5. A method, by a user equipment (UE), for switching a secondary evolved NodeB (SeNB) communicating with the UE in a wireless communication system supporting a master eNB (MeNB) and a plurality of SeNBs, the method comprising:communicating with the MeNB and a first SeNB among the plurality of SeNBs;
performing measurement with respect to the plurality of SeNBs including the first SeNB and a second SeNB;
determining whether predetermined switch criteria are satisfied based on a measurement result; and
transmitting, to the MeNB, a switch message indicating switching of a SeNB cooperating with the MeNB for communication with the UE from the first SeNB to the second SeNB, in response to determining that the predetermined switch criteria are satisfied.