Location service providing system and method

1. A location service providing system comprising:

a target SUPL (Secure User Plane for Location) Enabled Terminal (SET) for:

storing a positioning method determined in an initialization stage of a location service according to a location service request, wherein the positioning method is one of a Mobile Station (MS)-assisted Assisted Global Positioning System (A-GPS) method and an MS-based A-GPS method;

determining in a location calculation process whether the stored positioning method is available, when the target SET receives a new location service request, after storing the positioning method in the initialization stage;

providing the stored positioning method to a Home-SUPL Location Platform (H-SLP), if it is determined that the stored positioning method is available; and

requesting for re-determination of a positioning method to the H-SLP, if it is determined that the stored positioning method is unavailable.

2. The system of claim 1 , wherein if the stored positioning method is available, the target SET transmits a positioning initialization (SUPL POS INIT) message including a value corresponding to the stored positioning method to the H-SLP, and if the stored positioning method is unavailable, the target SET transmits the SUPL POS INIT message including a value for requesting re-determination of the positioning method to the H-SLP.

3. The system of claim 1 , wherein an SUPL agent requests the location service.

4. The system of claim 3 , wherein the SUPL agent requests the location service using a service-flag indicating a location service type.

5. The system of claim 4 , wherein the location service comprises at least one of an immediate location service, a triggered location service, an emergency location service, and a lawful location service.

6. The system of claim 1 , wherein the target SET and the H-SLP use a trigger-flag to indicate whether a party notifying of the beginning of the location calculation process is the target SET or the H-SLP.

7. The system of claim 1 , wherein the target SET and the H-SLP:

perform the location calculation process using at least one of a location session process, a stay warm session process, and a just calculation process; and

provide the location service according to the calculated position,

wherein during the location session process, the H-SLP creates assistant data and calculates a position of the target SET,

wherein during the stay warm session process, the H-SLP creates assistant data and transmits the created assistant data to the target SET, and the target SET calculates its position using the assistant data, and

wherein during the just calculation process, the target SET checks whether valid assistant data exists and, if valid assistant data exists, calculates its position using the valid assistant data.

8. A method for providing a location service in a target Secure User Plane for Location (SUPL) Enabled Terminal (SET), the method comprising:

storing, by the target SET, a positioning method determined in an initialization stage of a location service according to a location service request, wherein the positioning method is one of a Mobile Station (MS)-assisted Assisted Global Positioning System (A-GPS) method and an MS-based A-GPS method;

determining in a location calculation process whether the stored positioning method is available, when the target SET receives a new location service request;

providing the stored positioning method to a Home-SUPL Location Platform (H-SLP), if it is determined that the stored positioning method is available; and

requesting re-determination of a positioning method from the H-SLP, if it is determined that the stored positioning method is unavailable.

9. The method of claim 8 , wherein if the stored positioning method is available, the target SET transmits a positioning initialization (SUPL POS INIT) message including a value corresponding to the stored positioning method to the H-SLP, and if the stored positioning method is unavailable, the target SET transmits the SUPL POS INIT message including a value for requesting re-determination of the positioning method to the H-SLP.

10. The method of claim 8 , further comprising requesting, by an SUPL agent, the location service.

11. The method of claim 10 , wherein the step of requesting the location service comprises:

setting a value of a service-flag indicating a location service type to be requested; and

transmitting a message including the set service-flag to the H-SLP.

12. The method of claim 10 , wherein the location service comprises at least one of an immediate location service, a triggered location service, an emergency location service, and a lawful location service.

13. The method of claim 8 , wherein the target SET and the H-SLP use a trigger-flag to indicate whether a party notifying of the beginning of the location calculation process is the target SET or the H-SLP.

14. The method of claim 8 , further comprising:

performing the location calculation process using one of a location session process, a stay warm session process, and a just calculation process; and

providing the location service according to the calculated position,

wherein during the location session process, the H-SLP creates assistant data and calculates a position of the target SET,

wherein during the stay warm session process, the H-SLP creates assistant data and transmits the created assistant data to the target SET, and the target SET calculates its position using the assistant data, and

wherein during the just calculation process, the target SET checks whether valid assistant data exists and, if valid assistant data exists, calculates its position using the valid assistant data.

