| CPC H04W 76/36 (2018.02) [H04W 36/0061 (2013.01); H04W 76/27 (2018.02); H04W 92/20 (2013.01)] | 11 Claims |

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1. A method performed by a target base station for a mobility of a user equipment (UE) from a source base station, the method comprising:
receiving, by a central unit (CU)-control plane (CP) of the target base station from the source base station, a request message comprising a notification that a dual connection-based mobility is requested,
wherein the dual connection-based mobility is a mobility that maintains a connection with the source base station until releasing the connection with the source base station after a random access to the target base station;
transmitting, by the CU-CP of the target base station to a CU-user plane (UP) of the target base station, a bearer context setup request message comprising a notification that the dual connection-based mobility is requested;
receiving, by the CU-CP of the target base station from the CU-UP of the target base station, a bearer context setup response message;
transmitting, by the CU-CP of the target base station to the source base station, a response message for the request message, the response message comprising a notification that the dual connection-based mobility is accepted;
performing the random access with the UE; and
transmitting, by the CU-CP of the target base station to the source base station, a UE context release message related to releasing a UE context in the source base station, after performing the random access with the UE.
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