OFDM signal communication system, OFDM signal transmitting device and OFDM signal receiving device

• US 20020191535A1
• Filed: 04/05/2002
• Published: 12/19/2002
• Est. Priority Date: 04/09/2001
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Suzuki, Yasuo, Asai, Yusuke, Kurosaki, Satoshi, Uchida, Daisei, Sugiyama, Takatoshi, Umehira, Masahiro
• Granted Patent: US 7,242,720 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2027/0026 Correction of carrier offset
• CPC Class Codes: H04L 2027/0087 Out-of-band signals, (e.g. pilots)
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/26035 Maintenance of orthogonality, e.g. for signals exchanged between cells or users, or by using covering codes or sequences using different training sequence per antenna H04B7/0684; code allocation H04J13/16
• CPC Class Codes: H04L 27/2637 with direct modulation of individual subcarriers
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2679 Decision-aided

Abstract

An OFDM signal communication system used in broadband mobile communication, achieves stable operation under severe frequency selective fading environments, giving high quality. The OFDM signal communication system which transmits OFDM signals over the same radio frequency from N transmitting antennas, has an inverse matrix computer for computing an N×N inverse matrix constituted by propagation coefficients for respective propagation paths between each of N transmitting antennas and each of N receiving antennas, and a subcarrier demodulator which separates the signals of the respective propagation paths, based on the obtained inverse matrix.

Claims

1. An OFDM signal communication system comprising:

an OFDM signal transmitting device which includes a plurality of N transmitting antennas, for transmitting OFDM signals over the same radio frequency from the transmitting antennas,

an OFDM signal receiving device which includes N receiving antennas for receiving signals transmitted from the N transmitting antennas,

an inverse matrix computer for computing each of inverse matrices of N-dimensional square matrices for each subcarrier constituted by the propagation coefficients for the respective propagation paths between the respective transmitting antennas and the respective receiving antennas, and

an interference canceller for canceling interference components which occur between the OFDM signal transmitting device and the OFDM signal receiving device, based on the inverse matrix computed by the inverse matrix computer.

2. An OFDM signal communication system according to claim 1, wherein

the N transmitting antennas are two transmitting antennas which are polarization orthogonal to each other and

the N receiving antennas are two receiving antennas which are polarization orthogonal to each other.

3. An OFDM signal communication system according to claim 1, wherein

the inverse matrix computer and the interference canceller are provided in the OFDM signal receiving device, and

the OFDM signal transmitting device is further provided with:

OFDM modulators connected to the transmitting antennas, which operates based on transmission symbol timing; and

transmission frequency converters for converting the frequency band of outputs from the OFDM modulators into radio frequency in accordance with a local oscillator frequency, and outputting to the transmitting antennas, and

the OFDM signal receiving device is further provided with;

receiving frequency converters connected to the receiving antennas, for frequency converting radio frequency of a received signal received by the receiving antennas, in accordance with a local oscillator frequency, into a frequency suitable for demodulation; and

fast Fourier transformers connected to the receiving frequency converters, for performing Fourier transformation processing on the outputs of the receiving frequency converters based on reception symbol timing,

and the interference canceller computes the product of the inverse matrix and the received OFDM signals for the subcarriers output from the fast Fourier transformers, and outputs of an amplitude and phase for each of the subcarriers corresponding to the OFDM signals transmitted from the OFDM signal transmitting device.

4. An OFDM signal communication system according to claim 3, wherein

the OFDM signal transmitting device further comprises:

a pilot signal generator for generating N kinds of pilot signals corresponding to the respective OFDM modulators;

a combiner for combining transmission information signals of N systems and the pilot signals, and outputting to the OFDM modulators;

an OFDM symbol timing generator for supplying common OFDM symbol timing to all of the OFDM modulators as the transmission symbol timing; and

a transmission local oscillator for supplying a common local oscillator frequency to all of the transmission frequency converters,

and the OFDM signal receiving device further comprises;

a local oscillator for receiver for supplying a common local oscillator frequency to all of the receiving frequency converters; and

a timing signal generator for supplying OFDM symbol timing to the fast Fourier transformers so as to receive the pilot signals by the receiving antennas, as the reception symbol timing common to all of the fast Fourier transformers,

and the inverse matrix computer, for all of the combinations of the transmitting antennas and the receiving antennas, measures the propagation coefficients by normalizing the reception amplitude and phase of the pilot signals with an amplitude and phase of known pilot signals, and calculates and stores the inverse matrix with respect to a propagation coefficient matrix related to respective subcarriers.

