JP2002064457A - Orthogonal frequency-division multiple signal demodulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve carrier frequency synchronization with short lead-in time, and at the same time to eliminate the influence of phase fluctuation common to an entire sub carrier due to the phase noise of a tuner or the like in an OFDM signal demodulation device. SOLUTION: A differential detection circuit 26 allows the output of an FFT circuit 25 to be differentially detected between symbols, a correlation calculation circuit 27 calculates the correlation value between differential detection output and the arrangement information of the sub carrier for pilot transmission, a wideband carrier frequency error calculation circuit 28 calculates a frequency error in sub carrier interval units from the peak position of the correlation value, and a carrier frequency correction circuit 23 uses the frequency error for correcting a carrier frequency. Also, a phase averaging circuit 29 averages the phase of the differential detection output corresponding to the sub carrier for pilot transmission, and a phase fluctuation correction circuit 30 uses the averaged phase for correcting the phase fluctuation common to entire sub carriers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an orthogonal frequency division multiplexing signal demodulation apparatus used for digital broadcasting and digital communication by an orthogonal frequency division multiplexing transmission method, and more particularly, to a frequency synchronization technique of a reproduction carrier used for demodulation on a receiving side, The present invention relates to a technique for removing an influence of a phase variation common to all subcarriers due to a phase noise of a tuner or the like.

[0002]

2. Description of the Related Art In recent years, for digital audio broadcasting for mobile objects and digital television broadcasting for terrestrial systems, orthogonal frequency division multiplexing (hereinafter referred to as OFDM) has been proposed.
ency Division Multiplex)) Transmission schemes are receiving attention.

[0003] The OFDM transmission system is a system in which a number of subcarriers orthogonal to each other are modulated by digital data to be transmitted, and the modulated waves are multiplexed and transmitted. This method has a feature that when the number of subcarriers to be used increases from several hundreds to several thousands, the symbol period of each modulated wave becomes extremely long, so that it is hardly affected by multipath interference.

Hereinafter, the principle of the OFDM transmission system will be described.
This will be described with reference to FIG.

FIG. 20 is a block diagram showing the basic configuration of the OFDM transmission system. In FIG. 20, thick arrows indicate complex signals, and thin arrows indicate real signals.

First, on the transmitting side, the signal to be transmitted is OF
The data signal input to the DM signal modulator 11 is mapped by a mapping circuit 111 to signal points on a complex plane corresponding to the modulation scheme of each subcarrier, and then inverse Fourier transform (hereinafter, IFFT).
nsform)). The IFFT circuit 112 generates an effective symbol period signal by performing an IFFT process on a signal to be transmitted for one symbol and converting the signal into a time domain. It has a function of generating a baseband OFDM signal by adding it as a guard period signal before the effective symbol period signal. The baseband OFDM signal generated here is transmitted to the quadrature modulation circuit 1
13 is supplied. The orthogonal modulation circuit 113 frequency-converts the baseband OFDM signal into an intermediate frequency (hereinafter, IF) band signal by orthogonally modulating the carrier with the baseband OFDM signal. OFDM signal is transmitted to a radio frequency (hereinafter referred to as RF
(Radio Frequency))
Output to the transmission path 12.

On the other hand, on the receiving side, an OF
The OFDM signal input to the DM demodulator 13 is frequency-converted from an RF band to an IF band by a tuner 131, and is then supplied to a quadrature demodulation circuit 132. This quadrature demodulation circuit 132 demodulates the input IF band signal into a baseband OFDM signal by quadrature demodulation, and outputs a demodulated output by Fourier transform (hereinafter, FFT (Fast)).
Fourier Transform)) circuit 133. The FFT circuit 133 extracts an effective symbol period signal from the baseband OFDM signal, performs FFT processing on the signal, and converts the signal into a frequency domain. The output is supplied to a detection circuit 134. After detecting each subcarrier according to the modulation method, the detection circuit 134 restores the data signal by demapping.

However, in the above-described principle configuration, data cannot be accurately demodulated when there is an error between frequencies of carriers used for transmission and reception.
Therefore, conventionally, two automatic frequency controls (hereinafter, AFC) within the sub-carrier interval and in the unit of the sub-carrier interval are used.
(Auto Frequency Control)) There is disclosed a method of combining circuits to obtain a wide range of frequency synchronization (for example,
Proceedings of the 1996 IEICE Communications Society Conference, B-512, p. 512).

[0009] In the AFC system disclosed in the above document, the frequency error within the subcarrier interval is determined by OFDM.
Since the guard period signal in the signal is a copy of the rear part of the effective symbol period signal, it is calculated using the correlation between them. Further, the frequency error in subcarrier interval units is calculated on the transmitting side using a frequency synchronization reference symbol inserted at a predetermined cycle.

Hereinafter, the configuration and operation of a conventional OFDM signal demodulator using the AFC system disclosed in the above document will be described with reference to FIGS.

FIG. 22 is a schematic diagram showing an example of the configuration of a frequency synchronization reference symbol. In FIG. 22, the horizontal axis represents frequency, and the vertical axis represents amplitude. A solid line in the figure indicates that a subcarrier exists at that frequency, and a broken line indicates that there is no subcarrier at that frequency. In this example, the presence or absence of subcarriers is determined by a predetermined pseudo random
PN (Pseudo Noise) series.

FIG. 21 is a block diagram showing a configuration of a conventional OFDM signal demodulator. In FIG. 21, thick arrows indicate complex signals, and thin arrows indicate real signals. In addition, general control signals such as a clock necessary for the operation of each component are omitted so as not to complicate the description.

In FIG. 21, a tuner 21 converts the frequency of an OFDM signal input from a transmission path from an RF band to an IF band, and the output is supplied to a quadrature demodulation circuit 22. The quadrature demodulation circuit 22 demodulates an OFDM signal in the IF band into a baseband OFDM signal using a fixed carrier generated therein. First
Is supplied to the input terminal of This carrier frequency correction circuit 2
3 is a correction generated based on the wideband carrier frequency error signal in subcarrier interval units supplied to the second input terminal and the narrowband carrier frequency error signal within the subcarrier interval supplied to the third input terminal. The carrier frequency error is corrected by multiplying the carrier by the baseband OFDM signal supplied to the first input terminal, and the output is output from the narrowband carrier frequency error calculation circuit 24 and the FF.
It is supplied to the T circuit 25.

Narrow band carrier frequency error calculating circuit 24
Calculates the frequency error within the subcarrier interval by using the correlation between the guard period signal in the baseband OFDM signal and the rear part of the effective symbol period signal, and outputs the third error of the carrier frequency correction circuit 23. Is supplied to the input terminal of Also, the FFT circuit 25 has a baseband OFD
The effective symbol period signal in the M signal is subjected to the FFT processing and converted into the frequency domain.
And supplied to the detection circuit 31.

The power calculating circuit 41 includes an FFT circuit 25
And calculates the power of the signal corresponding to each subcarrier output from the correlation calculation circuit 42.
Supplied to The correlation calculation circuit 42 calculates a correlation value between the output of the power calculation circuit 41 and a PN sequence corresponding to the presence or absence of the subcarrier of the frequency synchronization reference symbol shown in FIG. It is supplied to the error calculation circuit 28. The wideband carrier frequency error calculating circuit 28 calculates a frequency error in subcarrier interval units from the peak position of the correlation value, and its output is supplied to a second input terminal of the carrier frequency correcting circuit 23. After detecting each subcarrier according to the modulation method, the detection circuit 31 restores the data signal by demapping.

[0016]

However, in the conventional method as described above, the transmitting side uses a frequency synchronization reference symbol inserted at a predetermined period (for example, a frame) and uses a frequency in subcarrier interval units. Since the error is calculated, the pull-in time of the frequency synchronization becomes relatively long.

In the conventional method, in order to reduce the error of the carrier frequency in the steady state, for example, FIG.
It is necessary to set the time constant of the loop filter provided inside the narrow band carrier frequency error calculation circuit 24 to about several hundred symbol periods. Therefore, it is not possible to follow a fast variation such as a phase noise of a tuner (not limited to this example, a general AFC circuit cannot follow a fast variation such as a phase noise of a tuner). Therefore, the residual frequency error is caused by interference between subcarriers (hereinafter, ICI (In
ter Carrier Interference) and phase variation common to all subcarriers (hereinafter referred to as CPE (Common Phase Erro
r)), which causes the error rate to deteriorate.

Accordingly, the present invention has been made to solve the above-mentioned problem, and to provide an OFDM signal demodulator capable of reducing the time required for pulling in frequency synchronization and eliminating the influence of CPE due to phase noise of a tuner. Aim.

[0019]

In order to solve the above-mentioned problems, an OFDM signal demodulator according to the present invention is configured as follows.

(1) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal includes a set of subcarriers arranged at a specific frequency having the same phase for each symbol. And Fourier transforming the orthogonal frequency division multiplexed signal to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transforming means between symbols, thereby obtaining By averaging the phase of the output of the differential detection means corresponding to the first pilot signal and the differential detection means for calculating the variation between symbols with respect to the subcarriers within a symbol, the differential detection means is common to all subcarriers. Phase averaging means for estimating the phase variation, and a correction vector for each symbol is calculated from the output of the phase averaging means. Zui and configured to and a phase variation correction means for correcting the common phase variation to all subcarriers.

(2) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal includes a set of subcarriers arranged at a specific frequency having the same phase as each symbol. And Fourier transforming the orthogonal frequency division multiplexed signal to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transforming means between symbols, thereby obtaining Differential detection means for calculating a variation between symbols with respect to subcarriers; correlation calculation for calculating a correlation between an output of the differential detection means and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier Means for detecting a peak position of an output of the correlation calculating means, thereby estimating a carrier frequency error per subcarrier interval. Carrier frequency error calculation means, wideband carrier frequency correction means for correcting a carrier frequency based on the output of the wideband carrier frequency error calculation means, and a phase of an output of the differential detection means corresponding to the first pilot signal By averaging within a symbol, phase averaging means for estimating a phase variation common to all subcarriers, and calculating a correction vector for each symbol from the output of the phase averaging means, based on the correction vector, Phase fluctuation correction means for correcting a phase fluctuation common to all subcarriers.

