Cooperating receiver selection for UMTS wireless location

• US 8,442,538 B2
• Filed: 12/29/2009
• Issued: 05/14/2013
• Est. Priority Date: 12/29/2009
• Status: Expired due to Fees

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Segall, Edward Joseph, Issakov, Simon, Mia, Rashidus S.
• Primary Examiner(s): Ajibade Akonai, Olumide T
• Assistant Examiner(s): Peaches, Randy
• Application Number:
  US12/648,783
• Publication Number:
  US 20110159891A1
• Time in Patent Office: 1,232 Days
• Field of Search: None
• US Class Current: 455/442
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 4/02 Services making use of location information
• 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 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 at least one cooperator LMU further comprises;

for each said base station, determining a geographic area associated with the base station and dividing the geographic area into radial segments; and

selecting, for each of the radial segments, cooperator LMUs such that the selected cooperator LMUs are substantially equally distributed among the base stations and a range of relative azimuths about each base station.

2. A method as recited in claim 1, wherein said selecting further comprises:

selecting cooperator LMUs based on a pre-computed static list of cooperator LMUs for a sector corresponding to the base stations in the active set.

3. A method as recited in claim 2, wherein the number of radial segments is eight.

4. A method as recited in claim 2, wherein said selecting further comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to a cooperator LMU list based on an associated quality metric for the radial segment.

5. A method as recited in claim 4, wherein said selecting further comprises cycling through the base stations in the active set in conjunction with said stepping through the radial segments.

6. A method as recited in claim 5, further comprising continuing the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments for the base stations in the active set have been analyzed.

7. A method as recited in claim 6, further comprising:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

8. A method as recited in claim 7, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

9. A method as recited in claim 1, wherein the radial segments are centered on a geographic centroid of each base station.

10. A method as recited in claim 1, wherein the WCN comprises a distributed antenna system (DAS) and at least one base station of the active set comprises DAS antennas, further comprising using the DAS antennas as at least part of the active set.

11. A method as recited in claim 1, wherein the WCN comprises a distributed antenna system (DAS) and at least one base station of the active set comprises DAS antennas, further comprising using as the active set the union of active set members without DAS antennas and DAS antennas of the remaining active set members.

12. 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 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 at least one cooperator LMU and at least one demodulator LMU further comprises;

determining a representative point based on geographic information for the active set and determining a geographic area associated with the representative point; and

dividing the geographic area into radial segments and selecting at least one cooperator LMU and at least one demodulator LMU based on the radial segments, wherein the number of radial segments is eight.

13. 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 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 at least one cooperator LMU and at least one demodulator LMU further comprises;

determining a representative point based on geographic information for the active set and determining a geographic area associated with the representative point; and

dividing the geographic area into radial segments and selecting at least one cooperator LMU and at least one demodulator LMU based on the radial segments,

wherein said selecting comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to a cooperator LMU list based on an associated quality metric for the radial segment.

14. A method as recited in claim 13, wherein said selecting further comprises cycling through the base stations in the active set in conjunction with said stepping through the radial segments.

15. A method as recited in claim 14, further comprising continuing the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments for the base stations in the active set have been analyzed.

16. A method as recited in claim 15, further comprising:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

17. A method as recited in claim 16, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

18. 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 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 at least one cooperator LMU and at least one demodulator LMU further comprises;

determining a common coverage area for the active set and a geographic centroid for the common coverage area;

dividing the common coverage area into radial segments centered around the geographic centroid and identifying at least one cooperator LMU and at least one demodulator LMU based on the radial segments; and

selecting cooperator LMUs based on a pre-computed static list of cooperator LMUs for a sector corresponding to the base stations in the active set.

19. A method as recited in claim 18, further comprising generating the pre-computed static list based on a radio propagation model for a service area.

20. A method as recited in claim 19, further comprising determining geographically distributed marker points within the common coverage area and, for each of the marker points, using the radio propagation model to determine a quality metric for sectors within a predetermined range of the common coverage area.

21. A method as recited in claim 20, further comprising averaging the quality metrics from each marker point to determine a quality metric for each sector.

22. A method as recited in claim 21, wherein the number of radial segments is eight.

23. A method as recited in claim 21, wherein said selecting comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to a cooperator LMU list based on an associated quality metric for the radial segment.

24. A method as recited in claim 23, further comprising repeating the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments have been analyzed.

25. A method as recited in claim 24, further comprising:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

26. A method as recited in claim 25, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

27. A method as recited in claim 18, wherein said determining a common coverage area further comprises employing a bounding polygon to approximate a geographic coverage area for each base station and determining an area of overlap as the common coverage area.

