Enhancing A-GPS Location Accuracy and Yield With Location Measurement Units and Network Timing Measurements

• US 20130122929A1
• Filed: 11/16/2012
• Published: 05/16/2013
• Est. Priority Date: 11/16/2011
• Status: Active Grant

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Al-Mufti, Khalid, Kalenahalli, Suryanarayana
• Granted Patent: US 8,805,410 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 64/003 locating network equipment
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

A system and method for determining the location of a mobile device. One or more location measurement units (LMUs) or components may be requested to provide timing relationship information from a respective cell site. These LMUs may then be tasked to measure uplink times of arrival of signals received by the LMUs from a target mobile device. A response message from the target mobile device may be received, the response message having reference epoch frame information whereby a Global Positioning System (GPS) time estimate at the reference epoch that the target mobile device used to make GPS satellite measurements is determined as a function of the requested timing relationship information. Satellite information may then be determined using the determined GPS time estimate, and a location of the mobile device performed using this satellite information.

Claims

1. A method of determining the location of a mobile device comprising the steps of:

(a) requesting by a node one or more location measurement units (LMUs) to provide timing relationship information from a respective cell site in a communications network;

(b) tasking the one or more LMUs to measure uplink times of arrival of signals received by the LMUs from a target mobile device;

(c) receiving a response message from the target mobile device, the response message having reference epoch frame information;

(d) determining a Global Positioning System (GPS) time estimate at the reference epoch that the target mobile device used to make GPS satellite measurements, wherein the determination is performed as a function of the requested LMU timing relationship information;

(e) determining satellite information using the determined GPS time estimate; and

(f) determining a location of the mobile device as a function of the determined satellite information.

2. The method of claim 1 further comprising the steps of:

(i) receiving a location request by the node for a target mobile device; and

(ii) transmitting a request message to the target mobile device in response to the location request.

3. The method of claim 2 wherein the steps of transmitting a request message and tasking one or more LMUs are performed at substantially the same time.

4. The method of claim 2 wherein the request message includes GPS time assistance measurement request elements.

5. The method of claim 2 wherein the location request includes one or more of tipping information for the target mobile device, uplink signal radio frequency information, and serving site identification.

6. The method of claim 2 further comprising the steps of:

(iii) receiving the position request by the target mobile device; and

(iv) receiving signals from one or more satellites as a function of information in the position request, the information including a selected reference epoch.

7. The method of claim 1 wherein the step of receiving a response message further comprises receiving a response message from the target mobile device, the response message having reference epoch frame number information in a reference frame and having reference frame information elements.

8. The method of claim 1 wherein the node is selected from the group consisting of a serving mobile location center (SMLC), a standalone SMLC (SAS), and a radio network controller (RNC).

9. The method of claim 1 wherein the timing relationship information is selected from the group consisting of Global System for Mobile Communications-Global Positioning System Broadcast Channel (GSM-GPS BCCH) information and system frame network (SFN) information.

10. The method of claim 1 wherein the determined GPS time estimate is determined using the relationship:

t<sub>RFGPS—

MS</sub>=t<sub>RFGPS—

LMU</sub>+τ

_p

where t<sub>RFGPS—

LMU</sub> represents the GPS-GSM or GPS-System timing relationship measured by the one or more LMUs and τ

_p represents propagation time from the mobile device to a serving cell.

11. The method of claim 1 wherein the communications network is selected from the group consisting of a Universal Mobile Telecommunications System (UMTS) network, a Global System for Mobile Communication (GSM) network, a Time Division Multiple Access (TDMA) network, Code Division Multiple Access (CDMA) network, a Worldwide Interoperability for Microwave Access (WiMax) network, a WiFi network, CDMA2000 network, and a network utilizing Evolution-Data Optimized (EVDO), Long Term Evolution (LTE), or 1 times Radio Transmission Technology (1×

RTT) standards.