15. A location service providing system comprising:

a Home-Secure User Plane for Location (SUPL) Location Platform (H-SLP) for providing the location service using a stored positioning method, if the stored positioning method is provided from a target SUPL Enabled Terminal (SET), when the target SET receives a new location service request, receiving a re-determination request of the positioning method from the target SET, re-determining a new positioning method of the target SET, and providing the location service by using the new positioning method,

wherein the stored positioning method is determined in an initialization stage of the location service according to a previous location service request, and the positioning method is one of a Mobile Station (MS)-assisted Assisted Global Positioning System (A-GPS) method and an MS-based A-GPS method.

16. The system of claim 15 , wherein an SUPL agent generates the location service request.

17. The system of claim 16 , wherein the location service request includes a service-flag indicating a location service type.

18. The system of claim 17 , wherein the location service type comprises at least one of:

an immediate location service;

a triggered location service;

an emergency location service; and

a lawful location service.

19. The system of claim 15 , wherein the target SET and the H-SLP use a trigger-flag to indicate whether a party notifying a beginning of a location calculation process is the target SET or the H-SLP.

20. The system of claim 15 , wherein the target SET and the H-SLP:

perform a location calculation process using at least one of a location session process, a stay warm session process, and a just calculation process; and

provide the location service according to a calculated position from the location calculation process,

wherein during the location session process, the H-SLP creates assistant data and calculates a position of the target SET,

wherein during the stay warm session process, the H-SLP creates assistant data and transmits the created assistant data to the target SET, and the target SET calculates its position using the assistant data, and

wherein during the just calculation process, the target SET checks whether valid assistant data exists and, if valid assistant data exists, calculates its position using the valid assistant data.

21. A method for providing a location service in Home-Secure User Plane for Location (SUPL) Location Platform (H-SLP), the method comprising:

providing the location service using a stored positioning method, if the stored positioning method is provided from a target SUPL Enabled Terminal (SET), when the target SET receives a new location service request;

receiving a re-determination request of the positioning method from the target SET;

re-determining a new positioning method of the target SET; and

providing the location service by using the new positioning method,

wherein the stored positioning method is determined in an initialization stage of the location service according to a previous location service request, and the positioning method is one of a Mobile Station (MS)-assisted Assisted Global Positioning System (A-GPS) method and an MS-based A-GPS method.

22. The method of claim 21 , wherein an SUPL agent generates the location service request.

23. The method of claim 22 , wherein the SUPL agent generates the location service request by setting a value of a service-flag indicating a location service type to be requested, and transmitting a message including the set service-flag to the H-SLP.

24. The method of claim 23 , wherein the location service includes at least one of an immediate location service, a triggered location service, an emergency location service, and a lawful location service.

25. The method of claim 21 , wherein the target SET and the H-SLP use a trigger-flag to indicate whether a party notifying a beginning of a location calculation process is the target SET or the H-SLP.

26. The method of claim 21 , further comprising:

determining whether a previous position exists;

if a previous position exists, performing a location calculation process using the previous position, without using the stored positioning method or a re-determined positioning method; and

providing the location service according to a calculated position from the location calculation process.

27. The method of claim 21 , wherein providing the location service comprises:

performing a location calculation process using one of a location session process, a stay warm session process, and a just calculation process; and

providing the location service according to a calculated position from the location calculation process,

wherein during the location session process, the H-SLP creates assistant data and calculates a position of the target SET,

wherein during the stay warm session process, the H-S LP creates assistant data and transmits the created assistant data to the target SET, and the target SET calculates its position using the assistant data, and

wherein during the just calculation process, the target SET checks whether valid assistant data exists and, if valid assistant data exists, calculates its position using the valid assistant data.