrestrial tracking with more than one receiver. Furthermore, terrestrial tracking of more than one receiver can be improved in areas where terrestrial tracking has been difficult to accomplish with acceptable accuracy, such as in rural areas where buildings can reflect satellite, and other, signals. For example, fast and precise position estimation in a short delay multipath environment can be solved by simultaneously estimating the position of multiple receivers using receiver to receiver distance ranges.

Claims

1. A computer program product comprising a non-transitory machine-readable medium storing instructions that, when executed by at least one programmable processor, cause the at least one programmable processor to perform operations comprising:

receiving, at the reference-receiver, receiver-distance information from one or more unknown-location receivers, the receiver-distance information including an indication of the distance between the reference-receiver and the one or more unknown-location receivers;

receiving at the reference-receiver beacon-distance information from the one or more unknown-location receivers, the beacon-distance information including an indication of the distance between one or more beacons and the one or more unknown-location-receivers;

receiving at the reference-receiver one or more signals from the one or more beacons; and

,

determining the locations of the one or more unknown-location receivers relative to the reference-receiver based on the received receiver-distance information from the one or more unknown-location receivers, and the received beacon-distance information from the one or more unknown-location receivers.

2. The computer program product as in claim 1, wherein the operations further comprise:

computing a local-coordinate system for the reference-receiver and the one or more unknown-location-receivers centered on the reference-receiver.

3. The computer program product as in claim 2, wherein the operations further comprise:

defining a sphere having a surface area on which individual ones of the one or more unknown-location receivers are positioned, the radius of the sphere based on the receiver-distance information received by the reference-receiver from individual ones of the one or more unknown-location receivers and the center of the sphere based on the local-coordinate system.

4. The computer program product as in claim 3, wherein the operations further comprise:

determining a plane on which the reference-receiver and at least some of the one or more unknown-location receivers reside to provide the radius of a circle on which the one or more unknown-location receivers are positioned relative to the reference-receiver.

5. The computer program product as in claim 4, wherein the operations further comprise:

determining a range of beacon-to-unknown-location-receiver distances based on the beacon-distance information received from the unknown-location receivers and constrained by the circle.

6. The computer program product method as in claim 1, wherein the operations further comprise:

computing, at the one or more unknown-location-receivers, one or more correlation coefficients using a correlation function and based on the ranges of beacon-to-unknown-location-receiver distances for the one or more unknown-location receivers; and

,

receiving, at the reference-receiver, the one or more correlation coefficients from the one or more unknown-location-receivers.

7. The computer program product as in claim 5, wherein the operations further comprise:

computing, at the one or more unknown-location-receivers, one or more correlation coefficients using a correlation function and based on the ranges of beacon-to-unknown-location-receiver distances for the one or more unknown-location receivers; and

,

receiving, at the reference-receiver, the one or more correlation coefficients from the one or more unknown-location-receivers.

8. The computer program product as in claim 7, wherein the operations further comprise:

filtering, at the reference-receiver, the one or more correlation coefficients based on constraints provided by the determined radii of the circles on which the one or more unknown-location-receivers are located to provide filtered correlation coefficients; and

,

computing, at the reference-receiver, the likely locations of the one or more unknown-location-receivers relative to the reference-receiver based on the filtered correlation coefficients.

9. The computer program product as in claim 8, wherein computing the likely location of the one or more unknown-location receivers relative to the reference-receiver includes applying each of the filtered correlation coefficients to a location algorithm to converge to a solution.

10. The computer program product as in claim 1, wherein the receiver-distance information is based on one or more wireless communications between the reference-receiver and the one or more unknown-location receivers.

11. The computer program product as in claim 10, wherein the one or more wireless communications include one or more of WiFi, Bluetooth, Near-Field-Communication, GSM, GPRS, and dictated short-range communication.

12. The computer program product of claim 1, wherein the received beacon-distance information from the one or more unknown-location receivers comprises one or more correlation coefficients for individual ones of the one or more beacons based on the one or more signals received at the unknown-location-receivers from the one or more beacons, each beacon emitting a signal containing a code specific to that beacon.

