FACILITATING METHOD FOR HANDOVER OF A MOBILE COMMUNICATION DEVICE

• US 20100002650A1
• Filed: 08/21/2007
• Published: 01/07/2010
• Est. Priority Date: 08/22/2006
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ahluwalia, Jagdeep Singh
• Granted Patent: US 8,228,869 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04L 1/1664 the supervisory signal being transmitted together with payload signals; piggybacking
• CPC Class Codes: H04L 1/1874 Buffer management
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04W 36/0005 Control or signalling for completing the hand-off
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off

Abstract

In a method of facilitating handover of a mobile communication device from a source node to a target node, the method includes buffering received user data packets in the target node during handover prior to sending to the mobile device.

Claims

1. A method of facilitating handover of a mobile communication device from a source node to a target node, the method comprising buffering received user data packets in the target node during handover prior to sending to the mobile device.

2. A method according to claim 1, wherein said buffering buffers downlink data packets forwarded from the source node during handover.

3. A method according to claim 2, further comprising sending the forwarded downlink data packets from the target node to the mobile device after completion of handover from the source node to the target node.

4. A method according to claim 3, further comprising ordering data packets in the target node prior to said sending.

5. A method according to claim 4, further comprising receiving data packets forwarded from the source node via a first interface, and receiving data packets from an external source via a second interfaces, wherein said ordering is performed based on the interface from which the data packets are received.

6. A method according to claim 5, wherein the ordering is performed such that the data packets received from the first interface are sent to the mobile device by the target node before data packets received from the second interface.

7. A method according to claim 5, wherein said receiving data packets from an external source via a second interface receives the data packets from the core network.

8. A method according to claim 1, performed by a base station of a mobile telecommunication network.

9. A method according to claim 8 performed by an eNodeB of a 3GPP-type network.

10. A method according to claim 1, further comprising receiving a handover request and sending a handover responses, wherein said buffering is performed between sending said handover response and handover completion.

65. A computer program or a computer program product comprising instructions which when executed by one or more processors of a telecommunications network cause the one or more processors to perform a method according to claim 1.

11. A target node of a mobile communication system comprising:

means for receiving a handover request, requesting handover of a mobile device from a source node to the target node;

means for sending a handover response;

means for receiving user data packets during handover, for transmission to the mobile device;

means for sending user data packets to the mobile device after handover completion; and

means for buffering the received user data packets during handover prior to sending to the mobile device.

12. A target node of a mobile communication system comprising:

a first receiver operable to receive a handover request, requesting handover of a mobile device from a source node to the target node;

a first transmitter operable to transmit a handover response;

a second receiver operable to receive user data packets during handover, for transmission to the mobile device;

a second transmitter operable to transmit user data packets to the mobile device after handover completion; and

a buffer operable to buffer the received user data packets during handover prior to transmission to the mobile device.

13. A method of facilitating handover of a mobile communication device from a source node to a target node, the method comprising, in response to receipt of a handover response at the source node, stopping forwarding of downlink user data packets to the mobile communication device while continuing to receive uplink user data packets from the user device and sending a handover command to the mobile device.

14. A method according to claim 13, further comprising forwarding to the target node downlink user data packets received after said stopping.

15. A method according to claim 14 wherein the data packets are forwarded to the target node from the source node via a first interface and wherein data packets are received by the target node from an external source via a second interface and further comprising ordering the received packets based on the interface from which the data packets are received.

16. A method according to claim 13, wherein said source and target nodes comprise base stations.

17. A source node of a mobile communication system comprising:

means for forwarding downlink data packets to a mobile communication device;

means for receiving uplink user data packets from the mobile communication device;

means for receiving a handover response indicating handover of the mobile communication device from the source node to a target node;

means for controlling said forwarding means, in response to receipt of said handover response, so that said forwarding means stops forwarding said downlink user data packets to the mobile communication device whilst said receiving means continues to receive uplink user data packets from the user device; and

means for sending a handover command to the mobile device after said forwarding means stops forwarding said downlink user data packets.