(3) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal is a m-phase PSK-modulated set of subcarriers arranged at a specific frequency. (M is a natural number) by performing a Fourier transform on the orthogonal frequency division multiplexed signal to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transform means between symbols. Differential detection means for calculating a variation between symbols for each subcarrier, a power means for raising the output of the differential detection means to the power m, and a phase of an output of the power means corresponding to the first pilot signal. Is averaged in a symbol, thereby estimating a phase variation common to all subcarriers. The output of the phase averaging means is 1 / m And a phase variation correction unit that calculates a correction vector for each symbol from the output of the coefficient unit and corrects a phase variation common to all subcarriers based on the correction vector. .

(4) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal is obtained by modulating a set of subcarriers arranged at a specific frequency with m-phase PSK modulation. (M is a natural number) by performing a Fourier transform on the orthogonal frequency division multiplexed signal to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transform means between symbols. A differential detection means for calculating a variation between symbols for each subcarrier, a power means for raising the output of the differential detection means to the mth power, an output of the power means, and the first A correlation calculating means for calculating a correlation with arrangement information indicating the presence or absence of a pilot signal, and a sub key by detecting a peak position of an output of the correlation calculating means. A wideband carrier frequency error calculating means for estimating a carrier frequency error of the rear spacing units, based on the output of the broadband carrier frequency error calculating means,
Estimating a phase variation common to all subcarriers by averaging, within a symbol, the phase of the output of the exponentiation means corresponding to the first pilot signal and the wideband carrier frequency correction means for correcting the carrier frequency. Phase averaging means, coefficient means for multiplying the output of the phase averaging means by 1 / m, a correction vector for each symbol is calculated from the output of the coefficient means, and a phase common to all subcarriers is calculated based on the correction vector. And phase fluctuation correction means for correcting fluctuation.

(5) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal is a m-phase PSK-modulated set of subcarriers arranged at a specific frequency. (M is a natural number) by performing a Fourier transform on the orthogonal frequency division multiplexed signal to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transform means between symbols. A differential detection means for calculating a variation between symbols for each subcarrier, and a determination is made as to which of the complex plane areas divided by the phase into m outputs from the differential detection means. By rotating the output complex vector of the differential detection means by an integral multiple of 2π / m according to the determination result, the phase after rotation is always included in the same region. Averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the vector rotator corresponding to the first pilot signal in a symbol. And a phase variation correction unit that calculates a correction vector for each symbol from the output of the phase averaging unit and corrects a phase variation common to all subcarriers based on the correction vector.

(6) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal is obtained by modulating a set of subcarriers arranged at a specific frequency with m-phase PSK modulation. (M is a natural number) by performing a Fourier transform on the orthogonal frequency division multiplexed signal to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transform means between symbols. A differential detection means for calculating a variation between symbols for each subcarrier, a power means for raising an output of the differential detection means to the m-th power, an output of the power means, and the first pilot for each carrier. Correlation calculation means for calculating a correlation with arrangement information indicating the presence or absence of a signal,
By detecting the peak position of the output of the correlation calculating means, a wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval, and a carrier frequency based on the output of the wideband carrier frequency error calculating means. The wideband carrier frequency correcting means for correcting and the output of the differential detection means are determined to be included in any of the complex plane areas divided into m by phase, and the differential is determined in accordance with the determination result. By rotating the output complex vector of the detection means by an integral multiple of 2π / m,
By averaging the phase of the output of the vector rotator corresponding to the first pilot signal and the vector rotator so that the phase after rotation is always included in the same region in the symbol, all the subcarriers are obtained. A phase averaging means for estimating a common phase fluctuation, and a phase fluctuation correction for calculating a correction vector for each symbol from an output of the phase averaging means, and correcting a phase fluctuation common to all subcarriers based on the correction vector. Means.

(7) In the configuration of (2), the correlation calculating means determines whether or not the first pilot signal is present for each of the sub-carriers and the complex vector signal output from the differential detection means. It is configured to calculate a correlation with the indicated arrangement information.

(8) In the configuration of (4) or (6), the correlation calculating means includes the complex vector signal output from the power means and the first vector for each of the subcarriers.
And a correlation with arrangement information indicating the presence / absence of a pilot signal.

(9) In the configuration of (2), the correlation calculation means includes: a signal obtained by averaging a complex vector signal output from the differential detection means in a symbol direction; It is configured to calculate a correlation with arrangement information indicating the presence or absence of the first pilot signal.

(10) In the configuration of (4) or (6), the correlation calculating means includes: a signal obtained by averaging a complex vector signal output from the power means in a symbol direction; To calculate the correlation with the arrangement information indicating the presence or absence of the first pilot signal.

(11) In the configuration of (2), the correlation calculation means includes: a magnitude of a signal obtained by averaging a complex vector signal output from the differential detection means in a symbol direction; To calculate the correlation with the arrangement information indicating the presence or absence of the first pilot signal.

(12) In the configuration of (4) or (6), the correlation calculating means may calculate the average of a complex vector signal output from the exponentiation means in a symbol direction in a symbol direction and the sub-signal. The configuration is such that a correlation with arrangement information indicating the presence or absence of the first pilot signal is calculated for each carrier.

(13) In the configuration of (2), the correlation calculation means averages the complex vector signal output from the differential detection means in the symbol direction, and calculates the magnitude of the averaged complex vector signal. The correlation between the binarized signal by comparing the magnitude with a predetermined threshold value and arrangement information indicating the presence or absence of the first pilot signal is calculated for each subcarrier.

(14) In the configuration of (4) or (6), the correlation calculating means averages a complex vector signal output from the exponentiation means in a symbol direction, and averages the averaged complex vector signal. Is compared with a predetermined threshold value to calculate a correlation between a binarized signal and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier.

(15) In the configuration of (2), the correlation calculating means averages the complex vector signal output from the differential detection means in the symbol direction, and calculates the magnitude of the averaged complex vector signal. And calculates a correlation between the binarized signal by comparing the magnitude with a predetermined threshold value and arrangement information indicating the presence / absence of the first pilot signal for each subcarrier. The threshold is changed based on the magnitude of the received signal.

(16) In the configuration of (4) or (6), the correlation calculating means averages a complex vector signal output from the exponentiation means in a symbol direction, and calculates an averaged complex vector signal. The correlation between the binarized signal by comparing the magnitude of the first pilot signal with a predetermined threshold value and the arrangement information indicating the presence or absence of the first pilot signal for each subcarrier is calculated. , The threshold is changed based on the magnitude of the received signal.

(17) In any one of the constitutions (2), (4) and (6), the wide-band carrier frequency correcting means may select a correction carrier based on an output of the wide-band carrier frequency error calculating means. The correction carrier is generated and multiplied by the input signal of the Fourier transform means.

(18) In any one of the constitutions (2), (4) and (6), the wide-band carrier frequency correcting means is configured to execute the Fourier transform based on an output of the wide-band carrier frequency error calculating means. The output signal of the conversion means is shifted in the frequency direction.

(19) In any one of the constitutions (1) to (6), the phase fluctuation correction means detects the output of the Fourier transform means in accordance with the modulation method of each subcarrier. The detection means is incorporated in the detection means, and performs a detection, and corrects a phase variation common to all subcarriers based on an output of the correction vector calculation means.

(20) In any one of the constitutions (1) to (6), in addition to the first pilot signal, a second pilot signal distributed and periodically arranged in a subcarrier-symbol area. An apparatus for demodulating an orthogonal frequency division multiplex signal transmitting a pilot signal, wherein the phase fluctuation correction means is incorporated in a detection means for detecting an output of the Fourier transform means according to a modulation method of each subcarrier. The detection means synchronously detects each subcarrier using the second pilot signal, and corrects a phase variation common to all subcarriers based on an output of the correction vector calculation means. .

(21) The apparatus according to any one of (1) to (6), wherein the apparatus demodulates an orthogonal frequency division multiplexed signal which is transmitted by differentially modulating a data signal between symbols. The phase variation correction means is incorporated in the detection means for detecting the output of the Fourier transform means according to the modulation method of each subcarrier, and the detection means performs differential detection between each subcarrier between symbols, It is configured to correct a phase variation common to all subcarriers based on an output of the correction vector calculation means.

(22) In any one of the constitutions (1) to (6), the phase averaging means averages an input complex vector signal in a symbol and calculates the phase thereof. , A configuration for estimating a phase variation common to all subcarriers.

(23) In the configuration of (2) or (4), the correlation calculating means includes the phase averaging means, and the arrangement indicating presence or absence of the first pilot signal for each subcarrier. Information and a correlation between the input complex vector signal are calculated and supplied to the wideband carrier frequency error calculating means, and a phase variation common to all subcarriers is estimated from a phase angle of a vector obtained by the correlation operation. Configuration.

(24) An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first
The pilot signal is obtained by modulating a set of subcarriers arranged at a specific frequency with the same phase for each symbol, and includes a tuner for performing band conversion of the orthogonal frequency division multiplexed signal, and the band-converted orthogonal frequency division Fourier transforming the multiplexed signal into a frequency axis signal by Fourier transforming; and differentially detecting the output of the Fourier transforming means between symbols to calculate a difference between symbols for each subcarrier. Dynamic detection means, and phase averaging means for estimating a phase variation common to all subcarriers by averaging a phase of an output of the differential detection means corresponding to the first pilot signal in a symbol, A correction vector for each symbol is calculated from the output of the phase averaging means, and is common to all subcarriers based on the correction vector. Phase fluctuation correction means for correcting phase fluctuation; correlation calculation means for calculating a correlation between the output of the differential detection means and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier; Detecting the peak position of the output of the calculating means, comprising a wideband carrier frequency error calculating means for estimating the carrier frequency error of the subcarrier interval unit, furthermore, the tuner, the output of the wideband carrier frequency error calculating means Based on this, the carrier frequency is corrected by controlling the local oscillation frequency of the tuner.

