Data Forwarding During Handover in a Self-Backhauled Cell

• US 20110075633A1
• Filed: 09/09/2008
• Published: 03/31/2011
• Est. Priority Date: 05/15/2008
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Racz, Andras, Mildh, Gunnar, Johansson, Niklas
• Granted Patent: US 9,338,710 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

A method is implemented in an anchor eNodeB of a network, where the anchor eNodeB communicates with a self-backhauled eNodeB via a radio interface and where the network further includes another eNodeB. The method includes determining whether a user equipment (UE) is being handed off from the first self-backhauled eNodeB to the other eNodeB. The determining is based on: receiving (820) a message from the self-backhauled eNodeB via the radio interface instructing the anchor eNodeB to stop delivering packets that are destined for the UE, or sniffing (1 105, 1 1 10, 1 1 15) into one or more messages sent from the self-backhauled eNodeB to the other eNodeB to identify that the UE is being handed off from the self-backhauled eNodeB to the other eNodeB. The method further includes storing (1 120), based on the determination of whether the UE is being handed off, received packets intended for the UE: and forwarding (1 120) the stored packets to the other eNodeB via a transport network for delivery to the UE.

Claims

1. A method implemented in an anchor base station of a network, where the anchor base station communicates with a self-backhauled base station via a radio interface and where the network further includes another base station, the method comprising:

determining whether a user equipment (UE) is being handed off from the self-backhauled base station to the other base station, where the determining is based on receiving a message from the self-backhauled base station via the radio interface instructing the anchor base station to stop delivering packets that are destined for the UE;

storing, based on the determination of whether the UE is being handed off, received packets intended for the UE; and

forwarding the stored packets to the other base station via a transport network for delivery to the UE.

2. The method of claim 1, where the other base station comprises another anchor base station that communicates with another self-backhauled base station via another radio interface.

3. The method of claim 2, where forwarding the stored packets to the other base station comprises:

forwarding the stored packets to the other anchor base station via the transport network for delivery to the UE via the other self-backhauled base station and the other radio interface.

4. The method of claim 2, further comprising:

allocating an Internet Protocol (IP) address, by the anchor base station, for the self-backhauled base station;

allocating an IP address, by the other anchor base station, for the other self-backhauled base station; and

using the IP addresses to forward the stored packets and signaling communication to the other self-backhauled base station.

5. The method of claim 1, where the determining is further based on analyzing one or more messages sent from the self-backhauled base station to the other base station.

6. A first base station connected to a second base station in a network via a radio interface, where the first base station receives packets destined for a user equipment (UE) on a downlink from the second base station and receives packets on an uplink from the UE, the first base station comprising:

a transceiver configured to;

send a handover request, associated with the UE, via the radio interface to the second base station for delivery to a target handover base station,

receive a handover response from the second base station via the radio interface, where the handover response was sent from the target handover base station,

send a notification message to the second base station instructing the second base station to stop delivering downlink packets destined for the UE;

a memory configured to store packets previously received from the second base station that are destined for the UE; and

a processing unit configured to;

retrieve the packets stored in the memory prior to receipt of the handover response, and

pass the retrieved packets to the transceiver for sending to the second base station via the radio interface for delivery to the target handover base station.

7. The first base station of claim 6, where the first base station comprises a first self-backhauled eNodeB, where the second base station comprises a first anchor eNodeB and where the target handover base station comprises a second self-backhauled eNodeB.

8. The first base station of claim 6, where the first base station comprises a first self-backhauled eNodeB, where the second base station comprises a first anchor eNodeB and where the target handover base station comprises an eNodeB.

9. The first base station of claim 6, where the network comprises an Internet Protocol (IP) transport network.

10. The first base station of claim 9, where the first self-backhauled eNodeB communicates with the IP transport network via the radio interface (135) to the first anchor eNodeB and where the first anchor eNodeB acts as an intermediate node between the first self-backhauled eNodeB and the IP transport network.

11. The first base station of claim 6, where the transceiver is further configured to:

send a second message to the second base station notifying the second base station to begin forwarding packets that are destined for the UE.

12. The first base station of claim 11, where the notification message and the second message are sent based on an X2 signaling protocol or based on a Radio Resource Control (RRC) protocol.

13. A system associated with a cellular network, the system comprising:

a first base station connected to a user equipment (UE) and to a second base station via a first radio interface;

the second base station connected to a transport network;

a third base station connected to the transport network;

a fourth base station connected to the third base station via a second radio interface, where the fourth base station is configured to provide wireless service to the UE;

where the first base station is configured to;

send a handover request associated with the UE to the fourth base station via the second base station, the transport network, and the third base station,

receive a handover response from the fourth base station via the third base station, the transport network and the second base station, where the handover response grants handover of the UE from the first base station to the fourth base station,

send a notification message to the second base station instructing the second base station to stop delivering packets destined for the UE to the first base station, and

forward packets destined for the UE to the fourth base station via the second base station, the transport network and the third base station for delivery to the UE,

where the second base station is configured to;

store received packets destined for the UE subsequent to receipt of the notification message.

14. The system of claim 13, where the second base station is further configured to:

analyze bypassing messages sent from the first base station to determine whether handover has been granted to hand off the UE from the first base station to the fourth base station.

15. The system of claim 14, where the second base station is further configured to:

forward packets destined for the UE to the fourth base station via the transport network and the third base station based on the analysis of the bypassing messages.

16. The system of claim 14, where, when analyzing the bypassing messages, the second base station is further configured to:

inspect contents of the bypassing messages to determine whether handover has been granted to hand off the UE from the first base station to the fourth base station.

17. The system of claim 13, where the second base station is further configured to:

inspect the received packets'"'"' inner tunnel header to identify a UE bearer.

18. The system of claim 13, where the first base station is further configured to:

send a message to the second base station instructing the second base station to begin forwarding stored packets to the fourth base station for delivery to the UE.

19. The system of claim 18, where the message to the second base station and the notification message may be sent based on a X2 signaling protocol or a Radio Resource Control (RRC) signaling protocol.

20. The system of claim 18, where the second base station is further configured to:

forward the stored packets and incoming downlink packets destined for the UE to the fourth base station via the transport network and the third base station when the message is received.

21. The system of claim 13, where the first base station comprises a first self-backhauled eNodeB, where the second base station comprises a first anchor eNodeB, where the third base station comprises a second anchor eNodeB, and where the fourth base station comprises a second self-backhauled eNodeB.

22. The system of claim 13, where the second base station acts as an intermediate node between the transport network and the first base station and where the third base station acts as an intermediate node between the transport network and the fourth base station.