A method is provided for operating by a user equipment (UE) connected with a master base station (BS) and a secondary BS in a wireless communication system. The UE configures a first cell supporting a contention based random access and a second cell other than the first cell. The first cell and the second cell are associated with the secondary BS. The UE determines whether a radio link problem is occurred on the first cell or the second cell. The UE indicates the radio link problem to an upper layer only if the radio link problem occurs on the first cell.