Disclosed is a communication apparatus. The communication apparatus comprises a setup unit and a transmission unit. The setup unit is used for setting up a first search region and a second search region of one PRB set of multiple physical resources block PRB sets in a data range of a first component carrier, wherein the second search region is set by a carrier wave indication field CIF value set by a first component carrier, the first search region comprises one ore multiple mapping candidates of first down link control information used by the first component carrier, the second search regioncomprises one ore multiple mapping candidates of second down link control information used by the second component carrier. The transmission unit utilizes the first search region to send the first down link control information and utilizes the second search region to send the second down link control information.