System and method for handling media in a seamless handoff environment

• US 20060183478A1
• Filed: 02/11/2005
• Published: 08/17/2006
• Est. Priority Date: 02/11/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Jagadeesan, Ramanathan T., Nguyen, Bich T., Chung, Andrew C., Ramalho, Michael A.
• Granted Patent: US 7,483,701 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04W 36/1443 between licensed networks
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A method for handling media in a make-before-break handoff between wireless networks is provided that includes communicating with a mobile station to facilitate a session handoff between two call legs of a session. The method also includes identifying a relevant frame of one of the legs, performing a cross correlation operation, generating a delay difference estimate between the two legs, and performing a level difference estimation for the two legs.

Claims

1. A method for handling media in a make-before-break handoff between wireless networks, comprising:

communicating with a mobile station to facilitate a session handoff between two call legs of a session;

identifying a relevant frame of one of the legs;

performing a cross-correlation operation;

generating a delay difference estimate between the two legs; and

performing a level difference estimation for the two legs.

2. The method of claim 1, wherein the cross correlation operation includes one or more peak picking operations.

3. The method of claim 1, wherein the level difference estimation operation includes:

determining an energy level in each frame; and

scaling selected frames relative to each other.

4. The method of claim 1, wherein the level difference estimation operation includes:

comparing two frames in order to resolve the two frames relative to each other, and wherein the two frames may be amplified or attenuated such that an end user associated with the session hears a similar level of signal.

5. The method of claim 1, wherein the identifying of the relevant frame operation includes:

selecting a frame with enough energy for a suitable cross correlation operation, and wherein the relevant frame is not associated with silence.

6. The method of claim 1, wherein the cross-correlation operation includes a vector dot-product operation.

7. The method of claim 1, wherein once the two legs are aligned a switchover transition frame is generated using a weighed overlap-and-add method.

8. The method of claim 1, wherein a voice activity detection (VAD) protocol is executed in conjunction with identifying the relevant frame.

9. A system for handling media in a make-before-break handoff between wireless networks, comprising:

a mobility application operable to communicate with a mobile station to facilitate a session handoff between two call legs of a session, wherein during the session handoff the mobility application is operable to;

identify a relevant frame of one of the legs;

perform a cross-correlation operation;

generate a delay difference estimate; and

perform a level difference estimation.

10. The system of claim 9, wherein the cross correlation includes one or more peak picking operations.

11. The system of claim 9, wherein the level difference estimation operation includes determining an energy level in each frame and then scaling selected frames relative to each other.

12. The system of claim 9, wherein the level difference estimation operation includes comparing two frames in order to resolve the two frames relative to each other, and wherein the two frames may be amplified or attenuated such that an end user associated with the session hears a similar level of signal.

13. The system of claim 9, wherein the identifying of the relevant frame operation includes selecting a frame with enough energy for a suitable cross correlation operation, and wherein the relevant frame is not associated with silence.

14. The system of claim 9, wherein the cross-correlation operation includes a vector dot-product operation.

15. The system of claim 9, wherein once the two legs are aligned a switchover transition frame is generated using a weighed overlap-and-add protocol.

16. The system of claim 9, wherein a voice activity detection (VAD) protocol is executed in conjunction with identifying the relevant frame.

17. Software for handling media in a make-before-break handoff between wireless networks, the software being embodied in a computer readable medium and comprising computer code such that when executed is operable to:

communicate with a mobile station to facilitate a session handoff between two call legs of a session;

identify a relevant frame of one of the legs;

perform a cross-correlation operation;

generate a delay difference estimate between the two legs; and

perform a level difference estimation for the two legs.

18. The medium of claim 17, wherein the cross correlation operation includes one or more peak picking operations.

19. The medium of claim 17, wherein the level difference estimation operation includes:

determining an energy level in each frame; and

scaling selected frames relative to each other.

20. The medium of claim 17, wherein the level difference estimation operation includes:

comparing two frames in order to resolve the two frames relative to each other, and wherein the two frames may be amplified or attenuated such that an end user associated with the session hears a similar level of signal.

21. The medium of claim 17, wherein the identifying of the relevant frame operation includes:

selecting a frame with enough energy for a suitable cross correlation operation, and wherein the relevant frame is not associated with silence.

22. The medium of claim 17, wherein a buffer of previous frames on the first call leg is maintained to facilitate the cross-correlation operation.

23. A system for handling media in a make-before-break handoff between wireless networks, comprising:

a mobile station operable to communicate with a mobility application to facilitate a session handoff between two call legs of a session, wherein during the session handoff a relevant frame of one of the legs is identified, a cross-correlation operation is performed, a delay difference estimate is generated, and a level difference estimation is performed for the session.

24. The system of claim 23, wherein the cross correlation includes one or more peak picking operations.

25. The system of claim 23, wherein the level difference estimation operation includes determining an energy level in each frame and then scaling selected frames relative to each other.

26. The system of claim 23, wherein the level difference estimation operation includes comparing two frames in order to resolve the two frames relative to each other, and wherein the two frames may be amplified or attenuated such that an end user associated with the session hears a similar level of signal.

27. The system of claim 23, wherein the identifying of the relevant frame operation includes selecting a frame with enough energy for a suitable cross correlation operation, and wherein the relevant frame is not associated with silence.

28. The system of claim 23, wherein once the two legs are aligned a switchover transition frame is generated using a weighed overlap-and-add protocol.

29. The system of claim 23, wherein a voice activity detection (VAD) protocol is executed in conjunction with identifying the relevant frame.