METHODS AND APPARATUS TO MAINTAIN CALL CONTINUITY

• US 20120044867A1
• Filed: 08/18/2011
• Published: 02/23/2012
• Est. Priority Date: 08/18/2010
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Faccin, Stefano, Bakker, Jan Hendrik Lucas, Burbidge, Richard Charles, Chin, Chen Ho
• Granted Patent: US 8,665,828 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 36/00226 wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 60/06 De-registration or detaching
• CPC Class Codes: H04W 76/25 Maintenance of established connections
• CPC Class Codes: H04W 76/34 Selective release of ongoing connections

Abstract

Example methods and apparatus to maintain call continuity are disclosed. A disclosed example method to control a user equipment (UE) includes the UE initiating a tracking area updating (TAU) procedure in an EMM_CONNECTED mode, identifying a lack of a voice service in response to the TAU procedure being successful, identifying a remaining bearer comprising a bearer context, and the UE staying in the EMM_CONNECTED mode until radio bearers associated with the bearer context are released.

Claims

1. A method to control a user equipment (UE) mode, comprising:

the UE initiating a tracking area updating (TAU) procedure in an EMM_CONNECTED mode;

identifying a lack of a voice service in response to the TAU procedure being successful;

identifying a remaining bearer comprising a bearer context; and

the UE staying in the EMM_CONNECTED mode until radio bearers associated with the bearer context are released.

2. A method as described in claim 1, further comprising the UE locally releasing an established non-access stratum signaling connection in response to the release of the bearer context.

3. A method as described in claim 2, further comprising entering an EMM-IDLE mode before selecting GERAN radio access technology.

4. A method as described in claim 2, further comprising entering an EMM-IDLE mode before selecting UTRAN radio access technology.

5. A method as described in claim 1, wherein the bearer context is an evolved packet system bearer context.

6. A method as described in claim 1, wherein the bearer context comprises a target quality of service control index value of 1.

7. A method as described in claim 1, further comprising an existing voice call session.

8. A method as described in claim 1, further comprising an existing application level call session.

9. A method as described in claim 8, further comprising refraining from dropping a call when an existing application level call session is ongoing.

10. A method as described in claim 1, wherein the UE receives a TRACKING AREA UPDATE ACCEPT message and EMM cause value #22.

11. A method as described in claim 10, wherein the EMM cause value #22 is associated with congestion.

12. A method as described in claim 10, wherein a tracking area updating counter is equal to 5.

13. A method as described in claim 1, wherein the UE receives a TRACKING AREA UPDATE ACCEPT message and EMM cause value #18.

14. A method as described in claim 13, wherein the EMM cause value #18 is associated with CS domain not available.

15. A method as described in claim 1, wherein the remaining bearer comprises an emergency bearer.

16. A method as described in claim 15, wherein the emergency bearer is for packet data network (PDN) connection for emergency services.

17. A method as described in claim 1, wherein the remaining bearer is for emergency bearer services.

18. A method as described in claim 1, wherein the remaining bearer is associated with an emergency session.

19. A method as described in claim 1, wherein the voice service is indicative of IMS voice not available.

20. A method as described in claim 1, wherein the remaining bearer is associated with a voice over packet switched (VoPS) session.

21. A method to control session release in a user equipment (UE), comprising:

receiving a DETACH REQUEST message having a detach type that indicates re-attach not required;

identifying a received EMM cause value of interest;

identifying a remaining bearer comprising a bearer context; and

the UE staying in EMM_CONNECTED mode until radio bearers associated with an EPS bearer are subsequently, normally or abnormally released, and disconnecting from the network.

22. A method as described in claim 21, wherein the bearer context comprises a quality of service control index (QCI) value of 1.

23. A method as described in claim 21, further comprising immediately disconnecting from the network when the UE has no EPS bearer with a target quality of service control index (QCI) value.

24. A method as described in claim 21, wherein disconnecting from the network comprises entering a deregistered state.

25. A method as described in claim 21, wherein the received EMM cause value of interest is associated with PLMN not allowed.

26. A method as described in claim 25, wherein disconnecting from the network further comprises entering a deregistered state of EMM-DEREGISTERED.PLMN-SEARCH.

27. A method as described in claim 21, wherein the received EMM cause value of interest is associated with tracking area not allowed.

28. A method as described in claim 27, wherein disconnecting from the network further comprises entering a deregistered state of EMM-DEREGISTERED.LIMITED-SERVICE.

29. A method as described in claim 21, wherein the received EMM cause value of interest is associated with roaming not allowed in this tracking area.

30. A method as described in claim 29, wherein disconnecting from the network further comprises entering a deregistered state of EMM-DEREGISTRED.PLMN-SEARCH.

31. A method as described in claim 21, wherein the received EMM cause value of interest is associated with no suitable cells in tracking area.

32. A method as described in claim 31, wherein disconnecting from the network further comprises entering a deregistered state of EMM-DEREGISTERED.LIMITED-SERVICE.

33. A method as described in claim 21, wherein the received EMM cause value of interest is associated with not authorized for this closed subscriber group.

34. A method as described in claim 33, wherein disconnecting from the network further comprises entering a deregistered state of EMM-DEREGISTERED.LIMITED-SERVICE.

35. A method as described in claim 21, further comprising a message of TRACKING AREA UPDATE ACCEPT.

36. A method as described in claim 35, wherein the message is associated with at least one of a normal TAU procedure, a combined TAU procedure or a periodic TAU procedure.

37. A method as described in claim 21, wherein at least one remaining bearer is for emergency bearer services.

38. A method as described in claim 21, wherein at least one remaining bearer is for an emergency bearer.

39. A method to control session release in a mobile station (MS), comprising:

receiving a DETACH REQUEST message having a detach type that indicates re-attach not required;

identifying a received cause code of interest; and

identifying whether RABs for PDP context having a traffic class of interest exist; and

deferring release of the MS connection until the RABs for PDP context are subsequently released.

40. A method as described in claim 39, wherein the traffic class of interest comprises at least one of conversational or streaming.

41. A method as described in claim 39, wherein the RAB is for emergency bearer services.

42. A method as described in claim 39, wherein the RAB is for an emergency bearer.

43. A method as described in claim 39, further comprising the MS operating in a mode of interest.

44. A method as described in claim 43, wherein the mode of interest comprises at least one of mode A or mode B.

45. A method as described in claim 39, wherein the detach type comprises at least one of PLMN not allowed, or roaming not allowed in this location area.

46. A method as described in claim 45, further comprising performing a PLMN selection.

47. A method as described in claim 39, wherein the detach type comprises location area not allowed.

48. A method as described in claim 47, further comprising performing a cell selection.

49. A method as described in claim 39, wherein the detach type comprises no suitable cells in location area.

50. A method as described in claim 49, further comprising searching for a suitable cell in another location area or a tracking area in the same PLMN.

51. A method as described in claim 39, wherein the detach type comprises not authorized for this CSG.

52. A method as described in claim 51, further comprising setting a GPRS update status to GU3 ROAMING NOT ALLOWED.

53. A method as described in claim 52, further comprising resetting a GPRS attach attempt counter.

54. A method as described in claim 52, further comprising changing the state to GMM-DEREGISTERED.LIMITED-SERVICE.

55. A method as described in claim 39, further comprising setting an update status to U3 ROAMING NOT ALLOWED after the RABs for PDP context are subsequently released.

56. A method as described in claim 39, further comprising a message of ROUTING AREA UPDATE ACCEPT.

57. A method as described in claim 56, wherein the message is associated with at least one of a normal RAU procedure, a combined RAU procedure or a periodic RAU procedure.

58-76. -76. (canceled)