18. A method of facilitating handover of a mobile communication device from a source node to a target node during which handover user data packets are forwarded from the source node to the target node, the method comprising receiving forwarded data packets at the target node from the source node via a first interface and receiving data packets from an external source via a second interface and ordering the data packets for transmission to the mobile communication device based on the interface from which the data packets are received.

19. A method according to claim 18, wherein the ordering is performed such that the data packets received from the first interface are sent to the mobile device by the target node before data packets received from the second interface.

20. A method according to claim 18, wherein said receiving data packets from an external source via a second interface receives the data packets from the core network.

21. A method according to claim 18, performed by a base station of a mobile telecommunication network.

22. A target node of a communication network comprising:

a first interface for receiving, during handover of a mobile device from a source node to the target node, downlink user data packets from the source node;

a second interface for receiving user data packets for the mobile device from an external source; and

means for ordering the data packets for transmission to the mobile communication device based on the interface from which the data packets are received.

23. A communication method performed in a source node of a telecommunication system, the method comprising:

receiving Service Data Units, SDUs, for transmission to a mobile communication device;

storing a copy of the SDUs in an SDU management buffer;

passing the SDUs to a concatenation and segmentation unit to generate Protocol Data Units, PDUs;

storing the PDUs in a transmit buffer for transmission to the mobile communication device;

sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the mobile communication device;

in response to the receipt of the feedback message, removing the identified SDU from the SDU management buffer; and

during handover of the mobile communication device from the source node to a target node, forwarding SDUs for the mobile communication device to the target node in dependence upon the SDUs stored in said SDU management buffer.

24. A method according to claim 23, further comprising receiving a handover response from a target node and in response stopping forwarding of data packets to the mobile communication device and forwarding SDUs stored in said SDU management buffer to the target node.

25. A method according to claim 24, further comprising continuing to receive at said source node data packets from the mobile communication device after stopping forwarding data packets to the mobile communication device from said source node.

26. A method according to claim 25, further comprising checking if those data packets received at the source node from the mobile communication device after stopping forwarding of data packets to the mobile device, include acknowledgements for any AM PDUs and, if appropriate, sending another feedback message to the SDU management buffer to remove an SDU from the SDU management buffer before it is forwarded to the target node.

27. A method according to claim 23, wherein for AM mode data, said feedback message is sent to said SDU management buffer from a PDU retransmission Buffer and management entity after the PDU retransmission buffer and management entity has received acknowledgement receipts for all the PDUs corresponding to the SDU.

28. A method according to claim 23, wherein for UM mode data, said feedback message is sent to said SDU management buffer by said transmit buffer after all the PDUs corresponding to the SDU have been forwarded from the transmission buffer.

29. A method according to claim 23, performed in the Outer ARQ layer of a 3GPP communication system.

30. A method according to claim 29, wherein a Radio Resource Control, RRC, layer in the source node receives a handover response from the target node and instructs the Outer ARQ layer to stop the downlink user data transmission.

31. A method according to claim 30, wherein said RRC layer instructs said ARQ layer to send a status report to the ARQ layer of the mobile telecommunication device before instructing the stopping of the downlink user data transmission.

32. A method according to claim 30, wherein said RRC layer instructs said Outer ARQ layer to forward downlink SDUs from said SDU management buffer to said target node after stopping the downlink user data transmission.

33. A method according to claim 23, further comprising receiving a status report from the mobile communication device and using the status report to select which SDUs from the SDU management buffer are forwarded to the target node.

34. A source node of a telecommunication system, the source node comprising:

means for receiving Service Data Units, SDUs, for transmission to a mobile communication device;

an SDU management buffer for storing a copy of the SDUs;

a concatenation and segmentation unit for generating Protocol Data Units, PDUs from the SDUs;

a transmission buffer for storing the PDUs prior to transmission to the mobile communication device;

means for sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the mobile communication device;

means for removing, in response to the receipt of the feedback message, the identified SDU from the SDU management buffer; and

means for forwarding, during handover of the mobile communication device from the source node to a target node, SDUs for the mobile communication device to the target node in dependence upon the SDUs stored in said SDU management buffer.

