BALANCING PAGING LOAD AND TRACKING AREA UPDATES

• US 20080220782A1
• Filed: 03/07/2008
• Published: 09/11/2008
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Miller, James M., Wang, Peter S., Wang, Jin, Somasundaram, Shankar, Olvera-Hernandez, Ulises, Mukherjee, Rajat P.
• Granted Patent: US 8,472,956 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 36/22 for handling the traffic
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data
• CPC Class Codes: H04W 36/36 by user or terminal equipment
• CPC Class Codes: H04W 36/362 Conditional handover
• CPC Class Codes: H04W 4/08 User group management
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 76/38 triggered by timers
• CPC Class Codes: H04W 8/186 Processing of subscriber group data
• CPC Class Codes: H04W 8/205 Transfer to or from user equipment or user record carrier
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems
• CPC Class Codes: H04W 84/105 PBS [Private Base Station] network H04W84/12 - H04W84/16 take precedence

Abstract

A method for assigning a tracking area (TA) is disclosed. A mobility state of a wireless transmit/receive unit (WTRU) is determined and the TA is assigned based on the determined mobility state. Also disclosed is a method for accessing a closed subscriber group (CSG) TA. A CSG TA identifier is received at a WTRU and is stored. A CSG TA broadcast is received and the broadcast CSG TA is accessed if an identifier of the broadcast CSG TA matches the stored CSG TA identifier. Also disclosed is a method for changing a mobility state of a WTRU. A current mobility state of the WTRU is determined and a predetermined metric of the WTRU is examined. The predetermined metric is evaluated to determine if the metric has crossed a threshold and the mobility state is changed based on the evaluated metric.

Claims

1. A method in a base station for assigning a tracking area (TA), comprising:

determining a mobility state of a wireless transmit/receive unit (WTRU); and

assigning the TA based on the determined mobility state.

2. The method according to claim 1, wherein said assigning includes assigning one TA to the WTRU when the WTRU is in one of a stationary state and a low mobility state.

3. The method according to claim 1, wherein said assigning includes assigning multiple TAs to the WTRU when the WTRU is in a high mobility state.

4. The method according to claim 1, wherein said assigning includes assigning a small TA to the WTRU when the WTRU is in one of a stationary state and a low mobility state.

5. The method according to claim 4, wherein the small TA includes more than one cell.

6. The method according to claim 1, wherein said assigning includes assigning a large TA to the WTRU when the WTRU is in a high mobility state.

7. The method according to claim 6, wherein the large TA includes a plurality of cells.

8. A method in a wireless transmit/receive unit (WTRU) for determining access to a closed subscriber group (CSG) cell, comprising:

receiving a CSG Tracking Area (TA) identifier;

storing the received CSG TA identifier;

receiving a CSG TA identifier broadcast by a CSG cell; and

determining that access to the CSG cell is allowed if the identifier broadcast by the CSG cell matches the stored CSG TA identifier.

9. The method according to claim 8, wherein said storing includes storing the CSG TA identifier on a Universal Integrated Circuit Card.

10. The method according to claim 8, wherein said storing includes storing a part of the CSG TA identifier on a Universal Integrated Circuit Card.

11. The method according to claim 8, wherein said storing includes storing the CSG TA identifier in a Universal Subscriber Identity Module application.

12. The method according to claim 8, wherein said storing includes storing a part of the CSG TA identifier in a Universal Subscriber Identity Module application.

13. The method according to claim 8, wherein the CSG TA identifier consists of a CSG TA code concatenated with a Public Land Mobile Network (PLMN) identifier.

14. The method according to claim 13, wherein the broadcast CSG TA identifier includes separate fields containing the CSG TA code and the PLMN identifier.

15. The method according to claim 14, further comprising:

constructing the broadcast CSG TA identifier by concatenating the CSG TA code and the PLMN identifier.

16. The method according to claim 13, wherein the CSG TA code has a different length than a macro-cell TA code.

17. The method according to claim 8, further comprising:

determining whether a tracking area update (TAU) procedure is to be performed when the WTRU accesses a CSG TA.