12. A method of determining the location of a mobile device comprising the steps of:

(a) requesting by a node one or more location measurement units (LMUs) to provide timing relationship information from a respective cell site in a communications network;

(b) tasking the one or more LMUs to measure uplink times of arrival of signals received by the one or more LMUs from a target mobile device;

(c) determining a range from the target mobile device to a serving cell as a function of the measured uplink times of arrival;

(d) determining a Global Positioning System (GPS) time estimate as a function of the requested LMU timing relationship information;

(e) populating GPS timing fields and corresponding system timing information in a fine-time assistance message as a function of the determined GPS time estimate;

(f) transmitting the fine-time assistance message to the target mobile device;

(g) determining satellite information using GPS timing information reported by the target mobile device in response to the transmitted fine-time assistance message; and

(h) determining a location of the mobile device as a function of the determined satellite information.

13. The method of claim 12 wherein the step of determining a GPS time estimate further comprises determining a GPS time estimate as a function of the relationship:

t_SystemMS=t_SystemLMU+τ

_p

where t_SystemLMU represents system time expressed in terms of GPS time and τ

_p represents propagation time from the mobile device to a serving cell.

14. The method of claim 12 wherein the node is selected from the group consisting of a serving mobile location center (SMLC), a standalone SMLC (SAS), and a radio network controller (RNC).

15. The method of claim 12 wherein the timing relationship information is selected from the group consisting of Global System for Mobile Communications-Global Positioning System Broadcast Channel (GSM-GPS BCCH) information and system frame network (SFN) information.

16. The method of claim 12 further comprising the steps of:

receiving the fine-time assistance message by the target mobile device;

(ii) receiving signals from one or more satellites as a function of information in the fine-time assistance message; and

(iii) transmitting a response message to the node with satellite measurements and GPS timing information.

17. The method of claim 12 wherein the communications network is selected from the group consisting of a Universal Mobile Telecommunications System (UMTS) network, a Global System for Mobile Communication (GSM) network, a Time Division Multiple Access (TDMA) network, Code Division Multiple Access (CDMA) network, a Worldwide Interoperability for Microwave Access (WiMax) network, a WiFi network, CDMA2000 network, and a network utilizing Evolution-Data Optimized (EVDO), Long Term Evolution (LTE), or 1 times Radio Transmission Technology (1×

RTT) standards.

18. A method of determining the location of a mobile device comprising the steps of:

(a) requesting by a node one or more location measurement units (LMUs) to provide timing relationship information from a respective cell site in a communications network;

(b) tasking the one or more LMUs to measure uplink times of arrival of signals received by the one or more LMUs from a target mobile device;

(c) determining an initial position estimate of the target mobile device using the measured uplink times of arrival measurements;

(d) determining a range from the initial position estimate of the target mobile device to a cell serving the target mobile device;

(e) determining a Global Positioning System (GPS) time estimate as a function of the requested LMU timing relationship information;

(f) populating GPS timing fields and corresponding system timing information in a fine-time assistance message as a function of the GPS time estimate;

(g) transmitting the fine-time assistance message to the target mobile device;

(h) determining satellite information using GPS timing information reported by the target mobile device in response to the transmitted fine-time assistance message; and

(i) determining a location of the target mobile device as a function of the determined satellite information.

19. The method of claim 18 wherein the node is selected from the group consisting of a serving mobile location center (SMLC), a standalone SMLC (SAS), and a radio network controller (RNC).

20. The method of claim 18 wherein the timing relationship information is selected from the group consisting of Global System for Mobile Communications-Global Positioning System Broadcast Channel (GSM-GPS BCCH) information and system frame network (SFN) information.

21. The method of claim 18 wherein ones of the LMUs are collocated with cell sites.

22. The method of claim 18 wherein the step of determining a range further comprises determining a range as a function of the relationship:

23. The method of claim 18 wherein the step of determining a range further comprises determining a range as a function of the relationship:

24. The method of claim 18 wherein the step of determining a range further comprises determining a range as a function of the relationship:

τ

_p=½

RTT_UMTS.

