Disclosed is a method by a base station in a wireless communication system. The method includes receiving cell measurement information related to the serving and neighboring cells from at least one terminal served by the base station, receiving status information including load information on serving cells of the small cell base station from the small cell base station, determining a secondary cell group (SCG) of the serving cells of the small cell base station that are capable of serving the terminal based on the cell measurement information and the status information and transmitting information on the SCG to the small cell base station.