Methods and systems for deriving seed position of a subscriber station in support of unassisted GPS-type position determination in a wireless communication system

• US 9,194,957 B2
• Filed: 09/13/2012
• Issued: 11/24/2015
• Est. Priority Date: 03/22/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rowitch, Douglas Neal, Row, Chang S., Tien, Ann Yun-En, Khushu, Sanjeev
• Primary Examiner(s): Issing, Gregory C
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US13/614,993
• Publication Number:
  US 20130002483A1
• Time in Patent Office: 1,167 Days
• Field of Search: 342/357.43, 342/357.64, 455/456.1
• US Class Current: 1/1
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

In a method and system for deriving a seed position of a subscriber station in a wireless communications system in supporting unassisted GPS-type position determination is provided, the subscriber station receives overhead messages from the wireless communications system, and derives the seed position from the parameter values. The subscriber station may use a data structure in its memory and map possible parameter values to corresponding positions that may serve as the seed positions.

Claims

1. A method comprising:

obtaining, by a subscriber station, a first value of a parameter from a first received overhead message;

determining by the subscriber station a satellite-based fix position for the subscriber station from a set of signals from a satellite position determination system;

storing by the subscriber station the first value and the determined satellite-based fix position as an entry in a data structure stored in memory of the subscriber station, the data structure including a plurality of entries comprising corresponding stored satellite-based fix positions associated with corresponding values of at least one parameter obtainable from overhead messages; and

using the stored determined satellite-based fix position as a seed position to facilitate searching for one or more satellite transmissions of the satellite position determination system, in order to derive a GPS-type position fix, when a second value is obtained, from a second received overhead message, that matches the stored first value;

wherein the stored determined satellite-based fix position is retrieved from the entry of the data structure in response to a determination that parameter values of the second received overhead message do not indicate a position of a base station or a base station sector in communication with the subscriber station, wherein the retrieved determined satellite-based fix position is used as the seed position in further response to a further determination that a position uncertainty, derived at least in part based on age of the stored determined satellite-based fix position, associated with the stored determined satellite-based fix position is smaller than an other, aged-based, position uncertainty associated with a most-recent satellite-based position estimate obtained for the subscriber station, and wherein the most-recent satellite-based position estimate is used as the seed position when the position uncertainty, associated with the stored determined satellite-based fix position, is larger than the other position uncertainty associated with the most-recent satellite-based position estimate for the subscriber station.

2. The method of claim 1, further comprising:

operating in an unassisted position location mode wherein significant acquisition or calculation assistance is not requested from dedicated position determination servers.

3. The method of claim 1, further comprising:

assigning a hash value to each of the plurality of entries to define a priority.

4. The method of claim 1, further comprising:

updating at least one entry in the data structure with a corresponding at least one new determined position associated with a corresponding at least one new uncertainty lower than a corresponding at least one stored uncertainty associated with a corresponding at least one stored position, wherein updating the at least one entry comprises;

determining the corresponding at least one new uncertainty associated with the corresponding at least one new determined position;

determining that the corresponding at least one new uncertainty associated with the corresponding at least one new determined position is lower than the corresponding at least one stored uncertainty associated with the corresponding at least one stored position; and

replacing, in the at least one entry, the at least one stored position with the corresponding at least one new determined position, and the corresponding at least one stored uncertainty of the corresponding at least one stored position with the corresponding at least one new uncertainty associated with the corresponding at least one new determined position.

5. The method of claim 1, further comprising:

receiving values of one or more parameters from a third received overhead message;

setting the seed position to a stored position from one of the plurality of entries of the data structure associated with corresponding stored values matching the values of the one or more parameters from the third received overhead message;

determining, based on the set seed position, a third position of the subscriber station from signals from the satellite position determination system;

in response to a determination, based on the determined third position and the stored position from the one of the plurality of entries, that an update condition exists, updating the one of the plurality of entries with the determined third position.

6. The method of claim 5, wherein the determination that the update condition exists comprises a determination that the determined third position is outside of a coverage area associated with the stored position from the one of the plurality of entries.

7. The method of claim 1, wherein the first value of the first received overhead message and the second value of the second received overhead message comprise:

a mobile country code (MCC), a system identifier (SID), a mobile network code (MNC), a location area code (LAC), a routing area code (RAC), a cell identity (CI), or a time zone, or combinations thereof.

