A method of a first distributed unit (DU) may comprise: receiving a measurement report from a user equipment (UE) through a serving (S)-master cell group (MCG) of the first DU; transmitting a first message including the measurement report to a first central unit (CU); performing a configuration operation of a target (T)-MCG between the first DU and the first CU; and transmitting configuration information of the T-MCG for the first DU to the UE, wherein the T-MCG for the first DU is configured with the UE based on the configuration information of the T-MCG.