Cooperating receiver selection for UMTS wireless location

• US 8,290,496 B2
• Filed: 12/29/2009
• Issued: 10/16/2012
• Est. Priority Date: 12/29/2009
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Segall, Edward Joseph, Issakov, Simon, Mia, Rashidus S.
• Primary Examiner(s): Doan, Kiet
• Assistant Examiner(s): Vu, Michael T
• Application Number:
  US12/648,753
• Publication Number:
  US 20110159876A1
• Time in Patent Office: 1,022 Days
• Field of Search: 4554561-457, 455/442, 455/436, 455/432.1, 455/456.2, 455/452, 370331- 33, 370/342, 370/465
• US Class Current: 455/442
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

For Wireless Communications Networks (WCNs) that support soft handover, cooperator receiver selection for a TDOA, AOA, TDOA/AOA, or hybrid network-based or network-overlay Wireless Location System (WLS) must contend with one or more network base stations as a serving cell. When the active set contains more than one member, two techniques for determining a set of cooperating and demodulating receivers to use in the signal collection for location estimation is disclosed. In one embodiment, the active set members are constructively reduced to a single member that is used as a proxy serving cell. In another embodiment, the information contained in the active set membership is retained and a new set of demodulating and cooperator receivers are generated based on the entire membership of the active set.

Claims

1. A method of identifying a set of cooperator and demodulator location measuring units (LMUs) for use in locating a mobile device in a Code Division Multiple Access (CDMA)-based wireless communications network (WCN), wherein the demodulator LMUs perform full or partial demodulation of an uplink signal from the mobile device and the cooperator LMUs receive the uplink signal from the mobile device without performing demodulation, comprising:

obtaining data identifying an active set of base stations through which active communication is established between the mobile device and the WCN;

based on the active set, identifying a proxy serving cell;

based on the proxy serving cell, identifying at least one cooperator LMU and at least one demodulator LMU;

employing the at least one cooperator LMU and the at least one demodulator LMU to collect signal data from the mobile device; and

employing the signal data to locate the mobile device;

wherein said identifying a proxy serving cell comprises selecting a base station having an associated demodulator LMU list that contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list; and

wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

2. The method recited in claim 1, wherein the proxy serving cell is identified and then cooperator and demodulator LMUs are identified based on a pre-computed static list of cooperator and demodulator LMUs for a sector corresponding to the proxy serving cell.

3. The method recited in claim 2, further comprising generating the pre-computed static list based on a radio propagation model for a service area.

4. The method recited in claim 1, wherein the method is used in a mixed mode system in which multi-mode LMUs are deployed for locating both Time Division Multiple Access/Frequency Division Multiple Access (TDMA/FDMA) and CDMA mobile devices.

5. The method recited in claim 1, further comprising detecting a triggering event to initiate location of the mobile device, and communicating triggering information and tasking information to a wireless location system (WLS), wherein the tasking information includes active set membership information.

6. The method recited in claim 5, wherein, upon detection by the WLS of multiple active set members, the WLS elects one of a set of predefined proxy methods;

and, once in a proxy method, the WLS identifies a proxy serving cell and retrieves the associated cooperator and demodulator lists for tasking LMUs for initial signal quality sampling.

7. The method recited in claim 6, further comprising using collected signal metrics to downselect from the cooperator and demodulator lists to a final set of cooperator and demodulator LMUs for signal collection.

8. The method recited in claim 7, wherein radio signals are collected via geographically distributed LMUs.

9. The method recited in claim 1, wherein said identifying a proxy serving cell further comprises determining a proxy serving cell closest to a geographic centroid of the base stations in the active set.

10. The method recited in claim 9, wherein the geographic centroid is determined by averaging geographic coordinates of the base stations.

11. The method recited in claim 9, wherein the geographic centroid is determined as a function of signal power levels received from the base stations.

12. The method recited in claim 9, wherein the geographic centroid is determined as a function of signal quality metrics associated with the base stations.

13. The method recited in claim 1, wherein said identifying a proxy serving cell further comprises selecting a base station whose demodulator LMU list contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list.

14. The method recited in claim 13, wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

15. The method recited in claim 1, wherein the base stations are each associated with a geographic coverage area and said identifying a proxy serving cell further comprises:

determining a common coverage area for the active set; and

identifying as the proxy serving cell a base station whose geographic coverage area most closely matches the common coverage area.

