Methods and apparatus for mobile station location estimation

• US 8,369,870 B2
• Filed: 12/22/2011
• Issued: 02/05/2013
• Est. Priority Date: 04/03/2001
• Status: Expired due to Fees

• Current Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Original Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Inventors: MacDonald, Alan Denis, Sather, Marc W., Snapp, John Lawrence
• Primary Examiner(s): Agosta, Steve D
• Application Number:
  US13/334,341
• Publication Number:
  US 20120094692A1
• Time in Patent Office: 411 Days
• Field of Search: 455/404.2, 455456-457, 370/310.2, 370/328
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/0252 Radio frequency fingerprinting
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04W 4/026 using orientation information, e.g. compass
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• 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 88/14 Backbone network devices

Abstract

Methods and apparatus for estimating mobile station location include receiving reported signal strengths or other attachment indicator values from a mobile station. The reported signal strengths are compared with characteristic received signal strength values in a coverage area of a mobile network. A mobile switching center determines if a local function is requested and initiates a location estimation process by a mobile location module (MLM). The MLM receives the reported signal strength contours associated with the attachment points. Based on a comparison of the reported attachment indicator values with characteristic values, the MLM provides a mobile location estimate.

Claims

1. A method, for determining a location of a mobile communication device, comprising:

obtaining, by a system having a processor, instantaneous location coordinates associated with the mobile communication device;

calculating, by the system, average coordinates based upon the instantaneous location coordinates;

calculating, by the system, an error value between the instantaneous location coordinates and the average coordinates;

determining, by the system, whether the error value is acceptable based upon a comparison of the error value to a pre-defined threshold; and

determining, by the system, in response to determining that the error value is acceptable, the location of the mobile communication device based at least in part on the instantaneous location coordinates, wherein determining the location of the mobile communication device using the instantaneous location coordinates further comprises;

determining a strength value of a signal received by the mobile communication device from a base station of each of a serving cell and two adjacent cells, and

determining, based on the strength value of each signal, distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells, wherein determining the distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells comprises determining the distances using the strength value of each signal, known constants corresponding to the base stations, and a first slope value, a second slope value, and a third slop value associated with respective propagation paths between the mobile communication device and each of the base stations.

2. The method of claim 1, further comprising:

updating, by the system in response to determining that the error value is acceptable, recent reliable coordinates with the instantaneous location coordinates; and

determining, by the system, in response to determining that the error value is not acceptable based upon the comparison of the error value to the threshold, the location of the mobile communication device using the recent reliable coordinates associated with the mobile communication device.

3. The method of claim 1, wherein obtaining the instantaneous location coordinates associated with the mobile communication device comprises:

receiving global positioning system information from the mobile communication device; and

deriving, from the global positioning system information, the instantaneous location coordinates.

4. The method of claim 1, wherein determining the location of the mobile communication device using the instantaneous location coordinates further comprises defining a first zone and a second zone, the first zone being a coverage area of the serving cell for the mobile communication device, and the second zone being defined using one of the distances between the mobile communication device and the base stations of the serving cell and the two adjacent cells.

5. The method of claim 4, wherein determining the location of the mobile communication device using the instantaneous location coordinates further comprises:

determining, if the instantaneous location coordinates are outside of the first zone, second-zone location coordinates of the second zone to be the location of the mobile communication device;

determining, if the instantaneous location coordinates are within the first zone and outside of the second zone, the instantaneous location coordinates to be the location of the mobile communication device; and

determining, if the instantaneous location coordinates are within the second zone, the instantaneous location coordinates to be the location of the mobile communication device.

6. The method of claim 1, further comprising determining a first angle formed by:

(i) a first line connecting the first base station and the mobile communication device; and

(ii) a second line connecting the second base station and the mobile communication device;

wherein the first angle is determined using;

(a) a first location of a first base station of a first cell of the three cells;

(b) a second location of a second base station of a second cell of the three cells;

(c) a first distance, separating the mobile communication device and the first base station, of the distances; and

(d) a second distance, separating the mobile communication device and the second base station, of the base stations.

7. The method of claim 6, further comprising:

determining a second angle formed by;

(i) a third line connecting the third base station and the mobile communication device, and

(ii) the second line; and

determining a third angle formed by;

(iii) the third line; and

(iv) the first line;

wherein the second angle is determined using;

(a) a third location of a third base station of a third cell of the serving cell and the two adjacent cells;

(b) the second location of the second base station;

(c) a third distance, separating the mobile communication device and the third base station; and

(d) the second distance; and

wherein the third angle is determined using;

(e) the third location;

(f) the first location;

(g) the third distance; and

(h) the first distance.

8. The method of claim 1, wherein the error value is acceptable if the error value is less than the threshold.

9. The method of claim 1, wherein determining the distances between the mobile communication device and the base stations further comprises performing acts including (a) varying the first slope, the second slope, and the third slope, thereby forming a varied first slope, a varied second slope, and a varied third slope, respectively, and (b) re-determining the distances with the varied slopes to form recalculated distances.

