System for automatically determining cell transmitter parameters to facilitate the location of wireless devices

• US 7,797,000 B2
• Filed: 12/01/2006
• Issued: 09/14/2010
• Est. Priority Date: 12/01/2006
• Status: Expired due to Fees

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J.
• Primary Examiner(s): Afshar; Kamran
• Assistant Examiner(s): Choo; Munsoon
• Application Number:
  US11/607,420
• Publication Number:
  US 20080132247A1
• Time in Patent Office: 1,383 Days
• Field of Search: 455/456.2, 455/404.2, 455/456.1, 455/456.3
• US Class Current: 455/456.2
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Several techniques for locating wireless devices involve the Mobile Stations (MS) making measurements of the signals transmitted by geographically distributed base stations within a wireless network. If some key site information is known about these transmitters, such as the transmitter location, transmit signal power, signal propagation, and transmit signal timing, measurements of these transmit signals by a MS can be used to determine the position of the MS. An automatic method to detect transmitters, identify key transmitter information, and utilize the base station transmit signals to perform location is presented. In addition, this method facilitates the use of cell site transmit signals that are part of multiple wireless networks.

Claims

1. A system for automatically collecting and storing key cell transmitter information for use in locating a mobile wireless device operating in a wireless communications network (WCN), wherein the WCN includes a network of base stations including base station transmitters configured to transmit broadcast signals in one or more prescribed wireless frequency bands, wherein the broadcast signals from different base station transmitters are not synchronized with one another, comprising:

a location processing node configured to determine key transmitter information concerning base station transmitters of the WCN, wherein said key transmitter information is determined using information automatically determined by wireless scanning devices;

a plurality of wireless scanning devices, wherein each of said wireless scanning devices is configured to communicate with said location processing node via a communications link, and to scan available wireless bands and to make scanning measurements of unsynchronized base station broadcast signals from one or more geographically distributed base station transmitters of the WCN, wherein each wireless scanning device is further configured to assist the location processing node in determining said key transmitter information, including cell identification information, cell transmitter location information, and cell transmitter signal timing information, by receiving and measuring characteristics of said signals and providing information about said characteristics via the communications link to said location processing node; and

a location server configured to communicate with a mobile station (MS) to be located, and to cause said MS to be located to make signal measurements of signals from one or more WCN cell transmitters and to provide measurement information, including signal timing and received power level, to said location processing node;

wherein the system is configured such that, once a set of cell transmitter positions is established, these positions are assumed to be correct in the future and are not solved for on a frequent basis, and wherein the system periodically checks for new cell identification information and determines the coordinates for new cell transmitters.

2. A system as recited in claim 1, wherein each said wireless scanning device is further configured to communicate said key transmitter information to said location processing node, wherein said information is used by said location processing node to compute the location of one or more wireless devices.

3. A system as recited in claim 1, wherein the system is configured to operate with said one or more transmitters, and wherein at least one transmitter is part of a first wireless communications network and a least one transmitter is part of a second wireless communications network, and each of said wireless scanning devices is configured to scan and report cell transmitter information for cell transmitters of two different wireless communications networks.

4. A system as recited in claim 1, wherein said location server is configured to communicate via a user plane data channel with each said wireless scanning device, and wherein each said wireless scanning device is configured to provide measurement information via the data channel to said location processing node.

5. A system as recited in claim 1, wherein said cell identification information includes at least one member of the group consisting of Cell ID, frequency channel, base station identity code, Cell Global Identity, and Base Station ID.

6. A system as recited in claim 1, wherein said cell transmitter location information includes latitude and longitude.

7. A system as recited in claim 1, wherein said signal measurements include relative signal timing.

8. A system as recited in claim 1, wherein said signal measurements include absolute signal timing.

9. A system as recited in claim 1, wherein said signal measurements include received power level.

10. A system as recited in claim 1, wherein said location processing node is programmed to compute a location solution based upon time difference measurements.

