Mid-Call Synchronization for U-TDOA and AOA Location in UMTS

• US 20110256887A1
• Filed: 06/29/2011
• Published: 10/20/2011
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Mia, Rashidus S.
• Granted Patent: US 8,204,511 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/02216 Timing or synchronisation of the receivers
• 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 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

In a wireless location system, a method for determining frame and slot timing information for use in receiving an uplink signal from a user equipment (UE) device assigned to an uplink Dedicated Physical Control Channel (DPCCH) includes receiving signals in the uplink DPCCH at a location measurement unit (LMU) of the WLS. The method also includes detecting a predefined bit pattern known to be present in a plurality of predefined slots of the uplink DPCCH. Next, the frame and slot timing information are determined for the uplink DPCCH based on the detected bit pattern. Finally, the frame and slot timing information is used for collecting uplink signals from the UE for use in location processing.

Claims

1. In a wireless location system for use in locating a mobile transmitter, a method for determining frame and slot timing information for use in receiving an uplink signal from a user equipment (UE) device assigned to an uplink Dedicated Physical Control Channel (DPCCH), comprising:

receiving uplink DPCCH signals in the uplink DPCCH at a location measurement unit (LMU) of the WLS, said uplink DPCCH signals being formatted into multiple frames and multiple slots per frame;

detecting a predefined bit pattern known to be present in a plurality of predefined slots of the uplink DPCCH signals;

examining the DPCCH signals across multiple frames;

determining the frame and slot timing information for the uplink DPCCH based on the detected bit pattern; and

using the frame and slot timing information, collecting uplink signals from the UE for use in location processing.

2. A method as recited in claim 1, wherein the step of collecting uplink signals from the UE comprises collecting uplink signals at a plurality of LMUs and using said signals in time difference of arrival (TDOA) processing to determine the location of the UE.

3. A method as recited in claim 2, wherein said predefined bit pattern comprises the bit pattern “

1-1-1”

.

4. A method as recited in claim 3, wherein said predefined slots comprise slots 0, 5, 6, and 9 of a 10 millisecond (ms) frame.

5. A method as recited in claim 4, wherein the WLS is overlaid on a UMTS wireless communications system, and wherein the UE to be located comprises a wireless device communicating with said UMTS wireless communications system.

11. A method as recited in claim 5 wherein said frame and slot timing information includes a start time for each frame and slot.

6. A wireless location system (WLS) for use in locating a mobile transmitter, comprising:

a network of location measurement units (LMUs); and

a processor configured to cause the system to determine frame and slot timing information for use in receiving an uplink signal from a user equipment (UE) device assigned to an uplink Dedicated Physical Control Channel (DPCCH), including receiving signals in the uplink DPCCH at a first LMU, said signals being formatted into multiple frames and multiple slots per frame;

detecting a predefined bit pattern known to be present in a plurality of predefined slots of the uplink DPCCH;

examining the signals across multiple frames;

determining the frame and slot timing information for the uplink DPCCH based on the detected bit pattern; and

using the frame and slot timing information to collect uplink signals from the UE for use in location processing.

7. A system as recited in claim 6, wherein the system is further configured to collect uplink signals at a plurality of LMUs and use said signals in time difference of arrival (TDOA) processing to determine the location of the UE.

8. A system as recited in claim 7, wherein said predefined bit pattern comprises the bit pattern “

1-1-1”

.

9. A system as recited in claim 8, wherein said predefined slots comprise slots 0, 5, 6, and 9 of a 10 millisecond (ms) frame.

10. A system as recited in claim 9, wherein the WLS is overlaid on a UMTS wireless communications system, and wherein the UE to be located comprises a wireless device communicating with said UMTS wireless communications system.

12. A system as recited in claim 6 wherein said frame and slot timing information includes a start time for each frame and slot.

13. A method for use by a wireless location system (WLS) in locating a user equipment (UE) device communicating via a wireless communications system configured in accordance with Universal Mobile Telephone System (UMTS) technical specifications, comprising:

receiving a task to locate said UE device mid-call, wherein said task is received following a process in which a Node B element of the UMTS system provides timing information via a broadcast channel;

said UE performs a cell search and accesses the UMTS system via a reverse access channel (RACH);

the Node B element determines fine timing information from a long pilot sequence; and

the UE device converses with the UMTS system using a Dedicated Physical Control Channel (DPCCH) and a Dedicated Physical Data Channel (DPDCH);

receiving uplink DPCCH signals from said UE device;

detecting a predefined bit pattern known to be present in a plurality of predefined slots of the uplink DPCCH signals;

performing a multi-frame examination of the DPCCH signals;

determining frame and slot timing information for the DPCCH, wherein said frame and slot timing information includes a start time for each frame and slot;

collecting uplink signals from said UE device via a network of location measurement units (LMUs); and

determining the location of said UE device using an uplink time difference of arrival (U-TDOA) location algorithm.

14. A method as recited in claim 13 wherein the step of collecting uplink signals from the UE comprises collecting uplink signals at a plurality of LMUs and using said signals in time difference of arrival (TDOA) processing to determine the location of the UE.

15. A method as recited in claim 14 wherein said predefined bit pattern comprises the bit pattern “

1-1-1”

.

16. A method as recited in claim 15 wherein said predefined slots comprise slots 0, 5, 6, and 9 of a 10 millisecond (ms) frame.

17. A method as recited in claim 16 wherein the WLS is overlaid on a UMTS wireless communications system, and wherein the UE to be located comprises a wireless device communicating with said UMTS wireless communications system.