5. An OFDM signal communication system according to claim 4, wherein

the OFDM signal transmitting device generates the pilot signals by means of the pilot signal generator with a timing mutually shifted so as not to overlap each other on the time domain, and sends these pilot signals to the OFDM signal receiving device,

and the OFDM signal receiving device receives the respective pilot signals which have been sent shifted on the time domain and separates these pilot signals by means of the fast Fourier transformers.

6. An OFDM signal communication system according to claim 4, wherein

the pilot signal generator of the OFDM signal transmitting device comprises:

a transmission subcarrier pilot matrix generator which, when the number of subcarriers is I, generates a transmission subcarrier pilot matrix with a pilot signal Pⁱ_mn of an m th symbol (m is an integer greater than or equal to 1 and less than or equal to N) transmitted by an n th (n is an integer greater than or equal to 1 and less than or equal to N) transmitting antenna in the i th (i is an integer greater than or equal to 1 and less than or equal to I) subcarrier, as a component of the m th row and n th column, and for which the determinant does not become 0 and which is a matrix other than a unit matrix and the matrix obtained by multiplying a complex number by the unit matrix; and

a transmission pilot signal composer which outputs to the combiner, the components of the m th row and n th column obtained from all of the transmission subcarrier pilot matrix Pⁱ of the i th subcarrier output from the transmission subcarrier pilot matrix generator as transmitted pilot signal components (P¹_mn, P²_mn, . . . , P^I_mn) of the m th symbol of the n th antenna,

and the inverse matrix computer of the OFDM signal receiving device comprises;

a receiving subcarrier pilot matrix composer which generates a receiving subcarrier pilot matrix PRⁱ of N rows and N columns with a received signal rⁱ_mn of the m th symbol of the n th receiving antenna of the i th subcarrier output from the fast Fourier transformers as the component of the m th row and n th column, based on the pilot signals of the N symbols received by the receiving antennas; and

I subcarrier propagation coefficient inverse matrix computers for computing a subcarrier propagation coefficient matrix sⁱ being the matrix of the propagation coefficients between the transmitting antennas and the receiving antennas for the i th subcarrier, by multiplying the receiving subcarrier pilot matrix PRⁱ by the inverse matrix of the transmission subcarrier pilot matrix Pⁱ, and then calculating the inverse matrix (Sⁱ)<sup>−

1</sup> of the subcarrier propagation coefficient matrix.

7. An OFDM signal communication system according to claim 4, wherein the OFDM signal receiving device further comprises:

N carrier frequency error estimators for estimating a frequency error between the transmission local oscillator and the local oscillator for receiver based on the outputs from the receiving frequency converters, and outputting a carrier frequency error estimation value;

an averaging circuit of carrier frequency error estimation value for calculating and outputting an average value of the carrier frequency error estimation value output from the N carrier frequency error estimators; and

N carrier frequency error correctors for correcting the carrier frequency errors of the respective outputs of the receiving frequency converters, based on the average value output from the averaging circuit of carrier frequency error estimation value.

8. An OFDM signal communication system according to claim 7, wherein

the pilot signal generator repetitively transmits a carrier frequency error estimation pilot signal, and

the carrier frequency error estimator comprises:

N delay circuits for delaying the outputs of the receiving frequency converters by the same time as the repetition interval of the carrier frequency error estimation pilot signal;

N complex conjugate circuits for calculating the complex conjugates of the outputs of the N delay circuits;

N complex multipliers for multiplying the outputs from the receiving frequency converters by the outputs from the complex conjugate circuits;

N integrating circuits for computing the sum of the outputs of the complex multipliers for a number of samples corresponding to the repetition interval of the carrier frequency error estimation pilot signal;

an averaging circuit for computing the average value of the output from the N integrating circuits;

an arc-tangent circuit for computing a phase variation proportional to the carrier frequency error, using the output from the averaging circuit; and

a phase converting circuit for converting the output of the arc-tangent circuit to a carrier frequency error per one sampling time.