13. The computer program product as in claim 1, wherein the operations further comprise:

receiving geographic location information at one of the reference-receiver or the one or more unknown-location-receivers; and

,

determining the geographic location of the reference-receiver and/or the one or more unknown-location-receivers based on the received geographic location information and the relative location of the reference-receiver to the one or more unknown-location receivers.

14. The computer program product as in claim 1, wherein the reference-receiver is a GPS receiver.

15. A method for determining the positions of one or more unknown-location-receivers at a reference-receiver configured to receive signals from one or more beacons, the method implemented by at least one programmable processor forming at least one computing device, the method comprising:

receiving, at the reference-receiver, receiver-distance information from one or more unknown-location receivers, the receiver-distance information including an indication of the distance between the reference-receiver and the one or more unknown-location receivers;

receiving at the reference-receiver beacon-distance information from the one or more unknown-location receivers, the beacon-distance information including an indication of the distance between one or more beacons and the one or more unknown-location-receivers;

receiving at the reference-receiver one or more signals from the one or more beacons; and

,

determining the locations of the one or more unknown-location receivers relative to the reference-receiver based on the received receiver-distance information from the one or more unknown-location receivers, and the received beacon-distance information from the one or more unknown-location receivers.

16. The method as in claim 15, further comprising:

computing a local-coordinate system for the reference-receiver and the one or more unknown-location-receivers centered on the reference-receiver.

defining a sphere having a surface area on which individual ones of the one or more unknown-location receivers are positioned, the radius of the sphere based on the receiver-distance information received by the reference-receiver from individual ones of the one or more unknown-location receivers and the center of the sphere based on the local-coordinate system;

determining a plane on which the reference-receiver and at least some of the one or more unknown-location receivers reside to provide the radius of a circle on which the one or more unknown-location receivers are positioned relative to the reference-receiver; and

,

determining a range of beacon-to-unknown-location-receiver distances based on the beacon-distance information received from the unknown-location receivers and constrained by the circle.

17. The method as in claim 15, further comprising:

computing, at the one or more unknown-location-receivers, one or more correlation coefficients using a correlation function and based on the ranges of beacon-to-unknown-location-receiver distances for the one or more unknown-location receivers; and

,

receiving, at the reference-receiver, the one or more correlation coefficients from the one or more unknown-location-receivers.

18. The method as in claim 17, further comprising:

filtering, at the reference-receiver, the one or more correlation coefficients based on constraints provided by the determined radii of the circles on which the one or more unknown-location-receivers are located to provide filtered correlation coefficients;

computing, at the reference-receiver, the likely locations of the one or more unknown-location-receivers relative to the reference-receiver based on the filtered correlation coefficients.

19. A system comprising:

a beacon-signal receiver configured to receive and decode signals received from one or more beacons having a known location, the signals from the one or more beacons comprising beacon-identifying information and a time at which the signals were emitted;

a transceiver configured to transmit and/or receive signals from one or more unknown-location receivers, the signals from the one or more unknown location receiver including;

beacon-distance information, the beacon-distance information including an indication of the distance between one or more beacons; and

,

receiver-distance information, the receiver-distance information including an indication of the distance between the reference-receiver and the one or more unknown-location receivers; and

,

at least one programmable processor, configured to perform the following operations;

determine the locations of the one or more unknown-location receivers relative to the reference-receiver based on the received receiver-distance information from the one or more unknown-location receivers, and the received beacon-distance information from the one or more unknown-location receivers.

20. The system as in claim 19, wherein:

the one or more unknown-location receivers are configured to compute one or more correlation coefficients using a correlation function and based on the ranges of beacon-to-unknown-location-receiver distances for the one or more unknown-location receivers;

the transceiver is configured to receive the one or more correlation coefficients from the one or more unknown-location-receivers; and

,

the at least one programmable processor is configured to;

filter the one or more correlation coefficients based on constraints provided by the determined radii of the circles on which the one or more unknown-location-receivers are located to provide filtered correlation coefficients; and

,

compute the likely locations of the one or more unknown-location-receivers relative to the reference-receiver based on the filtered correlation coefficients.