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 20100279705A1
• Filed: 09/25/2008
• Published: 11/04/2010
• Est. Priority Date: 03/22/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tien, Ann Yun-En, Row, Chang S., Rowitch, Douglas Neal, Khushu, Sanjeev
• Granted Patent: US 8,299,960 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• 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. In a subscriber station in a wireless communication system, a method of updating a data structure having a plurality of entries associating possible values of at least one parameter obtainable from at least one overhead message communicated by a wireless communications system, with corresponding positions, the method comprising:

receiving an overhead message from the wireless communications system indicating that an update condition is present; and

updating the data structure responsive to information from a central server accessible by the subscriber station.

2. The method of claim 1, wherein the information is an allocation of possible System Identifier (SID) values.

3. The method of claim 1, wherein the information is an allocation of ranges to countries.

4. The method of claim 1, wherein the information is an allocation of geographical regions.

5. The method of claim 1, wherein the information includes an identification of known conflicts in the use of System Identifier (SID) values.

6. A method of updating a data structure in memory of a subscriber station in a wireless communication system, the data structure having a plurality of entries, each entry comprising a stored position associated with a value of a parameter obtainable from overhead messages, the method comprising:

operating in an unassisted position location mode;

initializing an entry in the data structure; and

obtaining a value of a parameter from an overhead message;

determining the entry exists in the data structure based on the obtained value;

accessing the entry to obtain a seed position; and

determining, using the seed position, a position from signals from a satellite position system.

7. The method of claim 6, wherein the act of initialing comprises:

determining an initial position from signals from the satellite position system;

obtaining the value of the parameter from an initial overhead message; and

storing to the entry, based on the obtained value, the determined initial position as the stored position.

8. The method of claim 6, wherein the act of initialing comprises obtaining a SID country table containing entries from a server containing IFAST data, wherein the IFAST data comprises, for each of a plurality of the entries, a centroid location and a coverage radius associated with a country.

9. The method of claim 6, wherein the act of initialing comprises setting an initial seed position based on the subscriber station'"'"'s national registration, the act of setting comprising:

determining the subscriber station'"'"'s national registration;

determining the initial seed position based on the subscriber station'"'"'s national registration;

determining, using the initial seed position, an initial position from signals from the satellite position system; and

storing to the entry the determined initial position as the stored position.

10. The method of claim 6, wherein the act of initialing comprises assigning a hash value to each of the plurality of the entries to define a priority.

11. The method of claim 6, wherein each of the plurality of entries further comprises an uncertainty of the stored position.

12. The method of claim 11, wherein the uncertainty comprises a parameter from the overhead message, wherein the parameter is a maximum antenna range (MAR).

13. The method of claim 6, wherein each of the plurality of entries further comprises an uncertainty of the stored position, the method further comprising updating the entry with a position of lower uncertainty, the act of updating comprising:

determining an uncertainty value of the determined position;

determining the uncertainty value of the determined position is less than the uncertainty of the stored position; and

replacing, in the entry, the stored position with the determined position and the uncertainty with the uncertainty value of the determined position.

14. The method of claim 6, further comprising:

determining a SID conflict exists; and

updating the data structure to reflect existence of the SID conflict.

15. The method of claim 6, wherein the act of accessing the entry to obtain the seed position comprises:

determining a conflict exist between two entries in the lookup table having a common value equal to the obtained value; and

selecting a stored position, from one of the two entries based on a flag indicating relative probability.

16. The method of claim 6, wherein the parameter comprises a mobile country code (MCC).

17. The method of claim 16, wherein the parameter further comprises a mobile network code (MNC).

18. The method of claim 16, wherein the parameter further comprises a location area code (LAC).

19. The method of claim 16, wherein the parameter further comprises a routing area code (RAC).

20. The method of claim 16, wherein the parameter further comprises a cell identity (CI).

21. The method of claim 6, wherein the parameter comprises at least two of a mobile country code (MCC), a mobile network code (MNC), a location area code (LAC), a routing area code (RAC), a cell identity (CI), and a time zone.

22. The method of claim 6, wherein the wireless communication system comprises a UMTS wireless communication system.

23. The method of claim 6, wherein the satellite position system comprises a GPS system.

24. A subscriber station for updating a data structure in memory, the data structure having a plurality of entries, each entry comprising a stored position associated with a value of a parameter obtainable from overhead messages, the subscriber station comprising:

means for operating in an unassisted position location mode;

means for initializing an entry in the data structure; and

means for obtaining a value of a parameter from an overhead message;

means for determining the entry exists in the data structure based on the obtained value;

means for accessing the entry to obtain a seed position; and

means for determining, using the seed position, a position from signals from a satellite position system.

25. The subscriber station of claim 24, wherein the means for accessing the entry to obtain the seed position comprises:

means for determining a conflict exist between two entries in the lookup table having a common value equal to the obtained value; and

means for selecting a stored position, from one of the two entries based on a flag indicating relative probability.

26. A subscriber station for updating a data structure in memory, the data structure having a plurality of entries, each entry comprising a stored position associated with a value of a parameter obtainable from overhead messages, the subscriber station comprising:

a processor; and

memory, coupled to the processor, comprising

code to operate in an unassisted position location mode;

code to initialize an entry in the data structure; and

code to obtain a value of a parameter from an overhead message;

code to determine the entry exists in the data structure based on the obtained value;

code to access the entry to obtain a seed position; and

code to determine, using the seed position, a position from signals from a satellite position system.

27. A computer-readable product comprising a computer-readable medium comprising:

code for causing at least one computer to operate in an unassisted position location mode;

code for causing at least one computer to initialize an entry in the data structure; and

code for causing at least one computer to obtain a value of a parameter from an overhead message;

code for causing at least one computer to determine the entry exists in the data structure based on the obtained value;

code for causing at least one computer to access the entry to obtain a seed position; and

code for causing at least one computer to determine, using the seed position, a position from signals from a satellite position system.