Transmission and reception apparatus and method

1. A transmission apparatus comprising:

a plurality of orthogonal frequency division multiplexing (OFDM) modulation signal generators that generate a first OFDM modulation signal and a second OFDM modulation signal by:

inserting a symbol for demodulation in a first sub-carrier of the first OFDM modulation signal at a first time and inserting a symbol where both of an in-phase (I) signal and a quadrature-phase (Q) signal in an I-Q plane are made to be zero in a first sub-carrier of the second OFDM modulation signal at the first time;

inserting the symbol for demodulation in a second sub-carrier of the second OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a second sub-carrier of the first OFDM modulation signal at the first time;

inserting the symbol for demodulation in a third sub-carrier of the first OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a third sub-carrier of the second OFDM modulation signal at the first time;

inserting the symbol for demodulation in a fourth sub-carrier of the second OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a fourth sub-carrier of the first OFDM modulation signal at the first time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the first sub-carrier of the first OFDM modulation signal at a second time and inserting the symbol for demodulation in the first sub-carrier of the second OFDM modulation signal at the second time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the second sub-carrier of the second OFDM modulation signal at the second time and inserting the symbol for demodulation in the second sub-carrier of the first OFDM modulation signal at the second time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the third sub-carrier of the first OFDM modulation signal at the second time and inserting the symbol for demodulation in the third sub-carrier of the second OFDM modulation signal at the second time; and

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the fourth sub-carrier of the second OFDM modulation signal at the second time and inserting the symbol for demodulation in the fourth sub-carrier of the first OFDM modulation signal at the second time; and

a transmitter that transmits the first OFDM modulation signal from a first antenna and the second OFDM modulation signal from a second antenna, in an identical frequency band.

2. The transmission apparatus according to claim 1 , wherein the first OFDM modulation signal and the second OFDM modulation signal are comprised of data symbols.

3. The transmission apparatus according to claim 1 , wherein the symbol for demodulation is a pilot symbol.

4. The transmission apparatus according to claim 1 , wherein the symbol for demodulation is a preamble.

5. The transmission apparatus according to claim 1 , wherein the symbol for demodulation is a symbol to estimate a transmission path fluctuation.

6. The transmission apparatus according to claim 1 , wherein the symbol for demodulation is a symbol to estimate frequency offset.

7. The transmission apparatus according to claim 1 , wherein the symbol for demodulation is comprised of a phase shift keying (PSK) modulation symbol.

8. A reception apparatus comprising:

a plurality of antennas that receive a plurality of orthogonal frequency division multiplexing (OFDM) modulation signals;

a plurality of OFDM demodulators that transform the plurality of OFDM modulation signals to a plurality of reception signals using Fourier transform;

an estimator that outputs a distortion estimation signal using one or more symbols for demodulation included in the plurality of reception signals; and

a demodulator that compensates for distortion of the reception signals using the distortion estimation signal and demodulates a data symbol included in the reception signals,

wherein the plurality of OFDM modulation signals are formed by:

inserting a symbol for demodulation in a first sub-carrier of a first OFDM modulation signal at a first time and inserting a symbol where both of an in-phase (I) signal and a quadrature-phase (Q) signal in an I-Q plane are made to be zero in a first sub-carrier of a second OFDM modulation signal at the first time;

inserting the symbol for demodulation in a second sub-carrier of the second OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a second sub-carrier of the first OFDM modulation signal at the first time;

inserting the symbol for demodulation in a third sub-carrier of the first OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a third sub-carrier of the second OFDM modulation signal at the first time;

inserting the symbol for demodulation in a fourth sub-carrier of the second OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a fourth sub-carrier of the first OFDM modulation signal at the first time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the first sub-carrier of the first OFDM modulation signal at a second time and inserting the symbol for demodulation in the first sub-carrier of the second OFDM modulation signal at the second time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the second sub-carrier of the second OFDM modulation signal at the second time and inserting the symbol for demodulation in the second sub-carrier of the first OFDM modulation signal at the second time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the third sub-carrier of the first OFDM modulation signal at the second time and inserting the symbol for demodulation in the third sub-carrier of the second OFDM modulation signal at the second time; and

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the fourth sub-carrier of the second OFDM modulation signal at the second time and inserting the symbol for demodulation in the fourth sub-carrier of the first OFDM modulation signal at the second time.

9. The reception apparatus according to claim 8 , wherein the symbol for demodulation is a pilot symbol.

10. The reception apparatus according to claim 8 , wherein the symbol for demodulation is a preamble.

11. The reception apparatus according to claim 8 , wherein the symbol for demodulation is a symbol to estimate a transmission path fluctuation.

12. The reception apparatus according to claim 8 , wherein the symbol for demodulation is a symbol for estimating frequency offset.

13. The reception apparatus according to claim 8 , wherein the symbol for demodulation is comprised of a phase shift keying (PSK) modulation symbol.

14. A reception method comprising steps of:

receiving a plurality of orthogonal frequency division multiplexing (OFDM) modulation signals with a plurality of antennas;

transforming the plurality of OFDM modulation signals to a plurality of reception signals using Fourier transform;

outputting a distortion estimation signal using one or more symbols for demodulation included in the plurality of reception signals; and

compensating for distortion of the reception signals using the distortion estimation signal and demodulating a data symbol included in the reception signals,

wherein the plurality of OFDM modulation signals are formed by:

inserting a symbol for demodulation in a first sub-carrier of a first OFDM modulation signal at a first time and inserting a symbol where both of an in-phase (I) signal and a quadrature-phase (Q) signal in an I-Q plane are made to be zero in a first sub-carrier of a second OFDM modulation signal at the first time;

inserting the symbol for demodulation in a second sub-carrier of the second OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a second sub-carrier of the first OFDM modulation signal at the first time;

inserting the symbol for demodulation in a third sub-carrier of the first OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a third sub-carrier of the second OFDM modulation signal at the first time;

inserting the symbol for demodulation in a fourth sub-carrier of the second OFDM modulation signal at the first time and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a fourth sub-carrier of the first OFDM modulation signal at the first time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the first sub-carrier of the first OFDM modulation signal at a second time and inserting the symbol for demodulation in the first sub-carrier of the second OFDM modulation signal at the second time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the second sub-carrier of the second OFDM modulation signal at the second time and inserting the symbol for demodulation in the second sub-carrier of the first OFDM modulation signal at the second time;

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the third sub-carrier of the first OFDM modulation signal at the second time and inserting the symbol for demodulation in the third sub-carrier of the second OFDM modulation signal at the second time; and

inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the fourth sub-carrier of the second OFDM modulation signal at the second time and the symbol for demodulation in the fourth sub-carrier of the first OFDM modulation signal at the second time.

15. The reception method according to claim 14 , wherein the symbol for demodulation is a pilot symbol.

16. The reception method according to claim 14 , wherein the symbol for demodulation is a preamble.

17. The reception method according to claim 14 , wherein the symbol for demodulation is a symbol to estimate a transmission path fluctuation.

18. The reception method according to claim 14 , wherein the symbol for demodulation is a symbol for estimating frequency offset.

19. The reception method according to claim 14 , wherein the symbol for demodulation is comprised of a phase shift keying (PSK) modulation symbol.