Handover In A Wireless Data Packet Communication System That Avoid User Data Loss

• US 20090040982A1
• Filed: 08/06/2008
• Published: 02/12/2009
• Est. Priority Date: 08/08/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tenny, Nathan Edward, Attar, Rashid Ahmed Akbar, Meylan, Arnaud, Grilli, Francesco, Barany, Peter Anthony, Ho, Sai Yiu
• Granted Patent: US 8,451,795 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04L 1/1874 Buffer management
• CPC Class Codes: H04L 1/1896 ARQ related signaling
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04W 36/0033 with transfer of context information
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off

Abstract

An apparatus, method, processor(s), and computer program product avoids user data loss by network-controlled, user equipment assisted handover in a wireless data packet communication system. A wireless receiver receives radio link control (RLC) packet data units (PDUs) from user equipment (UE) being served by a source node. A wireless transmitter commands the UE to handover. A network communication interface transmits RLC Uplink (UL) context from the source node to the target node, and transmits RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs from the source node to the target node.

Claims

1. A method for network controlled handover in a wireless data packet communication system to avoid user data loss, comprising:

in a first session when a first user equipment (UE) is being served by a first node acting as source node that is to be handed over to a second node acting as target node, sending a handover command from the first node to the first user equipment (UE);

transmitting RLC Uplink (UL) context from the first node to the second node; and

transmitting in-transit DL RLC PDUs from the first node to the second node.

2. The method of claim 1, further comprising segmenting Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs) to form the RLC PDUs.

3. The method of claim 1, further comprising:

in a second session when a second user equipment (UE) is being served by the second node acting as source node that is to be handed over to the first node acting as target node, receiving RLC Uplink (UL) context from the first node at the second node;

receive RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs at the first node from the second node;

establishing a new downlink with the second UE; and

completing downlink transmission of failed DL RLC PDUs received from the second node as buffered in-transit DL RLC PDUs.

4. The method of claim 3, further comprising:

receiving an UL initialization message and receiving over-the-air UL RLC PDUs from the second UE at the first node during handover execution of the second session; and

transmitting the UL RLC PDUs from the first node to the second node.

5. The method of claim 3, further comprising:

transmitting an uplink allocation over-the-air from the first node to the second UE during execution handover execution of the second session;

transmitting an RLC uplink status report from the first node to the second UE utilizing the received RLC Uplink Context; and

receiving retransmitted UL RLC PDUs from the second UE during the uplink allocation.

6. The method of claim 3, further comprising:

receiving an RLC downlink status report from the second UE at the first node during handover execution of the second session; and

retransmitting to the second UE from the first node DL RLC packet data units (PDUs) reported as failed that were previously received from the second node.

7. The method of claim 1, further comprising transmitting RLC Uplink (UL) context by sending parameters of Internet Protocol (IP) bearer service network internal routing information for in-transit radio link control (RLC) packet data units (PDUs).

12. The apparatus of claim 1, further comprising a processor for segmenting Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs) to form the RLC PDUs.

8. At least one processor for network controlled handover in a wireless data packet communication system to avoid user data loss, comprising:

a first module for, in a first session when a first user equipment (UE) is being served by a first node acting as source node that is to be handed over to a second node acting as target node, sending a handover command from the first node to the first user equipment (UE);

a second module for transmitting RLC Uplink (UL) context from the first node to the second node; and

a third module for transmitting RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs from the first node to the second node.

9. A computer program product for network controlled handover in a wireless data packet communication system to avoid user data loss, comprising:

a computer-readable storage medium comprising,

a first set of codes for causing a computer, in a first session when a first user equipment (UE) is being served by a first node acting as source node that is to be handed over to a second node acting as target node, to send a handover command from the first node to the first user equipment (UE);

a second set of codes for causing the computer to transmit RLC Uplink (UL) context from the first node to the second node; and

a third set of codes for causing the computer to transmit RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs from the first node to the second node.

10. An apparatus for network controlled handover in a wireless data packet communication system to avoid user data loss, comprising:

means for, in a first session when a first user equipment (UE) is being served by a first node acting as source node that is to be handed over to a second node acting as target node, sending a handover command from the first node to the first user equipment (UE);

means for transmitting RLC Uplink (UL) context from the first node to the second node; and

means for transmitting RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs from the first node to the second node.

11. An apparatus for network controlled handover in a wireless data packet communication system to avoid user data loss, comprising:

a wireless transmitter for, in a first session when a first user equipment (UE) is being served by a first node acting as source node that is to be handed over to a second node acting as target node, sending a handover command from the first node to the first user equipment (UE); and

a network communication interface for transmitting RLC Uplink (UL) context from the first node to the second node, and for transmitting RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs from the first node to the second node.

13. The apparatus of claim 11, further comprising:

in a second session when a second user equipment (UE) is being served by the second node acting as source node that is to be handed over to the first node acting as target node, receiving RLC Uplink (UL) context from the first node at the second node;

a wireless receiver for receiving RLC Downlink (DL) initialization message and buffered in-transit DL RLC PDUs from the first node to the second node; and

the wireless transmitter for establishing a new downlink with the second UE and for completing downlink transmission of failed DL RLC PDUs received from the second node as buffered in-transit DL RLC PDUs.

14. The apparatus of claim 13, further comprising:

the wireless receiver for receiving an UL initialization message and for receiving over-the-air UL RLC PDUs from the second UE at the first node during handover execution of the second session; and

the network communication interface for transmitting the UL RLC PDUs from the first node to the second node.

