Determining motion zones in a space traversed by wireless signals

• US 10,404,387 B1
• Filed: 05/15/2019
• Issued: 09/03/2019
• Est. Priority Date: 05/15/2019
• Status: Active Grant

• Current Assignee: Cognitive Systems Corp.
• Original Assignee: Cognitive Systems Corp.
• Inventors: Devison, Stephen Arnold, Omer, Mohammad
• Primary Examiner(s): Ly, Anh Vu H
• Application Number:
  US16/413,109
• Time in Patent Office: 111 Days
• Field of Search: None
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 7/006 using shared front-end circuitry, e.g. antennas G01S13/765, G01S13/825 take precedence
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0222 Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds

Abstract

In a general aspect, a method for determining motion zones in a space traversed by wireless signals. In some aspects, the method includes obtaining, over a time frame, sets of channel response data based on wireless signals communicated over wireless links through a space between wireless communication devices. A time series of statistical parameters is generated for each wireless link based on a respective set of channel response data. The method additionally includes determining a plurality of motion zones in the space based on changes in the time series of statistical parameters for each wireless link. Sets of motion-zone parameters are generated that characterize respective motion zones of the plurality of motion zones. The method further includes storing, in a database of a motion detection system, the plurality of motion zones and sets of motion-zone parameters. The sets of motion-zone parameters are used to identify one of the plurality of motion zones based on a motion event detected by the motion detection system.

Claims

1. A method comprising:

obtaining, over a time frame, sets of channel response data based on wireless signals communicated over wireless links through a space between wireless communication devices, the sets of channel response data comprising one set of channel response data for each wireless link;

generating a time series of statistical parameters for each wireless link based on a respective set of channel response data, the time series of statistical parameters characterizing a statistical distribution of the respective set of channel response data at successive points of time in the time frame;

determining a plurality of motion zones in the space based on changes in the time series of statistical parameters for each wireless link;

generating sets of motion-zone parameters characterizing respective motion zones of the plurality of motion zones, each set of motion-zone parameters generated from portions of a time series of statistical parameters bounded by respective time intervals;

storing, in a database of a motion detection system, the plurality of motion zones and sets of motion-zone parameters; and

using the sets of motion-zone parameters to identify one of the plurality of motion zones based on a motion event detected by the motion detection system.

2. The method of claim 1, wherein determining the plurality of motion zones comprises:

identifying one or more time series of statistical parameters that change in magnitude greater than a predetermined amount within the time frame;

associating a time boundary in the time frame with each change in magnitude of the one or more time series of statistical parameters;

determining time intervals by identifying adjacent pairs of time boundaries that share a common time series of statistical parameters; and

assigning motion zones to each portion of the one or more time series of statistical parameters within a respective time interval, the motion zones collectively defining the plurality of motion zones.

3. The method of claim 2, wherein generating the sets of motion-zone parameters comprises:

generating a motion-zone parameter for each portion of the one or more time series of statistical parameters assigned a motion zone, the motion-zone parameter characterizing a statistical distribution of the portion within a respective time interval; and

identifying motion-zone parameters associated with a common motion zone, thereby defining a set of motion-zone parameters.

4. The method of claim 1,

wherein the time frame is a prior time frame;

and

wherein the method comprises;

repeating, over a subsequent time frame, the operations of obtaining sets of channel response data, generating a time series of statistical parameters, determining a plurality of motion zones, generating sets of motion-zone parameters, storing the plurality of motion zones, and using the sets of motion-zone parameters;

determining a difference by comparing the sets of motion-zone parameters from the subsequent time frame with the sets of motion zone parameters from the prior time frame; and

updating, in the database of the motion detection system, one or both of the plurality of motion zones and the sets of motion-zone parameters based on the difference.

5. The method of claim 4,

wherein determining the difference comprises identifying a new motion zone and a new respective set of motion-zone parameters;

and

wherein updating one or both of the plurality of motion zones and the sets of motion-zone parameters comprises adding the new motion zone and the new respective set of motion-zone parameters to the database of the motion detection system.