16. The method recited in claim 15, wherein said geographic coverage area is a predetermined bounding polygon.

17. The method recited in claim 1, wherein the base stations are each associated with a geographic coverage area and said identifying a proxy serving cell further comprises identifying as the proxy serving cell a base station with the smallest geographic coverage area.

18. The method recited in claim 1, wherein at least one of the demodulator or cooperator LMUs is overlaid on the WCN.

19. The method recited in claim 1, wherein at least one of the demodulator or cooperator LMUs is integral to the WCN.

20. A system configured to identify a set of cooperator and demodulator location measuring units (LMUs) for use in locating a mobile device in a Code Division Multiple Access (CDMA)-based wireless communications network (WCN), wherein the demodulator LMUs perform full or partial demodulation of an uplink signal from the mobile device and the cooperator LMUs receive the uplink signal from the mobile device without performing demodulation, the system comprising at least one processor and at least one storage medium communicatively coupled to said at least one processor, the storage medium having stored therein computer-executable instructions for instructing the processor in causing the following steps:

obtaining data identifying an active set of base stations through which active communication is established between the mobile device and the WCN;

based on the active set, identifying a proxy serving cell;

based on the proxy serving cell, identifying at least one cooperator LMU and at least one demodulator LMU;

employing the at least one cooperator LMU and the at least one demodulator LMU to collect signal data from the mobile device; and

employing the signal data to locate the mobile device;

wherein said identifying a proxy serving cell comprises selecting a base station having an associated demodulator LMU list that contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list; and

wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

21. The system of claim 20, wherein the proxy serving cell is identified and then cooperator and demodulator LMUs are identified based on a pre-computed static list of cooperator and demodulator LMUs for a sector corresponding to the proxy serving cell.

22. The system of claim 21, further comprising instructions for instructing the processor in causing the step of generating the pre-computed static list based on a radio propagation model for a service area.

23. The system of claim 20, wherein the system is a mixed mode system in which multi-mode LMUs are deployed for locating both Time Division Multiple Access/Frequency Division Multiple Access (TDMA/FDMA) and CDMA mobile devices.

24. The system of claim 20, further comprising instructions for instructing the processor in causing the steps of detecting a triggering event to initiate location of the mobile device, and communicating triggering information and tasking information to a wireless location system (WLS), wherein the tasking information includes active set membership information.

25. The system of claim 24, wherein, upon detection by the WLS of multiple active set members, the WLS elects one of a set of predefined proxy methods;

and, once in a proxy method, the WLS identifies a proxy serving cell and retrieves the associated cooperator and demodulator lists for tasking LMUs for initial signal quality sampling.

26. The system of claim 25, further comprising instructions for instructing the processor in causing the step of using collected signal metrics to downselect from the cooperator and demodulator lists to a final set of cooperator and demodulator LMUs for signal collection.

27. The system of claim 26, wherein radio signals are collected via geographically distributed LMUs.

28. The system of claim 20, wherein said identifying a proxy serving cell further comprises determining a proxy serving cell closest to a geographic centroid of the base stations in the active set.

29. The system of claim 28, wherein the geographic centroid is determined by averaging geographic coordinates of the base stations.

30. The system of claim 28, wherein the geographic centroid is determined as a function of signal power levels received from the base stations.

31. The system of claim 28, wherein the geographic centroid is determined as a function of signal quality metrics associated with the base stations.

32. The system of claim 20, wherein said identifying a proxy serving cell further comprises selecting a base station whose demodulator LMU list contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list.

33. The system of claim 32, wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

34. The system of claim 20, wherein the base stations are each associated with a geographic coverage area and said identifying a proxy serving cell further comprises:

determining a common coverage area for the active set; and

identifying as the proxy serving cell a base station whose geographic coverage area most closely matches the common coverage area.

35. The system of claim 34, wherein said geographic coverage area is a predetermined bounding polygon.

36. The system of claim 20, wherein the base stations are each associated with a geographic coverage area and said identifying a proxy serving cell further comprises identifying as the proxy serving cell a base station with the smallest geographic coverage area.