8. The method of claim 1, wherein the satellite position determination system comprises a GPS system.

9. The method of claim 1, further comprising:

receiving at least one value of at least one parameter from a further received overhead message; and

accessing one of the plurality of entries of the data structure corresponding to the received at least one value of the at least one parameter to obtain the seed position corresponding to a stored position estimate of the subscriber station associated with a stored position uncertainty smaller than another position uncertainty associated with another position estimate of the subscriber station stored in another of the plurality of entries of the data structure corresponding to the received at least one value of the at least one parameter.

10. The method of claim 1, wherein using the stored determined satellite-based fix position comprises:

selecting, based on the position uncertainty and the other position uncertainty, one of the stored determined satellite-based-fix position or the other position estimate; and

setting the seed position to the selected one of the stored determined satellite-based-fix position of the subscriber station or the most-recent satellite-based position estimate for the subscriber station.

11. The method of claim 1, further comprising:

dynamically ordering the plurality of entries of the data structure according to countries visited by the subscriber station during a previous time frame.

12. The method of claim 1, wherein when the parameter values of the second received overhead message indicate the position of the base station or the base station sector, the position of the base station or the base station sector is associated with a base station uncertainty equal to a maximum antenna range (MAR) associated with the base station from which the second overhead message was received.

13. The method of claim 1, further comprising:

updating one or more entries of the data structure in response to data in the second received overhead message indicating that information on a server maintaining system identifier (SID) information has changed or that an SID conflict, in which a particular SID is used by more than one country, exists, wherein the SID information maintained by the server includes a centroid location and a coverage radius associated with each SID.

14. A subscriber station comprising:

one or more processors;

memory comprising computer instructions that, when executed on the one or more processors, cause operations comprising;

obtaining a first value of a parameter from a first received overhead message;

determining a satellite-based fix position from a set of signals from a satellite position determination system;

storing the first value and the determined satellite-based fix position as an entry in a data structure stored in the memory of the subscriber station, the data structure including a plurality of entries comprising corresponding stored satellite-based fix positions associated with corresponding values of at least one parameter obtainable from overhead messages; and

using the stored determined satellite-based fix position as a seed position to facilitate searching for one or more satellite transmissions of the satellite position determination system, in order to derive a GPS-type position fix, when a second value is obtained, from a second received overhead message, that matches the stored first value;

wherein the stored determined satellite-based fix position being is retrieved from the entry of the data structure in response to a determination that parameter values of the second received overhead message do not indicate a position of a base station or a base station sector in communication with the subscriber station, wherein the retrieved determined satellite-based fix position is used as the seed position in further response to a further determination that a position uncertainty, derived at least in part based on age of the stored determined satellite-based fix position, associated with the stored determined satellite-based fix position is smaller than an other, aged-based, position uncertainty associated with a most-recent satellite-based position estimate obtained for the subscriber station, and wherein the most-recent satellite-based position estimate is used as the seed position when the position uncertainty, associated with the stored determined satellite-based fix position, is larger than the other position uncertainty associated with the most-recent satellite-based position estimate for the subscriber station.

15. The subscriber station of claim 14, wherein the memory further comprises computer instructions to cause further operations comprising:

operating in an unassisted position location mode wherein significant acquisition or calculation assistance is not requested from dedicated position determination servers.

16. The subscriber station of claim 14, wherein the memory further comprises computer instructions to cause further operations comprising:

assigning a hash value to each of the plurality of entries to define a priority.

17. The subscriber station of claim 14, wherein the memory further comprises computer instructions to cause further operations comprising:

updating at least one entry in the data structure with a corresponding at least one new determined position associated with a corresponding at least one new uncertainty lower than a corresponding at least one stored uncertainty associated with a corresponding at least one stored position, wherein updating the at least one entry comprises;

determining the corresponding at least one new uncertainty associated with the corresponding at least one new determined position;

determining that the corresponding at least one new uncertainty associated with the corresponding at least one new determined position is lower than the corresponding at least one stored uncertainty associated with the corresponding at least one stored position; and

replacing, in the at least one entry, the at least one stored position with the corresponding at least one new determined position, and the corresponding at least one stored uncertainty of the corresponding at least one stored position with the corresponding at least one new uncertainty associated with the corresponding at least one new determined position.

18. The subscriber station of claim 14, wherein the memory further comprises computer instructions to cause further operations comprising:

receiving values of one or more parameters from a third received overhead message;

setting the seed position to a stored position from one of the plurality of entries of the data structure associated with corresponding stored values matching the values of the one or more parameters from the third received overhead message;

determining, based on the set seed position, a third position of the subscriber station from signals from the satellite position determination system;

in response to a determination, based on the determined third position and the stored position from the one of the plurality of entries, that an update condition exists, updating the one of the plurality of entries with the determined third position.

