Femto-cell location by direct methods

• US 8,180,368 B2
• Filed: 11/11/2008
• Issued: 05/15/2012
• Est. Priority Date: 11/11/2008
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J., Mia, Rashidus S., Ward, Matthew L.
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Mapa, Michael
• Application Number:
  US12/268,989
• Publication Number:
  US 20100120447A1
• Time in Patent Office: 1,281 Days
• Field of Search: 4554561-458, 455/404.2, 455/444, 455/449
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/0242 Determining the position of transmitters to be subsequently used in positioning G01S5/0289 takes precedence
• CPC Class Codes: H04W 64/003 locating network equipment
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

Illustrative embodiments of the inventive subject matter described herein include, but are not limited to, the following: a femto-cell device, methods for use by a wireless location system (WLS) in locating a femto-cell device, and a wireless location system having certain features relating to the location of femto-cell devices. A femto-cell device used in a wireless communications system (WCS) includes a location subsystem configured to acquire information identifying the geographic location of the femto-cell device. The device also includes an antenna subsystem, a radio frequency (RF) block coupled to the antenna subsystem, a baseband block coupled to the RF block, and a communications block coupled to the baseband block. In addition, the device is configured to communicate with the WCS, including communicating at least some of the location information to the WCS.

Claims

1. A subsystem for use by a wireless location system (WLS) in locating a femto-cell device operating in a wireless communications system, wherein the WLS includes a serving mobile location center (SMLC), a plurality of location measuring units (LMUs) in communication with the SMLC, a plurality of link monitors in communication with the SMLC, and an SMLC database in communication with the SMLC and containing cell locations and other radio aspects of the wireless communications system, the subsystem comprising:

(a) a subsystem configured for discovering and initiating location of the femto-cell device, wherein said discovering and initiating comprises at least one of the following procedures;

(a1) receiving femto-cell ID information from the wireless communications system;

(a2) discovery of the femto-cell ID information via analysis of call detail records; and

(a3) discovery of the femto-cell ID information via monitoring of wireless communications system link traffic for new cell-IDs within messages related to call events;

(b) a subsystem configured for storing femto-cell identification information in the SMLC database;

(c) a subsystem configured for setting a trigger for location of the femto-cell, wherein said setting a trigger comprises at least one of the following procedures;

(c1) setting a femto-cell cell-ID trigger in the SMLC database via a wireless intelligent network (WIN) facility;

(c2) setting an internal femto-cell cell-ID trigger in the SMLC database to indicate to the WLS that mobile station (MS) location information should be examined to identify when the femto-cell device is serving the MS;

(c3) setting a femto-cell cell-ID trigger in a radio network monitor (RNM) or link monitoring system (LMS) associated with the WLS, wherein the WLS is configured such that detection of the femto-cell cell-ID provokes the WLS to attempt location of the femto-cell device;

(d) a subsystem configured for calculating the location of the femto-cell device;

(e) a subsystem configured for calculating a confidence factor relating to the calculated location of the femto-cell; and

(f) a subsystem configured for comparing the calculated confidence factor with a confidence factor stored in the SMLC database.

2. A subsystem as recited in claim 1, further comprising a subsystem configured for determining that the calculated confidence factor is better than the stored confidence factor, and in response thereto updating location information in the SMLC database.

3. A subsystem as recited in claim 1, further comprising a subsystem configured for determining that the calculated confidence factor is better than the stored confidence factor, and notifying an operator of the wireless communications system of an error in the stored location information associated with the femto-cell device.

4. A subsystem as recited in claim 1, further comprising a subsystem configured for determining that the calculated confidence factor is below a prescribed value and attempting to obtain a more accurate location of the femto-cell device.

5. A subsystem as recited in claim 1, wherein the location of the femto-cell device is calculated by the femto-cell device.

6. A subsystem as recited in claim 1, wherein the location of the femto-cell device is calculated by the WLS.

7. A subsystem as recited in claim 6, wherein the location of the femto-cell device is determined using uplink transmissions during a handover procedure.

