Reduced acquisition time for GPS cold and warm starts

• US 20020142783A1
• Filed: 08/29/2001
• Published: 10/03/2002
• Est. Priority Date: 03/28/2001
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Yoldi, Cesar Sanchez, Lebena, Alberto Martinez
• Application Number:
  US09/945,451
• Publication Number:
  US 20020142783A1
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view

Abstract

A system and method for reducing acquisition times in a GPS receiver enables determination at start-up of the GPS receiver of the occurrence of ephemeris data at the GPS receiver being older than approximately two hours or a change in a mobile country code and mobile network code of a cellular device associated with the GPS receiver. Data is obtained for the GPS receiver from a reference server responsive to occurrence of one of these conditions and the position of the GPS receiver is determined at a reduced acquisition time using the obtained data.

Claims

1. A method for reducing acquisition times in a GPS receiver associated with a cellular device, comprising the steps of:

determining at startup of the GPS receiver occurrence of at least one of the following conditions;

ephemeris data at the GPS receiver older than a predetermined period of time and a change in a mobile country code and mobile network code of the cellular device associated with of the GPS receiver;

obtaining data for the GPS receiver from a reference server responsive to occurrence of one of the conditions; and

calculating a current position of the GPS receiver at a reduced acquisition time using at least the obtained data.

2. The method of claim 1, wherein the step of obtaining further comprises the step of obtaining ephemeris and almanac data from the reference server via the internet.

3. The method of claim 1, wherein the step of obtaining further comprises the step of obtaining ephemeris and almanac data using a WAP protocol.

4. The method of claim 1, wherein the step of determining further comprises the step of comparing a present mobile country code and mobile network code with a previous mobile country code and mobile network code to determine if a change has occurred in the mobile country code and mobile network code of the GPS receiver.

5. The method of claim 1, further comprising the step of obtaining an approximate position of the GPS receiver based upon a present mobile country code and mobile network code associated with the GPS receiver.

6. The method of claim 5, wherein the approximate position comprises a longitude and latitude.

7. The method of claim 5, wherein the step of obtaining the approximate position further comprises the steps of:

comparing the present mobile country code and mobile network code with entries in a table of mobile country codes and mobile network codes having position data associated therewith to locate a corresponding mobile country code and mobile network code; and

selecting the position data associated with a corresponding mobile country code and mobile network code as the approximate position of the GPS receiver.

8. The method of claim 1, wherein the step of calculating a current position further comprises the step of determining a current position using the approximate position of the GPS receiver.

9. The method of claim 1, further comprising the step of obtaining a present time associated with the GPS receiver based upon the mobile country code and the mobile network code associated with the GPS receiver.

10. The method of claim 9, wherein the step of obtaining the present time further comprises the steps of:

accessing a table of mobile country codes and mobile network codes having position data associated therewith;

comparing the present mobile country code and mobile network code with entries in the table to locate a corresponding mobile country code and mobile network code;

determining if the position data has changed by a selected amount between the present mobile country code and mobile network code and the corresponding mobile network code and mobile country code; and

if the position data has not changed by the selected amount, determining a time for a previously used time zone.

11. The method of claim 1, wherein the predetermined period of time corresponds to approximately two hours.

12. The method of claim 1, wherein the step of obtaining further comprises the step of obtaining ephemeris and almanac data using a Mobile Internet Protocol.

14. The method of claim 13, further comprising the step of obtaining ephemeris and almanac data from a reference server via the internet.

15. The method of claim 14, wherein the step of obtaining further comprises the step of obtaining ephemeris and almanac data using a Mobile Internet Protocol.

16. The method of claim 14, wherein the step of obtaining further comprises the step of obtaining ephemeris and almanac data using a WAP protocol.

17. The method of claim 13, wherein the step of determining further comprises the step of comparing a present mobile country code and mobile network code with a previous mobile country code and mobile network code to determine a change has occurred in a mobile country code or mobile network code of the GPS receiver.