19. The subscriber station of claim 18, wherein the determination that the update condition exists comprises a determination that the determined third position is outside of a coverage area associated with the stored position from the one of the plurality of entries.

20. The subscriber station of claim 14, wherein the first value of the first received overhead message and the second value of the second received overhead message comprise:

a mobile country code (MCC), a system identifier (SID), a mobile network code (MNC), a location area code (LAC), a routing area code (RAC), a cell identity (CI), or a time zone, or combinations thereof.

21. The subscriber station of claim 14, wherein the satellite position determination system comprises a GPS system.

22. A non-transitory processor readable media programmed with a set of instructions executable on a processor that, when executed, cause operations comprising:

obtaining a first value of a parameter from a first received overhead message;

determining a satellite-based fix position from a set of signals from a satellite position determination system;

storing the first value and the determined satellite-based fix position as an entry in a data structure stored in memory of a subscriber station, the data structure including a plurality of entries comprising corresponding stored satellite-based fix positions associated with corresponding values of at least one parameter obtainable from overhead messages; and

using the stored determined satellite-based fix position as a seed position to facilitate searching for one or more satellite transmissions of the satellite position determination system, in order to derive a GPS-type position fix, when a second value is obtained, from a second received overhead message, that matches the stored first value;

wherein the stored determined satellite-based fix position is retrieved from the entry of the data structure in response to a determination that parameter values of the second received overhead message do not indicate a position of a base station or a base station sector in communication with the subscriber station, wherein the retrieved determined satellite-based fix position is used as the seed position in further response to a further determination that a position uncertainty, derived at least in part based on age of the stored determined satellite-based fix position, associated with the stored determined satellite-based fix position is smaller than an other, aged-based, position uncertainty associated with a most-recent satellite-based position estimate obtained for the subscriber station, and wherein the most-recent satellite-based position estimate is used as the seed position when the position uncertainty, associated with the stored determined satellite-based fix position, is larger than the other position uncertainty associated with the most-recent satellite-based position estimate for the subscriber station.

23. The processor readable media of claim 22, further comprising computer instructions to cause further operations comprising:

operating in an unassisted position location mode wherein significant acquisition or calculation assistance is not requested from dedicated position determination servers.

24. The processor readable media of claim 22, further comprising computer instructions to cause further operations comprising:

assigning a hash value to each of the plurality of entries to define a priority.

25. The processor readable media of claim 22, further comprising computer instructions to cause further operations comprising:

updating at least one entry in the data structure with a corresponding at least one new determined position associated with a corresponding at least one new uncertainty lower than a corresponding at least one stored uncertainty associated with a corresponding at least one stored position, wherein updating the at least one entry comprises;

determining the corresponding at least one new uncertainty associated with the corresponding at least one new determined position;

determining that the corresponding at least one new uncertainty associated with the corresponding at least one new determined position is lower than the corresponding at least one stored uncertainty associated with the corresponding at least one stored position; and

replacing, in the at least one entry, the at least one stored position with the corresponding at least one new determined position, and the corresponding at least one stored uncertainty of the corresponding at least one stored position with the corresponding at least one new uncertainty associated with the corresponding at least one new determined position.

26. The processor readable media of claim 22, further comprising computer instructions to cause further operations comprising:

receiving values of one or more parameters from a third received overhead message;

setting the seed position to a stored position from one of the plurality of entries of the data structure associated with corresponding stored values matching the values of the one or more parameters from the third received overhead message;

determining, based on the set seed position, a third position of the subscriber station from signals from the satellite position determination system;

in response to a determination, based on the determined third position and the stored position from the one of the plurality of entries, that an update condition exists, updating the one of the plurality of entries with the determined third position.

27. The processor readable media of claim 26, wherein the determination that the update condition exists comprises a determination that the determined third position is outside of a coverage area associated with the stored position from the one of the plurality of entries.

28. The processor readable media of claim 22, wherein the first value of the first received overhead message and the second value of the second received overhead message comprise:

a mobile country code (MCC), a system identifier (SID), a mobile network code (MNC), a location area code (LAC), a routing area code (RAC), a cell identity (CI), or a time zone, or combinations thereof.

29. The processor readable media of claim 22, wherein the satellite position determination system comprises a GPS system.