6. The method of claim 4,

wherein determining the difference comprises:

identifying a motion zone present in the database at the end of both the subsequent and prior time frames, the motion zone associated with a subsequent set of motion-zone parameters at the end of the subsequent time frame and a prior set of motion-zone parameters at the end of the prior time frame, and

determining a difference between the subsequent and prior sets of motion-zone parameters; and

wherein updating one or both of the plurality of motion zones and the sets of motion-zone parameters comprises replacing, based on the difference, the prior set of motion-zone parameters in the database with the subsequent set of motion-zone parameters.

7. The method of claim 1, wherein the time series of statistical parameters for each wireless link comprises a mean.

8. The method of claim 1, wherein the time series of statistical parameters for each wireless link comprises a standard deviation.

9. A system comprising:

wireless communication devices in a wireless communication network that are configured to exchange wireless signals over wireless links, each wireless link defined between a respective pair of the wireless communication devices; and

one or more processors; and

memory storing instructions that are configured to perform operations when executed by the one or more processors, the operations comprising;

obtaining, over a time frame, sets of channel response data based on wireless signals communicated over wireless links through a space between wireless communication devices, the sets of channel response data comprising one set of channel response data for each wireless link;

generating a time series of statistical parameters for each wireless link based on a respective set of channel response data, the time series of statistical parameters characterizing a statistical distribution of the respective set of channel response data at successive points of time in the time frame;

determining a plurality of motion zones in the space based on changes in the time series of statistical parameters for each wireless link;

generating sets of motion-zone parameters characterizing respective motion zones of the plurality of motion zones, each set of motion-zone parameters generated from portions of a time series of statistical parameters bounded by respective time intervals;

storing, in a database of a motion detection system, the plurality of motion zones and sets of motion-zone parameters; and

using the sets of motion-zone parameters to identify one of the plurality of motion zones based on a motion event detected by the motion detection system.

10. The system of claim 9, wherein determining the plurality of motion zones comprises:

identifying one or more time series of statistical parameters that change in magnitude greater than a predetermined amount within the time frame;

associating a time boundary in the time frame with each change in magnitude of the one or more time series of statistical parameters;

determining time intervals by identifying adjacent pairs of time boundaries that share a common time series of statistical parameters; and

assigning motion zones to each portion of the one or more time series of statistical parameters within a respective time interval, the motion zones collectively defining the plurality of motion zones.

11. The system of claim 10, wherein generating the sets of motion-zone parameters comprises:

generating a motion-zone parameter for each portion of the one or more time series of statistical parameters assigned a motion zone, the motion-zone parameter characterizing a statistical distribution of the portion within a respective time interval; and

identifying motion-zone parameters associated with a common motion zone, thereby defining a set of motion-zone parameters.

12. The system of claim 9,

wherein the time frame is a prior time frame;

and

wherein the operations comprise;

repeating, over a subsequent time frame, the operations of obtaining sets of channel response data, generating a time series of statistical parameters, determining a plurality of motion zones, generating sets of motion-zone parameters, storing the plurality of motion zones, and using the sets of motion-zone parameters;

determining a difference by comparing the sets of motion-zone parameters from the subsequent time frame with the sets of motion zone parameters from the prior time frame; and

updating, in the database of the motion detection system, one or both of the plurality of motion zones and the sets of motion-zone parameters based on the difference.

13. The system of claim 12,

wherein determining the difference comprises identifying a new motion zone and a new respective set of motion-zone parameters;

and

wherein updating one or both of the plurality of motion zones and the sets of motion-zone parameters comprises adding the new motion zone and the new respective set of motion-zone parameters to the database of the motion detection system.

14. The system of claim 12,

wherein determining the difference comprises:

identifying a motion zone present in the database at the end of both the subsequent and prior time frames, the motion zone associated with a subsequent set of motion-zone parameters at the end of the subsequent time frame and a prior set of motion-zone parameters at the end of the prior time frame, and

determining a difference between the subsequent and prior sets of motion-zone parameters; and

wherein updating one or both of the plurality of motion zones and the sets of motion-zone parameters comprises replacing, based on the difference, the prior set of motion-zone parameters in the database with the subsequent set of motion-zone parameters.