18. The method of claim 13, further comprising the step of obtaining a present time associated with the GPS receiver based upon the mobile country code and the mobile network code associated with the GPS receiver.

19. The method of claim 18, wherein the step of obtaining a present time further comprises the steps of:

accessing a table of mobile country codes and mobile network codes having position data associated therewith;

comparing the present mobile country code and mobile network code with entries in the table to locate a corresponding mobile country code and mobile network code; and

determining if the position data has changed by a selected amount determining if the position data has changed by a selected amount between the present mobile country code and mobile network code and the corresponding mobile network code and mobile country code; and

if the position data has not changed by the selected amount, determining a time for a previously used time zone.

13. A method for reducing acquisition times in a GPS receiver associated with a cellular device, comprising the steps of:

determining at startup of the GPS receiver occurrence of a change in a mobile country code or mobile network code of the cellular device associated with the GPS receiver;

accessing a table of mobile country codes and mobile network codes having position data associated therewith;

comparing the present mobile country code and mobile network code with entries in the table to locate a corresponding mobile country code and mobile network code;

selecting the position data associated with a corresponding mobile country code and mobile network code as an approximate position of the GPS receiver; and

calculating a current position using the approximate position of the GPS receiver at a reduced acquisition time using at least the position data.

20. A wireless communications device, comprising:

a wireless transceiver for establishing a connection with the Internet;

a GPS receiver for determining a position of the wireless communications device;

a table including a plurality of mobile country code and mobile network code pairs, each pair of mobile country codes and mobile network codes having a longitude and latitude associated therewith;

a controller configured to;

determine at startup of the GPS receiver occurrence of at least one of the following conditions;

ephemeris data at the GPS receiver older than a predetermined period of time and a change in a mobile country code and mobile network code of the wireless communications device;

obtain an approximate position of the GPS receiver from the table based upon a present mobile country code and mobile network code associated with the GPS receiver.

obtain data for the GPS receiver from a reference server on the Internet using the wireless transceiver responsive to occurrence of one of the conditions; and

determine a current position of the GPS receiver at a reduced acquisition time using at least the obtained data and the approximate position.

21. The wireless communications device of claim 20, wherein the predetermined period of time corresponds to approximately two hours.

22. The wireless communication device of claim 20, wherein the controller is further configured to obtain ephemeris and almanac data from the reference server via the internet.

23. The wireless communication device of claim 22, wherein the controller is further configured to obtain ephemeris and almanac data using a Mobile Internet Protocol.

24. The wireless communication device of claim 22, wherein the controller is further configured to obtain ephemeris and almanac data using a WAP protocol.

25. The wireless communication device of claim 20, wherein the controller is further configured to compare a present mobile country code and mobile network co de with a previous mobile country code and mobile network code to determine a change has occurred between mobile country code and mobile network code of the GPS receiver.

26. The wireless communication device of claim 20, wherein the approximate position comprises a longitude and latitude.

27. The wireless communication device of claim 20, wherein the controller is further configured to:

access the table of mobile country codes and mobile network codes having position data associated therewith;

compare the present mobile country code and mobile network code with entries in the table to locate a corresponding mobile country code and mobile network code; and

select the longitude and latitude associated with a corresponding mobile country code and mobile network code as the approximate position of the GPS receiver.

28. The wireless communication device of claim 20, wherein the controller is further configured to obtain a present time associated with the GPS receiver based upon the mobile country code and the mobile network code associated with the GPS receiver.

29. The wireless communication device of claim 28, wherein the controller is further configured to:

access a table of mobile country codes and mobile network codes having position data associated therewith;

compare the present mobile country code and mobile network code with entries in the table to locate a corresponding mobile country code and mobile network code; and

determine if the position data has changed by a selected amount;

if the position data has not changed by the selected amount, determine a time for a previously used time zone.