11. A system as recited in claim 1, wherein at least one of said wireless scanning devices is a mobile device.

12. A system as recited in claim 1, wherein at least one of said wireless scanning devices is a fixed device.

13. A system as recited in claim 1, wherein at least one of said wireless scanning devices is at a known location.

14. A system as recited in claim 1, wherein at least one of said wireless scanning devices is at an unknown location.

15. A system as recited in claim 1, wherein said location processing node is programmed to compute a location solution using said measurements and previously known information to solve for unknown information.

16. A system as recited in claim 1, wherein said location processing node is programmed to compute an error function based on known and unknown information, and to solve for the unknown information by minimizing the error function.

17. A system as recited in claim 16, wherein said location processing node is programmed to compute the error of each of the measurements as a function of the unknown information.

18. A system as recited in claim 17, wherein said location processing node is programmed to compute an error function for time difference measurements, wherein said error function is the difference between a measured time difference and a theoretical time difference, assuming a hypothesized set of transmitter positions, transmitter timing offsets and receiver positions.

19. A system as recited in claim 18, wherein said location processing node is programmed to compute the square error of each of the measurements based on the unknown information.

20. A system as recited in claim 19, wherein said location processing node is programmed to weight the square error of each of the measurements based on the quality of the measurement, and to sum the weighted errors to create an error value which is a function of the unknown data.

21. A system as recited in claim 20, wherein said location processing node is programmed to solve for the unknown data by minimizing the error function.

22. A system as recited in claim 21, wherein said location processing node is programmed to mark data values as known once determined, and to use the known values to simplify the solution of unknown information.

23. A system as recited in claim 22, wherein the known information includes previously determined transmitter position information.

24. A system as recited in claim 22, wherein the known information includes timing of a transmitter known to be synchronous with respect to a common timing source.

25. A system as recited in claim 22, wherein the known information includes positions of fixed receivers.

26. A system as recited in claim 22, wherein the known information includes positions of mobile receivers.

27. A system as recited in claim 15, wherein said location processing node is programmed to limit a portion of the location solution to a geographic region, and to then later combine the data from various regions to simplify solution of the unknown data.

28. A system as recited in claim 1, wherein said location processing node comprises a computer.

29. A system as recited in claim 1, wherein said location processing node comprises a wireless device.

30. A system as recited in claim 1, wherein the WCN is compliant with at least one technical standard, including at least one of GSM, UMTS, IS-95, and CDMA-2000, wherein each said wireless scanning device is further configured to communicate said key transmitter information to said location processing node, wherein said information is usable by said location processing node to compute the location of one or more wireless devices;

wherein said server is configured to communicate via a user plane data channel with each wireless scanning device, and wherein said MS to be located is configured to provide measurement information via the data channel to said location processing node.

31. A method for locating a mobile station (MS), comprising:

instructing at least one wireless scanning device to communicate with a location processing node via a communications link, and to make scanning measurements of broadcast signals from one or more unsynchronized, geographically distributed transmitters, and further instructing said at least one wireless scanning device to receive and measure characteristics of said signals and provide information about said characteristics via the communications link to said location processing node, wherein said characteristics are useful to determine key transmitter information;

instructing a MS to be located to make signal measurements of signals from one or more transmitters and to provide measurement information to said location processing node;

determining the key transmitter information using information automatically determined by the wireless scanning device(s), said key transmitter information including cell identification information, cell transmitter position information, and cell transmitter signal timing information;

periodically checking for new cell identification information and determining the coordinates for new cell transmitters; and

at the location processing node, using said key transmitter information and said measurement information to determine the geographic location of said MS to be located;

wherein the method is performed such that, once a set of cell transmitter positions is established, these positions are assumed to be correct in the future and are not solved for on a frequent basis.

32. A method as recited in claim 31, comprising instructing said at least one wireless scanning device to communicate said key transmitter information to said location processing node, wherein said information is used by said location processing node to compute the location of one or more wireless devices.

