Methods for operating a Base Station (BS) and a User Equipment (UE) in a wireless communication system using a primary frequency and one or more secondary frequencies, and apparatuses for the BS and UE for carry out the methods, are provided. The method for operating the BS includes determining whether to activate or deactivate at least one of the one or more secondary frequencies, and transmitting a message comprising a bitmap indicating the activation or deactivation of the at least one of the one or more secondary frequencies to the UE. The method for operating the UE includes receiving a message comprising a bitmap indicating activation or deactivation of at least one of the one or more secondary frequencies from the BS, and activating or deactivating the at least one of the one or more secondary frequencies based on the received message.