9. An OFDM signal communication system according to claim 7, wherein

the pilot signal generator repetitively transmits a carrier frequency error estimation pilot signal, and

the carrier frequency error estimator comprises:

N delay circuits for delaying the outputs of the receiving frequency converters by the same time as the repetition interval of the carrier frequency error estimation pilot signal;

N complex conjugate circuits for calculating the complex conjugates of the outputs of the N delay circuits;

N complex multipliers for multiplying the outputs from the receiving frequency converters by the outputs from the complex conjugate circuits;

N integrating circuits for computing the sums of the outputs of the complex multipliers for a number of samples corresponding to the repetition interval of the carrier frequency error estimation pilot signal;

an arc-tangent circuit for computing phase variations proportional to the carrier frequency errors, using the output from the N integrating circuits;

a phase converting circuit for converting the outputs of the arc-tangent circuit to a carrier frequency errors per one sampling time, and

an averaging circuit for computing the average value of the output from the N phase converting circuits.

10. An OFDM signal communication system according to claim 4, wherein

the OFDM signal transmitting device further comprises;

a forward error correction encoder for forward error correction encoding the transmission information signals; and

an interleaver which rearranges the output from the forward error correction encoder and outputs to the combiner, and

the OFDM signal receiving device further comprises;

a deinterleaver for performing a reverse operation to the interleaver on the outputs from the interference canceller; and

a forward error correction decoder for decoding the output from the deinterleaver.

11. An OFDM signal communication system according to claim 10, wherein

the OFDM signal receiving device further comprises:

a weighting factor computer for obtaining weighting factors for the output of the interference canceller; and

a multiplier for multiplying the output of the interference canceller by the weighting factors obtained by the weighting factor computer.

12. An OFDM signal communication system according to claim 10, wherein

the OFDM signal transmitting device further comprises:

a first switch for selecting to send signals for where the transmission information signals have been serial-parallel converted to the combiner, or to send the same transmission information signals to the combiner, and

the OFDM signal receiving device further comprises;

a communication quality measurer for measuring the quality of the outputs from the interference canceller related to an arbitrary subcarrier of the transmitted OFDM signal transmitted from the OFDM signal transmitting device; and

a second switch for outputting the signals output from the interference canceller directly in the case where the OFDM signal transmitting device transmits a signal for which the transmission information signals have been serial-parallel converted, and adding the outputs of the interference canceller or, outputting the one with the larger reception power of the interference canceller outputs in the case where the OFDM signal transmitting device sends the same transmission information signals, and

the first switch selects in accordance with the measurement result from the communication quality measurer.

13. An OFDM signal communication system according to claim 12 wherein

the OFDM signal receiving device further comprises:

an amplitude information coefficient computer for computing amplitude information coefficients used for reproducing the amplitudes of the received signals at the receiving antennas, from elements of the inverse matrix obtained by the inverse matrix computer;

an amplitude information coefficient multiplier for multiplying respective outputs from the interference canceller by the amplitude information coefficients obtained by the amplitude information coefficient computer;

a diversity coefficient computer for computing diversity coefficients used in weighting for diversity combining, from elements of the inverse matrix obtained by the inverse matrix computers or from the amplitude information coefficients computed by the amplitude information coefficient computer;

a diversity coefficient multiplier for multiplying the output signals of the amplitude information coefficient multiplier by the diversity coefficients computed by the diversity coefficient computer; and

an adder for outputting the OFDM signal, being the added result of the output signals of the diversity coefficient multiplier.

14. An OFDM signal communication system according to claim 1, wherein

the interference canceller is provided in the OFDM signal transmitting device, and

the OFDM signal transmitting device comprises:

a data converter for converting each of the transmission information signals of N systems into OFDM symbols;

the interference canceller for multiplying respective subcarriers of respective OFDM symbols generated by the data converter, by the inverse matrix obtained by the inverse matrix computer;

an inverse fast Fourier transformer for performing inverse Fourier transformation on the output from the interference canceller; and

transmission frequency converters for converting the frequency band of the output from the inverse fast Fourier transformer to radio frequency, and

the OFDM signal receiving device further comprises;

receiving frequency converters for converting radio frequency of received signals received by the receiving antennas, into a frequency suitable for demodulation;

N fast Fourier transformers for performing Fourier transformation on respective received signals of N systems output from the receiving frequency converters; and

a demodulator for converting the OFDM symbols for each of the antenna systems, output from the fast Fourier transformers into bit stream.

