A terminal apparatus which for communicating with a base station apparatus using a plurality of component carriers including at least a first component carrier and a second component carrier, the terminal apparatus comprising: a decoder that is adapted to store, in a retransmission buffer, first and second downlink data respectively received in the first and second component carriers, wherein a first configuration pattern of uplink and downlink subframes is set for the first component carrier and a second configuration pattern of uplink and downlink subframes is set for the second component carrier; wherein the first configuration pattern is one of a plurality of first configuration patterns with first indices and the second configuration pattern is one of a plurality of second configuration patterns with second indices, wherein the decoder is further adapted to specify a reference index of a reference configuration pattern of uplink and downlink subframes based on a plurality of combinations of the first indices and the second indices, wherein the reference index is associated with one of the first index of the set first configuration pattern, the second index of the set second configuration pattern and a third index of a third configuration pattern of a plurality of third configuration patterns of uplink and downlink subframes, which neither the first index of the set first configuration pattern nor the second index of the set second configuration pattern, and wherein the decoder is further adapted to store the second downlink data in the retransmission buffer in reference to a maximum number of downlink hybrid automatic repeat request, HARQ, retransmission processes executable in the reference configuration pattern specified with the reference index, and is adapted to decode the first and second downlink data; a signal generator that is adapted to generate a first response signal using a result of error detection of the first downlink data and a second response signal using a result of error detection of the second downlink data; and a transmitter that is adapted to transmit the second response signal in the first component carrier at a timing of an uplink subframe of the reference configuration pattern with the specified reference index, when the first configuration pattern and the second configuration pattern are different. a decoder that is adapted to store, in a retransmission buffer, first and second downlink data respectively received in the first and second component carriers, wherein a first configuration pattern of uplink and downlink subframes is set for the first component carrier and a second configuration pattern of uplink and downlink subframes is set for the second component carrier; wherein the first configuration pattern is one of a plurality of first configuration patterns with first indices and the second configuration pattern is one of a plurality of second configuration patterns with second indices, wherein the decoder is further adapted to specify a reference index of a reference configuration pattern of uplink and downlink subframes based on a plurality of combinations of the first indices and the second indices, wherein the reference index is associated with one of the first index of the set first configuration pattern, the second index of the set second configuration pattern and a third index of a third configuration pattern of a plurality of third configuration patterns of uplink and downlink subframes, which neither the first index of the set first configuration pattern nor the second index of the set second configuration pattern, and wherein the decoder is further adapted to store the second downlink data in the retransmission buffer in reference to a maximum number of downlink hybrid automatic repeat request, HARQ, retransmission processes executable in the reference configuration pattern specified with the reference index, and is adapted to decode the first and second downlink data; a signal generator that is adapted to generate a first response signal using a result of error detection of the first downlink data and a second response signal using a result of error detection of the second downlink data; and a transmitter that is adapted to transmit the second response signal in the first component carrier at a timing of an uplink subframe of the reference configuration pattern with the specified reference index, when the first configuration pattern and the second configuration pattern are different.