28. 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 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 at least one cooperator LMU further comprises;

for each base station, determining a geographic area associated with the base station and dividing the geographic area into radial segments; and

selecting, for each of the radial segments, cooperator LMUs such that the selected cooperator LMUs are substantially equally distributed among the base stations and a range of relative azimuths about each base station.

29. The system of claim 28, wherein said selecting further comprises:

selecting cooperator LMUs based on a pre-computed static list of cooperator LMUs for a sector corresponding to the base stations in the active set.

30. The system of claim 29, wherein the number of radial segments is eight.

31. The system of claim 29, wherein said selecting further comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to a cooperator LMU list based on an associated quality metric for the radial segment.

32. The system of claim 31, wherein said selecting further comprises cycling through the base stations in the active set in conjunction with said stepping through the radial segments.

33. The system of claim 32, further comprising instructions for instructing the processor in causing the step of continuing the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments for the base stations in the active set have been analyzed.

34. The system of claim 33, further comprising instructions for instructing the processor in causing the step of:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

35. The system of claim 34, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

36. The system of claim 28, wherein the radial segments are centered on a geographic centroid of each base station.

37. The system of claim 28, wherein the WCN comprises a distributed antenna system (DAS) and at least one base station of the active set comprises DAS antennas, further comprising using the DAS antennas as at least part of the active set.

38. The system of claim 28, wherein the WCN comprises a distributed antenna system (DAS) and at least one base station of the active set comprises DAS antennas, further comprising using as the active set the union of active set members without DAS antennas and DAS antennas of the remaining active set members.

39. 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 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 at least one cooperator LMU and at least one demodulator LMU further comprises;

determining a representative point based on geographic information for the active set and determining a geographic area associated with the representative point; and

dividing the geographic area into radial segments and identifying at least one cooperator LMU and at least one demodulator LMU based on the radial segments;

wherein the number of radial segments is eight.

40. 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 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 at least one cooperator LMU and at least one demodulator LMU further comprises;

determining a representative point based on geographic information for the active set and determining a geographic area associated with the representative point; and

dividing the geographic area into radial segments and selecting at least one cooperator LMU and at least one demodulator LMU based on the radial segments, wherein said selecting comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to a cooperator LMU list based on an associated quality metric for the radial segment.

41. The system of claim 40, wherein said selecting further comprises cycling through the base stations in the active set in conjunction with said stepping through the radial segments.

42. The system of claim 41, further comprising instructions for instructing the processor in causing the step of continuing the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments for the base stations in the active set have been analyzed.

43. The system of claim 42, further comprising instructions for instructing the processor in causing the step of:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

44. The system of claim 43, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

45. The system of claim 40, wherein said identifying further comprises:

determining a common coverage area for the active set and a geographic centroid for the common coverage area;

dividing the common coverage area into radial segments centered around the geographic centroid and identifying at least one cooperator LMU and at least one demodulator LMU based on the radial segments.

46. The system of claim 45, wherein said identifying further comprises selecting cooperator LMUs based on a pre-computed static list of cooperator LMUs for a sector corresponding to the base stations in the active set.

47. The system of claim 46, 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.

48. The system of claim 47, further comprising instructions for instructing the processor in causing the steps of determining geographically distributed marker points within the common coverage area and, for each of the marker points, using the radio propagation model to determine a quality metric for sectors within a predetermined range of the common coverage area.

49. The system of claim 48, further comprising instructions for instructing the processor in causing the step of averaging the quality metrics from each marker point to determine a quality metric for each sector.

50. The system of claim 49, wherein the number of radial segments is eight.

51. The system of claim 49, wherein said selecting comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to a cooperator LMU list based on an associated quality metric for the radial segment.

52. The system of claim 51, further comprising instructions for instructing the processor in causing the step of repeating the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments have been analyzed.

53. The system of claim 52, further comprising instructions for instructing the processor in causing the step of:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

54. The system of claim 53, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

55. The system of claim 45, wherein said determining a common coverage area further comprises employing a bounding polygon to approximate a geographic coverage area for each base station and determining an area of overlap as the common coverage area.

56. A tangible 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), 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 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 at least one cooperator LMU further comprises;

for each base station, determining a geographic area associated with the base station and dividing the geographic area into radial segments; and

selecting, for each of the radial segments, cooperator LMUs such that the selected cooperator LMUs are substantially equally distributed among the base stations and a range of relative azimuths about each base station.

57. The computer readable storage medium of claim 56, wherein said selecting further comprises:

selecting cooperator LMUs based on a pre-computed static list of cooperator LMUs for a sector corresponding to the base stations in the active set.