15. An OFDM signal communication system according to claim 14, wherein

the inverse matrix computer is provided on the OFDM signal receiving device, and

the OFDM signal receiving device further comprises an inverse matrix information transmitter for transmitting the inverse matrix obtained by the inverse matrix computer to the OFDM signal transmitting device, and

the OFDM signal transmitting device further comprises an inverse matrix information receiver for receiving the inverse matrix sent from the OFDM signal receiving device, and the interference canceller multiplies respective subcarriers of the respective OFDM symbols generated by the data converter, by the inverse matrix received by the inverse matrix information receiver.

16. An OFDM signal communication system according to claim 14 wherein

the inverse matrix computer is provided on the OFDM signal transmitting device, and

the OFDM signal transmitting device further comprises:

a pilot signal generator for generating N kinds of pilot signals respectively corresponding to the transmitting antennas;

a combiner for combining the N kinds of pilot signals respectively with the N systems outputs from the interference cancellers, and outputting to the inverse fast Fourier transformer; and

a pilot information receiver for receiving reception information of the pilot signals sent from the OFDM signal receiving device, and

the inverse matrix computer computes the inverse matrix based on reception information of the pilot signal received by the pilot information receiver, and

the OFDM signal receiving device further comprises;

a pilot information transmitter for detecting the amplitude and phase of the received N pilot signals from the outputs of the fast Fourier transformers for each of the subcarriers, and transmitting the reception information of the pilot signals to the OFDM signal transmitting device.

17. An OFDM signal communication system according to claim 1 wherein

the receiving antenna is a first group of antennas further provided with a transmit function,

the transmitting antenna is a second group of antenna further provided with a receive function, and

the inverse matrix computer and the interference canceller are provided on the OFDM signal transmitting device, and

the OFDM signal receiving device further comprises:

a pilot signal generator for generating N kinds of pilot signals respectively corresponding to the second group of antennas;

a first group of inverse fast Fourier transformers for performing inverse fast Fourier transformation on N kinds of pilot signals output from the pilot signal generator;

a first group of transmission frequency converters for converting signals output from the first group of inverse fast Fourier transformers into radio frequency suitable for transmission;

a first group of receiving frequency converters for converting received signals of radio frequency received by the first group of antennas, into a frequency suitable for demodulation;

a first group of fast Fourier transformers for performing Fourier transformation on respective received signals of N systems output from the first group of receiving frequency converters;

N demodulators for converting the OFDM symbols for each of the antenna systems output from the first group of fast Fourier transformers, into a bit stream; and

a first group of transmission/reception switches for switching the transmission of signals output from the first group of transmission frequency converters, and the reception of the received signals supplied to the first group of receiving frequency converters, for the first group of antennas, and

the OFDM signal transmitting device comprises;

a second group of receiving frequency converters for converting radio frequency of the pilot signals sent from the OFDM signal receiving device and received by the second group of antennas, into a frequency suitable for demodulation;

a second group of fast Fourier transformers for performing Fourier transformation on the signals output from the second group of receiving frequency converters;

the inverse matrix computer for computing the inverse matrix based on signals extracted from the output of the second group of fast Fourier transformers;

N data converters for respectively converting the input transmission information signals of N systems into OFDM symbols;

the interference canceller for multiplying the respective subcarriers of the respective OFDM symbols generated by the data converters, by the inverse matrix obtained by the inverse matrix computer;

a second group of inverse fast Fourier transformers for performing inverse Fourier transformation on outputs from the interference cancellers;

a second group of transmission frequency converters for converting the frequency band of signals output from the second group of inverse fast Fourier transformers, into radio frequency; and

a second group of transmission/reception switches for switching the transmission of signals output from the second group of transmission frequency converters, and the reception of the received signals supplied to the second group of receiving frequency converters, for the second group of antennas.

19. An OFDM signal transmitting device according to claim 18, wherein

the N transmitting antennas are two transmitting antennas for transmitting the OFDM signals using mutually orthogonal polarizations, towards two receiving antennas provided in the OFDM signal receiving device as the N receiving antennas and which are polarization orthogonal to each other.