37. The system recited in claim 20, wherein at least one of the demodulator or cooperator LMUs is overlaid on the WCN.

38. The system recited in claim 20, wherein at least one of the demodulator or cooperator LMUs is integral to the WCN.

39. A non-transitory computer readable storage medium storing thereon computer executable instructions for identifying a set of cooperator and demodulator location measuring units (LMUs) for use in locating a mobile device in a Code Division Multiple Access (CDMA)-based wireless communications network (WCN), wherein the demodulator LMUs perform full or partial demodulation of an uplink signal from the mobile device and the cooperator LMUs receive the uplink signal from the mobile device without performing demodulation, said computer executable instructions for:

obtaining data identifying an active set of base stations through which active communication is established between the mobile device and the WCN;

based on the active set, identifying a proxy serving cell;

based on the proxy serving cell, identifying at least one cooperator LMU and at least one demodulator LMU;

employing the at least one cooperator LMU and the at least one demodulator LMU to collect signal data from the mobile device; and

employing the signal data to locate the mobile device;

wherein said identifying a proxy serving cell comprises selecting a base station having an associated demodulator LMU list that contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list; and

wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

40. The non-transitory computer readable storage medium of claim 39, wherein the proxy serving cell is identified and then cooperator and demodulator LMUs are identified based on a pre-computed static list of cooperator and demodulator LMUs for a sector corresponding to the proxy serving cell.

41. The non-transitory computer readable storage medium of claim 40, further comprising instructions for generating the pre-computed static list based on a radio propagation model for a service area.

42. The non-transitory computer readable storage medium of claim 39, wherein the set of cooperator and demodulator LMUs is identified in a mixed mode system in which multi-mode LMUs are deployed for locating both Time Division Multiple Access/Frequency Division Multiple Access (TDMA/FDMA) and CDMA mobile devices.

43. The non-transitory readable storage medium of claim 39, further comprising instructions for detecting a triggering event to initiate location of the mobile device, and communicating triggering information and tasking information to a wireless location system (WLS), wherein the tasking information includes active set membership information.

44. The non-transitory computer readable storage medium of claim 43, wherein, upon detection by the WLS of multiple active set members, the WLS elects one of a set of predefined proxy methods;

and, once in a proxy method, the WLS identifies a proxy serving cell and retrieves the associated cooperator and demodulator lists for tasking LMUs for initial signal quality sampling.

45. The non-transitory computer readable storage medium of claim 44, further comprising instructions for using collected signal metrics to downselect from the cooperator and demodulator lists to a final set of cooperator and demodulator LMUs for signal collection.

46. The non-transitory computer readable storage medium of claim 45, wherein radio signals are collected via geographically distributed LMUs.

47. The non-transitory computer readable storage medium of claim 39, wherein said instructions for identifying a proxy serving cell further comprises instructions for determining a proxy serving cell closest to a geographic centroid of the base stations in the active set.

48. The non-transitory computer readable storage medium of claim 47, wherein the geographic centroid is determined by averaging geographic coordinates of the base stations.

49. The non-transitory computer readable storage medium of claim 47, wherein the geographic centroid is determined as a function of signal power levels received from the base stations.

50. The non-transitory computer readable storage medium of claim 47, wherein the geographic centroid is determined as a function of signal quality metrics associated with the base stations.

51. The non-transitory computer readable storage medium of claim 39, wherein said instructions for identifying a proxy serving cell further comprises selecting a base station whose demodulator LMU list contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list.

52. The non-transitory computer readable storage medium of claim 51, wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

53. The non-transitory computer readable storage medium of claim 39, wherein the base stations are each associated with a geographic coverage area and said instructions for identifying a proxy serving cell further comprise instructions for:

determining a common coverage area for the active set; and

identifying as the proxy serving cell a base station whose geographic coverage area most closely matches the common coverage area.

54. The non-transitory computer readable storage medium of claim 53, wherein said geographic coverage area is a predetermined bounding polygon.

55. The non-transitory computer readable storage medium of claim 39, wherein the base stations are each associated with a geographic coverage area and said instructions for identifying a proxy serving cell further comprises instructions for identifying as the proxy serving cell a base station with the smallest geographic coverage area.

56. The non-transitory computer readable storage medium recited in claim 39, wherein at least one of the demodulator or cooperator LMUs is overlaid on the WCN.

57. The non-transitory readable storage medium recited in claim 39, wherein at least one of the demodulator or cooperator LMUs is integral to the WCN.

