System And Method For Detecting And Locating Contraband Devices In A Secure Environment

• US 20180167774A1
• Filed: 12/14/2016
• Published: 06/14/2018
• Est. Priority Date: 12/14/2016
• Status: Active Grant

• Current Assignee: Global Tel-Link Corporation
• Original Assignee: Global Tel-Link Corporation
• Inventors: Hodge, Stephen L.
• Granted Patent: US 10,206,064 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 2205/01 specially adapted for specific applications
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04L 67/55 Push-based network services
• CPC Class Codes: H04M 3/205 Eavesdropping prevention - indication of insecurity of line or network
• CPC Class Codes: H04M 3/2281 Call monitoring, e.g. for law enforcement purposes; Call tracing; Detection or prevention of malicious calls
• CPC Class Codes: H04M 3/38 Graded-service arrangements, i.e. some subscribers prevented from establishing certain connections queuing arrangements H04Q3/64
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 12/122 Counter-measures against attacks; Protection against rogue devices
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 40/244 using a network of reference devices, e.g. beaconing
• CPC Class Codes: H04W 48/04 based on user or terminal location or mobility data, e.g. moving direction, speed
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

There is a growing problem in correctional facilities in which contraband devices may be smuggled into a correctional facility. These devices are not subject to the typical monitoring and control provided by the inmate communication system provided by the correctional facility, and thus pose a significant security risk. The present disclosure provides details of a system and method that leverages the sanctioned mobile devices and the wireless infrastructure of the inmate communication system to scan for and triangulate the location of contraband devices. The mobile and wireless infrastructure devices scan for transmissions indicative of a contraband device and send alerts to each other and to a central monitoring system. The central monitoring system then leverages multiple alerts to determine a location of the contraband device using multiple triangulation techniques. The triangulation may also be performed by the mobile devices themselves.

Claims

1. A system designed to locate a contraband device in a controlled environment, comprising:

a memory that stores a plurality of previous alerts, each previous alert of the plurality of previous alerts having been received from one of a plurality of first mobile devices, and having a corresponding location and a corresponding timestamp;

a network interface configured to;

receive a current alert from a second mobile device, the current alert signifying that the current mobile device has detected a wireless transmission sent or received by the contraband device, and the current alert including an alert timestamp and an alert location; and

an application server configured to;

compare the current alert to the plurality of previous alerts;

determine, based on the comparison, a subset of alerts from among the stored plurality of previous alerts that are related to the received current alert by at least one of location or timestamp, wherein a previous alert is determined to be related to the current alert by timestamp in response to a timestamp of the previous alert being within a predetermined time period of the alert timestamp of the current alert, and wherein the previous alert is determined to be related to the current alert by location in response to a location of the previous alert being within a predetermined distance of the alert location of the current alert; and

determine a contraband device location based at least on the alert location and the locations corresponding to the previous alerts of the subset of alerts.

2. The system of claim 1, wherein the determining of the subset of alerts includes, for a candidate alert from among the plurality of alerts:

calculating a distance between the alert location and the location corresponding to the candidate alert; and

adding the candidate alert to the subset of alerts in response to determining that the distance is less than the predetermined distance.

3. The system of claim 1, wherein the current alert further includes an alert received signal strength indicator (RSSI) measurement,

wherein each previous alert of the subset of alerts further includes a corresponding RSSI measurement, the subset of alerts including at least a first alert and a second alert, and

wherein the application server is further configured to:

determine an alert distance based on a transmit power of the contraband device and the current alert RSSI measurement, the alert distance being a radius of an alert circle whose center is the alert location;

determine a first distance based on the transmit time and the RSSI measurement associated with the first alert, the first distance being a radius of a first circle whose center is the location corresponding to the first alert;

determine a second distance based on a transmit time and the RSSI measurement associated with the second alert, the second distance being a radius of a second circle whose center is the location corresponding to the second alert; and

determine the contraband device location as a point of intersection between all of the alert circle, the first circle, and the second circle.

