System and method for asset location in wireless networks

• US 7,373,154 B2
• Filed: 12/07/2006
• Issued: 05/13/2008
• Est. Priority Date: 02/25/2005
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Katz, Joseph, Sharony, Jacob
• Primary Examiner(s): Eng; George
• Assistant Examiner(s): Miller; Brandon J.
• Application Number:
  US11/635,099
• Publication Number:
  US 20070105566A1
• Time in Patent Office: 523 Days
• Field of Search: 455/456.2, 455/456.3, 455/456.4, 455/456.5, 455/456.6, 455/115.1, 455/456.1, 340/539.13, 340/825.49
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A computing arrangement for determining a location of a wireless communications device includes a memory arrangement, a communication arrangement and a processor. The memory arrangement stores a location of each of at least three access points. The communication arrangement receives first data which includes at least one of first signal strength data and second signal strength data. The first signal strength data is indicative of a strength of a first signal transmitted by the device and received by the at least three access points. The second signal strength data is indicative of a strength of a second signal transmitted by the at least three access points and received by the device. The processor determines a location area of the device as a function of the first data and the location of each of the at least three access points, the location area being within a predetermined reception range of the at least three access points. The processor determines the location of the device within the location area as a function of second data. The second data is indicative of a travel time of a third signal from the device to each of the at least three access points.

Claims

1. A computing arrangement for determining a location of a wireless communications device, comprising:

a memory arrangement storing a location of each of at least three access points; and

a communication arrangement receiving first data, the first data including at least one of first signal strength data and second signal strength data, the first signal strength data being indicative of a strength of a first signal transmitted by the device and received by the at least three access points, the second signal strength data being indicative of a strength of a second signal transmitted by the at least three access points and received by the device; and

a processor determining a location area of the device as a function of the first data and the location of each of the at least three access points, the location area being within a predetermined reception range of the at least three access points,

wherein the processor determines the location of the device within the location area as a function of second data, the second data being indicative of a travel time of a third signal from the device to each of the at least three access points.

2. The computing arrangement according to claim 1, wherein at least one of the at least three access points includes a smart antenna which directs a focused signal beam towards the location area.

3. The computing arrangement according to claim 1, wherein the location area is a coarse location of the device.

4. The computing arrangement according to claim 1, wherein the device includes at least one of a cell phone, a radio frequency tag, a laptop, a wireless transducer, a barcode scanner and a handheld computer.

5. The computing arrangement according to claim 1, wherein at least one of the first and second signal strength data includes received signal strength indicator (“

RSSI”

) data.

6. The computing arrangement according to claim 1, wherein the second data includes time difference of arrival (“

TDoA”

) data.

7. A method for determining a location of a wireless communication device, comprising:

determining a location area of the device as a function of first data and a location of each of at least three access points, the first data including at least one of first signal strength data and second signal strength data, the first signal strength data being indicative of a strength of a first signal transmitted by the device and received by the at least three access points, the second signal strength data being indicative of a strength of a second signal transmitted by the at least three access points and received by the device, the location area being within a predetermined reception range of the at least three access points; and

determining the location of the device within the location area as a function of second data, the second data being indicative of a travel time of a third signal from the device to each of the at least three access points.

8. The method according to claim 7, wherein at least one of the at least three access points includes a smart antenna for directing a focused signal beam towards the location area.

9. The method according to claim 8, further comprising:

transmitting an instruction to the at least one of the at least three access points to transmit the focused signal beam towards the location area.

10. The method according to claim 7, wherein the location area is a coarse location of the device.

11. The method according to claim 7, wherein the device includes at least one of a cell phone, a radio frequency tag, a laptop, a wireless transducer, a barcode scanner and a handheld computer.

12. The method according to claim 7, wherein at least one of the first and second signal strength data includes received signal strength indicator (“

RSSI”

) data.

13. The method according to claim 7, wherein the second data includes time difference of arrival (“

TDoA”

) data.

14. A system for determining a location of a wireless communications device, comprising:

at least three wireless access points; and

a computing arrangement communicating with the at least three access points, the arrangement determining a location area of the device as a function of first data and a location of each of the at least three access points, the first data including at least one of first signal strength data and second signal strength data, the first signal strength data being indicative of a strength of a first signal transmitted by the device and received by the at least three access points, the second signal strength data being indicative of a strength of a second signal transmitted by the at least three access points and received by the device, the location area being within a predetermined reception range of the at least three access points,

wherein the arrangement determines the location of the device within the location area as a function of second data, the second data being indicative of a travel time of a third signal from the device to each of the at least three access points.

15. The system according claim 14, wherein the device includes at least one of a cell phone, a radio frequency tag, a laptop, a wireless transducer, a barcode scanner and a handheld computer.

16. The system according claim 14, wherein at least one of the at least three access points includes a smart antenna for directing a focused signal beam towards the location area.

17. The system according to claim 14, wherein at least one of the first and second signal strength data includes received signal strength indicator (“

RSSI”

) data.

18. The system according to claim 14, wherein the second data includes time difference of arrival (“

TDoA”

) data.

19. The system according to claim 14, wherein the computing arrangement is a server.

20. A computing arrangement for determining a location of a wireless communications device, comprising:

a memory means for storing a location of each of at least three access points; and

a communication means for receiving first data, the first data including at least one of first signal strength data and second signal strength data, the first signal strength data being indicative of a strength of a first signal transmitted by the device and received by the at least three access points, the second signal strength data being indicative of a strength of a second signal transmitted by the at least three access points and received by the device; and

a processing means for determining a location area of the device as a function of the first data and the location of each of the at least three access points, the location area being within a predetermined reception range of the at least three access points,

wherein the processing means determines the location of the device within the location area as a function of second data, the second data being indicative of a travel time of a third signal from the device to each of the at least three access points.