Patent ID: 7545873

Claim:
A radio transmission apparatus comprising: a modulator that maps transmission data on a modulation symbol comprised of an I component and a Q component; a phase rotator which rotates a phase of the modulation symbol by a predetermined angle and maps a signal point of the modulation symbol at a signal point of an M-ary modulation level higher by two ranks; a first IQ separator that separates the modulation symbol with the phase rotated to the I component and the Q component with reference to an IQ axis rotated a predetermined angle; a first interleaver that interleaves the I component and/or the Q component separated in the first IQ separator; a first IQ combiner that combines the I component and the Q component output from the first interleaver; a second IQ separator that separates the modulation symbol obtained in the first IQ combiner into the I component and the Q component; a second interleaver that interleaves the I component and/or the Q component separated in the second IQ separator; a second IQ combiner that combines the I component and the Q component output from the second interleaver; and a transmitter that transmits the symbol obtained in the second IQ combiner.