A communication apparatus comprising: a receiver configured to receive configuration information from a base station apparatus, the configuration information including • a first component carrier, CC, identification index of an added CC, • a second component carrier, CC, identification index indicating a downlink component carrier used for a transmission by the base station apparatus of physical downlink control information, including resource allocation information of data transmitted in the added CC and • a carrier indicator field value, CIF value, assigned to the added CC; and circuitry configured to configure the downlink component carrier based on the second component carrier identification index indicated by the configuration information, and to add a correspondence relationship between the CIF value and the first component carrier identification index into one-to-one correspondence relationships between one or more CIF values and one or more component carrier identification indices based on the CIF value indicated by the configuration information; wherein the one-to-one correspondence relationships are maintained when the correspondence relationship between the CIF value and the first component carrier identification index is added, wherein the correspondence relationship between the CIF value and the first component carrier identification index is deleted based on further configuration information, received from the base station apparatus, indicating the deletion of the added CC, while maintaining the one-to-one correspondence relationships of undeleted component carriers. a receiver configured to receive configuration information from a base station apparatus, the configuration information including • a first component carrier, CC, identification index of an added CC, • a second component carrier, CC, identification index indicating a downlink component carrier used for a transmission by the base station apparatus of physical downlink control information, including resource allocation information of data transmitted in the added CC and • a carrier indicator field value, CIF value, assigned to the added CC; and • a first component carrier, CC, identification index of an added CC, • a second component carrier, CC, identification index indicating a downlink component carrier used for a transmission by the base station apparatus of physical downlink control information, including resource allocation information of data transmitted in the added CC and • a carrier indicator field value, CIF value, assigned to the added CC; and circuitry configured to configure the downlink component carrier based on the second component carrier identification index indicated by the configuration information, and to add a correspondence relationship between the CIF value and the first component carrier identification index into one-to-one correspondence relationships between one or more CIF values and one or more component carrier identification indices based on the CIF value indicated by the configuration information; wherein the one-to-one correspondence relationships are maintained when the correspondence relationship between the CIF value and the first component carrier identification index is added, wherein the correspondence relationship between the CIF value and the first component carrier identification index is deleted based on further configuration information, received from the base station apparatus, indicating the deletion of the added CC, while maintaining the one-to-one correspondence relationships of undeleted component carriers. <EOS>