Mobile Location

• US 20090011779A1
• Filed: 04/10/2006
• Published: 01/08/2009
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Smith Micro Software Incorporated
• Original Assignee: Seeker Wireless Pty., Limited
• Inventors: Brown, Stephen, MacNaughtan, Malcolm, Drane, Christopher Ridgway, Scott, Craig Andrew
• Granted Patent: US 8,700,069 B2
• Time in Patent Office: Days
• US Class Current: 455/456.600
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/02525 Gathering the radio frequency fingerprints
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method and system for calculating the location of a mobile radio terminal in a radio communications network. The method provides for the collection of measurements of radio signal parameters at the mobile radio terminal which are then processed and transmitted to a network processor for calculating the location of the mobile radio terminal. The collected measurements may be filtered and subsets of the measurements may also be selected according to their suitability for particular applications.

Claims

1. A method of obtaining location data for use in a location calculation, the method comprising:

obtaining at least one measurement of a plurality of radio signal parameters at a first time;

obtaining at least one subsequent measurement of a plurality of subsequent radio signal parameters at a second time;

applying the at least one measurement and the at least one subsequent measurement to a filter to obtain the location data.

2. A method as claimed in claim 1 wherein the at least one measurement and the at least one subsequent measurement are obtained by a mobile radio communications terminal.

3. A method as claimed in claim 2 wherein the location data is stored for subsequent transmission to a processor for use in the location calculator.

4. A method as claimed in claim 3 wherein the location data is transmitted to the processor intermittently.

5. A method as claimed in claim 3 wherein the location data is transmitted to the processor at regular time intervals.

6. A method as claimed in claim 3 wherein the location data is transmitted to the processor upon request.

7. A method as claimed in claim 5 wherein the location data is transmitted to the processor upon request of the processor.

8. A method as claimed in claim 5 wherein the location data is transmitted to the processor upon request of the processor.

9. A method as claimed in claim 5 wherein the location data is transmitted to the processor upon request of a user of the mobile radio terminal.

10. A method as claimed in claim 9 wherein the location data is transmitted upon a change in location of the mobile radio terminal.

11. A method as claimed in claim 2 wherein further measurements of a further plurality of radio signal parameters are obtained, until a buffer of the mobile radio terminal is full.

12. A method according to claim 1 further comprising selecting a subset of the obtained at least one measurement and at least one subsequent measurement for filtering according to a specific application.

13. A method according to claim 1 further comprising storing a plurality of location data.

14. A method according to claim 13 further comprising selecting a subset of the location data according to a specific application.

15. A method according to claim 1 wherein the location data is transmitted in a variable length data message.

16. A method as claimed in claim 15 wherein the length of the data message is determined according to a specific application.

17. A method as claimed in claim 1 further comprising periodically removing one or more of the at least one measurement and the at least one subsequent measurement.

18. A method as claimed in claim 17 wherein the step of periodically removing the one or more of the at least one measurement and the one or more of the at least one subsequent measurement is done according to their relevance.

19. A method as claimed in claim 1 further selecting a subset of obtained location data for transmission, according to the relevance of the subset.

20. A method as claimed in claim 1 further comprising selecting a subset of obtained location data for transmission, according to the size of the transmission data message.

21. A method as claimed in claim 1 wherein the plurality of radio signal parameters include at least one unambiguous radio signal parameter and at least one ambiguous radio signal parameter.

22. A method according to claim 21 wherein the ambiguous radio signal parameter is resolved before being applied to the filter.

23. A method according to claim 22 wherein the step of resolving the ambiguous radio signal parameter is deferred for as long as possible prior to being applied to the filter.

24. A method according to claim 2 further comprising sending assistance information to the mobile radio terminal.

25. A method as claimed in claim 24 wherein a location estimation is calculated at the mobile radio terminal using the assistance information.

30. A system for performing the steps of claim 1.

31. A mobile radio terminal for performing the steps of claim 1.

32. The method of claim 1 further comprising periodically removing one or more of the at least one measurement or the at least one subsequent measurement.

26. A method for calculating a location of a mobile radio terminal in a radio communications network the method comprising:

receiving location data generated by,

obtaining at least one measurement of a plurality of radio signal parameters at a first time;

obtaining at least one subsequent measurement of a plurality of subsequent radio signal parameters at a second time;

applying the at least one measurement and the at least one subsequent measurement to a filter to obtain the location data;

said location data relating to the location of the mobile radio terminal; and

processing the location data to calculate the location of the mobile radio terminal.

27. A method as claimed in claim 26 wherein the step of processing comprises minimising a cost function.

28. A method as claimed in claim 27 wherein the cost function is given by:

C(x)=C_r(x)+C_t(x)+C_u(x)

where;

C_r is the cost associated with signal strength observations;

C_t is the cost associated with timing advance observations; and

C_u is the cost associated with unreported cell observations.

29. A method as claimed in claim 28 wherein C_r, C_t and C_u are calculated as follows:

$C_r<br><br>\left(x\right)=\underset{i=1}{\overset{N_r}{\sum <br><br>}}<br><br><br><br>\frac{{\left(r_i-p_r<br><br>\left(k_{r_i},x\right)\right)}^2}{2<br><br><br><br>{\mathrm{\sigma <br><br>}}_r^2};<br><br>$ $C_t<br><br>\left(x\right)=\underset{i=1}{\overset{N_r}{\sum <br><br>}}<br><br><br><br>\frac{{\left(t_i-p_t<br><br>\left(k_{t_i},x\right)\right)}^2}{2<br><br><br><br>{\mathrm{\sigma <br><br>}}_t^2};<br><br>\mathrm{and}$ $C_u<br><br>\left(x\right)=-\underset{i=1}{\overset{N_u}{\sum <br><br>}}<br><br><br><br>\log <br><br>\left[\frac{1}{2}<br><br>\left(1+\mathrm{erf}<br><br>\left(\frac{r_u-p_u<br><br>\left(k_{u_i},x\right)}{\sqrt{2}<br><br>{\mathrm{\sigma <br><br>}}_r}\right)\right)\right]$