Wireless local area network with geo-location capability

• US 20020118655A1
• Filed: 11/29/2001
• Published: 08/29/2002
• Est. Priority Date: 12/01/2000
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Wherenet Corporation (Zebra Technologies Corporation)
• Inventors: Belcher, Donald K., Boyd, Robert W., Wisherd, David, Harrington, Timothy C.
• Granted Patent: US 6,987,744 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• 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: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system of the present invention is operative for locating a wireless mobile device in communication with a wireless local area network (WLAN) that includes a plurality of cells defining a wireless local area network each having an access point base station. The access point base stations communicate with wireless mobile devices using wireless communication signals as typically spread spectrum communication signals. A processor is operatively connected to each of the access point base stations and operative to process communication signals transmitted from a mobile device and determine which signals are first-to-arrive signals based on a common timing signal and conduct differentiation of the first-to-arrive signals to locate the mobile device.

Claims

1. A system for locating a wireless station in communication with a wireless local area network comprising:

a plurality of cells defining a wireless local area network (WLAN) and each having an access point base station and adapted for communicating with wireless mobile devices using wireless communications signals; and

a processor operatively connected to each of said access point base stations and operative to process communications signals transmitted from a mobile device and determining which signals are first-to-arrive signals based on a common timing signal and conducting differentiation of the first-to-arrive signals to locate the mobile device.

2. A system according to claim 1, wherein said common timing signal comprises a wireless timing signal broadcast to each of said access point base stations.

3. A system according to claim 2, wherein a mobile station located at a known location is operative for generating the common timing signal.

4. A system according to claim 2, wherein an access point base station is operative for generating the common timing signal.

5. A system according to claim 1, and further comprising a common bus operatively connected to each of said access point base stations through which a common timing signal is provided to each access point base station.

6. A system according to claim 1, wherein any communications signals transmitted from mobile devices further comprise a location pulse appended to the wireless communications signal.

7. A system according to claim 6, wherein said location pulse is appended to a rising edge of the wireless communications signal transmitted from the mobile device.

8. A system according to claim 6, wherein said location pulse is appended to the falling edge of the wireless communications signal transmitted from the mobile device.

9. A system according to claim 1, and further comprising a network interconnecting each of said access point base stations and a server.

10. A system according to claim 9, wherein said network comprises an ethernet local area network.

11. A system according to claim 1, wherein said wireless communications signals comprise spread spectrum communications signals.

13. A system according to claim 12, wherein said common timing signal comprises a wireless timing signal broadcast to the edge detection circuitry of each of said access point base stations.

14. A system according to claim 12, wherein a mobile device located at a known location is operative for generating the common timing signal.

15. A system according to claim 12, wherein an access point base station at a known location is operative for generating the common timing signal.

16. A system according to claim 12, and further comprising a common bus operatively connected to each of said access point base stations and edge detection circuitry through which a common timing signal is provided.

17. A system according to claim 12, and further comprising a network interconnecting each of said access point base stations and a server.

18. A system according to claim 17, wherein said network comprises an ethernet local area network.

20. A system according to claim 19, wherein said correlator comprises a spread spectrum matched filter.

21. A system according to claim 19, wherein said common timing signal comprises a wireless timing signal broadcast to each of said access point base stations.

22. A system according to claim 19, wherein a mobile station located at a known location is operative for generating the common timing signal.

23. A system according to claim 19, wherein an access point base station at a known location is operative for generating the common timing signal.

24. A system according to claim 19, and further comprising a common bus operatively connected to each of said access point base stations through which a common timing signal is provided.

25. A system according to claim 19, and further comprising a network interconnecting each of said access point base stations and said server.

26. A system according to claim 25, wherein said network comprises an ethernet local area network.

28. A system according to claim 27, and further comprising a radio frequency (RF) switch operatively connected to said WLAN transmitter and said location transmitter for allowing transmission through a common antenna.

29. A system according to claim 28, and further comprising a signal detect circuit operatively connected to said WLAN transmitter and said location transmitter for triggering said location transmitter and said RF switch.

30. A system according to claim 27, wherein each base station further comprises a location receiver for receiving the location pulse.

31. A system according to claim 27, wherein said common timing signal comprises a wireless timing signal broadcast to each of said access point base stations.

32. A system according to claim 27, wherein a mobile station located at a known location is operative for generating the common timing signal.

33. A system according to claim 27, wherein an access point base station at a known location is operative for generating the common timing signal.

34. A system according to claim 27, and further comprising a common bus operatively connected to each of said access point base stations through which a common timing signal is provided.

35. A system according to claim 27, and further comprising a network interconnecting each of said access point base stations and said server.

36. A system according to claim 35, wherein said network comprises an ethernet local area network.

12. A system for locating a wireless station in communication with a wireless local area network comprising:

a plurality of cells defining a wireless local area network (WLAN) and each having an access point base station and adapted for communicating with wireless mobile devices using wireless spread spectrum communications signals, each base station further comprising edge detection circuitry time for detecting the leading edge of a communications signal transmitted from a mobile device; and

a processor operatively connected to each of said access point base stations and operative to process the detected leading edge of received communications signals and determining first-to-arrive signals based on a common timing signal and conducting differentiation of the first-to-arrive signals to locate the mobile station.

19. A system for locating a wireless station in communication with a wireless local area network comprising:

a plurality of cells defining a wireless local area network (WLAN) and each having an access point base station and adapted for communicating with wireless mobile devices contained within a cell using wideband spread spectrum communications signals; and

a correlator operative with each of said access point base stations and time referenced with a common timing signal for receiving a portion of a wideband spread spectrum communications signal received from a mobile device for determining first-to-arrive signals and conducting differentiation of the first-to-arrive signals to locate the mobile device.

27. A system for locating a wireless station in communication with a wireless local area network comprising:

a plurality of cells defining a wireless local area network (WLAN) and each having an access point base station time;

at least one wireless mobile station for communicating with said access point base stations and each comprising a wireless local area network (WLAN) transmitter for transmitting a wireless communication signal to base stations and a location transmitter for appending a spread spectrum location pulse onto one of a rising or falling edge of the wireless communication signal; and

a processor operatively connected to each of said access point base stations and operative to receive and process the appended location pulse from a mobile station and determining which signals are first-to-arrive signals based on a common timing signal and conducting differentiation of the first-to-arrive signals to locate the mobile station.