(25) An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein
Is a set of subcarriers arranged at a specific frequency, which is obtained by performing m-phase PSK modulation (m is a natural number). The tuner performs band conversion of the orthogonal frequency division multiplexed signal, and the band-converted Fourier transforming the orthogonal frequency division multiplexed signal to perform a Fourier transform to convert to a frequency axis signal, and differentially detecting the output of the Fourier transform between the symbols, the variation between symbols with respect to each subcarrier is reduced. By calculating the differential detection means, the power means for raising the output of the differential detection means to the m-th power, and averaging the phase of the output of the power means corresponding to the first pilot signal in a symbol, Phase averaging means for estimating a phase variation common to all subcarriers, coefficient means for multiplying the output of the phase averaging means by 1 / m, and said coefficient means Calculating a correction vector for each symbol from the output, and correcting a phase fluctuation common to all subcarriers based on the correction vector; an output of the exponentiation means; A correlation calculating means for calculating a correlation with arrangement information indicating the presence or absence of a pilot signal, and a wideband carrier frequency error for estimating a carrier frequency error per subcarrier interval by detecting a peak position of an output of the correlation calculating means. Calculating means, wherein the tuner is configured to correct a carrier frequency by controlling a local oscillation frequency of the tuner based on an output of the wideband carrier frequency error calculating means.

(26) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein
Is a set of subcarriers arranged at a specific frequency, which is obtained by performing m-phase PSK modulation (m is a natural number). The tuner performs band conversion of the orthogonal frequency division multiplexed signal, and the band-converted Fourier transforming the orthogonal frequency division multiplexed signal to perform a Fourier transform to convert to a frequency axis signal, and differentially detecting the output of the Fourier transform between the symbols, the variation between symbols with respect to each subcarrier is reduced. The differential detection means to be calculated, the power means for raising the output of the differential detection means to the power m, and the output of the differential detection means are included in any one of m complex plane areas divided by phase. By rotating the output complex vector of the differential detection means by an integral multiple of 2π / m according to the determination result,
By averaging the phase of the output of the vector rotator corresponding to the first pilot signal and the vector rotator so that the phase after rotation is always included in the same region in the symbol, all the subcarriers are obtained. A phase averaging means for estimating a common phase fluctuation, and a phase fluctuation correction for calculating a correction vector for each symbol from an output of the phase averaging means and correcting a phase fluctuation common to all subcarriers based on the correction vector. Means, a correlation calculating means for calculating a correlation between an output of the exponentiation means and arrangement information indicating the presence or absence of the first pilot signal for each carrier, and detecting a peak position of an output of the correlation calculating means. And a wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval. Based on the output of the broadband carrier frequency error calculating means adapted to correct the carrier frequency by controlling the local oscillation frequency of the tuner.

(27) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein
Is a signal obtained by modulating a set of subcarriers arranged at a specific frequency with the same phase for each symbol, orthogonal demodulation means for orthogonally demodulating the orthogonal frequency division multiplexed signal, and the orthogonal demodulated orthogonal frequency Fourier transforming the division multiplexed signal to a Fourier transform means to convert it to a frequency axis signal, and differentially detecting the output of the Fourier transform means between symbols to calculate a variation between symbols for each subcarrier. Differential detection means, and phase averaging means for averaging the phase of the output of the differential detection means corresponding to the first pilot signal within a symbol to thereby estimate a phase variation common to all subcarriers. Calculating a correction vector for each symbol from the output of the phase averaging means, and sharing the correction vector for all subcarriers based on the correction vector. Phase fluctuation correction means for correcting a phase fluctuation, correlation calculation means for calculating the correlation between the output of the differential detection means, and the arrangement information indicating the presence or absence of the first pilot signal for each subcarrier, Wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval by detecting a peak position of an output of the correlation calculating means, and the quadrature demodulating means further comprises: The carrier frequency is corrected by controlling the local oscillation frequency of the quadrature demodulation means on the basis of the output of.

(28) An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first
Is a set of subcarriers arranged at a specific frequency, which is obtained by performing m-phase PSK modulation (m is a natural number), and an orthogonal demodulation means for orthogonally demodulating the orthogonal frequency division multiplexed signal; Fourier transforming the orthogonal frequency division multiplexed signal to a Fourier transform means for transforming the orthogonal frequency division multiplexed signal to a frequency axis signal; , An exponentiation means for raising the output of the differential detection means to the m-th power, and averaging the phase of the output of the exponentiation means corresponding to the first pilot signal in a symbol. Phase averaging means for estimating a phase variation common to all subcarriers, coefficient means for multiplying the output of the phase averaging means by 1 / m, A correction vector for each symbol is calculated from the output of the above, based on the correction vector, based on the correction vector, a phase variation correction means for correcting a phase variation common to all subcarriers, an output of the exponentiation means, A wideband carrier frequency for estimating a carrier frequency error per subcarrier interval by detecting a peak position of an output of the correlation calculating means; Error calculating means, further comprising the quadrature demodulating means,
The carrier frequency is corrected by controlling the local oscillation frequency of the quadrature demodulation means based on the output of the wideband carrier frequency error calculation means.

(29) An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first
Is a set of subcarriers arranged at a specific frequency, which is obtained by performing m-phase PSK modulation (m is a natural number), and an orthogonal demodulation means for orthogonally demodulating the orthogonal frequency division multiplexed signal; Fourier transforming the orthogonal frequency division multiplexed signal to a Fourier transform means for transforming the orthogonal frequency division multiplexed signal to a frequency axis signal; , An exponentiation means for raising the output of the differential detection means to the m-th power, and an output of the differential detection means included in any of the complex plane areas divided into m by phase. By rotating the output complex vector of the differential detection means by an integral multiple of 2π / m according to the determination result,
By averaging the phase of the output of the vector rotator corresponding to the first pilot signal and the vector rotator so that the phase after rotation is always included in the same region in the symbol, all the subcarriers are obtained. A phase averaging means for estimating a common phase fluctuation, and a phase fluctuation correction for calculating a correction vector for each symbol from an output of the phase averaging means and correcting a phase fluctuation common to all subcarriers based on the correction vector. Means, a correlation calculating means for calculating a correlation between an output of the exponentiation means and arrangement information indicating the presence or absence of the first pilot signal for each carrier, and detecting a peak position of an output of the correlation calculating means. And a wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval, and the quadrature demodulating means further comprises: On the basis of the output of the broadband carrier frequency error calculating means adapted to correct the carrier frequency by controlling the local oscillation frequency of the quadrature demodulation means.

[0049]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, as an OFDM transmission system according to the present invention, DVB-T (Digital Video Broadcasting-T) which is a terrestrial digital television broadcasting system in Europe.
An embodiment of the present invention will be described with reference to FIG. 1 to FIG. 19, taking a 2k mode (the number of subcarriers used for transmission is 1705) of the errestrial standard as an example.

In the above standard, a scattered (dispersed) pilot (hereinafter referred to as a
Two types of pilot signals called SP (Scattered Pilots)) and continuous pilots (hereinafter, CP (Continual Pilots)) are transmitted.

FIG. 19 is a schematic diagram showing a pilot signal arrangement according to the DVB-T standard. In FIG. 19, k on the horizontal axis represents a subcarrier index, and n on the vertical axis represents a symbol index. Further, black circles represent subcarriers for transmitting pilot signals, and white circles represent subcarriers for transmitting other data.

[0052] Scatter de pilots is transmitted using the subcarrier index k = k _p that satisfies the following formula (1). In the equation (1), mod represents a remainder operation, and p is an arbitrary non-negative integer.

[0053]

(Equation 1)

Also, the continuous pilot:
k = ｛0,48,54,87,141,156,19
2,201,255,279,282,333,43
2,450,483,525,531,618,63
6,714,759,765,780,804,87
3,888,918,939,942,969,98
4,1050,1101,1107,1110,113
7, 1140, 1146, 1206, 1269, 132
Transmission is performed using 45 subcarriers that satisfy 3,1377,1491,1683,1704}.

These pilot signals are modulated based on the PN sequence w _k corresponding to the subcarrier index k to be arranged, and are multiplexed with the same amplitude and the same phase for each symbol as shown in equation (2). Is done.
In the equation (2), Re {c _{k, n} } represents the real part of the complex vector c _{k, n} corresponding to the subcarrier with the subcarrier index k and the symbol index n.
m {c _{k, n} } represents an imaginary part.

[0056]

(Equation 2)

Further, in the above standard, a transmission parameter signal (hereinafter referred to as TPS) is transmitted using a predetermined subcarrier.
(Transmission Parameter Signaling)).

The TPS is k = ｛34,50,209,3
46,413,569,595,688,790,90
1,1073, 1219, 1262, 1286, 146
Transmission is performed using 17 subcarriers that satisfy 9,1594,1687}, and the same information bit is transmitted in subcarriers within the same symbol.

[0059] At this time, when the information bits to be transmitted in symbol index n and S _n, TPS is (3) differential phase between the symbols as shown in equation PSK (Phase Shift
Keying) modulated.

[0060]

(Equation 3)

[0061] However, with respect to the first symbol of the frame (symbol index n = 0), (4) as shown in the expression is the absolute phase modulated based on the PN sequence w _k above.

[0062]

(Equation 4)

(First Embodiment) FIG. 1 is a block diagram showing a configuration of an OFDM signal demodulator according to a first embodiment of the present invention. 1, the same parts as those in FIG. 21 are denoted by the same reference numerals. Note that, also in this figure, thick arrows indicate complex signals, and thin arrows indicate real signals. In addition, general control signals such as a clock necessary for the operation of each component are omitted so as not to complicate the description.

