Methods and apparatuses are described for wireless communication supporting carrier aggregation. The method includes monitoring, by a user equipment (UE), a downlink control channel in a first search space to receive first control information in the first search space; monitoring, by the UE, a downlink control channel in a second search space to receive second control information in the second search space; and receiving, by the UE, data on a first carrier based on the received first control information or on a second carrier based on the received second control information.