Method for updating ca in cloud lan environment

Disclosed is a method for updating a CA, the method comprising the steps of: receiving a plurality of CACs which are broadcasted from a plurality of RRUs by a user equipment which is in a RRC idle state; comparing a plurality of CAIs generated from the plurality of CACs with a CAI list previously stored in the user equipment; determining to update a CA indicating a position of the user equipment when a CAI which does not exist in the CAI list is identified from among the plurality of CAIs as a result of the comparison; and transmitting a CAU request message which makes a request for updating the CA of the user equipment to a new CA corresponding to the CAI which does not exist in the CAI list when the user equipment is in a RRC connection state.