58. A method of identifying a set of cooperator and demodulator location measuring units (LMUs) for use in locating a mobile device in a Code Division Multiple Access (CDMA)-based wireless communications network (WCN), comprising:

obtaining data identifying an active set of base stations through which active communication is established between the mobile device and the WCN;

based on the active set, identifying a proxy serving cell;

based on the proxy serving cell, identifying at least one cooperator LMU and at least one demodulator LMU; and

employing the at least one cooperator LMU and the at least one demodulator LMU to collect signal data from the mobile device;

wherein said identifying a proxy serving cell further comprises selecting a base station whose demodulator LMU list contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list; and

wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

59. The method recited in claim 58, further comprising employing the signal data to locate the mobile device.

60. The method recited in claim 58, wherein the proxy serving cell is identified and then cooperator and demodulator LMUs are identified based on a list of cooperator and demodulator LMUs for a sector corresponding to the proxy serving cell.

61. The method recited in claim 58, wherein the method is used in a mixed mode system in which multi-mode LMUs are deployed for locating both Time Division Multiple Access/Frequency Division Multiple Access (TDMA/FDMA) and CDMA mobile devices.

62. The method recited in claim 58, further comprising detecting a triggering event to initiate location of the mobile device, and communicating triggering information and tasking information to a wireless location system (WLS), wherein the tasking information includes active set membership information.

63. The method recited in claim 58, wherein said identifying a proxy serving cell comprises at least one of the following methods:

determining a proxy serving cell closest to a geographic centroid of the base stations in the active set;

determining a common coverage area for the active set, and identifying as the proxy serving cell a base station whose geographic coverage area most closely matches the common coverage area; and

identifying as the proxy serving cell a base station with the smallest geographic coverage area.

64. A system configured to identify a set of cooperator and demodulator location measuring units (LMUs) for use in locating a mobile device in a Code Division Multiple Access (CDMA)-based wireless communications network (WCN), the system comprising at least one processor and at least one storage medium communicatively coupled to said at least one processor, the storage medium having stored therein computer-executable instructions for instructing the processor in causing the following steps:

obtaining data identifying an active set of base stations through which active communication is established between the mobile device and the WCN;

based on the active set, identifying a proxy serving cell;

based on the proxy serving cell, identifying at least one cooperator LMU and at least one demodulator LMU; and

employing the at least one cooperator LMU and the at least one demodulator LMU to collect signal data from the mobile device;

wherein said identifying a proxy serving cell further comprises selecting a base station whose demodulator LMU list contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list; and

wherein when more than one base station includes said greatest number in the active set, the proxy serving cell is selected from among the base stations including said greatest number in the active set using a predetermined selection method.

65. The system recited in claim 64, further comprising means for employing the signal data to locate the mobile device.

66. The system recited in claim 64, wherein the proxy serving cell is identified and then cooperator and demodulator LMUs are identified based on a list of cooperator and demodulator LMUs for a sector corresponding to the proxy serving cell.

67. The system recited in claim 64, wherein the system is configured to be used in a mixed mode system in which multi-mode LMUs are deployed for locating both Time Division Multiple Access/Frequency Division Multiple Access (TDMA/FDMA) and CDMA mobile devices.

68. The system recited in claim 64, further comprising means for detecting a triggering event to initiate location of the mobile device, and communicating triggering information and tasking information to a wireless location system (WLS), wherein the tasking information includes active set membership information.

69. The system recited in claim 64, wherein the step of identifying a proxy serving cell comprises at least one of the following:

determining a proxy serving cell closest to a geographic centroid of the base stations in the active set;

determining a common coverage area for the active set, and identifying as the proxy serving cell a base station whose geographic coverage area most closely matches the common coverage area; and

identifying as the proxy serving cell a base station with the smallest geographic coverage area.

70. A non-transitory computer readable storage medium storing thereon computer executable instructions for identifying a set of cooperator and demodulator signal collection receivers for use in locating a mobile device in a Code Division Multiple Access (CDMA)-based wireless communications network (WCN), said computer executable instructions including:

instructions for obtaining data identifying an active set of base stations through which active communication is established between the mobile device and the WCN;

instructions for identifying a proxy serving cell based on the active set;

instructions for identifying at least one cooperator location measuring unit (LMU) and at least one demodulator LMU based on the proxy serving cell; and

instructions for employing the at least one cooperator LMU and the at least one demodulator LMU to collect signal data from the mobile device;

wherein said instructions for identifying a proxy serving cell further comprise instructions for selecting a base station whose demodulator LMU list contains all of the base stations of the active set, and when no base station'"'"'s demodulator LMU list contains all of the base stations of the active set, selecting a base station with a greatest number of base stations in the active set in its demodulator LMU list.