E-OTD augmentation to U-TDOA location system

• US 20050136945A1
• Filed: 12/20/2004
• Published: 06/23/2005
• Est. Priority Date: 12/19/2003
• Status: Active Grant

• Current Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Rowe, Robert, Alles, Martin, Carlson, John P., Kennedy, Joseph P., Graube, Nicolas
• Granted Patent: US 7,627,333 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for use in a wireless communication system with a network overlay geolocation system having a sparse deployment network in which base stations of the wireless communication system may or may not have a co-located wireless location sensor (WLS). The method uses U-TDOA measurements on the uplink (reverse) signal and E-OTD measurements on the downlink (forward) signals to estimate a location for a mobile appliance.

Claims

1. A method of locating a mobile appliance in a network overlay geolocation system having a plurality of base stations and a second plurality of wireless location sensors comprising:

measuring the TOA of a reverse signal from the mobile appliance at one or more of the second plurality of wireless location sensors to create TDOA measurements;

synchronizing the TDOA measurements of the reverse signal to a common time base and;

measuring the TOA of a forward channel from one or more of the plurality of base stations at the mobile appliance to create E-OTD measurements; and

,

determining a location estimate based on the TDOA measurements of the reverse signal and the TOA measurements of the forward channel.

2. The method of claim 1, comprising the step of synchronizing the E-OTD measurements of the forward channels to a second common time base;

3. The method of claim 2 comprising the step of synchronizing the E-OTD measurements by making over determined location measurements of mobiles at a plurality of locations.

4. The method of claim 2 comprising the step of synchronizing the E-OTD measurements with WLS measurements on the forward channel from one or more of the plurality of base stations.

5. The method of claim 4, wherein the step of synchronizing EOTD measurements to a common time base comprises the step of monitoring the BCCH of the forward channels from the one or more of the plurality of base stations.

6. The method of claim 1 wherein E-OTD measurements are provided to a geo-location control system by an Abis monitoring unit.

7. The method of claim 1, wherein E-OTD measurements are provided to a processing center separate from the network overlay geolocation system by an Abis interface.

8. The method of claim 1 comprising the step of determining surfaces associated with TDOA measurements and E-OTD measurements.

9. The method of claim 8, comprising the step of determining the location estimate based at least in part by the intersection of the surfaces associated with TDOA measurements and E-OTD measurements.

10. The method of claim 1, wherein the common time base is a GPS clock.

11. The method of claim 1, wherein the common time base is selected from the group comprising Global Orbiting Navigation Satellite System, Global Navigation Satellite System and CDMA network.

12. The method of claim 1, wherein the first plurality of base stations is greater than the second plurality wireless location sensors.

13. The method of claim 2, wherein the first time base and the second time base are the same.

14. The method of claim 8, wherein the location surfaces determined from E-OTD measurements are determined separate from the network overlay geolocation system.

15. In a sparse geo-location network overlay system having a plurality of base stations and at least two wireless location sensors, wherein uplink signals are received by the at least two wireless location sensors and downlink signals are received by a mobile appliance, a method of locating the mobile appliance comprising:

synchronizing the time of arrival of the uplink signal at the at least two wireless location sensors to a common clock;

synchronizing the time of arrival of a downlink signal from one or more of the plurality of base stations at the mobile appliance to a second common clock;

determining a location estimate based on the synchronized time of arrival of the downlink signal and the synchronized time of arrivals of the uplink signals.

16. The method of claim 15, wherein the step of synchronizing the time of arrival of the downlink signal is done by making over determined location measurements of mobiles at a plurality of locations.

17. The method of claim 15 comprising the step of synchronizing the time of arrival of the downlink signal with WLS measurements on the downlink channel from one or more of the plurality of base stations.

18. The method of claim 15, wherein the step of synchronizing the time of arrival of the uplink signal comprises monitoring the BCCH of the forward channels from the one or more of the plurality of base stations.

19. The method of claim 15, wherein the time of arrival of the downlink signals is provided to a geo-location control system by an Abis monitoring unit.

20. The method of claim 15, wherein time of arrival of the downlink signals is provided to a processing center separate from the network overlay geolocation system by an Abis interface.

21. The method of claim 15, comprising the step of determining location surfaces associated with time of arrival of the uplink and downlink signals.

22. The method of claim 21, comprising the step of determining the location estimate based at least in part by the intersection of the surfaces associated with time of arrival of the uplink and downlink signals.

23. The method of claim 15, wherein the common clock is a Global Positioning System clock.

24. The method of claim 15, wherein the common clock is selected from the group comprising Global Orbiting Navigation Satellite System, Global Navigation Satellite System and CDMA network.

25. The method of claim 15, wherein the common clock and the second common clock the same.

26. A method for estimating the location of a mobile appliance operating in a wireless communication system comprising:

measuring a first attribute of an uplink signal from the mobile appliance received at a plurality of wireless location sensors;

determining a location estimate based at least in part on the attribute of the uplink signal;

determining a location accuracy of the location estimate;

comparing the location accuracy to a predetermined threshold;

if the location accuracy is less that the predetermined threshold;

measuring second attributes of downlink signals from a plurality of base stations at the mobile appliance;

determining a second location estimate based at least in part on the second attributes of the downlink signals;

determining a second location accuracy of the second location estimate;

comparing the second location accuracy to the predetermined threshold;

if the second location accuracy is less than the predetermined threshold;

determining a third location estimate based at least in part on the first attribute and the second attribute.

27. The method of claim 26, wherein the first and second attributes are time of arrival.

28. The method of claim 26, wherein the first and second attributes are synchronized to a common time base.

29. The method of claim 28, wherein the common time base is a GPS clock.

30. The method of claim 28, wherein the common time base is selected from the group comprising Global Orbiting Navigation Satellite System, Global Navigation Satellite System and CDMA network.

31. The method of claim 26, wherein at least one location surface is generated from the first attribute and at least another location surface is generated from the second attribute.

32. The method of claim 31, wherein the third location estimate is based at least in part on the intersection of the at least one location surface and the at least another location surface.

33. The method of claim 26, wherein the first location estimate and the second location estimate are determined at a GCS.

34. The method of claim 26, wherein the first location estimate is determined at a GCS and the second location estimate is determined at a processing center separate from the GCS.

35. The method of claim 33, wherein the GCS receives the second attributes from an Abis monitoring unit.

36. In a wireless communication system having a sparse deployment of wireless location sensors wherein one or more base stations of the wireless communication system are not associated with a co-located wireless location sensor and wherein a geographic area served by the wireless communication system has a no location area, a method of determining the location of a mobile appliance comprising:

determining if the mobile appliance is in the no location area, and;

using E-OTD measurements from the forward link and TOA measurements from the reverse link to estimate the location of the mobile appliance.

37. The method of claim 36, wherein the step of determining if the mobile appliance is in the no location area comprises determining if a U-TDOA location estimate exists.

38. The method of claim 36, wherein the step of determining if the mobile appliance is in the no location area comprises accessing a database.

39. The method of claim 36, wherein data for E-OTD is provided by an Abis monitoring unit.