Radio communication device and constellation control method

摘要

Provided is a radio communication device which can improve the NACK error rate characteristic. The device includes: a scrambling unit (214) which multiplies a response signal after modulated, by a scrambling code "1" or "-1" so as to inverse a constellation for each of response signals on a cyclic shift axis; a spread unit (215) which performs a primary spread of the response signal by using a ZAC sequence set by a control unit (209); and a spread unit (218) which performs a secondary spread of the response signal after subjected to the primary spread, by using a block-wise spread code sequence set by the control unit (209).