15. The system of claim 9, wherein the time series of statistical parameters for each wireless link comprises a mean.

16. The system of claim 9, wherein the time series of statistical parameters for each wireless link comprises a standard deviation.

17. A non-transitory computer-readable medium storing instructions that, when executed by data processing apparatus, cause the data processing apparatus to perform operations comprising:

obtaining, over a time frame, sets of channel response data based on wireless signals communicated over wireless links through a space between wireless communication devices, the sets of channel response data comprising one set of channel response data for each wireless link;

generating a time series of statistical parameters for each wireless link based on a respective set of channel response data, the time series of statistical parameters characterizing a statistical distribution of the respective set of channel response data at successive points of time in the time frame;

determining a plurality of motion zones in the space based on changes in the time series of statistical parameters for each wireless link;

generating sets of motion-zone parameters characterizing respective motion zones of the plurality of motion zones, each set of motion-zone parameters generated from portions of a time series of statistical parameters bounded by respective time intervals;

storing, in a database of a motion detection system, the plurality of motion zones and sets of motion-zone parameters; and

using the sets of motion-zone parameters to identify one of the plurality of motion zones based on a motion event detected by the motion detection system.

18. The computer-readable medium of claim 17, wherein determining the plurality of motion zones comprises:

identifying one or more time series of statistical parameters that change in magnitude greater than a predetermined amount within the time frame;

associating a time boundary in the time frame with each change in magnitude of the one or more time series of statistical parameters;

determining time intervals by identifying adjacent pairs of time boundaries that share a common time series of statistical parameters; and

assigning motion zones to each portion of the one or more time series of statistical parameters within a respective time interval, the motion zones collectively defining the plurality of motion zones.

19. The computer-readable medium of claim 18, wherein generating the sets of motion-zone parameters comprises:

generating a motion-zone parameter for each portion of the one or more time series of statistical parameters assigned a motion zone, the motion-zone parameter characterizing a statistical distribution of the portion within a respective time interval; and

identifying motion-zone parameters associated with a common motion zone, thereby defining a set of motion-zone parameters.

20. The computer-readable medium of claim 17,

wherein the time frame is a prior time frame;

and

wherein the operations comprise;

repeating, over a subsequent time frame, the operations of obtaining sets of channel response data, generating a time series of statistical parameters, determining a plurality of motion zones, generating sets of motion-zone parameters, storing the plurality of motion zones, and using the sets of motion-zone parameters;

determining a difference by comparing the sets of motion-zone parameters from the subsequent time frame with the sets of motion zone parameters from the prior time frame; and

updating, in the database of the motion detection system, one or both of the plurality of motion zones and the sets of motion-zone parameters based on the difference.

21. The computer-readable medium of claim 20,

wherein determining the difference comprises identifying a new motion zone and a new respective set of motion-zone parameters;

and

wherein updating one or both of the plurality of motion zones and the sets of motion-zone parameters comprises adding the new motion zone and the new respective set of motion-zone parameters to the database of the motion detection system.

22. The computer-readable medium of claim 20,

wherein determining the difference comprises:

identifying a motion zone present in the database at the end of both the subsequent and prior time frames, the motion zone associated with a subsequent set of motion-zone parameters at the end of the subsequent time frame and a prior set of motion-zone parameters at the end of the prior time frame, and

determining a difference between the subsequent and prior sets of motion-zone parameters; and

wherein updating one or both of the plurality of motion zones and the sets of motion-zone parameters comprises replacing, based on the difference, the prior set of motion-zone parameters in the database with the subsequent set of motion-zone parameters.

23. The computer-readable medium of claim 17, wherein the time series of statistical parameters for each wireless link comprises a mean.

24. The computer-readable medium of claim 17, wherein the time series of statistical parameters for each wireless link comprises a standard deviation.