Provided is a method of performing a radio resource control (RRC) connection resume procedure by a user equipment (UE), the method including receiving an RRC release message including suspend configuration information, transiting to an RRC_INACTIVE mode, based on the RRC release message, performing an RRC connection resume procedure with a first base station if a certain condition is satisfied, receiving, from the first base station, an RRC resume message including secondary cell group (SCG) configuration information, and performing a random access procedure with a second base station, based on the SCG configuration information.