Seamless context switching for radio link protocol

• US 8,611,303 B2
• Filed: 02/04/2008
• Issued: 12/17/2013
• Est. Priority Date: 02/02/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rezaiifar, Ramin, Black, Peter
• Primary Examiner(s): Jaroenchonwanit, Bunjob
• Application Number:
  US12/012,786
• Publication Number:
  US 20080186920A1
• Time in Patent Office: 2,143 Days
• Field of Search: None
• US Class Current: 370/331
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 80/06 Transport layer protocols, e.g. TCP [Transport Control Protocol] over wireless transmission control protocol/Internet protocol [TCP/IP] or user datagram protocol [UDP] H04L69/16

Abstract

Techniques to support handover of a terminal from a source base station to a target base station are described. In one design, a determination is made whether a change in personality is requested by the terminal. If the answer is ‘Yes’, then the personality of the terminal may be switched by sending one or more appropriate messages. The connection and RLP for the terminal may be reset due to the change in personality. A buffer of data reported by the source base station as being served to the terminal (e.g., no NAK was sent) may be saved by a BSC/PCF. The buffer of data may be sent to the target base station when handover occurs. New data may thereafter be sent to the target base station. This buffer of duplicate data may avoid both loss of data and retransmission timeout by TCP during the handover.

Claims

1. An apparatus for wireless communication, comprising:

a memory coupled to at least one processor; and

the at least one processor configured;

to reset a connection for a terminal in response to handover from a source base station to a target base station,

to identify a duplicate of a first data from the source base station, the first data reported as having been served to the terminal by the source base station prior to the reset but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset,

to store the duplicate of the first data identified from the source base station,

after the storing, to send the duplicate of the first data to the target base station after the handover, and

to send new data for the terminal to the target base station after sending the duplicate of the first data.

2. The apparatus of claim 1, wherein the at least one processor is configured to determine when a session configuration change for the terminal is requested, and to switch the session configuration of the terminal when requested.

3. The apparatus of claim 2, wherein the at least one processor is configured to switch the session configuration of the terminal in response to the handover from the source base station to the target base station.

4. The apparatus of claim 2, wherein the at least one processor is configured to reset Radio Link Protocol (RLP) for the terminal in response to the switch in the session configuration of the terminal.

5. The apparatus of claim 1, wherein the source base station supports a first revision of an air interface and the target base station supports a second revision of the air interface.

6. The apparatus of claim 1, wherein the at least one processor is configured to send the first data to the source base station prior to the handover.

7. The apparatus of claim 1, wherein the at least one processor is configured to store a predetermined amount of data most recently served to the terminal by the source base station.

8. The apparatus of claim 7, wherein the at least one processor is configured to determine the data most recently served to the terminal by the source base station based on a flow control message received from the source base station.

9. The apparatus of claim 1, wherein the at least one processor is configured to store an amount of data corresponding to a maximum packet size.

10. The apparatus of claim 1, wherein the at least one processor is configured to send the stored duplicate of the first data to the target base station after the handover to avoid retransmission timeout (RTO) of Transmission Control Protocol (TCP).

11. A method for wireless communication, comprising:

resetting a connection for a terminal in response to handover from a source base station to a target base station;

identifying a duplicate of a first data from the source base station, the first data reported as having been served to the terminal by the source base station prior to the resetting but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset;

storing the duplicate of the first data identified from the source base station;

after storing, sending the duplicate of the first data to the target base station after the handover; and

sending new data for the terminal to the target base station after sending the duplicate of the first data.

12. The method of claim 11, further comprising:

determining when a session configuration change for the terminal is requested; and

switching the session configuration of the terminal when requested.

13. The method of claim 11, further comprising:

resetting Radio Link Protocol (RLP) for the terminal in response to the switch in the session configuration of the terminal.

14. The method of claim 11, wherein storing the duplicate of the first data comprises storing a predetermined amount of data most recently served to the terminal by the serving base station.

15. The method of claim 11, wherein the sending the stored duplicate of the first data comprises sending the stored duplicate of the first data to the target base station after the handover to avoid retransmission timeout (RTO) of Transmission Control Protocol (TCP).