33. A method as recited in claim 31, wherein the method is performed with at least one transmitter of a first wireless communications network and a least one transmitter of a second wireless communications network.

34. A method as recited in claim 31, wherein communications between one or more wireless devices and said location processing node are conducted via a user plane data channel.

35. A method as recited in claim 31, wherein said key transmitter information includes cell identification information.

36. A method as recited in claim 35, wherein said cell identification information includes at least one member of the group consisting of Cell ID, frequency channel, base station identity code, Cell Global Identity, and Base Station ID.

37. A method as recited in claim 31, wherein said key transmitter information includes cell transmitter location information.

38. A method as recited in claim 37, wherein said cell transmitter location information includes latitude and longitude.

39. A method as recited in claim 31, wherein said key transmitter information includes cell transmitter signal timing information.

40. A method as recited in claim 31, wherein said signal measurements include relative signal timing.

41. A method as recited in claim 31, wherein said signal measurements include absolute signal timing.

42. A method as recited in claim 31, wherein said signal measurements include received power level.

43. A method as recited in claim 31, wherein said location processing node is programmed to compute a location solution based upon time difference measurements.

44. A method as recited in claim 31, wherein said at least one wireless scanning device is a mobile device.

45. A method as recited in claim 31, wherein said at least one wireless scanning device is a fixed device.

46. A method as recited in claim 31, wherein said at least one wireless scanning device is at a known location.

47. A method as recited in claim 31, wherein said at least one wireless scanning device is at an unknown location.

48. A method as recited in claim 31, wherein said location processing node is programmed to compute a location solution using said measurements and previously known information to solve for unknown information.

49. A method as recited in claim 31, wherein said location processing node is programmed to compute an error function based on known and unknown information, and to solve for the unknown information by minimizing the error function.

50. A method as recited in claim 49, wherein said location processing node is programmed to compute the error of each of the measurements as a function of the unknown information.

51. A method as recited in claim 50, wherein said location processing node is programmed to compute an error function for time difference measurements, wherein said error function is the difference between a measured time difference and a theoretical time difference, assuming a hypothesized set of transmitter positions, transmitter timing offsets and receiver positions.

52. A method as recited in claim 51, wherein said location processing node is programmed to compute the square error of each of the measurements based on the unknown information.

53. A method as recited in claim 52, wherein said location processing node is programmed to weight the square error of each of the measurements based on the quality of the measurement, and to sum the weighted errors to create an error value which is a function of the unknown data.

54. A method as recited in claim 53, wherein said location processing node is programmed to solve for the unknown data by minimizing the error function.

55. A method as recited in claim 54, wherein said location processing node is programmed to mark data values as known once determined, and to use the known values to simplify the solution of unknown information.

56. A method as recited in claim 55, wherein the known information includes previously determined transmitter position information.

57. A method as recited in claim 55, wherein the known information includes timing of a transmitter known to be synchronous with respect to a common timing source.

58. A method as recited in claim 55, wherein the known information includes positions of fixed receivers.

59. A method as recited in claim 55, wherein the known information includes positions of mobile receivers.

60. A method as recited in claim 48, wherein said location processing node is programmed to limit a portion of the location solution to a geographic region, and to then later combine the data from various regions to simplify solution of the unknown data.

61. A method as recited in claim 31, wherein said location processing node comprises a computer.

62. A method as recited in claim 31, wherein said location processing node comprises a wireless device.

63. A method as recited in claim 31, wherein said at least one wireless scanning device is further instructed to communicate said key transmitter information to said location processing node, wherein said information is used by said location processing node to compute the location of one or more wireless devices;

wherein said wireless devices are operative to communicate via a user plane data channel, and wherein said MS to be located is operative to provide measurement information via the data channel to said location processing node;

wherein said key transmitter information includes cell identification information, cell transmitter location information, and cell transmitter signal timing information; and

wherein said signal measurements include signal timing and received power level.