20. An OFDM signal transmitting device according to claim 18 comprising:

transmission frequency converters for converting the outputs of the OFDM modulators into radio frequency in accordance with a local oscillator frequency and outputting to the transmitting antennas;

the pilot signal generator;

a combiner for combining transmission information signals of N systems and the pilot signals;

OFDM modulators connected to the combiner, which operates based on transmission symbol timing;

an OFDM symbol timing generator for supplying common OFDM symbol timing to all of the OFDM modulators as the transmission symbol timing; and

a transmission local oscillator for supplying a common local oscillator frequency to all of the transmission frequency converters, and

the pilot signal generator generates corresponding to the respective OFDM modulators, pilot signals of the N kinds used by the inverse matrix computer provided in the OFDM signal receiving device for computing the inverse matrix related to respective subcarriers, by normalizing the reception amplitude and phase of the N kinds of pilot signals with the amplitude and phase of known pilot signals.

21. An OFDM signal transmitting device according to claim 20, wherein the pilot signal generator generates the pilot signals with a timing mutually shifted so as not to overlap each other on the time domain.

22. An OFDM signal transmitting device according to claim 20, wherein the pilot signal generator comprises:

a transmission subcarrier pilot matrix generator which, when the number of subcarriers is I, generates a transmission subcarrier pilot matrix with a pilot signal P¹_mn of an m th symbol (m is an integer greater than or equal to 1 and less than or equal to N) transmitted by an n th (n is an integer greater than or equal to 1 and less than or equal to N) transmitting antenna in the i th (i is an integer greater than or equal to 1 and less than or equal to I) subcarrier, as a component of the m th row and n th column, and for which the determinant does not become 0 and which is a matrix other than a unit matrix and the matrix obtained by multiplying a complex number by the unit matrix; and

a transmission pilot signal composer which outputs to the combiner, the components of the m th row and n th column obtained from all of the transmission subcarrier pilot matrix Pⁱ of the i th subcarrier output from the transmission subcarrier pilot matrix generator as transmission pilot signal components (p¹_mn, p²_mn, . . . , p¹_mn) of the m th symbol of the n th antenna.

23. An OFDM signal transmitting device according to claim 20, further comprising:

a forward error correction encoder for forward error correction encoding the transmission information signals, and

an interleaver for rearranging output from the forward error correction encoder and outputting to the combiner.

24. An OFDM signal transmitting device according to claim 23, further comprising:

a first switch for selecting to send a signal for where the transmission information signals have been serial-parallel converted to the combiner, or to send the same transmission information signals to the combiner, in accordance with quality measured by the OFDM signal receiving device for an arbitrary subcarrier of the OFDM signals transmitted towards the OFDM signal receiving device.

25. An OFDM signal transmitting device according to claim 18, comprising:

a data converter for respectively converting the transmission information signals of N systems into OFDM symbols;

the interference canceller for multiplying the respective subcarriers of the respective OFDM symbols generated by the data converter, by the inverse matrix obtained by the inverse matrix computer;

inverse fast Fourier transformers for performing inverse Fourier transformation on the output from the interference canceller; and

transmission frequency converters for converting the frequency band of the output from the inverse fast Fourier transformers, into radio frequency.

26. An OFDM signal transmitting device according to claim 25, further comprising an inverse matrix information receiver for receiving the inverse matrix output from the inverse matrix computer provided in the OFDM signal receiving device, and

the interference canceller multiplies the respective subcarriers of the respective OFDM symbols generated by the data converter, by the inverse matrix received by the inverse matrix information receiver.

27. An OFDM signal transmitting device according to claim 25, comprising:

the inverse matrix computer;

the pilot signal generator;

a combiner for combining the N kinds of pilot signals respectively with the N systems outputs from the interference cancellers, and outputting to the inverse fast Fourier transformers; and

a pilot information receiver for receiving reception information of the pilot signals sent from the OFDM signal receiving device corresponding to the pilot signals sent to the OFDM signal receiving device, and

the inverse matrix computer computes the inverse matrix based on reception information of the pilot signals received by the pilot information receiver.

28. An OFDM signal transmitting device according to claim 18, wherein the transmitting antenna is a transmitting/receiving antenna further provided with a reception function, the device further comprising:

receiving frequency converters for converting N kinds of pilot signals received by the transmitting/receiving antennas sent from the OFDM signal receiving device respectively corresponding to the transmitting/receiving antennas, to a frequency suitable for demodulation;

fast Fourier transformers for performing Fourier transformation on signals output from the receiving frequency converters;

the inverse matrix computer for computing the inverse matrix based on signals extracted from the output of the fast Fourier transformers;

N data converters for converting input transmission information signals of N systems into OFDM symbols;

the interference canceller for multiplying respective subcarriers of respective OFDM symbols generated by the data converter, by the inverse matrix obtained by the inverse matrix computer;

an inverse fast Fourier transformer for performing inverse Fourier transformation on signals outputs from the interference cancellers;

transmission frequency converters for converting the frequency band of signals output from the inverse fast Fourier transformer in radio frequency; and

a transmission/reception switch for selecting the transmitting/receiving antennas to transmit signals output from the transmission frequency converters, or to receive the pilot signals supplied to the receiving frequency converters.