35. A communication method performed in a mobile communication device of a telecommunication system, the method comprising:

receiving Service Data Units, SDUs, for transmission to a source node of the telecommunication system;

storing a copy of the SDUs in an SDU management buffer;

passing the SDUs to a concatenation and segmentation unit to generate Protocol Data Units, PDUs;

storing the PDUs in a transmit buffer for transmission to the source node;

sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the source node;

in response to the receipt of the feedback message, removing the identified SDU from the SDU management buffer;

receiving a status report from the source node;

receiving a handover command from the source node after receiving the status report; and

after completing handover to a target node, using the received status report to control which SDUs are passed to the concatenation and segmentation unit to form PDUs for transmission to the target node.

36. A method according to claim 35, further comprising receiving downlink user data packets from the source node and wherein in response to receiving said handover command, sending a status report to the source node indicating the downlink user data packets that have been received by the mobile communication device and then stopping forwarding of PDUs from the transmission buffer to the source node.

37. A method according to claim 35, wherein a Radio Resource Control, RRC, layer in the mobile communication device receives said handover command from the source node and in response instructs the Outer ARQ layer in the mobile communication device to stop the uplink user data transmission.

38. A method according to claim 37, wherein said RRC layer of said mobile communication device instructs said ARQ layer of the mobile communication device to send said status report to the ARQ layer of the source node before instructing the stopping of the uplink user data transmission.

39. A mobile communication device comprising:

means for receiving Service Data Units, SDUs, for transmission to a source node of the telecommunication system;

an SDU management buffer for storing a copy of the SDUs;

a concatenation and segmentation unit for generating Protocol Data Units, PDUs from the SDUs;

a transmit buffer for storing the PDUs prior to transmission to the source node;

means for sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the source node;

means for removing, in response to the receipt of the feedback message, the identified SDU from the SDU management buffer;

means for receiving a status report from the source node;

means for receiving a handover command from the source node after receiving the status report; and

means for using, after completing handover to a target node, the received status report to control which SDUs are passed to the concatenation and segmentation unit to form PDUs for transmission to the target node.

40. A method performed by a source node of a telecommunication node, the method comprising:

buffering downlink user data packets for transmission to a mobile communication device in a buffer;

sending downlink user data packets to the mobile communication device;

receiving a handover response indicating handover of the mobile communication device to a target node; and

selectively forwarding user data packets from said buffer to said target node in dependence upon an RLC status report or HARQ feedback information.

41. A method according to claim 40, wherein said RLC status report or said HARQ feedback information is received from said mobile communication device.

42. A method according to claim 40, wherein said selectively forwarding selectively forwards user data packets from said buffer to said target node in dependence upon an RLC status report.

43. A method according to claim 40, wherein said selectively forwarding selectively forwards user data packets from said buffer to said target node in dependence upon HARQ feedback information.

44. A communication method performed in a source node of a telecommunication system, the method comprising:

receiving Service Data Units, SDUs, for transmission to a mobile communication device;

storing a copy of the SDUs in an SDU management buffer;

passing the SDUs to a concatenation and segmentation unit to generate Protocol Data Units, PDUs;

storing the PDUs in a transmit buffer for transmission to the mobile communication device;

sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the mobile communication device;

in response to the receipt of the feedback message, removing the identified SDU from the SDU management buffer; and

during handover of the mobile communication device from the source node to a target node, selectively forwarding SDUs for the mobile communication device to the target node in dependence upon an RLC status report or HARQ feedback information.

45. A source node of a telecommunication node, the source node comprising:

a buffer for buffering downlink user data packets for transmission to a mobile communication device;

means for sending downlink user data packets to the mobile communication device;

means for receiving a handover response indicating handover of the mobile communication device to a target node; and

means for selectively forwarding user data packets from said buffer to said target node in dependence upon an RLC status report or HARQ feedback information.

