CIRCUIT SWITCHED FALLBACK PROCEDURE

• US 20110216645A1
• Filed: 09/07/2010
• Published: 09/08/2011
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ramachandran, Shyamal, Ulupinar, Fatih, Song, Osok
• Granted Patent: US 8,934,331 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 36/08 Reselecting an access point

Abstract

A CS fallback procedure handles conflict that may arise when handover operations occur during CS fallback. If CS fallback is initiated for an access terminal and handover of that access terminal is then initiated before the CS fallback completes, the target for the handover is informed of the CS fallback so that the target may perform the appropriate CS fallback operations.

Claims

1. A method of communication, comprising:

sending a message to a first access point, wherein the message includes a circuit switched fallback indicator associated with an access terminal;

determining, after the message is sent to the first access point, that handover of the access terminal from the first access point to a second access point has been initiated; and

sending a message to the second access point as a result of the determination, wherein the message sent to the second access point includes the circuit switched fallback indicator associated with the access terminal.

2. The method of claim 1, wherein the message sent to the first access point comprises a UE Context Modification Request.

3. The method of claim 1, wherein the message sent to the first access point comprises an Initial Context Setup Request.

4. The method of claim 1, wherein the determination comprises receiving another message that is indicative of the handover of the access terminal.

5. The method of claim 4, wherein the another message comprises a handover notify message.

6. The method of claim 4, wherein the another message comprises a path switch request message.

7. The method of claim 1, wherein the messages sent to the first and second access points comprise UE Context Modification Requests that include the circuit switched fallback indicator.

8. The method of claim 1, wherein the sending of the message to the second access point comprises sending the message to the second access point if the handover of the access terminal is completed.

9. The method of claim 1, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a handover notify message.

10. The method of claim 1, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a path switch request message.

11. The method of claim 1, further comprising sending, as a result of the determination, an indication of circuit switched fallback for the access terminal from a first mobility management entity associated with the first access point to a second mobility management entity associated with the second access point.

12. The method of claim 11, wherein the indication is included in context information sent from the first mobility management entity to the second mobility management entity.

13. The method of claim 1, wherein:

the determination comprises receiving a rejection to the message sent to the first access point; and

the rejection comprises an indication that the handover is in progress.

14. The method of claim 1, wherein:

the sending of the message to the first access point comprises an S1 interface procedure; and

the determination comprises receiving a rejection to the S1 interface procedure; and

the rejection comprises an indication that the handover is in progress.

15. The method of claim 14, wherein the sending of the message to the second access point comprises reattempting the S1 interface procedure with the second access point if the handover is completed.

16. An apparatus for communication, comprising:

a circuit switched fallback controller configured to send a message to a first access point, wherein the message includes a circuit switched fallback indicator associated with an access terminal; and

a handover controller configured to determine, after the message is sent to the first access point, that handover of the access terminal from the first access point to a second access point has been initiated,

wherein the circuit switched fallback controller is further configured to send a message to the second access point as a result of the determination, and wherein the message sent to the second access point includes the circuit switched fallback indicator associated with the access terminal.

17. The apparatus of claim 16, wherein the message sent to the first access point comprises a UE Context Modification Request.

18. The apparatus of claim 16, wherein the message sent to the first access point comprises an Initial Context Setup Request.

19. The apparatus of claim 16, wherein the determination comprises receiving another message that is indicative of the handover of the access terminal.

20. The apparatus of claim 19, wherein the another message comprises a handover notify message.

21. The apparatus of claim 19, wherein the another message comprises a path switch request message.

22. The apparatus of claim 16, wherein the messages sent to the first and second access points comprise UE Context Modification Requests that include the circuit switched fallback indicator.

23. The apparatus of claim 16, wherein the sending of the message to the second access point comprises sending the message to the second access point if the handover of the access terminal is completed.

24. The apparatus of claim 16, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a handover notify message.

25. The apparatus of claim 16, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a path switch request message.

26. The apparatus of claim 16, wherein the circuit switched fallback controller is further configured to send, as a result of the determination, an indication of circuit switched fallback for the access terminal from a first mobility management entity associated with the first access point to a second mobility management entity associated with the second access point.

27. The apparatus of claim 26, wherein the indication is included in context information sent from the first mobility management entity to the second mobility management entity.

28. The apparatus of claim 16, wherein:

the determination comprises receiving a rejection to the message sent to the first access point; and

the rejection comprises an indication that the handover is in progress.

29. The apparatus of claim 16, wherein:

the sending of the message to the first access point comprises an S1 interface procedure; and

the determination comprises receiving a rejection to the S1 interface procedure; and

the rejection comprises an indication that the handover is in progress.