30. An OFDM signal receiving device according to claim 29, wherein

the N receiving antennas are two receiving antennas for receiving using mutually orthogonal polarizations, the OFDM signals transmitted using mutually orthogonal polarizations by two transmitting antennas provided in the OFDM signal transmitting device as the N transmitting antennas.

31. An OFDM signal receiving device according to claim 29 further comprising:

the inverse matrix computer;

the interference canceller;

receiving frequency converters connected to each of the receiving antennas, for frequency converting radio frequency of a received signal received by the receiving antennas, in accordance with a local oscillator frequency, into a frequency suitable for modulation; and

fast Fourier transformers respectively connected to the receiving frequency converters, for performing Fourier transformation processing on the output of the receiving frequency converters based on reception symbol timing,

and the interference canceller computes the product of the inverse matrix and the received OFDM signals for the subcarriers output from the fast Fourier transformers, and output signals having an amplitude and phase for each of the subcarriers corresponding to the OFDM signals transmitted from the OFDM signal transmitting device.

32. An OFDM signal receiving device according to claim 31, further comprising:

a local oscillator for receiver for supplying a common local oscillator frequency to all of the receiving frequency converters, and

a timing signal generator for supplying common OFDM symbol timing to all of the fast Fourier transformers so as to receive the pilot signals of N kinds generated by the OFDM signal transmitting device corresponding to the respective transmitting antennas by the receiving antennas, as the reception symbol timing;

and the inverse matrix computer, for all of the combinations of the transmitting antennas and the receiving antennas, measures the propagation coefficient by normalizing the reception amplitude and phase of the pilot signals with an amplitude and phase of known pilot signals, and calculates and stores the inverse matrix with respect to a propagation coefficient matrix related to respective subcarriers.

33. An OFDM signal receiving device according to claim 32, wherein

the receiving antennas receive pilot signals transmitted with timing mutually shifted so as to not overlap on the time domain, from the OFDM signal transmitting device, and outputs to the receiving frequency converters, and

the fast Fourier transformers separate pilot signals frequency converted by the receiving frequency converters for each subcarrier and output these pilot signals.

34. An OFDM signal receiving device according to claim 32, wherein

the inverse matrix computer comprises:

a receiving subcarrier pilot matrix composer which, when the number of subcarriers is I, generates a receiving subcarrier pilot matrix PRⁱ of N rows and N columns with a received signal rⁱ_mn of the m th symbol of the n th receiving antenna of the i th (i is an integer greater than or equal to 1 and less than or equal to I) subcarrier output from the fast Fourier transformers as the component of the m th row and the n th column, based on the N symbol pilot signals received by the receiving antennas, and

I subcarrier propagation coefficient inverse matrix computers for computing the inverse matrix (Sⁱ)<sup>−

1</sup> of a subcarrier propagation coefficient matrix Sⁱ being a matrix of the propagation coefficients between the transmitting antennas and the receiving antennas for the i th subcarrier, by multiplying the inverse matrix of a transmission subcarrier pilot matrix Pⁱ transmitted from the OFDM signal transmitting device being a matrix other than the unit matrix and the matrix obtained by multiplying a complex number by the unit matrix for which the determinant is not zero and with the pilot signal Pⁱ_mn of the m th symbol (m is an integer greater than or equal to 1 and less than or equal to N) transmitted by the n th (where n is an integer greater than or equal to 1 and less than or equal to N) transmitting antenna in the i th subcarrier, as the component of the m th row and n th column, by the receiving subcarrier pilot matrix PRⁱ.