18. The method according to claim 17, wherein said determining includes receiving an indication of signaling free mobility and the TAU procedure is performed if signaling free mobility is not indicated.

19. The method according to claim 18, wherein the indication includes a bit set on a received broadcast.

20. The method according to claim 18, wherein the indication includes determining whether the broadcast CSG TA identifier is in a signaling free mobility TA identifier list.

21. The method according to claim 20, wherein the signaling free mobility TA identifier list includes a list of TAs assigned to the WTRU in a TA Update Accept message.

22. The method according to claim 8, wherein if the broadcast CSG TA identifier does not match a stored CSG TA identifier, the WTRU does not attempt to access the CSG cell.

23. The method according to claim 22, wherein a TA Update procedure is not performed on the CSG cell.

24. The method according to claim 8, wherein if the broadcast CSG TA identifier does not match a stored CSG TA identifier, further comprising:

attempting a temporary registration procedure with the CSG TA.

25. The method according to claim 24, wherein the temporary registration procedure includes executing a predetermined code.

26. The method according to claim 24, wherein the temporary registration procedure includes executing a two factor authentication procedure.

27. A method in a base station for changing a mobility state of a wireless transmit/receive unit (WTRU), comprising:

determining a current mobility state of the WTRU;

examining a predetermined metric of the WTRU;

evaluating whether the predetermined metric has crossed a threshold; and

changing the mobility state based on said evaluating.

28. The method according to claim 27, wherein

the current mobility state is a low mobility state;

the predetermined metric is a count of a number of tracking area updates (TAUs) performed by the WTRU;

said evaluating includes determining whether the number of TAUs is greater than the threshold; and

said changing includes transitioning the WTRU to a high mobility state.

29. The method according to claim 27, wherein

the current mobility state is a low mobility state;

the predetermined metric is a count of a number of cell reselections performed by the WTRU;

said evaluating includes determining whether the number of cell reselections is greater than the threshold; and

said changing includes transitioning the WTRU to a high mobility state.

30. The method according to claim 27, wherein

the current mobility state is a high mobility state;

the predetermined metric is a count of a number of cell reselections performed by the WTRU;

said evaluating includes determining whether the number of cell reselections is less than the threshold; and

said changing includes transitioning the WTRU to a low mobility state.

31. The method according to claim 27, wherein said evaluating includes examining WTRU positioning measurement results.

32. A wireless transmit/receive unit (WTRU), comprising:

an antenna;

a transmitter/receiver connected to said antenna;

a reporting function in communication with said transmitter/receiver, said reporting function configured to report information about the WTRU;

a tracking area update function in communication with said reporting function, said tracking area update function configured to perform tracking area updates;

a cell reselection function in communication with said reporting function, said cell reselection function configured to perform cell reselections; and

a WTRU positioning function in communication with said reporting function, said WTRU positioning function configured to determine the WTRU'"'"'s current position.

33. The WTRU according to claim 32, further comprising:

a mobility state function in communication with said reporting function, said mobility state function configured to monitor the mobility state of the WTRU.

34. A method in a base station for managing a paging load in a wireless communication system, comprising:

determining a mobility state of a wireless transmit/receive unit (WTRU);

setting a timer for the WTRU to a predetermined time, the predetermined time being based on the mobility state of the WTRU; and

receiving a tracking area update from the WTRU upon expiration of the timer, whereby using the timer minimizes the paging load.

35. The method according to claim 34, wherein the timer is reset if the mobility state of the WTRU changes.

36. The method according to claim 34, wherein the timer is reset if the WTRU moves into a different tracking area.

37. The method according to claim 34, wherein said setting includes setting a timer for each assigned tracking area.

38. The method according to claim 34, wherein said setting includes setting a timer for each mobility state.

39. The method according to claim 38, wherein three timers are set, one timer for each of a stationary state, a low mobility state, and a high mobility state.