In FIG. 1, a tuner 21 converts the frequency of an OFDM signal input from a transmission line from an RF band to an IF band, and the output is supplied to a quadrature demodulation circuit 22. The quadrature demodulation circuit 22 demodulates an IF band OFDM signal into a base band OFDM signal using a fixed carrier generated therein. 1 input.

The carrier frequency correction circuit 23
A correction carrier is generated based on a wideband carrier frequency error signal in subcarrier interval units supplied to an input terminal of the subcarrier and a narrowband carrier frequency error signal within a subcarrier interval supplied to a third input terminal. The carrier frequency error is corrected by multiplying the carrier by the baseband OFDM signal supplied to the first input terminal.
And supplied to the FFT circuit 25.

Narrow band carrier frequency error calculating circuit 24
Calculates the frequency error within the subcarrier interval by using the correlation between the guard period signal in the baseband OFDM signal and the rear part of the effective symbol period signal, and outputs the third error of the carrier frequency correction circuit 23. Is supplied to the input terminal of Also, the FFT circuit 25 has a baseband OFD
The effective symbol period signal in the M signal is subjected to FFT processing and converted into the frequency domain, and the output is output from the differential detection circuit 26.
And a first input terminal of the phase variation correction circuit 30.

The differential detection circuit 26 calculates the inter-symbol phase variation by performing inter-symbol differential detection of a signal corresponding to each subcarrier output from the FFT circuit 25. The calculation result is as follows. The signal is supplied to the correlation calculating circuit 27 and the phase averaging circuit 29. The correlation calculation circuit 27
The correlation value between the output of the differential detection circuit 26 and the arrangement information of the subcarriers transmitting the CP is calculated, and the correlation value is supplied to the wideband carrier frequency error calculation circuit 28. The wideband carrier frequency error calculating circuit 28 calculates a frequency error in subcarrier interval units from the peak position of the correlation value, and its output is supplied to a second input terminal of the carrier frequency correcting circuit 23.

The phase averaging circuit 29 estimates the CPE by averaging the phase of the output of the differential detection circuit 26 corresponding to the CP within the symbol. Is supplied to the input terminal of The phase fluctuation correction circuit 30 calculates a correction vector generated based on the output of the phase averaging circuit 29 supplied to the second input terminal,
The CPE is corrected by multiplying the output of the FFT circuit 25 supplied to the first input terminal, and the output is supplied to the detection circuit 31. After detecting each subcarrier according to the modulation method, the detection circuit 31 restores the data signal by demapping.

The differential detection circuit 26 is specifically configured as shown in FIG. 2, and the output of the FFT circuit 25 is supplied to the one symbol period delay circuit 261 and the complex multiplier 263. One symbol period delay circuit 261
The output of the FFT circuit 25 is delayed by one symbol period, and the delayed output is supplied to the conjugate circuit 262. The conjugate circuit 262 calculates the complex conjugate by inverting the sign of the imaginary part of the output of the one-symbol period delay circuit 261, and the calculation result is supplied to the complex multiplier 263.
The complex multiplier 263 multiplies the output of the FFT circuit 25 by the output of the conjugate circuit 262, and the operation result is supplied to the correlation calculation circuit 27 and the phase averaging circuit 29 as the output of the differential detection circuit 26.

FIG. 3 shows a first configuration example of the correlation calculation circuit 27 in FIG. This correlation calculation circuit 27
In this configuration, the differential detection output from the differential detection circuit 26 is supplied to the shift register 2701. The shift register 2701 has a plurality of tap outputs corresponding to the arrangement of subcarriers for transmitting the CP, and these tap outputs are supplied to the input terminal of the summing circuit 2702. The sum circuit 2702 calculates the sum of the tap outputs of the shift register 2701, and the calculation result is supplied to the power calculation circuit 2703. The power calculation circuit 2703 calculates the power of the output of the summation circuit 2702, and the calculation result is supplied to the wideband carrier frequency error calculation circuit 28 as the output of the correlation calculation circuit 27.

According to the configuration shown in FIG. 3, when the subcarrier transmitting the CP is output to all tap outputs of shift register 2701, the output of correlation calculating circuit 27 shows a peak value. Therefore, by detecting the peak value of the output of the correlation calculating circuit 27 in the wideband carrier frequency error calculating circuit 28 and calculating the deviation from the predetermined timing, the carrier frequency error in subcarrier interval units can be estimated.

FIG. 4 shows a second configuration example of the correlation calculation circuit 27 in FIG. 4, the same parts as those in FIG. 3 are denoted by the same reference numerals, and different parts will be described here.

In the correlation calculation circuit 27, the differential detection output from the differential detection circuit 26 is
04. The inter-symbol filter circuit 2704 averages the output of the differential detection circuit 26 in the symbol direction, and the output is supplied to the shift register 2701. This shift register 2701
Subsequent configurations and operations are the same as those of the first configuration example shown in FIG.

The inter-symbol filter circuit 27 in FIG.
4 is specifically configured as shown in FIG. 5, and the output of the differential detection circuit 26 is supplied to the subtractor 27041. The subtractor 27041 subtracts the output of the one-symbol period delay circuit 27044 from the output of the differential detection circuit 26, and the output is supplied to a coefficient unit 27042. The coefficient unit 27042 multiplies the output of the subtractor 27041 by a coefficient α (0 ≦ α ≦ 1), and the operation result is supplied to an adder 27043. This adder 27
Numeral 043 is for adding the output of the coefficient unit 27042 and the output of the one-symbol period delay circuit 27044, and the operation result is supplied to the shift register 2701 as the output of the inter-symbol filter circuit 2704. One-symbol period delay circuit 27044 outputs the output of adder 27043 to 1
Delay for symbol period.

The inter-symbol filter circuit 2704 configured as shown in FIG. 5 has an infinite impulse response (hereinafter, IIR).
It operates as an (Infinite Impulse Response) type low-pass filter, and averages complex vectors corresponding to each subcarrier output from the differential detection circuit 26 in the symbol direction. In the differential detection circuit 26, a signal obtained by differentially detecting a subcarrier for transmitting a CP between symbols is represented by C
If the PE component is neglected, it can be regarded as a DC signal having the same amplitude and the same phase for each symbol, and most of the DC signal passes through the inter-symbol filter circuit 2704. Signals obtained by performing inter-symbol differential detection on other subcarriers are signals having a random amplitude and phase for each symbol, and are blocked by the inter-symbol filter circuit 2704. Also,
Since the noise component is also a random signal for each symbol, it is blocked by the inter-symbol filter circuit 2704.

Therefore, the correlation calculation circuit 2 shown in FIG.
By adding an inter-symbol filter circuit 2704 to 7, the output floor of the correlation calculation circuit 27 is suppressed, and errors in estimating errors in the wideband carrier frequency error calculation circuit 28 can be reduced.

FIG. 6 shows a third configuration example of the correlation calculation circuit 27 in FIG. 6, the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals, and different parts will be described here.

In the correlation calculation circuit 27, the output of the differential detection circuit 26 is averaged in the symbol direction by the inter-symbol filter circuit 2704, and is then supplied directly to the power calculation circuit 2703. That is, the power calculation circuit 2703 in this case is
Calculate the output power of the output unit 04. The calculation result is supplied to the shift register 2705. This shift register 27
05 has a plurality of tap outputs corresponding to the arrangement of the subcarriers for transmitting the CP, and these tap outputs are supplied to the input terminal of the summing circuit 2706. This summation circuit 2706
Calculates the sum of the tap outputs of the shift register 2705, and the calculation result is supplied to the wideband carrier frequency error calculation circuit 28 as the output of the correlation calculation circuit 27.

In FIG. 6, shift register 2705
Holds the real number signal, and the sum circuit 2706 also calculates the sum of the real number signals. Therefore, the scale can be reduced as compared with the shift register 2701 and the sum circuit 2702 in FIGS.

FIG. 7 shows a fourth configuration example of the correlation calculation circuit 27 in FIG. 7, the same parts as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

A comparison circuit 2707 in FIG. 7 extracts a subcarrier for transmitting a CP by comparing the output of the power calculation circuit 2703 with the threshold value set by the threshold value setting circuit 2708. If the output is larger, “1” is output and the threshold setting circuit 270
If the output of 8 is larger, "0" is output. The output of the comparison circuit 2707 is supplied to a shift register 2709. This shift register 2709 has a plurality of tap outputs corresponding to the arrangement of subcarriers for transmitting the CP, and those tap outputs are supplied to the input terminal of the summing circuit 2710. This summation circuit 2710 is a shift register 2
The calculation result is supplied to the wideband carrier frequency error calculation circuit 28 as the output of the correlation calculation circuit 27.

In FIG. 7, shift register 2709
Holds the binary signal, and the summing circuit 2710 also calculates the sum of the binary signals, so that the scale can be greatly reduced as compared with the shift register 2701 and the summing circuit 2702 in FIGS. . Also, the threshold setting circuit 27
If the threshold output from 08 is controlled by the magnitude of the received signal, it is possible to prevent erroneous determination due to a change in the output level of the power calculation circuit 2703.

FIG. 8 shows the phase fluctuation correction circuit 3 in FIG.
0 shows a configuration example. This phase fluctuation correction circuit 3
At 0, the output of the phase averaging circuit 29 is supplied to the adder 301. This adder 301 constitutes a cumulative adder together with a register 302 for holding a signal for one symbol period, and performs cumulative addition of the output of the phase averaging circuit 29 for each symbol, thereby calculating the cumulative value of the inter-symbol phase variation from the start of the operation. The calculation result (adder 30
1) is a correction vector calculation circuit (e− ^jφ ) 303
Supplied to The correction vector calculation circuit 303 calculates a complex vector having an amplitude of 1 with a phase angle of −1 times the output of the adder 301, and the calculation result is supplied to a multiplier 304. The multiplier 304 multiplies the output of the correction vector calculation circuit 303 and the output of the FFT circuit 25. With this operation, the CPE can be corrected.

