Radio communication device and response signal diffusion method

A base station apparatus comprising:

• a transmitting unit configured to transmit data to a mobile station apparatus;
• and
• a receiving unit configured to receive an ACK/NACK signal or a CQI signal, which is spread with a sequence defined by one of a plurality of cyclic shift values and which is transmitted from the mobile station apparatus,
• wherein, in each symbol that forms the ACK/NACK signal or the CQI signal, the ACK/NACK signal or the CQI signal is spread with one of first cyclic shift values, which form a portion of the plurality of the cyclic shift values and which are adjacent to each other, for the ACK/NACK signal, or is spread with one of second cyclic shift values, which are not within the portion of the plurality of the cyclic shift values, for the CQI signal, and a cyclic shift value that is cyclically subsequent to the second cyclic shift values is not used for either the ACK/NACK signal or the CQI signal.

A method for spreading a signal comprising:

• first-spreading an ACK/NACK signal or a CQI signal with a sequence defined by one of a plurality of cyclic shift values;
• and
• second-spreading the ACK/NACK signal with one of a plurality of orthogonal sequences;
• wherein in the first-spreading, in each symbol that forms the ACK/NACK signal or the CQI signal, one of first cyclic shift values, which form a portion of the plurality of the cyclic shift values and which are adjacent to each other, is used for the ACK/NACK signal;
• one of second cyclic shift values, which are not within the portion of the plurality of the cyclic shift values, is used for the CQI signal;
• and a cyclic shift value that is cyclically subsequent to the second cyclic shift values is not used for either the ACK/NACK signal or the CQI signal.