Multipath rejection using cooperative GPS receivers

• US 10,330,790 B2
• Filed: 05/12/2015
• Issued: 06/25/2019
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: LinQuest Corporation
• Original Assignee: LinQuest Corporation
• Inventors: Munoz, Michael, Wu, Shawkang, Mousavi, Faezeh
• Primary Examiner(s): Magloire, Vladimir
• Assistant Examiner(s): Malley, Sr., Daniel P
• Application Number:
  US14/710,497
• Publication Number:
  US 20150323675A1
• Time in Patent Office: 1,505 Days
• Field of Search: 24235743
• 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 of a reference-receiver that includes a beacon-signal receiver and a transceiver, cause the at least one programmable processor to perform operations comprising:

receiving, at the transceiver of the reference-receiver, receiver-distance information from one or more unknown-location receivers using at least one inter-receiver communication link, the receiver-distance information including an indication of the distance between the reference-receiver and the one or more unknown-location receivers, and distances between the unknown-location receivers determined using at least one inter-receiver communication link, wherein the unknown-location receivers and the reference-receiver form an ad hoc antenna system;

receiving at the transceiver of 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 beacon-signal receiver the reference-receiver, one or more signals from the one or more beacons;

determining, using the at least one programmable processor, based on one or more positions of the one or more beacons, one or more expected delays of a receipt of one or more beacon-to-receiver signals at each receiver, including each unknown-location receiver and the reference-receiver;

generating, using the at least one programmable processor, based on the one or more determined expected delays, a correlation function representative of cross-correlations between known beacon-to-receiver distances and received beacon-to-receiver distances;

identifying, using the at least one programmable processor, based on the generating, a maximum value of the correlation function; and

searching, using the at least one programmable processor, locations of the unknown-location receivers and selecting locations for the one or more unknown-location receivers based on the identified maximum value of the correlation function; and

determining, using the at least one programmable processor of the reference-receiver, based on the selecting, 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, the one or more correlation coefficients 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, the one or more correlation coefficients 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 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.

12. 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.

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

14. A method for determining the positions of one or more unknown-location-receivers at a reference-receiver that includes a beacon-signal receiver and a transceiver and 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 transceiver of the reference-receiver, receiver-distance information from one or more unknown-location receivers using at least one inter-receiver communication link, the receiver-distance information including an indication of the distance between the reference-receiver and the one or more unknown-location receivers, and distances between the unknown-location receivers determined using at least one inter-receiver communication link, wherein the unknown-location receivers and the reference-receiver form an ad hoc antenna system;

receiving, at the transceiver of 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 beacon-signal receiver of the reference-receiver, one or more signals from the one or more beacons;

determining, by at least one programmable processor, based on one or more positions of the one or more beacons, one or more expected delays of a receipt of one or more beacon-to-receiver signals at each receiver, including each unknown-location receiver and the reference-receiver;

generating, by at least one programmable processor, based on the one or more determined expected delays, a correlation function representative of cross-correlations between known beacon-to-receiver distances and received beacon-to-receiver distances;

identifying, by at least one programmable processor, based on the generating, a maximum value of the correlation function;

searching, by at least one programmable processor, locations of the unknown-location receivers and selecting locations for the one or more unknown-location receivers based on the identified maximum value of the correlation function; and

determining, by at least one programmable processor, based on the selecting, 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.

15. The method as in claim 14, 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.

16. The method as in claim 14, further comprising:

computing, at the one or more unknown-location-receivers, the one or more correlation coefficients 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.

17. The method as in claim 16, 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.

18. 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 receivers including;

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

distances between the unknown-location receivers, the information determined using at least one inter-receiver communication link; and

,

receiver-distance information, the receiver-distance information including an indication of the distance between a reference-receiver and the one or more unknown-location receivers received using at least one inter-receiver communication link, wherein the unknown-location receivers and the reference-receiver form an ad hoc antenna system; and

,

at least one programmable processor of the reference-receiver, configured to perform the following operations;

determine, based on one or more positions of the one or more beacons, one or more expected delays of a receipt of one or more beacon-to-receiver signals at each receiver, including each unknown-location receiver and the reference-receiver;

generate, based on the one or more determined expected delays, a correlation function representative of cross-correlations between known beacon-to-receiver distances and received beacon-to-receiver distances;

identify, based on the generating, a maximum value of the correlation function;

search locations of the unknown-location receivers and select locations for the one or more unknown-location receivers based on the identified maximum value of the correlation function; and

determine, based on the selecting, 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.

19. The system as in claim 18, wherein:

the one or more unknown-location receivers are configured to compute the one or more correlation coefficients 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.