46. A source node of a telecommunication system, the source node comprising:

means for receiving Service Data Units, SDUs, for transmission to a mobile communication device;

an SDU management buffer for storing a copy of the SDUs;

a concatenation and segmentation unit for generating Protocol Data Units, PDUs;

a transmit buffer for storing the PDUs for transmission to the mobile communication device;

means for sending a feedback message to the SDU management buffer identifying an SDU that can be removed from the SDU management buffer when, for Unacknowledge Mode, UM, data, the PDUs corresponding to that SDU have been forwarded from the transmission buffer or when, for Acknowledge Mode, AM, data, receipt of the PDUs corresponding to that SDU have been acknowledged by the mobile communication device;

means for removing, in response to the receipt of the feedback message, the identified SDU from the SDU management buffer; and

means for selectively forwarding, during handover of the mobile communication device from the source node to a target node, SDUs for the mobile communication device to the target node in dependence upon an RLC status report or HARQ feedback information.

47. A method of facilitating handover of a mobile communication device from a source node to a target node, the method comprising:

at the source node, in response to receiving a handover response from the target node;

sending a status packet to the mobile communication device and after sending the status packet stopping the transmission of downlink user data from the source node to the mobile communication device; and

at the mobile communication device, in response to receiving a handover command from the source node;

sending a status packet to the source node and after sending the status packet stopping the transmission of uplink user data from the mobile communication device to the source node.

48. A method according to claim 47, further comprising, at the source node, continuing to receive uplink user data packets from the mobile communication device after stopping the transmission of downlink user data from the source node to the mobile communication device.

49. A method according to claim 47, wherein said source node transmits said handover command to said mobile communication device after stopping the transmission of said downlink user data.

50. A method according to claim 47, further comprising forwarding user data packets from the source node to the target node after the source node stops forwarding the user data packets to the mobile communication device.

51. A method according to claim 50, further comprising using information contained in the status packet received by the source node from the mobile communication device to control the forwarding of user data packets from the source node to the target node.

52. A method according to claim 51, further comprising using the information contained in the status packet received by the source node from the mobile communication device to select user data packets held by the source node to be forwarded from the source node to the target node.

53. A method according to claim 47, wherein said source node comprises a base station.

54. A method according to claim 47, wherein said stopping is performed such that no downlink user data packets are transmitted to the mobile communication device after sending said status report.

55. A source node of a telecommunication system, the source node comprising:

means for receiving uplink user data packets from a mobile communication device;

means for transmitting downlink user data packets to the mobile communication device;

means for receiving a handover response indicating handover of the mobile communication device from the source node to a target node;

means for generating, in response to receipt of said handover response, a status report indicating uplink data packets received from the mobile communication device;

means for sending the generated status report to the mobile communication device; and

means for stopping the transmission of downlink user data from the source node to the mobile communication device after sending said status report.

56. A mobile communication device comprising:

means for receiving downlink user data packets from a source node of a telecommunication system;

means for transmitting uplink user data packets to said source node;

means for receiving a handover command from the source node indicating handover to a target node of the telecommunication system;

means for generating, in response to receiving said handover command, a status packet indicating downlink user data packets that have been received;

means for sending the status report to the source node; and

means for stopping the transmission of uplink user data packets from the mobile communication device to the source node after sending said status report.

57. A method of facilitating handover of a mobile communication device from a source node to a target node, the method being performed in the source node and comprising:

receiving a status packet from the mobile communication device; and

forwarding user data packets to the target node in dependence upon information contained in the received status packet.

58. A method according to claim 57, performed in response to receiving a handover response from the target node.

59. A method according to claim 57, further comprising stopping the transmission of downlink user data from the source node to the mobile communication device.

60. A method according to claim 59, further comprising transmitting a handover command to said mobile communication device after stopping the transmission of said downlink user data;

61. A method according to claim 59, further comprising sending a status report to the mobile communication device indicating uplink user data packets received from the mobile communication device prior to stopping said transmission.

62. A method according to claim 59, wherein said receiving said status report happens after said stopping.

63. A method according to claim 57, wherein the source node is comprises a base station.

64. A source node of a telecommunication system, the source node comprising:

means for receiving a handover response from a target node indicating handover of a mobile communication device from the source node to the target node;

means for stopping, in response to receiving said handover response, transmission of downlink user data from the source node to the mobile communication device;

means for transmitting a handover command to said mobile communication device after stopping the transmission of said downlink user data;

means for receiving a status packet from the mobile communication device; and

means for forwarding user data packets to the target node in dependence upon information contained in the received status packet.