8. A system, comprising:

a wireless communications system (WCS), wherein the WCS is associated with a serving mobile location center (SMLC) and an SMLC database containing network cell identifiers, network antenna identifiers, and network antenna locations;

a femto-cell device;

a location subsystem configured to acquire information identifying an estimate of the geographic location of the femto-cell device;

a communications subsystem configured to provide for communication between the WCS and the femto-cell device, including communicating location information to the WCS for storage in the SMLC database together with location records including femto-cell locations and identifiers; and

a triggering mechanism configured to actuate the location subsystem so as to cause the location subsystem to determine the location estimate for the femto-cell device;

wherein the SMLC is configured to use location resources to confirm the femto-cell location estimate and to determine a confidence factor representing a measure of the quality of the location estimate based on factors including cell size, number of sectors, and received power levels, and to attempt to re-locate the femto-cell if the confidence factor indicates that the location estimate is inadequate.

9. A method for use by a wireless location system (WLS) in locating a femto-cell device operating in a wireless communications system, wherein the WLS includes a serving mobile location center (SMLC), a plurality of location measuring units (LMUs) in communication with the SMLC, a plurality of link monitors in communication with the SMLC, and an SMLC database in communication with the SMLC and containing cell locations and other radio aspects of the wireless communications system, the method comprising:

discovering and initiating location of the femto-cell device, wherein said discovering and initiating comprises at least one of the following procedures;

receiving femto-cell ID information from the wireless communications system;

discovery of the femto-cell ID information via analysis of call detail records; and

discovery of the femto-cell ID information via monitoring of wireless communications system link traffic for new cell-IDs within messages related to call events;

storing femto-cell identification information in the SMLC database;

setting a trigger for location of the femto-cell, wherein said setting a trigger comprises at least one of the following procedures;

setting a femto-cell cell-ID trigger in the SMLC database via a wireless intelligent network (WIN) facility;

setting an internal femto-cell cell-ID trigger in the SMLC database to indicate to the WLS that mobile station (MS) location information should be examined to identify when the femto-cell device is serving the MS;

setting a femto-cell cell-ID trigger in a radio network monitor (RNM) or link monitoring system (LMS) associated with the WLS, wherein the WLS is configured such that detection of the femto-cell cell-ID provokes the WLS to attempt location of the femto-cell device;

determining the location of the femto-cell device and providing location information to the SMLC database;

calculating a confidence factor relating to the determinded location of the femto-cell device;

comparing the calculated confidence factor with a confidence factor stored in the SMLC database;

determining that the calculated confidence factor is better than the stored confidence factor; and

taking a further action including at least one of;

(a) notifying an operator of the wireless communications system of an error in the stored location information associated with the femto-cell device; and

(b) updating location information in the SMLC database.

10. A method as recited in claim 9, further comprising determining that the calculated confidence factor is below a prescribed value and attempting to obtain a more accurate location of the femto-cell device.

11. A method as recited in claim 9, further comprising use of the femto-cell location for radio freqeuncy (RF) planning and coordination.

12. A method as recited in claim 11, wherein said RF planning and coordination includes preventing the femto-cell device from interfering with other cells when the femto-cell device is re-located.

13. A method as recited in claim 9, further comprising use of the femto-cell location for emergency services.

14. A method as recited in claim 9, further comprising use of the femto-cell location for warning, alert and response network (WARN) services.

15. A method as recited in claim 9, further comprising use of the femto-cell location for commercial location services.

16. A method as recited in claim 9, wherein the wireless communications system comprises, in addition to said femto-cell, a plurality of macro-cells and at least one micro-cell.

17. A method as recited in claim 16, wherein said femto-cell device is deployed as an under-lay femto-cell situated within a radio footprint of a single macro-cell.

18. A method as recited in claim 16, wherein said femto-cell device is deployed as a border femto-cell situated within the radio footprints of multiple macro-cells.

19. A method as recited in claim 16, wherein said femto-cell device is deployed as a remote femto-cell situated outside the radio footprint and coverage areas of all macro-cells of the wireless communications system.

20. A method as recited in claim 9, wherein the location of the femto-cell device is calculated by the femto-cell device.

21. A method as recited in claim 20, wherein the femto-cell device is a Global Navigation Satellite System (GNSS)-capable device comprising a receiver capable of receiving GNSS satellite signals.

22. A method as recited in claim 9, wherein the location of the femto-cell device is calculated by the WLS.

23. A method as recited in claim 22, wherein the location of the femto-cell device is determined using uplink transmissions during a handover procedure.