Method and apparatus for transmitting indication in wireless communication system

1. A method for transmitting an indication in a wireless communication system, the method performed by a user equipment (UE) and comprising:

receiving, from a primary serving cell (PCell) of a master eNodeB (MeNB), cell change information,

wherein the cell change information is information for a target secondary serving cell (SCell) of a target secondary eNB (SeNB), and

wherein the UE supports dual connectivity with the MeNB and the target SeNB;

performing a cell change procedure from a source SCell of a source SeNB to the target SCell of the target SeNB based on the cell change information; and

if the cell change procedure is successfully performed, transmitting, to the PCell, the indication while the UE maintains connection with the PCell,

wherein the indication indicates that the cell change procedure from the source SCell to the target SCell was successfully performed.

2. The method of claim 1 , wherein the PCell and the source SCell are controlled by different eNodeBs (eNBs) respectively, and

wherein the PCell and the target SCell are controlled by different eNBs respectively.

3. The method of claim 1 , wherein the PCell is a macro cell controlled by the MeNB; and

wherein the target SCell is a small cell controlled by the target SeNB.

4. The method of claim 1 , wherein the cell change procedure includes a random access procedure.

5. The method of claim 1 , wherein the cell change information is received via a radio resource control (RRC) connection reconfiguration message.

6. The method of claim 1 , wherein the indication is transmitted via an RRC connection reconfiguration complete message.

7. The method of claim 1 , wherein the UE receives control signaling from the MeNB and receives data from the target SeNB in the dual connectivity, and

wherein an interface between the MeNB and the target SeNB is non-ideal backhaul in the dual connectivity.

8. The method of claim 1 , wherein the UE further supports dual connectivity with the MeNB and the source SeNB.

9. A method for transmitting, an indication in a wireless communication system, the method performed by a user equipment (UE) and comprising:

receiving, from a primary serving cell (PCell) of a master eNB (MeNB), cell change information,

wherein the cell change information is information for a target secondary serving cell (SCell) of a target secondary eNB (SeNB), and

wherein the UE supports dual connectivity with the MeNB and the target SeNB;

performing a cell change procedure from a source SCell of a source SeNB to the target SCell of the target SeNB based on the cell change information; and

if the cell change procedure is not successfully performed, transmitting, to the PCell, the indication while the UE maintains connection with the PCell,

wherein the indication indicates that the cell change procedure from the source SCell to the target SCell has failed.

10. The method of claim 9 , wherein the indication is transmitted via an RRC connection re-establishment request message.

11. The method of claim 9 , wherein the PCell and the target SCell are controlled by different eNodeBs (eNBs) respectively.

12. The method of claim 9 , wherein the cell change procedure includes a random access procedure.

13. The method of claim 9 , wherein the UE receives control signaling from the MeNB and receives data from the target SeNB in the dual connectivity, and

wherein an interface between the MeNB and the target SeNB is non-ideal backhaul in the dual connectivity.

14. The method of claim 9 , wherein the UE further supports dual connectivity with the MeNB and the source SeNB.