10. The method of claim 1, wherein determining the location of the mobile communication device using the recent reliable coordinates further comprises:

defining a first zone and a second zone, the first zone being a coverage area of the serving cell for the mobile communication device, and the second zone being defined using one of the distances between the mobile communication device and the base stations of the serving cell and the two adjacent cells;

determining, if the instantaneous location coordinates are outside of the first zone, second-zone location coordinates of the second zone to be the location of the mobile communication device;

determining, if the instantaneous location coordinates are within the first zone and outside of the second zone, the instantaneous location coordinates to be the location of the mobile communication device; and

determining, if the instantaneous location coordinates are within the second zone, the instantaneous location coordinates to be the location of the mobile communication device.

11. The method of claim 1, further comprising:

determining a first angle formed by;

(i) a first line connecting the first base station and the mobile communication device; and

(ii) a second line connecting the second base station and the mobile communication device;

determining a second angle formed by;

(iii) a third line connecting the third base station and the mobile communication device; and

(iv) the second line; and

determining a third angle formed by;

(vi) the third line; and

(vii) the first line;

wherein the first angle is determined using;

(a) a first location of a first base station of a first cell of the serving cell and the two adjacent cells;

(b) a second location of a second base station a second cell of the serving cell and the two adjacent cells;

(c) a first distance, separating the mobile communication device and the first base station, of the distances; and

(d) a second distance, separating the mobile communication device and the second base station, of the base stations;

wherein the second angle is determined using;

(e) a third location of a third base station of a third cell of the serving cell and the two adjacent cells;

(f) the second location of the second base station;

(g) a third distance, separating the mobile communication device and the third base station; and

(h) the second distance; and

wherein the third angle is determined using;

(j) the third location;

(k) the first location;

(l) the third distance; and

(m) the first distance.

12. The method of claim 1, wherein determining the distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells comprises:

determining the distances using the strength value of each signal, known constants corresponding to the base stations, and a first slope value, a second slope value, and a third slop value associated with respective propagation paths between the mobile communication device and each of the base stations; and

performing acts including (a) varying the first slope, the second slope, and the third slope, thereby forming a varied first slope, a varied second slope, and a varied third slope and (b) re-determining the distances with the varied slopes to form recalculated distances.

13. A location system, for determining a location of a mobile communication device, comprising:

a processor; and

a computer-readable storage device having computer-executable instructions that, when executed by the processor, cause the processor to perform operations comprising;

obtaining instantaneous location coordinates associated with the mobile communication device;

calculating average coordinates based upon the instantaneous location coordinates;

calculating an error value between the instantaneous location coordinates and the average coordinates;

determining whether the error value is acceptable based upon a comparison of the error value to a pre-defined threshold; and

determining, in response to determining that the error value is acceptable, the location of the mobile communication device based at least in part on the instantaneous location coordinates, wherein determining the location of the mobile communication device based on at least in part the instantaneous location coordinates further comprises;

determining a strength value of a signals received by the mobile communication device from a base station of each of a serving cell and two adjacent cells, and

determining, based on the strength value of each signal, distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells, wherein determining the distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells comprises determining the distances using the strength value of each signal, known constants corresponding to the base stations, and a first slope value, a second slope value, and a third slop value associated with respective propagation paths between the mobile communication device and each of the base stations.

14. The location system of claim 13, wherein the computer-executable instructions, when executed by the processor, further cause the processor to perform the operations further comprising:

updating, in response to determining that the error value is acceptable, recent reliable coordinates with the instantaneous location coordinates; and

determining, if the error value is not acceptable based upon the comparison of the error value to the threshold, the location of the mobile communication device using the recent reliable coordinates associated with the mobile communication device.

15. A tangible non-transitory computer-readable storage device comprising instructions that, when executed by a processor, cause the processor to perform operations, for determining a location of a mobile communication device, comprising:

obtaining instantaneous location coordinates associated with the mobile communication device;

calculating average coordinates based upon the instantaneous location coordinates;

calculating an error value between the instantaneous location coordinates and the average coordinates;

determining whether the error value is acceptable based upon a comparison of the error value to a pre-defined threshold; and

determining, in response to determining that the error value is acceptable, the location of the mobile communication device based at least in part on the instantaneous location coordinates, wherein determining the location of the mobile communication device using the instantaneous location coordinates further comprises;

determining a strength value of a signal received by the mobile communication device from a base station of each of a serving cell and two adjacent cells, and

determining, based on the strength value of each signal, distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells, wherein determining the distances between the mobile communication device and the base station of each of the serving cell and the two adjacent cells comprises determining the distances using the strength value of each signal, known constants corresponding to the base stations, and a first slope value, a second slope value, and a third slop value associated with respective propagation paths between the mobile communication device and each of the base stations.

16. The tangible non-transitory computer-readable storage device of claim 15, wherein the instructions, when executed by the processor, cause the processor to perform the operations further comprising:

updating, in response to determining that the error value is acceptable, recent reliable coordinates with the instantaneous location coordinates; and

determining, if the error value is not less than the threshold, the location of the mobile communication device using the recent reliable coordinates associated with the mobile communication device.