58. The computer readable storage medium of claim 57, wherein the number of radial segments is eight.

59. The computer readable storage medium of claim 57, wherein said selecting further comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to the cooperator LMU list based on an associated quality metric for the radial segment.

60. The computer readable storage medium of claim 59, wherein said selecting further comprises cycling through the base stations in the active set in conjunction with said stepping through the radial segments.

61. The computer readable storage medium of claim 60, further comprising instructions for continuing the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments for the base stations in the active set have been analyzed.

62. The computer readable storage medium of claim 61, further comprising instructions for:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMU within a predetermined proximity and a predetermined average path loss.

63. The computer readable storage medium of claim 62, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

64. The computer readable storage medium of claim 56, wherein the radial segments are centered on a geographic centroid of each base station.

65. The computer readable storage medium of claim 56, wherein the WCN comprises a distributed antenna system (DAS) and at least one base station of the active set comprises DAS antennas, further comprising instructions for using the DAS antennas as at least part of the active set.

66. The computer readable storage medium of claim 56, wherein the WCN comprises a distributed antenna system (DAS) and at least one base station of the active set comprises DAS antennas, further comprising instructions for using as the active set the union of active set members without DAS antennas and DAS antennas of the remaining active set members.

67. A tangible 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, comprising:

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, based on the active set, identifying at least one cooperator LMU and at least one demodulator LMU;

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

instructions for employing the signal data to locate the mobile device;

wherein said instructions for identifying at least one cooperator LMU and at least one demodulator LMU further comprise;

instructions for determining a representative point based on geographic information for the active set and for determining a geographic area associated with the representative point;

instructions for dividing the geographic area into radial segments; and

instructions for selecting at least one cooperator LMU and at least one demodulator LMU based on the radial segments, wherein the number of radial segments is eight.

68. A tangible 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, comprising:

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, based on the active set, identifying at least one cooperator LMU and at least one demodulator LMU;

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

instructions for employing the signal data to locate the mobile device;

wherein said instructions for identifying at least one cooperator LMU and at least one demodulator LMU further comprise;

instructions for determining a representative point based on geographic information for the active set and for determining a geographic area associated with the representative point;

instructions for dividing the geographic area into radial segments; and

instructions for selecting at least one cooperator LMU and at least one demodulator LMU based on the radial segments, wherein said instructions for selecting comprise instructions for stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to the cooperator LMU list based on an associated quality metric for the radial segment.

69. The computer readable storage medium of claim 68, wherein said selecting further comprises cycling through the base stations in the active set in conjunction with said stepping through the radial segments.

70. The computer readable storage medium of claim 69, further comprising instructions for continuing the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments for the base stations in the active set have been analyzed.

71. The computer readable storage medium of claim 70, further comprising instructions for:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

72. The computer readable storage medium of claim 71, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.

73. A tangible 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, comprising:

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, based on the active set, identifying at least one cooperator LMU and at least one demodulator LMU;

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

instructions for employing the signal data to locate the mobile device;

wherein said instructions for identifying at least one cooperator LMU and at least one demodulator LMU comprise;

instructions for determining a common coverage area for the active set and a geographic centroid for the common coverage area;

instructions for dividing the common coverage area into radial segments centered around the geographic centroid; and

instructions for identifying at least one cooperator LMU and at least one demodulator LMU based on the radial segments, wherein said instructions for identifying comprise instructions for selecting cooperator LMUs based on a pre-computed static list of cooperator LMUs for a sector corresponding to the base stations in the active set.

74. The computer readable storage medium of claim 73, further comprising instructions for generating the pre-computed static list based on a radio propagation model for a service area.

75. The computer readable storage medium of claim 74, further comprising instructions for determining geographically distributed marker points within the common coverage area and, for each of the marker points, using the radio propagation model to determine a quality metric for sectors within a predetermined range of the common coverage area.

76. The computer readable storage medium of claim 75, wherein the number of radial segments is eight.

77. The computer readable storage medium of claim 75, wherein said selecting comprises stepping through the radial segments using a spatially symmetric pattern and adding cooperator LMUs to the cooperator LMU list based on an associated quality metric for the radial segment.

78. The computer readable storage medium of claim 77, further comprising instructions for repeating the selection of cooperator LMUs until a predetermined number of cooperator LMUs is reached or all radial segments have been analyzed.

79. The computer readable storage medium of claim 78, further comprising instructions for:

for each added cooperator LMU, determining an average path loss for the added cooperator LMU and adding cooperator LMUs within a predetermined proximity and a predetermined average path loss.

80. The computer readable storage medium of claim 79, wherein the at least one demodulator LMU is identified as a cooperator LMU within a predetermined proximity.