With the above configuration, according to the configuration of the present embodiment, the carrier frequency error in subcarrier interval units is calculated from the allocation information of the subcarriers for transmitting the CP included in each symbol. The time required for pulling in the frequency synchronization can be reduced as compared with the conventional example.

Further, since the phase fluctuation between symbols is calculated and corrected using the CP for each symbol, the influence of the CPE due to the phase noise of the tuner 21 or the like can be eliminated.

(Second Embodiment) FIG. 9 is a block diagram showing a configuration of an OFDM signal demodulator according to a second embodiment of the present invention. In FIG. 9, the same parts as those in FIG. 1 are denoted by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

The OFDM signal demodulation device shown in FIG.
In this embodiment, the tuner 32 corrects a carrier frequency error instead of the carrier frequency correction circuit 23 in FIG. The tuner 32 is configured to locally control the wideband carrier frequency error signal in subcarrier interval units supplied to the second input terminal and the narrowband carrier frequency error signal within the subcarrier interval supplied to the third input terminal. Oscillation frequency is controlled, and OF is supplied to a first input terminal.
The frequency conversion of the DM signal from the RF band to the IF band is performed, and the output is supplied to the quadrature demodulation circuit 22. Other configurations and operations are the same as those in FIG.

(Third Embodiment) FIG. 10 is a block diagram showing a configuration of an OFDM signal demodulator according to a third embodiment of the present invention. In FIG. 10, the same parts as those in FIG. 1 are denoted by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

The OFDM signal demodulation device shown in FIG. 10 is such that a carrier frequency error is corrected in a quadrature demodulation circuit 33 instead of the carrier frequency correction circuit 23 in FIG. This quadrature demodulation circuit 33 has a second
Controlling the local oscillation frequency based on the wideband carrier frequency error signal in subcarrier interval units supplied to the input terminal of the subcarrier and the narrowband carrier frequency error signal within the subcarrier interval supplied to the third input terminal; The OFDM signal in the IF band supplied to the input terminal of
The demodulated output is supplied to a narrowband carrier frequency error calculation circuit 24 and an FFT circuit 25. Other configurations and operations are the same as those in FIG.

(Fourth Embodiment) FIG. 11 is a block diagram showing a configuration of an OFDM signal demodulator according to a fourth embodiment of the present invention. In FIG. 11, the same parts as those in FIG. 1 are indicated by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

In the OFDM signal demodulator shown in FIG. 11, a carrier frequency (fc) correction circuit 34 corrects a narrow band carrier frequency error within a subcarrier interval, and a shift circuit 35 corrects a wideband carrier frequency error per subcarrier interval. The correction is made. The carrier frequency correction circuit 34 generates a correction carrier based on a narrow band carrier frequency error signal within a subcarrier interval supplied to a second input terminal, and supplies the correction carrier to a base supplied to the first input terminal. A carrier frequency error is corrected by multiplying the band OFDM signal.
And supplied to the FFT circuit 25. The shift circuit 35
Based on the wideband carrier frequency error signal in subcarrier interval units supplied to the second input terminal, the FFT circuit 25
Is shifted in the frequency direction, and the output is supplied to the differential detection circuit 26 and the first input terminal of the phase fluctuation correction circuit. Other configurations and operations are the same as those in FIG.

Here, the carrier frequency error in the subcarrier interval unit is a frequency error in which the effective symbol period length is an integer period, but since the OFDM signal has a guard period, the deviation in the subcarrier unit in the frequency domain. At the same time, a phase rotation for each symbol depending on the guard period length is generated. Therefore, when the wideband carrier frequency error is corrected by the shift in the frequency domain as in the configuration of FIG. 11, means for correcting the phase rotation is required. However, since this phase rotation is common to all subcarriers, when a circuit for removing CPE is provided as shown in FIG. 11, the phase fluctuation correction circuit 30 automatically corrects the phase rotation.

(Fifth Embodiment) FIG. 12 is a block diagram showing a configuration of an OFDM signal demodulating apparatus according to a fifth embodiment of the present invention. 12, the same parts as those in FIG. 1 are indicated by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

The OFDM signal demodulation device shown in FIG. 12 is such that a CPE is corrected in a detection circuit 36 instead of the phase fluctuation correction circuit 30 in FIG.
The detection circuit 36 generates a correction vector based on the output of the phase averaging circuit 29 supplied to the second input terminal, and multiplies the correction vector by a detection vector corresponding to the modulation method of each subcarrier. Then, the output of the FFT circuit 25 is detected using the detection vector, the CPE is corrected, and the data signal is restored by demapping. Other configurations and operations are the same as those in FIG.

FIG. 13 shows the detection circuit 36 in FIG.
1 shows a configuration example corresponding to a modulation method on the premise of synchronous detection using an SP signal. This detection circuit 36
In this configuration, the output of the FFT circuit 25 is supplied to the first input terminal of the complex divider 3604 and the first input terminal of the complex divider 3608. Pilot generation circuit 360
Numeral 3 generates an SP in synchronization with the output of the FFT circuit 25, and the output is supplied to the second input terminal of the complex divider 3604. This complex divider 3604 outputs the SP included in the output of the FFT circuit 25 supplied to the first input terminal.
To a pilot generating circuit 36 supplied to a second input terminal.
03 by dividing by the regular SP output by SP
This is to calculate the transmission path characteristics acting on. The output is supplied to the output of the memory 3606 and selectively to the first input terminal of the complex multiplier 3602 by a switch (SW) 3605.

On the other hand, the output of the phase averaging circuit 29 is supplied to a correction vector calculation circuit ( ^ejφ ) 3601. The correction vector calculation circuit 3601 calculates a complex vector having an amplitude of 1 using the output of the phase averaging circuit 29 as a phase angle, and the calculation result is supplied to a second input terminal of the complex multiplier 3602. . The switch 3605 selects the output of the complex divider 3604 when the output of the complex divider 3604 corresponds to SP (one symbol out of four symbols when focusing on one subcarrier), and otherwise selects the output of the complex divider 3604. The output of the memory 3606 is selected and output to (3 symbols out of symbols).

The complex multiplier 3602 includes an output of the complex divider 3604 or an output of the memory 3606 selectively supplied from the first input terminal by the switch 3605 and a correction vector calculation circuit supplied to the second input terminal. 3601 and the output of the filter circuit 3
607 and also to the memory 3606. This memory 3606 holds the output of the complex multiplier 3602 for four symbol periods (until the next SP is transmitted on the subcarrier of interest). By these operations, S
The CPE can be corrected for the transmission path characteristics acting on the subcarrier transmitting P (1 subcarrier among 3 subcarriers).

The filter circuit 3607 includes the complex multiplier 36
02 is interpolated in the frequency (subcarrier) direction to obtain transmission path characteristics (CPE corrected) acting on all subcarriers. The output is a complex divider 3608
Is supplied to a second input terminal. This complex divider 3608
Is to synchronously detect the output of the FFT circuit 25 by dividing the output of the FFT circuit 25 supplied to the first input terminal by the output of the filter circuit 3607 supplied to the second input terminal. . Its output is the demapping circuit 3
609. This demapping circuit 3609
Restores the data signal by demapping the output of the complex divider 3608 according to the modulation scheme.

FIG. 14 shows the detection circuit 36 in FIG.
2 shows a configuration example corresponding to a modulation method on the premise of differential detection. In this detection circuit 36, the FFT circuit 2
5 is supplied to the one symbol period delay circuit 3610 and the first input terminal of the complex divider 3611. One-symbol period delay circuit 3610 delays the output of FFT circuit 25 by one symbol period.
Its output is provided to a first input of a complex multiplier 3602. On the other hand, the output of the phase averaging circuit 29 is supplied to a correction vector calculation circuit (e ^jφ ) 3601.

The correction vector calculation circuit 3601 calculates a complex vector having an amplitude of 1 using the output of the phase averaging circuit 29 as a phase angle. The calculation result is input to a second input terminal of the complex multiplier 3602. Supplied. The complex multiplier 3602 multiplies the output of the one-symbol period delay circuit 3610 supplied to the first input terminal by the output of the correction vector calculation circuit 3601 supplied to the second input terminal, thereby obtaining 1 The signal before the symbol period is subjected to CPE correction, and the operation result is supplied to a second input terminal of the complex divider 3611.

The complex divider 3611 divides the output of the FFT circuit 25 supplied to the first input terminal by the output of the complex multiplier 3602 supplied to the second input terminal, thereby obtaining the FFT circuit 2511. Is subjected to differential detection, and the output is supplied to a demapping circuit 3612. This demapping circuit 3612 includes a complex divider 36
The data signal is restored by demapping the output of No. 11 according to the modulation method.

With the above configuration, according to the present embodiment, a part of the processing of the phase fluctuation correction circuit 30 and the detection circuit 31 in the first embodiment can be shared, so that the circuit scale can be reduced. .

(Sixth Embodiment) FIG. 15 is a block diagram showing a configuration of an OFDM signal demodulator according to a sixth embodiment of the present invention. In FIG. 15, the same parts as those in FIG. 1 are denoted by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

In the OFDM signal demodulating device shown in FIG. 15, the processing of both the correlation calculating circuit 27 and the phase averaging circuit 29 in FIG.

FIG. 16 shows an example of the configuration of the correlation circuit 37 in FIG. 15. The output of the differential detection circuit 26 is supplied to a shift register 371. This shift register 371 is
A plurality of tap outputs corresponding to the arrangement of subcarriers for transmitting the CP are provided.
Is supplied to the input terminal of The sum circuit 372 calculates the sum of the tap outputs of the shift register 371, and the calculation result is obtained by a power calculation circuit 373 and a phase calculation circuit (ta
n ^-1 ) 374.

The power calculating circuit 373 calculates the power of the output of the summing circuit 372, and the calculation result is supplied to the wideband carrier frequency error calculating circuit 28 as the first output of the correlation calculating circuit 37. On the other hand, the phase calculation circuit 374 calculates the phase of the output of the summation circuit 372, and the calculation result is supplied to the second input terminal of the phase fluctuation correction circuit 30 as the second output of the correlation calculation circuit 37.

