Sparsed U-TDOA Wireless Location Networks

• US 20080261611A1
• Filed: 04/18/2007
• Published: 10/23/2008
• Est. Priority Date: 04/18/2007
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J., Mia, Rashidus S., Lefever, Ronald
• Granted Patent: US 8,045,506 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

In an overlay, U-TDOA-based, Wireless Location System, LMUs typically co-located with BTSs, are used to collect radio signaling both in the forward and reverse channels. Techniques are used to compensate for sparse LMU deployments where sections of the U-TDOA service area are uplink demodulation or downlink beacon discovery limited.

Claims

1. An iterative method for designing a sparse wireless location system (WLS) from an initial network design, comprising:

performing a preliminary network design analysis to determine that at least one of the following performance limiting factors affects said initial network design;

downlink beacon discovery, accuracy, and uplink demodulation; and

modifying the initial network design based on the performance limiting factor determined as affecting said initial network design.

2. A method as recited in claim 1, wherein said WLS comprises an uplink time difference of arrival (U-TDOA) system including a plurality of geographically dispersed location measuring units (LMUs).

3. A method as recited in claim 1, wherein said WLS is overlaid on a GSM wireless communications system comprising a plurality of geographically dispersed base transceiver stations (BTSs).

4. A method as recited in claim 1, further comprising identifying at least one cluster of co-synchronized cell sectors and performing an intelligent network design process to produce said initial network design.

5. A method as recited in claim 1, further comprising modifying the initial network design by performing at least one of the following actions based on a determination that the performance limiting factor affecting the initial network design is accuracy:

increasing an integration time at one or more location measuring units (LMUs);

deploying a hybrid time difference of arrival (TDOA)/enhanced cell identification (ECID) location process in the WLS;

deploying a hybrid time TDOA/angle of arrival (AoA) location process in the WLS; and

adding at least one LMU to the network design.

6. A method as recited in claim 1, further comprising removing at least one location measuring unit (LMU) from the network design based on a determination that no performance limiting factor affects the initial network design.

7. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

deploying at least one enhanced downlink antenna.

8. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

deploying downlink interference cancellation.

9. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

deploying base transceiver station (BTS) synchronization.

10. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

adding at least one location measuring unit (LMU) to the network design.

11. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

determining that an Abis monitoring system (AMS) is not deployed, and then deploying at least one downlink-only location measuring unit (LMU) at an identified site.

12. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

determining that an Abis monitoring system (AMS) is deployed, and then enabling the use of Enhanced Beacon Synchronization (EBS) and AMS-derived beacon timing functions.

13. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

determining that communications system demodulation data is enabled, and enabling a demodulated data feature.

14. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

determining that communications system demodulation data is not enabled, and determining that an Abis monitoring system (AMS) is not deployed and enabling a mid-amble only correction feature.

15. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

determining that communications system demodulation data is not enabled, and determining that an Abis monitoring system (AMS) is deployed and enabling an AMS-derived demodulated data feature.

16. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

adding at least one location measuring unit (LMU) to the network design.

17. A method as recited in claim 1, further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

adding at least one dedicated antenna facility to the network design.

18. A software tool stored on a computer readable medium, comprising computer readable instructions for carrying out an iterative method for designing a sparse uplink time difference of arrival (U-TDOA) wireless location system (WLS) including a plurality of geographically dispersed location measuring units (LMUs), wherein said WLS is overlaid on a GSM wireless communications system comprising a plurality of geographically dispersed base transceiver stations (BTSs), said iterative method comprising:

providing an initial network design;

determining that at least one of the following performance limiting factors affects said initial network design;

downlink beacon discovery, accuracy, and uplink demodulation; and

modifying the initial network design based on the performance limiting factor determined as affecting said initial network design.

19. A software tool as recited in claim 18, said iterative method further comprising identifying at least one cluster of co-synchronized cell sectors and producing the initial network design.

20. A software tool as recited in claim 18, said iterative method further comprising modifying the initial network design by performing at least one of the following actions based on a determination that the performance limiting factor affecting the initial network design is accuracy:

increasing an integration time at one or more location measuring units (LMUs);

deploying a hybrid time difference of arrival (TDOA)/enhanced cell identification (ECID) location process in the WLS;

deploying a hybrid time TDOA/angle of arrival (AoA) location process in the WLS; and

adding at least one LMU to the network design.

21. A software tool as recited in claim 18, said iterative method further comprising removing at least one location measuring unit (LMU) from the network design based on a determination that no performance limiting factor affects the initial network design.

22. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

deploying at least one enhanced downlink antenna.

23. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

deploying downlink interference cancellation.

24. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

deploying base transceiver station (BTS) synchronization.

25. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

adding at least one location measuring unit (LMU) to the network design.

26. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

determining whether an Abis monitoring system (AMS) is deployed, and if not deploying at least one downlink-only location measuring unit (LMU) at an identified site.

27. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is downlink beacon discovery:

determining whether an Abis monitoring system (AMS) is deployed, and if so enabling the use of Enhanced Beacon Synchronization (EBS) and AMS-derived beacon timing functions.

28. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

determining whether communications system demodulation data is enabled, and if so enabling a demodulated data feature.

29. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

determining whether communications system demodulation data is enabled, and if not determining that an Abis monitoring system (AMS) is not deployed and enabling a mid-amble only correction feature.

30. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

determining whether communications system demodulation data is enabled, and if not determining that an Abis monitoring system (AMS) is deployed and enable an AMS-derived demodulated data feature.

31. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

adding at least one location measuring unit (LMU) to the network design.

32. A software tool as recited in claim 18, said iterative method further comprising the following step based on a determination that the performance limiting factor affecting the initial network design is uplink demodulation:

adding at least one dedicated antenna facility to the network design.

33. A method for use in operating a wireless location system (WLS), comprising:

employing a link monitoring subsystem (LMS) to supply a set of demodulated data bits;

using said demodulated data bits to produce a reference signal; and

correlating said reference signal against at least one recorded received signal at a remote receiving site at which a location measuring unit (LMU) is deployed to provide a time difference of arrival (TDOA) estimate for use in location processing.