Radio communication device and constellation control method
View Patent ↗Provided is a radio communication device which can improve the negative acknowledgement (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 zero auto correlation (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 ).
1. A radio communication apparatus comprising:
a first spreading section that performs first spreading of a transmission signal using one of a plurality of first sequences that can be separated from each other because of different cyclic shift values; and
an inverting section that, with reference to a first constellation of a transmission signal allocated to a first channel group formed with channels using a part of the plurality of first sequences, inverts a second constellation of a transmission signal allocated to a second channel group formed with channels using other first sequences than the part of the plurality of first sequences.
2. The radio communication apparatus according to claim 1 , further comprising a second spreading section that performs second spreading of the transmission signal subjected to the first spreading, using one of a plurality of second sequences that are orthogonal to each other.
3. The radio communication apparatus according to claim 1 , wherein the channels belonging to the first channel group and the channels belonging to the second channel group are alternately allocated on a cyclic shift axis.
4. The radio communication apparatus according to claim 1 , wherein, with reference to the first constellation only in a specific slot among a plurality of slots forming one subframe, the inverting section inverts the second constellation.
5. The radio communication apparatus according to claim 1 , wherein, with reference to a constellation of one of two transmission signals subject to the first spreading by first sequences of a same cyclic shift value, the inverting section inverts a constellation of the other transmission signal between two adjacent cells.
6. A constellation control method comprising:
performing first spreading of a transmission signal using one of a plurality of first sequences that can be separated from each other because of different cyclic shift values; and
with reference to a first constellation of a transmission signal allocated to a first channel group formed with channels using a part of the plurality of first sequences, inverting a second constellation of a transmission signal allocated to a second channel group formed with channels using other first sequences than the part of the plurality of first sequences.