4. The system of claim 1, wherein the current alert further includes an alert time of arrival (TOA) measurement,

wherein each previous alert of the subset of alerts further includes a corresponding TOA measurement, the subset of alerts including at least a first alert and a second alert, and

wherein the application server is further configured to:

determine an alert distance based on a transmit time and the alert TOA measurement, the alert distance being a radius of an alert circle whose center is the alert location;

determine a first distance based on the transmit time and the TOA measurement associated with the first alert, the first distance being a radius of a first circle whose center is the location corresponding to the first alert;

determine a second distance based on a transmit time and the TOA measurement associated with the second alert, the second distance being a radius of a second circle whose center is the location corresponding to the second alert; and

determine the contraband device location as a point of intersection between all of the alert circle, the first circle, and the second circle.

5. The system of claim 2, wherein the alert location includes an alert wireless access point that is connected to the mobile device when the current alert is received and the location corresponding to the candidate alert includes a candidate wireless access point, and the distance is calculated as the distance between the alert wireless access point and the candidate wireless access point.

6. The system of claim 5, wherein each of the locations corresponding to the previous alerts of the subset of alerts includes a corresponding wireless access point, and the application server is further configured to determine the contraband device location as being within an area of overlapping coverage between the alert wireless access point and the wireless access points corresponding to the alerts of the subset of alerts.

7. The system of claim 2, wherein the alert location includes a first designated area of the controlled environment that the mobile device occupies when the current alert is received, and the location corresponding to the candidate alert includes a second designated area of the controlled environment.

8. A method for locating a contraband device at a server, comprising:

receiving, at the server, a current alert from a mobile device, the alert signifying that the mobile device has detected a wireless transmission sent or received by the contraband device, and the alert including an alert timestamp and an alert location;

compare the current alert to a plurality of previously-stored alerts;

determining a subset of alerts from among the plurality of previously-stored alerts stored at the server that are related to the current alert by at least one of location or timestamp, each of the previously-stored alerts of the plurality of previously-stored alerts having been received from one of a plurality of mobile devices and having a corresponding location and a corresponding timestamp, wherein a previous alert is determined to be related to the current alert by timestamp in response to a timestamp of the previous alert being within a predetermined time period of the alert timestamp of the current alert, and wherein the previous alert is determined to be related to the current alert by location in response to a location of the previous alert being within a predetermined distance of the alert location of the current alert; and

determining a contraband device location based at least in part on the alert location and the locations corresponding to the previously-stored alerts of the subset of alerts.

9. The method of claim 8, wherein the determining of the subset of alerts includes, for a candidate alert from among the plurality of alerts:

calculating a distance between the alert location and the location corresponding to the candidate alert; and

adding the candidate alert to the subset of alerts in response to determining that the distance is less than the predetermined distance.

10. The method of claim 8, wherein the current alert further includes an alert received signal strength indicator (RSSI) measurement,

wherein each previously-stored alert of the subset of alerts further includes a corresponding RSSI measurement, the subset of alerts including at least a first alert and a second alert, and

wherein the method further comprises:

determining an alert distance based on a transmit power of the contraband device and the alert RSSI measurement, the alert distance being a radius of an alert circle whose center is the alert location;

determining a first distance based on the transmit power and the RSSI measurement associated with the first alert, the first distance being a radius of a first circle whose center is the location corresponding to the first alert;

determining a second distance based on the transmit power and the RSSI measurement associated with the second alert, the second distance being a radius of a second circle whose center is the location corresponding to the second alert; and

determining the contraband device location as a point of intersection between all of the alert circle, the first circle, and the second circle.

11. The method of claim 8, wherein the current alert further includes an alert time of arrival (TOA) measurement,

wherein each previously-stored alert of the subset of alerts further includes corresponding TOA measurement, the subset of alerts including at least a first alert and a second alert, and

wherein the method further comprises:

determining an alert distance based on a transmit time of the contraband device and the alert TOA measurement, the alert distance being a radius of an alert circle whose center is the alert location;

determining a first distance based on the transmit time and the TOA measurement associated with the first alert, the first distance being a radius of a first circle whose center is the location corresponding to the first alert;

determining a second distance based on the transmit time and the TOA measurement associated with the second alert, the second distance being a radius of a second circle whose center is the location corresponding to the second alert; and

determining the contraband device location as a point of intersection between all of the alert circle, the first circle, and the second circle.