25. The method of claim 18 wherein the step of determining a GPS time estimate further comprises determining a GPS time estimate as a function of the relationship:

t_SystemMS=t_SystemLMU+τ

_p

where t_SystemLMU represents system time expressed in terms of GPS time and τ

_p represents propagation time from the mobile device to a serving cell.

26. The method of claim 18 wherein the step of determining a range from the initial position estimate of the target mobile device to a cell serving the target mobile device is performed using the relationship

τ

_p=distance(Serving cell(x,y),initial phone location()).

27. The method of claim 18 wherein the step of determining an initial position estimate of the target mobile device further comprises using observed time difference of arrival of signals received by the target mobile device to determine the initial position estimate.

28. The method of claim 27 wherein the step of determining a range from the initial position estimate of the target mobile device to a cell serving the target mobile device is performed using the relationship

τ

_p=distance(Serving cell(x,y),initial phone location()_OTDOA).

29. The method of claim 18 further comprising the steps of:

(i) receiving the fine-time assistance message by the target mobile device;

(ii) receiving signals from one or more satellites as a function of information in the fine-time assistance message; and

(iii) transmitting a response message to the node with satellite measurements and GPS timing information.

30. The method of claim 18 wherein the communications network is selected from the group consisting of a Universal Mobile Telecommunications System (UMTS) network, a Global System for Mobile Communication (GSM) network, a Time Division Multiple Access (TDMA) network, Code Division Multiple Access (CDMA) network, a Worldwide Interoperability for Microwave Access (WiMax) network, a WiFi network, CDMA2000 network, and a network utilizing Evolution-Data Optimized (EVDO), Long Term Evolution (LTE), or 1 times Radio Transmission Technology (1×

RTT) standards.

31. A method of determining the location of a mobile device comprising the steps of:

(a) receiving at a node timing relationship information from a respective cell site in a communications network;

(b) measuring uplink times of arrival of signals from a target mobile device;

(c) receiving a response message from the target mobile device, the response message having reference epoch frame information;

(d) determining a Global Positioning System (GPS) time estimate at the reference epoch that the target mobile device used to make GPS satellite measurements, wherein the determination is performed as a function of the received timing relationship information;

(e) determining satellite information using the determined GPS time estimate; and

(f) determining a location of the mobile device as a function of the determined satellite information.

32. A method of determining the location of a mobile device comprising the steps of:

(a) receiving at a node timing relationship information from a respective cell site in a communications network;

(b) measuring uplink times of arrival of signals from a target mobile device;

(c) determining a range from the target mobile device to a serving cell as a function of the measured uplink times of arrival;

(d) determining a Global Positioning System (GPS) time estimate as a function of the requested timing relationship information;

(e) populating GPS timing fields and corresponding system timing information in a fine-time assistance message as a function of the determined GPS time estimate;

(f) transmitting the fine-time assistance message to the target mobile device;

(g) determining satellite information using GPS timing information reported by the target mobile device in response to the transmitted fine-time assistance message; and

(h) determining a location of the mobile device as a function of the determined satellite information.

33. A method of determining the location of a mobile device comprising the steps of:

(a) receiving at a node timing relationship information from a respective cell site in a communications network;

(b) measuring uplink times of arrival of signals from a target mobile device;

(c) determining an initial position estimate of the target mobile device using the measured uplink times of arrival measurements;

(d) determining a range from the initial position estimate of the target mobile device to a cell serving the target mobile device;

(e) determining a Global Positioning System (GPS) time estimate as a function of the requested timing relationship information;

(f) populating GPS timing fields and corresponding system timing information in a fine-time assistance message as a function of the GPS time estimate;

(g) transmitting the fine-time assistance message to the target mobile device;

(h) determining satellite information using GPS timing information reported by the target mobile device in response to the transmitted fine-time assistance message; and

(i) determining a location of the target mobile device as a function of the determined satellite information.