Here, when the carrier frequencies are synchronized, the sub-carrier for transmitting the CP is output to the tap output of the shift register 371. Therefore, the output of the summation circuit 372 shows the variation between the symbols of the sub-carrier for transmitting the CP. It becomes the average in the symbol.

With the above configuration, according to the present embodiment, a part of the processing of the correlation calculation circuit 27 and the phase averaging circuit 29 in the first embodiment can be shared, so that the circuit scale can be reduced. .

(Seventh Embodiment) FIG. 17 is a block diagram showing a configuration of an OFDM signal demodulator according to a seventh embodiment of the present invention. 17, the same parts as those in FIG. 1 are denoted by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

The OFDM signal demodulator shown in FIG.
The carrier frequency synchronization and the CPE removal are performed using the PS.
8 and a coefficient unit 39 are added.

Here, the exponentiation circuit 38 calculates the square of a complex vector corresponding to each subcarrier output from the differential detection circuit 26. The calculation result is obtained by the correlation calculation circuit 27 and the phase averaging circuit 29. And supplied to. This squaring operation eliminates the 180 degree uncertainty of the phase variation due to the TPS being subjected to differential two-phase PSK modulation between symbols.

The correlation calculation circuit 27 calculates a correlation value between the output of the exponentiation circuit 38 and at least one of the allocation information among the subcarriers for transmitting the CP and the subcarriers for transmitting the TPS. Is supplied to the wideband carrier frequency error calculation circuit 28. Phase averaging circuit 29
Is to estimate the CPE by averaging the phase of the output of the power circuit 38 corresponding to at least one of CP and TPS in the symbol, and the output is supplied to the coefficient unit 39. The coefficient unit 39 corrects by halving the phase fluctuation between symbols doubled by the power circuit 38, and the output is supplied to the second input terminal of the phase fluctuation correction circuit 30. .

Generally, TPS is used for m-phase PSK modulation (m
Is a natural number), the exponentiation circuit 38 calculates the m-th power of a complex vector corresponding to each subcarrier output from the differential detection circuit 26, and the coefficient unit 39 outputs the output of the phase averaging circuit 29 by 1 / M times.

With the above configuration, in this embodiment, the TPS is used in addition to the CP to calculate and correct the carrier frequency error in subcarrier interval units and the phase variation between symbols. The error due to the influence of noise can be reduced as compared with the embodiment.

(Eighth Embodiment) FIG. 18 is a block diagram showing a configuration of an OFDM signal demodulator according to an eighth embodiment of the present invention. In FIG. 18, the same parts as those in FIG. 1 are denoted by the same reference numerals. Also in this figure, thick arrows indicate complex signals, thin arrows indicate real signals, and general control signals such as clocks necessary for the operation of each component are described so as not to complicate the description. Omitted.

The OFDM signal demodulator shown in FIG.
The carrier frequency synchronization and the CPE removal are performed by using the PS.
8 and a vector rotation circuit 40 are added.

Here, the exponentiation circuit 38 calculates the square of a complex vector corresponding to each subcarrier output from the differential detection circuit 26, and the calculation result is supplied to the correlation calculation circuit 27. This squaring operation eliminates the 180 degree uncertainty of the phase variation due to the TPS being subjected to differential two-phase PSK modulation between symbols. The correlation calculation circuit 27 calculates a correlation value between the output of the exponentiation circuit 38 and at least one of the arrangement information of the subcarrier transmitting the CP and the subcarrier transmitting the TPS.
The correlation value is supplied to the wideband carrier frequency error calculation circuit 28.

On the other hand, the vector rotation circuit 40 determines which of the complex plane areas divided by the imaginary axis is included in the output of the differential detection circuit 26, and performs differential detection in accordance with the determination result. By rotating the output complex vector of the circuit 26 by π / 2 so that the phase after the rotation is always included in the same region, the TPS can be used as the differential two-phase PS between symbols.
This eliminates the 180 degree uncertainty of the phase fluctuation caused by the K modulation, and the output is supplied to the phase averaging circuit 29. The phase averaging circuit 29 includes CP and T
The CPE is estimated by averaging the phase of the output of the vector rotation circuit 40 corresponding to at least one of the PSs in the symbol, and the output is supplied to the second input terminal of the phase fluctuation correction circuit 30. Is done.

In general, TPS has m-phase PSK modulation (m
Is a natural number), the vector rotation circuit 40
It is determined which of the complex plane regions divided by the phase the output of the differential detection circuit 26 includes into m,
By rotating the output complex vector of the differential detection circuit 26 by an integral multiple of π / m according to the determination result, the phase after rotation is always included in the same region.

With the above configuration, in the present embodiment, similarly to the seventh embodiment, the carrier frequency error in subcarrier interval units and the phase variation between symbols are calculated using TPS in addition to CP. Since the correction is performed, errors due to the influence of noise can be reduced as compared with the first embodiment.

In the embodiment of the present invention, the power calculation inside the correlation calculation circuits 27 and 37 is not limited as long as it calculates the signal magnitude such as the amplitude or the sum of the amplitudes of the real part and the imaginary part. Good.

In the embodiment of the present invention, the phase averaging circuit 29 averages the output complex vector of the differential detection circuit 26 or the vector rotation circuit 40 corresponding to at least one of CP and TPS in a symbol. The CPE may be approximated by calculating the phase and calculating the phase.

In the embodiment of the present invention, the wideband carrier frequency error calculating circuit 28
7, the synchronization state of the carrier frequency is determined based on the output of the sub-carrier 7, and when the synchronization state is established, the output of the carrier frequency error signal in subcarrier interval units is stopped. If provided, malfunctions due to the influence of noise, fading, and the like can be prevented.

Further, in the above description, the 2k mode of the DVB-T standard has been described as an example. However, in the first to eighth embodiments, the set of subcarriers arranged at the same frequency for each symbol is the same for each symbol. Any transmission system that transmits a signal modulated by phase may be used. In the seventh and eighth embodiments, a set of subcarriers arranged at the same frequency for each symbol is subjected to m-phase PSK modulation (m is a natural number). Needless to say, any transmission method that transmits a signal may be used.

[0125]

As described above, the OFDM signal demodulation apparatus according to the present invention calculates the frequency error per subcarrier interval using the pilot signal arranged at the same frequency for each symbol, thereby achieving frequency synchronization as compared with the conventional example. Can be shortened.

Further, by calculating and correcting the phase fluctuation between symbols by using a pilot signal arranged at the same frequency for each symbol, C
The effect of PE can be eliminated.

As described above, according to the present invention, the time required for pulling in the frequency synchronization is further reduced, and the influence of the CPE due to the phase noise of the tuner can be eliminated.
A signal demodulation device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an OFDM signal demodulation device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of an internal configuration of a differential detection circuit in FIG. 1;

FIG. 3 is a block diagram showing a first internal configuration example of the correlation calculation circuit in FIG. 1;

FIG. 4 is a block diagram showing a second internal configuration example of the correlation calculation circuit in FIG. 1;

FIG. 5 is a block diagram showing an example of the internal configuration of an inter-symbol filter circuit in FIG. 4;

FIG. 6 is a block diagram illustrating a third internal configuration example of the correlation calculation circuit in FIG. 1;

FIG. 7 is a block diagram illustrating a fourth internal configuration example of the correlation calculation circuit in FIG. 1;

8 is a block diagram showing an example of an internal configuration of a phase fluctuation correction circuit in FIG.

FIG. 9 is a block diagram illustrating a configuration of an OFDM signal demodulation device according to a second embodiment of the present invention.

FIG. 10 shows an OFDM according to a third embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a signal demodulation device.

FIG. 11 shows an OFDM according to a fourth embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a signal demodulation device.

FIG. 12 shows an OFDM according to a fifth embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a signal demodulation device.

FIG. 13 is a block diagram showing a first internal configuration example of the detection circuit in FIG. 12;

FIG. 14 is a block diagram illustrating a second internal configuration example of the detection circuit in FIG. 12;

FIG. 15 shows an OFDM according to a sixth embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a signal demodulation device.

16 is a block diagram showing an example of the internal configuration of the correlation calculation circuit in FIG.

FIG. 17 shows an OFDM according to a seventh embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a signal demodulation device.

FIG. 18 shows an OFDM according to an eighth embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a signal demodulation device.

FIG. 19 is a schematic diagram showing an example of pilot signal arrangement according to the present invention.

FIG. 20 is a block diagram showing an example of a principle configuration of an OFDM transmission system.

FIG. 21 is a block diagram illustrating a configuration example of a conventional OFDM signal demodulation device.