12. The method of claim 9, wherein the alert location includes an alert wireless access point that is connected to the mobile device when the current alert is received, the location corresponding to the candidate alert includes a candidate wireless access point, and the distance is calculated as the distance between the alert wireless access point and the candidate wireless access point.

13. The method of claim 12, wherein each of the locations corresponding to the previously-stored alerts of the subset of alerts includes a corresponding wireless access point, and the method further comprises determining the contraband device location as being within an area of overlapping coverage between the alert wireless access point and the wireless access points corresponding to the previously-stored alerts of the subset of alerts.

14. The method of claim 9, wherein the alert location includes a first designated area of the controlled environment that the mobile device occupies when the current alert is received, and the location corresponding to the candidate alert includes a second designated area of the controlled environment.

15. A mobile device, comprising:

a memory that stores a plurality of previous alerts, each previous alert of the plurality of previous alerts having been received from one of a plurality of external mobile devices and including a corresponding location and a corresponding timestamp;

a radio interface circuit, coupled to an antenna, configured to;

scan a frequency band for an unauthorized transmission;

detect a contraband monitoring device based on the scan; and

a processor configured to;

in response to detecting a contraband monitoring device;

generate a current alert including an alert timestamp and an alert location;

compare the current alert to the plurality of previous alerts;

determine a subset of alerts from the stored plurality of previous alerts that are related to the current alert by at least one of location or timestamp, wherein a previous alert is determined to be related to the current alert by timestamp in response to a timestamp of the previous alert being within a predetermined time period of the alert timestamp of the current alert, and wherein the previous alert is determined to be related to the current alert by location in response to a location of the previous alert being within a predetermined distance of the alert location of the current alert; and

determine a contraband device location based at least on the alert location and the locations corresponding to the alerts of the subset of previous alerts.

16. The mobile device of claim 15, wherein the radio interface circuit is further configured to:

transmit the current alert to a contraband monitoring center;

receive an external alert from an external mobile device from among the plurality of external mobile devices, the external alert signifying that the external mobile device has detected a wireless transmission sent or received by another contraband device, and the external alert including an external alert timestamp and an external alert location; and

add the external alert to the plurality of alerts.

17. The mobile device of claim 15, wherein the processor, in response to detecting a contraband monitoring device, is further configured to:

obtain biometric information, the biometric information including audio and/or video; and

add the biometric information to the current alert.

18. The mobile device of claim 15, wherein the determining of the subset of alerts includes, for a candidate alert from among the plurality of previous alerts:

calculating a distance between the alert location and the location corresponding to the candidate alert; and

adding the candidate alert to the subset of alerts in response to determining that the distance is less than the predetermined distance.

19. The mobile device of claim 18, wherein the alert location includes a first global positioning system (GPS) coordinate, the location corresponding to the candidate alert includes a second GPS coordinate, and the distance is calculated using the first GPS coordinate and the second GPS coordinate.

20. The mobile device of claim 15, wherein the current alert further includes an alert time of arrival (TOA) measurement,

wherein each previous alert of the subset of alerts further includes a corresponding TOA measurement, the subset of alerts includes at least a first alert and a second alert, and

wherein the processor is further configured to:

determine an alert distance based on a transmit time of the contraband device and the alert TOA measurement, the alert distance being a radius of an alert circle whose center is the alert location;

determine a first distance based on the transmit time and the TOA measurement associated with the first alert, the first distance being a radius of a first circle whose center is the location corresponding to the first alert;

determine a second distance based on the transmit time and the TOA measurement associated with the second alert, the second distance being a radius of a second circle whose center is the location corresponding to the second alert; and

determine the contraband device location as a point of intersection between all of the alert circle, the first circle, and the second circle.