Enhanced Mobile Location

• US 20090047973A1
• Filed: 03/20/2006
• Published: 02/19/2009
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Smith Micro Software Incorporated
• Original Assignee: Seeker Wireless Pty., Limited
• Inventors: Drane, Christopher R., Scott, Craig A., MacNaughtan, Malcolm
• Granted Patent: US 8,355,737 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G08B 21/0247 System arrangements wherein the alarm criteria uses signal strength
• CPC Class Codes: G08B 21/0283 via a telephone network, e.g. cellular GSM
• 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 obtaining a local path loss versus range model in a radio communications network is disclosed. The method comprises obtaining at least one path loss measurement and an associated range measurement at an approximated location of a mobile radio terminal within the radio communications network and applying this to a path loss versus range model to obtain the local path loss versus range model. The local model may also be used to obtain a more accurate location of the mobile radio terminal within the radio communications network.

Claims

1. A method for obtaining a local path loss versus range model for a radio communications network, the method comprising:

obtaining at least one path loss and corresponding range measurement at an approximated mobile radio terminal location in the radio communications network; and

applying the at least one path loss and corresponding range measurement to a path loss versus range model to obtain the local path loss versus range model for the approximated mobile radio terminal location.

2. A method as claimed in claim 1 wherein the step of obtaining the at least one path loss and corresponding range measurement comprises obtaining a range of the mobile radio terminal at the approximated location of the mobile radio terminal from one or more transmitters in the radio communications network.

3. A method as claimed in claim 2 wherein the step of obtaining the at least one path loss measurement measuring a signal level at the mobile radio terminal transmitted by the one or more transmitters.

4. A method as claimed in claim 3 wherein the path loss versus range model comprises a range dependent component.

5. A method as claimed in claim 4 wherein the path loss versus range model comprises a non range dependent component.

6. A method as claimed in claim 4 wherein the path loss versus range model comprises both a range dependent and a non range dependent component.

7. A method as claimed in claim 6 wherein path loss versus range model is of the form:

L_p(r)=β

+α

*10*log 10(r)

Where;

Lp is the path loss given in units of decibels;

β

is a non-range dependent term characteristic of the local environment;

α

is the parameter defining the range dependence; and

r is the range.

8. A method as claimed in claim 7 further comprising estimating the range dependent component and/or the non-range dependent component of the path loss versus range model.

9. A method as claimed in claim 7 wherein β

comprises a general non-range dependent component β

_gen and a user non-range dependent component β

_user.

10. A method as claimed in claim 7 wherein α

is obtained from published data.

11. A method as claimed in claim 7 wherein α

is obtained from one or more measurements from the radio mobile terminal.

12. A method as claimed in claim 7 wherein α

is obtained from one or more measurements from a plurality of radio mobile terminals in the vicinity of the radio mobile terminal.

13. A method as claimed in claim 7 wherein α

is obtained from one or more measurements from the radio mobile terminal and from one or more measurements from a plurality of radio mobile terminals in the vicinity of the radio mobile terminal.

14. A method as claimed in claim 10 wherein β

is obtained using the obtained value for α

.

18. A method of locating a mobile radio terminal in a radio communications network, the method comprising:

calculating the location of the mobile radio terminal using the local path loss model obtained from the method of claim 1.

22. A machine readable medium containing instructions to cause a machine to perform the method of claim 1.

15. A method for obtaining a local path loss versus range model for a radio communications network, the method comprising:

obtaining an approximate location of the mobile radio terminal in the radio communications network;

obtaining at least one path loss and corresponding range measurement at the approximated mobile radio terminal location in the radio communications network; and

applying the at least one path loss and corresponding range measurement to a path loss versus range model to obtain the local path loss versus range model for the approximated mobile radio terminal location.

16. A method according to claim 15 wherein the step of obtaining the approximate location of the mobile radio terminal comprises use of one or more of the following parameters:

one or more serving cell identifiers;

one or more round trip delay measurements relating to a serving cell;

one or more Neighbour cell identifiers; and

one or more RTDs.

17. A method according to claim 15 wherein the step of obtaining the approximate location of the mobile radio terminal comprises obtaining the approximate location of the mobile radio terminal externally from the radio communications network.

19. A radio communications network comprising:

means for obtaining at least one path loss and corresponding range measurement at an approximated mobile radio terminal location in the radio communications network; and

means for applying the at least one path loss and corresponding range measurement to a path loss versus range model to obtain the local path loss versus range model for the approximated mobile radio terminal location.

20. A radio communications network as claimed in claim 19 further comprising means for approximating the mobile radio terminal location in the radio communications network.

21. A radio communications network as claimed in claim 19 further comprising means for calculating a location of the mobile radio network terminal using the local path loss versus range model.