35. An OFDM signal receiving device according to claim 32, further comprising:

N carrier frequency error estimators for estimating a frequency error between a carrier wave in the OFDM signal transmitting device and the local oscillator for receiver, based on the output from the receiving frequency converters, and outputting a carrier frequency error estimation value;

an averaging circuit of carrier frequency error estimation value for calculating and outputting an average value of the carrier frequency error estimation values output from the N carrier frequency error estimators; and

N carrier frequency error correctors for correcting the carrier frequency errors of the respective outputs of the receiving frequency converters, based on the average value output from the averaging circuit of carrier frequency error estimation value.

36. An OFDM signal receiving device according to claim 35, wherein

the carrier frequency error estimator comprises:

N delay circuits for delaying the outputs of the receiving frequency converters by the same time as the repetition interval of carrier frequency error estimation pilot signal repetitively transmitted from the OFDM signal transmitting device;

N complex conjugate circuits for calculating the complex conjugates of the outputs of the N delay circuits;

N complex multipliers for multiplying the outputs from the receiving frequency converters by the outputs from the complex conjugate circuits;

N integrating circuits for computing the sum of the outputs of the complex multipliers for a number of samples corresponding to the repetition interval of the carrier frequency error estimation pilot signal;

an averaging circuit for computing the average value of the outputs from the N integrating circuits;

an arc-tangent circuit for computing a phase variant proportional to the carrier frequency error, using the output from the averaging circuit; and

a phase converting circuit for converting the output of the arc-tangent circuit to a carrier frequency error per one sampling time.

37. An OFDM signal receiving device according to claim 35, wherein

the carrier frequency error estimator comprises:

N delay circuits for delaying the output of the receiving frequency converters by the same time as the repetition interval of carrier frequency error estimation pilot signal repetitively transmitted from the OFDM signal transmitting device;

N complex conjugate circuits for calculating the complex conjugates of the outputs of the N delay circuits;

N complex multipliers for multiplying the outputs from the receiving frequency converters by the outputs from the complex conjugate circuits;

N integrating circuits for computing the sum of the outputs of the complex multipliers for a number of samples corresponding to the repetition interval of the carrier frequency error estimation pilot signal;

an arc-tangent circuit for computing a phase variant proportional to the carrier frequency error, using the outputs from the N integrating circuits;

a phase converting circuit for converting the output of the arc-tangent circuit to a carrier frequency error per one sampling time, and

an averaging circuit for computing the average value of the output from the N phase converting circuits.

38. An OFDM signal receiving device according to claim 32, further comprising:

a deinterleaver for performing an operation to restore the order of the codes of transmission information signals which have been rearranged in the OFDM signal transmitting device, on the output from the interference canceller, and

a forward error correction decoder for decoding the output from the deinterleaver, corresponding to the forward error correction coding for the transmission information signals performed in the OFDM signal transmitting device.

39. An OFDM signal receiving device according to claim 38, further comprising:

a weighting factor computer for obtaining weighting factors for the output of the interference canceller; and

a multiplier for multiplying the output of the interference canceller by the weighting factors obtained by the weighting factor computer.

40. An OFDM signal receiving device according to claim 38, further comprising:

a communication quality measurer for measuring the quality of the outputs from the interference canceller related to an arbitrary subcarrier of the transmitted OFDM signal transmitted from the OFDM signal transmitting device; and

a second switch for outputting the signal outputs from the interference canceller directly in the case where the OFDM signal transmitting device transmits a signal for which the transmission information signals have been serial-parallel converted, and adding the outputs of the interference canceller or, outputting the one with the larger reception power of the interference canceller outputs, in the case where the OFDM signal transmitting device sends the same transmission information signals,

and the communication quality measurer outputs the quality to the OFDM signal transmitting device for switching to output the signal for which the transmission information signals have been serial-parallel converted, or to output the same transmission information signals.

41. An OFDM signal receiving device according to claim 40, further comprising:

an amplitude information coefficient computer for computing amplitude information coefficients used for reproducing the amplitude of the received signals at the receiving antennas, from elements of the inverse matrix obtained by the inverse matrix computer;

an amplitude information coefficient multiplier for multiplying respective outputs from the interference canceller by the amplitude information coefficients obtained by the amplitude information coefficient computer;

a diversity coefficient computer for computing diversity coefficients used in weighting for diversity combining, from elements of the inverse matrix obtained by the inverse matrix computer or from the amplitude information coefficients computed by the amplitude information coefficient computer;

a diversity coefficient multiplier for multiplying the output signals of the amplitude information coefficient multiplier by the diversity coefficients computed by the diversity coefficient computer; and

an adder for outputting the OFDM signal, being the added result of the outputs signal of the diversity coefficient multiplier.

