Method and apparatus for managing data radio bearers for dual connectivity in wireless communication system

1. A method for establishing, by a master eNodeB (MeNB) in dual connectivity, data radio bearers (DRBs) in a wireless communication system, the method comprising:

receiving an E-RAB setup request message from a mobility management entity (MME);

transmitting a request message, which includes information on E-UTRAN radio access bearers (E-RABs) to be set up, to a secondary eNB (SeNB) in dual connectivity through an X2 interface;

receiving a response message, which includes radio resource control (RRC) connection reconfiguration related information based on the E-RABs to be set up, as a response to the request message from the SeNB through the X2 interface; and

upon receiving the response message, transmitting an RRC connection reconfiguration message, which includes the RRC connection reconfiguration related information received via the response message, to a user equipment (UE).

2. The method of claim 1 , wherein the request message is a newly defined X2-E-RAB setup request message.

3. The method of claim 1 , wherein the request message is included in an existing X2 message.

4. The method of claim 1 , wherein the response message is a newly defined X2-E-RAB setup response message.

5. The method of claim 1 , wherein the RRC connection reconfiguration related information includes at least one of a radio bearer quality of service (QoS), a session management request, and an evolved packet system (EPS) RB identity.

6. The method of claim 1 , wherein the RRC connection reconfiguration message indicates that corresponding DRBs correspond to the SeNB.

7. The method of claim 1 , further comprising:

receiving an RRC connection reconfiguration complete message from the UE.

8. The method of claim 1 , further comprising:

transmitting a newly defined X2-E-RAB setup confirm message, which informs the SeNB that E-RAB setup procedure of the SeNB is completed, to the SeNB through the X2 interface.

9. A method for modifying, by a master eNodeB (MeNB) in dual connectivity, data radio bearers (DRBs) in a wireless communication system, the method comprising:

receiving an E-RAB modify request message from a mobility management entity (MME);

transmitting an X2-E-RAB modify request message, which includes information on E-UTRAN radio access bearers (E-RABs) to be modified, to a secondary eNB (SeNB) in dual connectivity through an X2 interface;

receiving an X2-E-RAB modify response message, which includes radio resource control (RRC) connection reconfiguration related information based on the E-RABs to be modified, as a response to the X2-E-RAB modify request message from the SeNB through the X2 interface; and

upon receiving the X2-E-RAB modify response message, transmitting an RRC connection reconfiguration message, which includes the RRC connection reconfiguration related information received via the X2-E-RAB modify response message, to a user equipment (UE).

10. The method of claim 9 , further comprising:

receiving an RRC connection reconfiguration complete message from the UE.

11. The method of claim 9 , further comprising:

transmitting a newly defined X2-E-RAB modify confirm message, which informs the SeNB that E-RAB modification procedure of the SeNB is completed, to the SeNB through the X2 interface.

12. A method for releasing, by a master eNodeB (MeNB) in dual connectivity, data radio bearers (DRBs) in a wireless communication system, the method comprising:

receiving an E-RAB release command message from a mobility management entity (MME);

transmitting an X2-E-RAB release command message, which includes information on E-UTRAN radio access bearers (E-RABs) to be released, to a secondary eNB (SeNB) in dual connectivity through an X2 interface;

receiving an X2-E-RAB release response message, which includes radio resource control (RRC) connection reconfiguration related information based on the E-RABs to be released, as a response to the X2-E-RAB release command message from the SeNB through the X2 interface; and

upon receiving the X2-E-RAB release response message, transmitting an RRC connection reconfiguration message, which includes the RRC connection reconfiguration related information received via the X2-E-RAB release response message, to a user equipment (UE).

13. The method of claim 12 , further comprising:

receiving an RRC connection reconfiguration complete message from the UE.

14. The method of claim 12 , further comprising:

transmitting a newly defined X2-E-RAB release confirm message, which informs the SeNB that E-RAB release procedure of the SeNB is completed, to the SeNB through the X2 interface.