16. An apparatus for wireless communication, comprising:

means for resetting a connection for a terminal in response to handover from a source base station to a target base station;

means for identifying a duplicate of a first data from the source base station, the first data reported as having been served to the terminal by the source base station prior to resetting the connection but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset;

means for storing the duplicate of the first data identified from the source base station;

means for sending the duplicate of the first data, after storing the duplicate of the first data, to the target base station after the handover; and

means for sending new data for the terminal to the target base station after sending the duplicate of the first data.

17. The apparatus of claim 16, further comprising:

means for determining when a session configuration change for the terminal is requested; and

means for switching the session configuration of the terminal when requested.

18. The apparatus of claim 16, further comprising:

means for resetting Radio Link Protocol (RLP) for the terminal in response to the switch in the session configuration of the terminal.

19. The apparatus of claim 16, wherein the means for storing the duplicate of the first data comprises means for storing a predetermined amount of data most recently served to the terminal by the serving base station.

20. The apparatus of claim 16, wherein the means for sending the duplicate of the first data comprises means for sending the duplicate of the first data to the target base station after the handover to avoid retransmission timeout (RTO) of Transmission Control Protocol (TCP).

21. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code for causing at least one computer to reset a connection for a terminal in response to handover from a source base station to a target base station;

code for causing at least one computer to identify a duplicate of a first data from the source base station, the first data reported as having been served to the terminal by the source base station prior to the reset but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset;

code for causing the at least one computer to store the duplicate of the first data identified from the source base station;

code for causing the at least one computer to send the duplicate of the first data, after storing the duplicate of the first data, to the target base station after the handover; and

code for causing the at least one computer to send new data for the terminal to the target base station after sending the duplicate of the first data.

22. An apparatus for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory and configured;

to reset a connection for a terminal in response to handover from a source base station to a target base station,

to identify a duplicate of a first data from the source base station prior to the handover, in which the first data is reported as having been served to the terminal by the source base station prior to the reset but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset,

to receive the duplicate of the first data that is stored prior to handover from the target base station after the handover, and to receive new data from the target base station after receiving the duplicate data.

23. The apparatus of claim 22, wherein the at least one processor is configured to switch a session configuration of the terminal in response to the handover.

24. The apparatus of claim 22, wherein the at least one processor is configured to discard the duplicate data received from the target base station, and to reassemble packets based on the new data received from the target base station and prior data received from the source base station.

25. A method for wireless communication, comprising:

resetting a connection for a terminal in response to handover from a source base station to a target base station;

identifying a duplicate of a first data from the source base station prior to the handover, in which the first data is reported as having been served to the terminal by the source base station prior to the reset but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset;

receiving the duplicate of the first data that is stored prior to handover from the target base station after the handover; and

receiving new data from the target base station after receiving the duplicate data.

26. The method of claim 25, further comprising:

switching a session configuration of the terminal in response to the handover.

27. The method of claim 25, further comprising:

discarding the duplicate data received from the target base station; and

reassembling packets based on the new data received from the target base station and prior data received from the source base station.

28. An apparatus for wireless communication, comprising:

means for resetting a connection for a terminal in response to handover from a source base station to a target base station;

means for identifying a duplicate of a first data from the source base station prior to the handover, in which the first data is reported as having been served to the terminal by the source base station prior to resetting the connection but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset;

means for receiving the duplicate of the first data that is stored prior to handover from the target base station after the handover; and

means for receiving new data from the target base station after receiving the duplicate data.

29. The apparatus of claim 28, further comprising:

means for switching a session configuration of the terminal in response to the handover.

30. The apparatus of claim 28, further comprising:

means for discarding the duplicate data received from the target base station; and

means for reassembling packets based on the new data received from the target base station and prior data received from the source base station.

31. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code for causing at least one computer to reset a connection for a terminal in response to handover from a source base station to a target base station;

code for causing the at least one computer to identify a duplicate of a first data from the source base station prior to the handover, in which the first data is reported as having been served to the terminal by the source base station prior to the reset but not acknowledged as being received by the terminal, the unacknowledged first data being subject to a purge as a result of the reset;

code for causing the at least one computer to receive a duplicate of the first data that is stored prior to handover from the target base station after the handover; and

code for causing the at least one computer to receive new data from the target base station after receiving the duplicate data.