Radio transmission device, radio reception device, and method for selecting transmission cancellation subcarriers

1. A radio transmission apparatus comprising:

a coding section that encodes a transmission bit to generate a systematic bit and a parity bit;

a modulation section that modulates the systematic bit and the parity bit generated by said coding section to generate symbols each consisting of two or more bits;

a selection section that selects at least one subcarrier to which a symbol consisting of only parity bits is mapped out of the symbols generated by said modulation section;

a generating section that generates a multicarrier signal using subcarriers other than the subcarrier selected by said selection section; and

a transmission section that transmits the multicarrier signal generated by said generating section.

2. The radio transmission apparatus according to claim 1 , further comprising a table showing the correspondence between a plurality of patterns of values that are possibly taken by the symbols generated by said modulation section and a plurality of selection patterns of subcarriers selected by said selection section as subcarriers to be excluded from transmission, wherein said selection section references said table based on the values of the symbols generated by said modulation section and selects a selection pattern with to minimum peak power out of said plurality of selection patterns.

3. The radio transmission apparatus according to claim 1 , further comprising a detection section that detects peak power of the multicarrier signal generated by said generating section, wherein said selection section selects a selection pattern with to minimum power out of a plurality of selection patterns of the subcarriers to be excluded from transmission.

4. The radio transmission apparatus according to claim 1 , further comprising a detection section that detects power of the multicarrier signal generated by said generating section, wherein said selection section carries out said selection processing only when the peak power reaches or exceeds a threshold.

5. The radio transmission apparatus according to claim 1 , further comprising a detection section that detects peak power of the multicarrier signal generated by said generating section, wherein said transmission section transmits a multicarrier signal whose power is lower than a threshold out of the multicarrier signals generated by said generating section.

6. The radio transmission apparatus according to claim 1 , further comprising a power control section that assigns power corresponding a power decrease that occurs when transmission of the subcarrier selected by said selection section is excluded to a subcarrier other than the subcarrier to be excluded from transmission.

7. The radio transmission apparatus according to claim 6 , wherein:

said selection section selects N subcarriers of K subcarriers to which the symbols generated by said modulation section are mapped as subcarriers to be excluded from transmission, and

said power control section controls power of K−N subcarriers other than subcarriers to be excluded from transmission to the power multiplied by K/(K−N).

8. The radio transmission apparatus according to claim 1 , further comprising an order control section that controls the order in which the systematic bit and the parity bit generated by said coding section are input to said modulation section so that a symbol consisting of only parity bits is generated.

9. The radio transmission apparatus according to claim 1 , wherein said selection section selects, as the subcarrier to be excluded from transmission, a subcarrier to which a symbol consisting of only the parity bit out of the symbols generated by said modulation section is mapped and for which a pilot whose reception power measured by a radio reception apparatus that receives the multicarrier signal falls to or below a threshold.

10. The radio transmission apparatus according to claim 1 , further comprising a retransmission section that retransmits the symbol generated by said modulation section, wherein at the time of retransmission by said retransmission section, said selection section selects a subcarrier different from the subcarrier at the time of initial transmission.

11. A radio reception apparatus comprising:

a reception section that receives the multicarrier signal transmitted from the radio transmission apparatus according to claim 1 ;

a measuring section that measures reception power of a plurality of subcarriers constituting the multicarrier signal received by said reception section; and

a selection section that selects subcarriers to be excluded from demodulation, said subcarriers to be excluded from demodulation selected up to a number of the subcarriers regarded as subcarriers to be excluded from transmission by said radio transmission apparatus from a subcarrier corresponding to a lowest reception power measured by said measuring section.

12. A radio transmission method in a radio transmission apparatus, the radio transmission method comprising the steps of:

coding a transmission bit into a systematic bit and a parity bit;

modulating the systematic bit and the parity bit to generate symbols each having two or more bits;

selecting at least one subcarrier to which a symbol having only parity bits is assigned from a plurality of subcarriers; and

transmitting a multicarrier signal including subcarriers other than the selected subcarrier.

13. A radio transmission apparatus comprising:

a coding section operable to code a transmission bit into a systematic bit and a parity bit;

a modulating section operable to modulate the systematic bit and the parity bit to generate symbols each having two or more bits;

a selecting section operable to select at least one subcarrier to which a symbol having only parity bits is assigned from a plurality of subcarriers; and

a transmitter operable to transmit a multicarrier signal including subcarriers other than the selected subcarrier.