METHOD AND APPARATUS FOR CANCELING A CIRCUIT SWITCHED FALLBACK

• US 20100172301A1
• Filed: 01/06/2010
• Published: 07/08/2010
• Est. Priority Date: 01/06/2009
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Somasundaram, Shankar, Olvera-Hernandez, Ulises, Watfa, Mahmoud, Aghili, Behrouz
• Granted Patent: US 8,340,023 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 76/15 Setup of multiple wireless link connections
• CPC Class Codes: H04W 76/18 Management of setup rejection or failure

Abstract

A method and apparatus may be used to cancel a communication session. The apparatus may transmit a first message to initiate a communication session and then transmit a second message that indicates a request to cancel the communication session. If the apparatus determines that there is an ongoing Packet Switched (PS) session, the apparatus may continue the ongoing PS session on a current Radio Access Technology (RAT) without performing an intersystem change. If the apparatus receives a handover (HO) command, the apparatus may transmit a message to reject the HO command, or it may ignore the HO command.

Claims

1. A method for canceling a Circuit Switched (CS) Fallback (CSFB) procedure for a wireless transmit/receive unit (WTRU), the method comprising:

transmitting a first message to initiate a CSFB procedure;

transmitting a second message that indicates a request to cancel the CSFB procedure;

determining that there is an ongoing Packet Switched (PS) session; and

continuing the ongoing PS session on a current Radio Access Technology (RAT) without performing an intersystem change.

2. The method of claim 1, wherein the first message is an Extended Service Request (ESR) message and the second message is a modified ESR message.

3. The method of claim 2, wherein the modified ESR message is a non-access stratum (NAS) message.

4. The method of claim 1, wherein the request to cancel the CSFB procedure is indicated in a Service Type field of the second message.

5. The method of claim 1, wherein the second message is a non-access stratum (NAS) message that includes a Service Withdraw Identity field that indicates a service type to cancel.

6. The method of claim 1, wherein the intersystem change includes a PS handover (HO).

7. The method of claim 1, wherein the current RAT is a Long Term Evolution (LTE) RAT.

8. The method of claim 1 further comprising:

receiving a handover (HO) command; and

transmitting a message to reject the HO command.

9. The method of claim 8, wherein the message to reject the HO command is a non-access stratum (NAS) message transmitted to a mobility management entity (MME).

10. The method of claim 8, wherein the message to reject the HO command is a radio resource control (RRC) message transmitted to an evolved NodeB (eNB).

11. The method of claim 1 further comprising:

receiving a handover (HO) message that includes a CSFB indicator; and

ignoring the HO message based on a knowledge of transmitting the second message that indicates the request to cancel the CSFB procedure.

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

a transmitter configured to

transmit a first message to initiate a Circuit Switched (CS) Fallback (CSFB) procedure; and

transmit a second message that indicates a request to cancel the CSFB procedure; and

a processor configured to determine that there is an ongoing Packet Switched (PS) session and continue the ongoing PS session on a current Radio Access Technology (RAT) without performing an intersystem change.

13. The WTRU of claim 12, wherein the transmitter is configured to transmit the first message as an Extended Service Request (ESR) message and the second message as a modified ESR message.

14. The WTRU of claim 13, wherein the transmitter is configured to transmit the modified ESR message as a non-access stratum (NAS) message.

15. The WTRU of claim 12, wherein the transmitter is configured to transmit an indication of the request to cancel the CSFB procedure in a Service Type field of the second message.

16. The WTRU of claim 12, wherein the transmitter is configured to transmit the second message as a non-access stratum (NAS) message that includes a Service Withdraw Identity field that indicates a service type to cancel.

17. The WTRU of claim 12 further comprising:

a receiver configured to receive a handover (HO) command, wherein the transmitter is further configured to transmit a message to reject the HO command.

18. The WTRU of claim 17, wherein the transmitter is configured to transmit the message to reject the HO command as a non-access stratum (NAS) message to a mobility management entity (MME).

19. The WTRU of claim 17, wherein the transmitter is configured to transmit the message to reject the HO command as a radio resource control (RRC) message to an evolved NodeB (eNB).

20. The WTRU of claim 12 further comprising:

a receiver configured to receive a handover (HO) message that includes a CSFB indicator, wherein the processor is further configured to ignore the HO message based on a knowledge of transmitting the second message that indicates the request to cancel the CSFB procedure.