15. The apparatus of claim 13, further comprising:

the wireless transmitter for transmitting an uplink allocation over-the-air from the first node to the second UE during execution handover execution of the second session;

transmitting an RLC uplink status report from the first node to the second UE utilizing the received RLC Uplink Context; and

receiving retransmitted UL RLC PDUs from the second UE during the uplink allocation.

16. The apparatus of claim 13, further comprising:

the wireless receiver for receiving an RLC downlink status report from the second UE at the first node during handover execution of the second session; and

the wireless transmitter for retransmitting to the second UE from the first node DL RLC packet data units (PDUs) reported as failed that were previously received from the second node.

17. The apparatus of claim 11, further comprising the network communication interface for transmitting RLC Uplink (UL) context by sending parameters of Internet Protocol (IP) bearer service network internal routing information for in-transit radio link control (RLC) packet data units (PDUs).

18. A method for user equipment assisted handover in a wireless data packet communication system to avoid user data loss, comprising:

synchronizing a user equipment (UE) to a target node in response to receiving a handover command from a serving source node;

receiving over-the-air an RLC status report from the target node based upon RLC Uplink (UL) context previously transmitted from the source node to the target node; and

receiving in-transit RLC PDUs from the target node previously transmitted from the source node to the target node based upon RLC Downlink (DL) initialization message.

19. The method of claim 18, further comprising:

transmitting over-the-air RLC PDUs from the UE to the target node during handover execution; and

receiving downlink RLC PDUs at the UE from the source node previously transmitted from the target node.

20. The method of claim 18, further comprising segmenting Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs) to form the RLC PDUs.

21. The method of claim 18, further comprising:

receiving an uplink allocation over-the-air at the UE from the target node;

receiving an RLC uplink status report at the UE from the target node utilizing the received RLC Uplink Context; and

retransmitting RLC PDUs from the UE to the target node during the uplink allocation responsive to the RLC uplink status report.

22. The method of claim 18, further comprising:

transmitting an RLC status report from the UE to the target node; and

receiving at the UE from the target node retransmitted RLC packet data units (PDUs) reported as failed that the target node previously received from the source node.

23. The method of claim 18, further comprising receiving over-the-air RLC status report from the target node based upon RLC Uplink (UL) context comprising parameters of Internet Protocol (IP) bearer service network internal routing information for in-transit radio link control (RLC) packet data units (PDUs).

24. At least one processor for user equipment assisted handover in a wireless data packet communication system to avoid user data loss, comprising:

a first module for synchronizing a user equipment (UE) to a target node in response to receiving a handover command from a serving source node;

a second module for receiving over-the-air an RLC status report from the target node based upon RLC Uplink (UL) context previously transmitted from the source node to the target node; and

a third module for receiving in-transit RLC PDUs from the target node previously transmitted from the source node to the target node based upon RLC Downlink (DL) initialization message.

25. A computer program product for user equipment assisted handover in a wireless data packet communication system to avoid user data loss, comprising:

a computer-readable storage medium comprising,

a first set of codes for causing a computer to synchronize a user equipment (UE) to a target node in response to receiving a handover command from a serving source node;

a second set of codes for causing the computer to receive over-the-air an RLC status report from the target node based upon RLC Uplink (UL) context previously transmitted from the source node to the target node; and

a third set of codes for causing the computer to receive in-transit RLC PDUs from the target node previously transmitted from the source node to the target node based upon RLC Downlink (DL) initialization message.

26. An apparatus for user equipment assisted handover in a wireless data packet communication system to avoid user data loss, comprising:

means for synchronizing a user equipment (UE) to a target node in response to receiving a handover command from a serving source node;

means for receiving over-the-air an RLC status report from the target node based upon RLC Uplink (UL) context previously transmitted from the source node to the target node; and

means for receiving in-transit RLC PDUs from the target node previously transmitted from the source node to the target node based upon RLC Downlink (DL) initialization message.

27. An apparatus for user equipment assisted handover in a wireless data packet communication system to avoid user data loss, comprising:

a wireless receiver for,

synchronizing a user equipment (UE) to a target node in response to receiving a handover command from a serving source node;

receiving over-the-air an RLC status report from the target node based upon RLC Uplink (UL) context previously transmitted from the source node to the target node; and

receiving in-transit RLC PDUs from the target node previously transmitted from the source node to the target node based upon RLC Downlink (DL) initialization message.

28. The apparatus of claim 27, further comprising:

a wireless transmitter for transmitting over-the-air RLC PDUs from the UE to the target node during handover execution; and

the wireless receiver for receiving downlink RLC PDUs at the UE from the source node previously transmitted from the target node.

29. The apparatus of claim 27, further comprising a controller for segmenting Packet Data Convergence Protocol (PDCP) Service Data Units (SDUs) to form the RLC PDUs.

30. The apparatus of claim 27, further comprising:

the wireless receiver for receiving an uplink allocation over-the-air at the UE from the target node, and for receiving an RLC uplink status report at the UE from the target node utilizing the received RLC Uplink Context; and

a wireless transmitter for retransmitting RLC PDUs from the UE to the target node during the uplink allocation responsive to the RLC uplink status report.

31. The apparatus of claim 27, further comprising:

a wireless transmitter for transmitting an RLC status report from the UE to the target node; and

the wireless receiver for receiving at the UE from the target node retransmitted RLC packet data units (PDUs) reported as failed that the target node previously received from the source node.

32. The apparatus of claim 27, further comprising the wireless receiver for receiving over-the-air RLC status report from the target node based upon RLC Uplink (UL) context comprising parameters of Internet Protocol (IP) bearer service network internal routing information for in-transit radio link control (RLC) packet data units (PDUs).