Patent ID: 8199792

Claim:
A radio communication apparatus comprising: a spreading unit configured to spread an ACK or NACK with an orthogonal sequence, which is one of plural orthogonal sequences, and with a sequence defined by a cyclic shift value, which is one of plural cyclic shift values and which is associated with the orthogonal sequence; and a transmitting unit configured to transmit the ACK or NACK, wherein: each of the plural orthogonal sequences is an orthogonal sequence comprised of 4 codes and having a length 4; the plural orthogonal sequences include a first orthogonal sequence and a second orthogonal sequence, wherein a sequence comprised of 2 codes in the first half of the first orthogonal sequence is not orthogonal to a sequence comprised of 2 codes in the first half of the second orthogonal sequence, and a sequence comprised of 2 codes in the second half of the first orthogonal sequence is not orthogonal to a sequence comprised of 2 codes in the second half of the second orthogonal sequence; and a cyclic shift value associated with the first orthogonal sequence is different from a cyclic shift value associated with the second orthogonal sequence.