42. An OFDM signal receiving device according to claim 29, further comprising:

receiving frequency converters for converting radio frequency of received signals received by the receiving antennas, into a frequency suitable for demodulation;

N fast Fourier transformers for performing Fourier transformation on respective received signals of N systems output from the receiving frequency converters;

a demodulator for converting the OFDM symbols for each of the antenna systems, output from the fast Fourier transformers into a bit stream;

the inverse matrix computer; and

an inverse matrix information transmitter for transmitting the inverse matrix obtained by the inverse matrix computer to the OFDM signal transmitting device, as an inverse matrix for the interference canceller provided in the OFDM signal transmitting device to multiply the respective subcarriers of the respective OFDM symbols.

43. An OFDM signal receiving device according to claim 29, further comprising:

receiving frequency converters for radio frequency of converting received signals received by the receiving antennas, into a frequency suitable for demodulation;

N fast Fourier transformers for performing Fourier transformation on respective received signals of N systems output from the receiving frequency converters;

a demodulator for converting the OFDM symbols for each of the antenna systems, output from the fast Fourier transformers Into a bit stream; and

a pilot information transmitter for detecting the amplitude and phase of the N pilot signals output from the fast Fourier transformers for each subcarrier corresponding to the N kinds of pilot signals transmitted from the OFDM signal transmitting device, and generating reception information for the pilot signal, and transmitting the reception information to the OFDM signal transmitting device for use by the inverse matrix computer provided in the OFDM signal transmitting device for computing the inverse matrix.

44. An OFDM signal receiving device according to claim 29, wherein

the receiving antennas are transmitting/receiving antennas further provided with a transmission function, and the device further comprises:

the pilot signal generator;

an inverse fast Fourier transformer for performing inverse fast Fourier transformation on N kinds of pilot signals output from the pilot signal generator;

transmission frequency converters for converting signals output from the inverse fast Fourier transformer into radio frequency suitable for transmission;

receiving frequency converters for converting radio frequency of received signals received by the receiving antennas, into a frequency suitable for demodulation;

fast Fourier transformers for performing Fourier transformation processing on respective N systems of received signals output from the receiving frequency converters;

N demodulators for converting OFDM symbols for each of the antenna systems, output from the fast Fourier transformers, to a bit stream; and

a transmission/reception switch for selecting the transmitting/receiving antennas to transmit signals output from the transmission frequency converters, or to receive signals supplied to the receiving frequency converters.

18. An OFDM signal transmitting device used in an OFDM signal communication system for transmitting OFDM signals over the same radio frequency from an OFDM signal transmitting device comprising a plurality of N transmitting antennas to an OFDM signal receiving device comprising N receiving antennas, wherein the OFDM signal communication system comprises:

an inverse matrix computer for computing each of inverse matrices of N-dimensional square matrices for each subcarrier constituted by the propagation coefficients for the respective propagation paths between the respective transmitting antennas and the respective receiving antennas;

an interference canceller for canceling interference components which occur between the OFDM signal transmitting device and the OFDM signal receiving device, based on the inverse matrix computed by the inverse matrix computer; and

a pilot signal generator for generating N kinds of pilot signals for use by the inverse matrix computer to compute the inverse matrix, and

the OFDM signal transmitting device is furnished with at least one of the inverse matrix computer, the interference canceller and the pilot signal generator.

29. An OFDM signal receiving device used in an OFDM signal communication system for transmitting OFDM signals over the same radio frequency from an OFDM signal transmitting device comprising a plurality of N transmitting antennas to an OFDM signal receiving device comprising N receiving antennas, wherein the OFDM signal communication system comprises:

an inverse matrix computer for computing each of inverse matrices of N-dimensional square matrices for each subcarrier constituted by the propagation coefficients for the respective propagation paths between the respective transmitting antennas and the respective receiving antennas;

an interference canceller for canceling interference components which occur between the OFDM signal transmitting device and the OFDM signal receiving device, based on the inverse matrix computed by the inverse matrix computer; and

a pilot signal generator for generating a pilot signal of N kinds for use by the inverse matrix computer to compute the inverse matrix, and

the OFDM signal receiving device is furnished with at least one of the inverse matrix computer, the interference canceller and the pilot signal generator.