Radio communication device and constellation control method

1. A mobile station for transmitting an acknowledgement or negative acknowledgement (ACK/NACK) signal comprising:

a processor configured to multiply an ACK/NACK signal either by a first value for rotating a constellation of the ACK/NACK signal by 0 degrees or by a second value for rotating the constellation of the ACK/NACK signal by N degrees, which is different from 0 degrees;

a transmitter configured to transmit the ACK/NACK signal multiplied by the first value or the second value;

wherein, in a case where a Physical Uplink Control Channel (PUCCH) index used by the mobile station is in a first PUCCH index group, the processor is configured to multiply the ACK/NACK signal by the same value for both transmitting in a first slot and transmitting in a second slot, and in a case where the PUCCH index used by the mobile station is in a second PUCCH index group, the processor is configured to multiply the ACK/NACK signal by different values for transmitting in the first slot and transmitting in the second slot, respectively.

2. The mobile station according to claim 1 , wherein all PUCCH indexes available in a sub frame are included in either the first PUCCH index group or the second PUCCH index group, wherein the subframe consists of the first slot and the second slot.

3. The mobile station according to claim 2 , wherein PUCCH indexes available in a sub frame include at least one PUCCH index included in the first PUCCH index group and at least one PUCCH index included in the second PUCCH index group.

4. The mobile station according to claim 2 , wherein the processor is configured to multiply the ACK/NACK signal by an orthogonal sequence having a sequence index corresponding to the PUCCH index used by the mobile station, and by a sequence defined by a cyclic shift amount corresponding to the PUCCH index used by the mobile station.

5. The radio communication apparatus according to claim 1 , wherein the processor is further configured to use a first modulation scheme in a first slot of a subframe of the transmission signal and to use a second modulation scheme in a second slot of a subframe of the transmission signal.

6. A transmitting method for a mobile station to transmit an acknowledgement or negative acknowledgement (ACK/NACK) signal, the method comprising:

using a processor to multiply an ACK/NACK signal either by a first value for rotating a constellation of the ACK/NACK signal by 0 degrees or by a second value for rotating the constellation of the ACK/NACK signal by N degrees, which is different from 0 degrees on an axis of rotation; and

transmitting the ACK/NACK signal multiplied by the first value or the second value; wherein the ACK/NACK signal is multiplied by the same value for both transmission in a first slot and transmission in a second slot, in a case where a Physical Uplink Control Channel (PUCCH) index used by the mobile station is in a first PUCCH index group, and the ACK/NACK signal is multiplied by different values for transmission in the first slot and transmission in the second slot, respectively, in a case where the PUCCH index used by the mobile station is included in a second PUCCH index group.

7. The transmitting method according to claim 6 , wherein all PUCCH indexes available in a sub frame are included in either the first PUCCH index group or the second PUCCH index group, wherein the subframe consists of the first slot and the second slot.

8. The transmitting method according to claim 6 , wherein PUCCH indexes available in a sub frame include at least one PUCCH index included in the first PUCCH index group and at least one PUCCH index included in the second PUCCH index group.

9. The transmitting method according to claim 6 , wherein the ACK/NACK signal is multiplied by an orthogonal sequence having a sequence index corresponding to the PUCCH index used by the mobile station, and by a sequence defined by a cyclic shift amount corresponding to the PUCCH index used by the mobile station.

10. The transmitting method according to claim 6 , further comprising using a first modulation scheme in a first slot of a subframe of the transmission signal and using a second modulation scheme in a second slot of a subframe of the transmission signal.

11. A base station for receiving an acknowledgement or negative acknowledgement (ACK/NACK) signal, comprising:

a transmitter configured to transmit a control signal using one or a plurality of Control Channel Elements (CCE(s));

a receiver configured to receive an ACK/NACK signal; and

a processor configured to process the received ACK/NACK signal, the ACK/NACK signal having been multiplied by an orthogonal sequence, by a sequence defined by a cyclic shift, and by either a first value or a second value, wherein the first value rotates a constellation of the ACK/NACK signal by 0 degrees and the second value rotates the constellation of the ACK/NACK signal by N degrees, which is different from 0 degrees on an axis of rotation, and wherein the orthogonal sequence has a sequence index corresponding to a Physical Uplink Control Channel (PUCCH) index associated with a first CCE number of said one or a plurality of CCE(s) and the cyclic shift corresponds to the PUCCH index;

wherein, in a case where said PUCCH index is in a first PUCCH index group, the ACK/NACK signal has been multiplied by the same one of the first value or the second value for both communication in a first slot and communication in a second slot, and in a case where said PUCCH index is in a second PUCCH index group, the ACK/NACK signal has been multiplied by different ones of the first value and the second value, respectively, for communication in the first slot and communication in the second slot.

12. The base station according to claim 11 , wherein all PUCCH indexes available in a subframe are included in either the first PUCCH index group or the second PUCCH index group, wherein the subframe consists of the first slot and the second slot.

13. The base station according to claim 11 , wherein PUCCH indexes available in a subframe include at least one PUCCH index included in the first PUCCH index group and at least one PUCCH index included in the second PUCCH index group, wherein the subframe consists of the first slot and the second slot.

14. A receiving method for a base station to receive an acknowledgement or negative acknowledgement (ACK/NACK) signal, the method comprising:

transmitting a control signal using one or a plurality of Control Channel Elements (CCE(s); and

receiving an ACK/NACK signal;

using a processor to process the received ACK/NACK signal, the received ACK/NACK signal having been multiplied by an orthogonal sequence, by a sequence defined by a cyclic shift, and by either a first value or a second value, wherein the first value rotates a constellation of the ACK/NACK signal by 0 degrees and the second value rotates the constellation of the ACK/NACK signal by N degrees, which is different from 0 degrees on an axis of rotation, and wherein the orthogonal sequence has a sequence index corresponding to a Physical Uplink Control Channel (PUCCH) index associated with a first CCE number of said one or a plurality of CCE(s) and the cyclic shift corresponds to the PUCCH index;

wherein, in a case where said PUCCH index is in a first PUCCH index group, the ACK/NACK signal has been multiplied by the same one of the first value or the second value for both communication in a first slot and communication in a second slot, and in a case where said PUCCH index is in a second PUCCH index group, the ACK/NACK signal has been multiplied by different ones of the first value and the second value, respectively, for communication in the first slot and communication in the second slot.

15. The receiving method according to claim 14 , wherein all PUCCH indexes available in a subframe are included in either the first PUCCH index group or the second PUCCH index group, wherein the subframe consists of the first slot and the second slot.

16. The receiving method according to claim 14 , wherein PUCCH indexes available in a subframe include at least one PUCCH index included in the first PUCCH index group and at least one PUCCH index included in the second PUCCH index group, wherein the subframe consists of the first slot and the second slot.