FIG. 22 is a schematic diagram illustrating a configuration example of a frequency synchronization reference symbol related to a conventional OFDM signal demodulation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... OFDM signal modulation device 111 ... Mapping circuit 112 ... IFFT circuit 113 ... Quadrature modulation circuit 114 ... Up converter 12 ... Transmission line 131 ... Tuner 13 ... OFDM signal demodulation device 131 ... Tuner 132 ... Quadrature demodulation circuit 133 ... FFT circuit 134 ... Detection circuit 21 Tuner 22 Quadrature demodulation circuit 23 Carrier frequency error correction circuit 24 Narrow band carrier frequency error calculation circuit 25 FFT circuit 26 Differential detection circuit 27 Correlation calculation circuit 28 Broadband carrier frequency error calculation circuit 29 ... Phase averaging circuit 30 ... Phase fluctuation correction circuit 31 ... Detection circuit 32 ... Tuner 33 ... Quadrature demodulation circuit 34 ... Carrier frequency error correction circuit 35 ... Shift circuit 36 ... Detection circuit 37 ... Correlation calculation circuit 38 ... Power circuit 39 ... Coefficient unit 40 ... Vector rotation circuit 1 ... power calculation circuit 42 ... correlation calculating circuit

Continued on the front page (72) Inventor Tomohiro Kimura 5-2-8 Akasaka, Minato-ku, Tokyo Next Generation Digital Television Broadcasting System Research Laboratories Co., Ltd. (72) Inventor Sadaji Kageyama 5-2-2 Akasaka, Minato-ku, Tokyo No. 8 Next Generation Digital Television Broadcasting System Laboratory Co., Ltd. (72) Inventor Yasuo Harada 5-2-2 Akasaka, Minato-ku, Tokyo Inside Next Generation Digital Television Broadcasting System Laboratories Co., Ltd. (72) Inventor Akira Kisoda 5-2-8 Akasaka, Minato-ku, Tokyo Next Generation Digital Television Broadcasting System Laboratory Co., Ltd. (72) Inventor Shigeru Soga Researcher, Next-Generation Digital Television Broadcasting System 5-28-8 Akasaka, Minato-ku, Tokyo In-house (72) Inventor Seiji Sakashita 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 5K022 DD01 DD33 DD42 DD43

Claims (29)