30. The apparatus of claim 29, wherein the sending of the message to the second access point comprises reattempting the S1 interface procedure with the second access point if the handover is completed.

31. An apparatus for communication, comprising:

means for sending a message to a first access point, wherein the message includes a circuit switched fallback indicator associated with an access terminal;

means for determining, after the message is sent to the first access point, that handover of the access terminal from the first access point to a second access point has been initiated; and

means for sending a message to the second access point as a result of the determination, wherein the message sent to the second access point includes the circuit switched fallback indicator associated with the access terminal.

32. The apparatus of claim 31, wherein the message sent to the first access point comprises a UE Context Modification Request.

33. The apparatus of claim 31, wherein the message sent to the first access point comprises an Initial Context Setup Request.

34. The apparatus of claim 31, wherein the determination comprises receiving another message that is indicative of the handover of the access terminal.

35. The apparatus of claim 34, wherein the another message comprises a handover notify message.

36. The apparatus of claim 34, wherein the another message comprises a path switch request message.

37. The apparatus of claim 31, wherein the messages sent to the first and second access points comprise UE Context Modification Requests that include the circuit switched fallback indicator.

38. The apparatus of claim 31, wherein the sending of the message to the second access point comprises sending the message to the second access point if the handover of the access terminal is completed.

39. The apparatus of claim 31, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a handover notify message.

40. The apparatus of claim 31, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a path switch request message.

41. The apparatus of claim 31, further comprising means for sending, as a result of the determination, an indication of circuit switched fallback for the access terminal from a first mobility management entity associated with the first access point to a second mobility management entity associated with the second access point.

42. The apparatus of claim 41, wherein the indication is included in context information sent from the first mobility management entity to the second mobility management entity.

43. The apparatus of claim 31, wherein:

the determination comprises receiving a rejection to the message sent to the first access point; and

the rejection comprises an indication that the handover is in progress.

44. The apparatus of claim 31, wherein:

the sending of the message to the first access point comprises an S1 interface procedure; and

the determination comprises receiving a rejection to the S1 interface procedure; and

the rejection comprises an indication that the handover is in progress.

45. The apparatus of claim 44, wherein the sending of the message to the second access point comprises reattempting the S1 interface procedure with the second access point if the handover is completed.

46. A computer-program product, comprising:

computer-readable medium comprising code for causing a computer to;

send a message to a first access point, wherein the message includes a circuit switched fallback indicator associated with an access terminal;

determine, after the message is sent to the first access point, that handover of the access terminal from the first access point to a second access point has been initiated; and

send a message to the second access point as a result of the determination, wherein the message sent to the second access point includes the circuit switched fallback indicator associated with the access terminal.

47. The computer-program product of claim 46, wherein the message sent to the first access point comprises a UE Context Modification Request.

48. The computer-program product of claim 46, wherein the message sent to the first access point comprises an Initial Context Setup Request.

49. The computer-program product of claim 46, wherein the determination comprises receiving another message that is indicative of the handover of the access terminal.

50. The computer-program product of claim 49, wherein the another message comprises a handover notify message.

51. The computer-program product of claim 49, wherein the another message comprises a path switch request message.

52. The computer-program product of claim 46, wherein the messages sent to the first and second access points comprise UE Context Modification Requests that include the circuit switched fallback indicator.

53. The computer-program product of claim 46, wherein the sending of the message to the second access point comprises sending the message to the second access point if the handover of the access terminal is completed.

54. The computer-program product of claim 46, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a handover notify message.

55. The computer-program product of claim 46, wherein the determination that the handover has been initiated comprises determining that the handover is complete based on reception of a path switch request message.

56. The computer-program product of claim 46, wherein the computer-readable medium further comprises code for causing the computer to send, as a result of the determination, an indication of circuit switched fallback for the access terminal from a first mobility management entity associated with the first access point to a second mobility management entity associated with the second access point.

57. The computer-program product of claim 56, wherein the indication is included in context information sent from the first mobility management entity to the second mobility management entity.

58. The computer-program product of claim 46, wherein:

the determination comprises receiving a rejection to the message sent to the first access point; and

the rejection comprises an indication that the handover is in progress.

59. The computer-program product of claim 46, wherein:

the sending of the message to the first access point comprises an S1 interface procedure; and

the determination comprises receiving a rejection to the S1 interface procedure; and

the rejection comprises an indication that the handover is in progress.

60. The computer-program product of claim 59, wherein the sending of the message to the second access point comprises reattempting the S1 interface procedure with the second access point if the handover is completed.