[Claims] 1. An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal includes a set of subcarriers arranged in a specific frequency at the same phase for each symbol. Fourier transform means for transforming the orthogonal frequency division multiplexed signal into a frequency axis signal by performing Fourier transform on the orthogonal frequency division multiplexed signal. Differential detection means for calculating a variation between symbols with respect to a carrier, and by averaging the phase of the output of the differential detection means corresponding to the first pilot signal in a symbol,
A phase averaging unit for estimating a phase variation common to all subcarriers, a correction vector for each symbol is calculated from an output of the phase averaging unit, and a phase variation common to all subcarriers is corrected based on the correction vector. An orthogonal frequency division multiplexing signal demodulation device comprising: a phase fluctuation correction unit. 2. An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first pilot signal includes a set of subcarriers arranged at a specific frequency at the same phase for each symbol. Fourier transform means for transforming the orthogonal frequency division multiplexed signal into a frequency axis signal by performing Fourier transform on the orthogonal frequency division multiplexed signal. Differential detection means for calculating a variation between symbols with respect to a carrier; correlation calculation means for calculating a correlation between an output of the differential detection means and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier And detecting a peak position of an output of the correlation calculating means, thereby estimating a carrier frequency error per subcarrier interval. Carrier frequency error calculation means, wideband carrier frequency correction means for correcting a carrier frequency based on the output of the wideband carrier frequency error calculation means, and a phase of an output of the differential detection means corresponding to the first pilot signal. By averaging within the symbol
A phase averaging unit for estimating a phase variation common to all subcarriers, a correction vector for each symbol is calculated from an output of the phase averaging unit, and a phase variation common to all subcarriers is corrected based on the correction vector. An orthogonal frequency division multiplexing signal demodulation device comprising: a phase fluctuation correction unit. 3. An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged in a specific frequency by m-phase PSK modulation ( m is a natural number)
Fourier transforming the orthogonal frequency division multiplexed signal into a frequency axis signal by performing a Fourier transform, and differentially detecting the output of the Fourier transforming means between symbols, each subcarrier Differential detection means for calculating the variation between symbols with respect to the following; power means for raising the output of the differential detection means to the m-th power; phase of the output of the power means corresponding to the first pilot signal, By averaging, phase averaging means for estimating a phase variation common to all subcarriers, coefficient means for multiplying the output of the phase averaging means by 1 / m, and a correction vector for each symbol from the output of the coefficient means And a phase variation correction unit that calculates and corrects a phase variation common to all subcarriers based on the correction vector. Exchange frequency division multiplex signal demodulator. 4. An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged at a specific frequency by m-phase PSK modulation ( m is a natural number)
Fourier transforming the orthogonal frequency division multiplexed signal into a frequency axis signal by performing a Fourier transform, and differentially detecting the output of the Fourier transforming means between symbols, each subcarrier Differential detection means for calculating the variation between symbols with respect to, power means for raising the output of the differential detection means to the power m, output of the power means, and the presence or absence of the first pilot signal for each subcarrier. Correlation calculating means for calculating a correlation with the arrangement information shown; wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval by detecting a peak position of an output of the correlation calculating means; Broadband carrier frequency correction means for correcting the carrier frequency based on the output of the carrier frequency error calculation means A phase averaging means for estimating a phase variation common to all subcarriers by averaging a phase of an output of the power means corresponding to the first pilot signal in a symbol; and an output of the phase averaging means. And a phase variation correction unit that calculates a correction vector for each symbol from the output of the coefficient unit and corrects a phase variation common to all subcarriers based on the correction vector. And an orthogonal frequency division multiplexing signal demodulator. 5. An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged in a specific frequency by m-phase PSK modulation ( m is a natural number)
Fourier transforming the orthogonal frequency division multiplexed signal into a frequency axis signal by performing a Fourier transform, and differentially detecting the output of the Fourier transforming means between symbols, each subcarrier Differential detection means for calculating the variation between symbols with respect to, The output of the differential detection means, to determine which region of the complex plane region divided into m by phase,
Vector rotation means for rotating the output complex vector of the differential detection means by an integral multiple of 2π / m in accordance with the determination result so that the phase after rotation is always included in the same region; Phase averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the vector rotation means corresponding to the pilot signal of And a phase variation correction means for correcting a phase variation common to all subcarriers based on the correction vector. 6. An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged at a specific frequency with m-phase PSK modulation (PSK modulation). m is a natural number)
Fourier transforming the orthogonal frequency division multiplexed signal into a frequency axis signal by performing a Fourier transform, and differentially detecting the output of the Fourier transforming means between symbols, each subcarrier Differential detection means for calculating the variation between symbols with respect to the following; power means for raising the output of the differential detection means to the power m; output of the power means; and presence / absence of the first pilot signal for each carrier. Correlation calculating means for calculating a correlation with the arrangement information; wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval by detecting a peak position of an output of the correlation calculating means; Based on the output of the frequency error calculation means, a wideband carrier frequency correction means for correcting the carrier frequency, The output of the differential detection means is determined to be included in any of the complex plane regions divided into m by the phase,
Vector rotation means for rotating the output complex vector of the differential detection means by an integral multiple of 2π / m in accordance with the determination result so that the phase after rotation is always included in the same region; Phase averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the vector rotation means corresponding to the pilot signal of And a phase variation correction means for correcting a phase variation common to all subcarriers based on the correction vector. 7. The correlation calculation unit calculates a correlation between a complex vector signal output from the differential detection unit and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier. The orthogonal frequency division multiplex signal demodulation device according to claim 2, characterized in that: 8. The correlation calculating means calculates a correlation between a complex vector signal output from the power means and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier. The orthogonal frequency division multiplex signal demodulation device according to claim 4. 9. The correlation calculating means includes: a signal obtained by averaging a complex vector signal output from the differential detection means in a symbol direction; and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier. The orthogonal frequency division multiplexing signal demodulation device according to claim 2, wherein a correlation with the orthogonal frequency division multiplexing signal is calculated. 10. The correlation calculating means, comprising: a signal obtained by averaging a complex vector signal output from the power means in a symbol direction; and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier. The orthogonal frequency division multiplex signal demodulator according to claim 4 or 6, wherein the correlation is calculated. 11. The correlation calculating means indicates a magnitude of a signal obtained by averaging a complex vector signal output from the differential detecting means in a symbol direction and presence / absence of the first pilot signal for each subcarrier. The orthogonal frequency division multiplex signal demodulator according to claim 2, wherein a correlation with the arrangement information is calculated. 12. The method according to claim 12, wherein the correlation calculation unit calculates a magnitude of a signal obtained by averaging a complex vector signal output from the exponentiation unit in a symbol direction and the first signal for each of the subcarriers.
The orthogonal frequency division multiplexing signal demodulation device according to claim 4 or 6, wherein the correlation with the arrangement information indicating the presence or absence of the pilot signal is calculated. 13. The correlation calculating unit averages a complex vector signal output from the differential detection unit in a symbol direction, and compares the averaged magnitude of the complex vector signal with a predetermined threshold. The orthogonal frequency division multiplexed signal demodulation apparatus according to claim 2, wherein a correlation between the binarized signal and arrangement information indicating the presence or absence of the first pilot signal is calculated for each subcarrier. 14. The correlation calculating means averages the complex vector signal output from the power means in the symbol direction, and compares the averaged magnitude of the complex vector signal with a predetermined threshold to obtain a binary value. The orthogonal frequency division multiplexing signal demodulation device according to claim 4 or 6, wherein a correlation between the converted signal and arrangement information indicating the presence or absence of the first pilot signal is calculated for each subcarrier. 15. The correlation calculating means, by averaging the complex vector signal output from the differential detection means in the symbol direction and comparing the magnitude of the averaged complex vector signal with a predetermined threshold value, The correlation between the binarized signal and the arrangement information indicating the presence or absence of the first pilot signal is calculated for each subcarrier, and the correlation calculation unit changes the threshold based on the size of the received signal. The orthogonal frequency division multiplex signal demodulation device according to claim 2, characterized in that: 16. The correlation calculating means averages the complex vector signal output from the power means in the symbol direction, and compares the magnitude of the averaged complex vector signal with a predetermined threshold to obtain a binary value. And calculating the correlation between the converted signal and the arrangement information indicating the presence or absence of the first pilot signal for each subcarrier. Further, the correlation calculation unit changes the threshold based on the size of the received signal. Claim 4 or Claim 6
4. The orthogonal frequency division multiplexed signal demodulator according to item 1. 17. The wideband carrier frequency correction unit generates a correction carrier based on an output of the wideband carrier frequency error calculation unit, and multiplies the correction carrier by an input signal of the Fourier transform unit. Item 7. The orthogonal frequency division multiplexed signal demodulation device according to any one of Items 2, 4, and 6. 18. The method according to claim 2, wherein said wideband carrier frequency correction means shifts an output signal of said Fourier transform means in a frequency direction based on an output of said wideband carrier frequency error calculation means. 7. The orthogonal frequency division multiplex signal demodulator according to any one of 6. 19. The phase fluctuation correcting means is incorporated in a detecting means for detecting an output of the Fourier transform means according to a modulation method of each subcarrier, wherein the detecting means comprises:
The orthogonal frequency division multiplex signal demodulator according to any one of claims 1 to 6, wherein detection is performed and a phase variation common to all subcarriers is corrected based on an output of the correction vector calculation unit. . 20. In addition to the first pilot signal,
An apparatus for demodulating an orthogonal frequency division multiplexed signal transmitting a second pilot signal dispersed and periodically arranged in a subcarrier-symbol region, wherein the phase fluctuation correction unit outputs an output of the Fourier transform unit. Incorporated in a detecting means for detecting according to a modulation method of each subcarrier, the detecting means synchronously detects each subcarrier using the second pilot signal, and outputs to the output of the correction vector calculating means. 7. A phase variation common to all sub-carriers is corrected based on the variation.
The orthogonal frequency division multiplex signal demodulator according to any one of the above. 21. An apparatus for demodulating an orthogonal frequency division multiplexed signal for transmitting a data signal by performing differential modulation between symbols between the symbols, wherein the phase fluctuation correction means outputs an output of the Fourier transform means to each subcarrier. The detection means is incorporated in a detection means for detecting according to a modulation method, and the detection means performs differential detection between symbols on each subcarrier and a phase common to all subcarriers based on an output of the correction vector calculation means. The orthogonal frequency division multiplex signal demodulator according to any one of claims 1 to 6, wherein the fluctuation is corrected. 22. The phase averaging means for averaging an input complex vector signal in a symbol and calculating a phase thereof, thereby estimating a phase variation common to all subcarriers. Item 7. An orthogonal frequency division multiplex signal demodulation device according to any one of Items 1 to 6. 23. The correlation calculating means includes the phase averaging means, and calculates a correlation between arrangement information indicating the presence or absence of the first pilot signal for each of the subcarriers and an input complex vector signal. 5. The orthogonal frequency according to claim 2, wherein the orthogonal frequency is supplied to the wideband carrier frequency error calculating means, and a phase variation common to all subcarriers is estimated from a phase angle of a vector obtained by the correlation operation. Division multiplex signal demodulator. 24. An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal is obtained by combining a set of subcarriers arranged at a specific frequency with the same phase for each symbol. A tuner for performing band conversion of the orthogonal frequency division multiplexed signal, a Fourier transform unit for performing a Fourier transform on the band-converted orthogonal frequency division multiplexed signal to convert the orthogonal frequency division multiplexed signal into a frequency axis signal, Differential detection means for calculating a symbol-to-symbol variation for each subcarrier by differentially detecting the output of the conversion means between symbols; and an output of the differential detection means corresponding to the first pilot signal. By averaging the phase within the symbol,
A phase averaging unit for estimating a phase variation common to all subcarriers, a correction vector for each symbol is calculated from an output of the phase averaging unit, and a phase variation common to all subcarriers is corrected based on the correction vector. Phase fluctuation correction means, correlation calculation means for calculating a correlation between the output of the differential detection means, and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier, and output of the correlation calculation means Wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval by detecting a peak position, and further comprising: the tuner, based on an output of the wideband carrier frequency error calculating means, Frequency division multiplexing signal, wherein the carrier frequency is corrected by controlling the local oscillation frequency of the signal. Demodulator. 25. An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal is obtained by modulating a set of subcarriers arranged at a specific frequency with m-phase PSK modulation. m is a natural number)
A tuner that performs band conversion of the orthogonal frequency division multiplexed signal; a Fourier transform unit that performs a Fourier transform on the band-converted orthogonal frequency division multiplexed signal to convert the orthogonal frequency division multiplexed signal into a frequency axis signal; Differential detection means for calculating the inter-symbol variation for each subcarrier by differentially detecting the output of the means between symbols; power means for raising the output of the differential detection means to the m-th power; Phase averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the power means corresponding to the pilot signal of A coefficient means for multiplying, a correction vector for each symbol is calculated from the output of the coefficient means, and based on the correction vector, Phase fluctuation correcting means for correcting a common phase fluctuation; correlation calculating means for calculating a correlation between an output of the power means and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier; Detecting the peak position of the output of the calculating means, comprising a wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval, further comprising the tuner, the output of the wideband carrier frequency error calculating means An orthogonal frequency division multiplexing signal demodulation device for correcting a carrier frequency by controlling a local oscillation frequency of the tuner based on the signal. 26. An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged in a specific frequency by m-phase PSK modulation ( m is a natural number)
A tuner that performs band conversion of the orthogonal frequency division multiplexed signal; a Fourier transform unit that performs a Fourier transform on the band-converted orthogonal frequency division multiplexed signal to convert the orthogonal frequency division multiplexed signal into a frequency axis signal; Differential detection means for calculating a variation between symbols for each subcarrier by differentially detecting the output of the means between symbols; a power means for raising the output of the differential detection means to the m-th power; It is determined which of the complex plane regions divided by the phase the output of the detection means is divided into m,
Vector rotation means for rotating the output complex vector of the differential detection means by an integral multiple of 2π / m in accordance with the determination result so that the phase after rotation is always included in the same region; Phase averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the vector rotation means corresponding to the pilot signal of Phase variation correction means for calculating a correction vector for the phase variation common to all subcarriers based on the correction vector; an output of the power means; and presence or absence of the first pilot signal for each carrier. A correlation calculation unit for calculating a correlation with the arrangement information indicating the subcarrier interval unit by detecting a peak position of an output of the correlation calculation unit A wideband carrier frequency error calculating means for estimating a carrier frequency error, wherein the tuner corrects the carrier frequency by controlling a local oscillation frequency of the tuner based on an output of the wideband carrier frequency error calculating means. And an orthogonal frequency division multiplexing signal demodulator. 27. An apparatus for demodulating an orthogonal frequency division multiplexed signal including a first pilot signal, wherein the first pilot signal includes a set of subcarriers arranged at a specific frequency at the same phase for each symbol. Orthogonal demodulation means for orthogonally demodulating the orthogonal frequency division multiplexed signal, Fourier transforming the orthogonally demodulated orthogonal frequency division multiplexed signal into a frequency axis signal, Differential detection means for calculating a symbol-to-symbol variation for each subcarrier by differentially detecting the output of the Fourier transform means between symbols; and an output of the differential detection means corresponding to the first pilot signal. By averaging the phase of
A phase averaging unit for estimating a phase variation common to all subcarriers, a correction vector for each symbol is calculated from an output of the phase averaging unit, and a phase variation common to all subcarriers is corrected based on the correction vector. Phase fluctuation correction means, correlation calculation means for calculating a correlation between the output of the differential detection means, and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier, and output of the correlation calculation means By detecting the peak position, comprising a wideband carrier frequency error calculation means for estimating the carrier frequency error of the subcarrier interval unit, the quadrature demodulation means, based on the output of the wideband carrier frequency error calculation means, Orthogonal frequency division, wherein the carrier frequency is corrected by controlling the local oscillation frequency of the orthogonal demodulation means. Multiplex signal demodulator. 28. An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged at a specific frequency by m-phase PSK modulation ( m is a natural number)
Orthogonal demodulation means for orthogonally demodulating the orthogonal frequency division multiplexed signal; Fourier transforming means for transforming the orthogonally demodulated orthogonal frequency division multiplexed signal into a frequency axis signal by performing a Fourier transform; Differential detection means for calculating the inter-symbol variation for each subcarrier by differentially detecting the output of the conversion means between symbols; power means for raising the output of the differential detection means to the m-th power; Phase averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the power means corresponding to one pilot signal within a symbol; a coefficient means for multiplying by m, a correction vector for each symbol is calculated from the output of the coefficient means, and all subcarriers are calculated based on the correction vector. A phase variation correction unit that corrects a phase variation common to: a correlation calculation unit that calculates a correlation between an output of the exponentiation unit and arrangement information indicating the presence or absence of the first pilot signal for each subcarrier. Detecting the peak position of the output of the correlation calculating means, comprising a wideband carrier frequency error calculating means for estimating a carrier frequency error per subcarrier interval, further comprising the quadrature demodulating means, the wideband carrier frequency error calculating means An orthogonal frequency division multiplexing signal demodulator, wherein a carrier frequency is corrected by controlling a local oscillation frequency of the orthogonal demodulation means based on an output. 29. An apparatus for demodulating an orthogonal frequency division multiplex signal including a first pilot signal, wherein the first pilot signal modulates a set of subcarriers arranged at a specific frequency by m-phase PSK modulation ( m is a natural number)
Orthogonal demodulation means for orthogonally demodulating the orthogonal frequency division multiplexed signal; Fourier transforming means for transforming the orthogonally demodulated orthogonal frequency division multiplexed signal into a frequency axis signal by performing a Fourier transform; Differential detection means for calculating a variation between symbols for each subcarrier by differentially detecting an output of the conversion means between symbols; a power means for raising an output of the differential detection means to the m-th power; The output of the dynamic detection means is determined to be included in any of the complex plane regions divided into m by the phase,
Vector rotation means for rotating the output complex vector of the differential detection means by an integral multiple of 2π / m in accordance with the determination result so that the phase after rotation is always included in the same region; Phase averaging means for estimating a phase variation common to all subcarriers by averaging the phase of the output of the vector rotation means corresponding to the pilot signal of Phase variation correction means for calculating a correction vector for the phase variation common to all subcarriers based on the correction vector; an output of the power means; and presence or absence of the first pilot signal for each carrier. A correlation calculation unit for calculating a correlation with the arrangement information indicating the subcarrier interval unit by detecting a peak position of an output of the correlation calculation unit A wideband carrier frequency error calculating means for estimating a carrier frequency error, further comprising the quadrature demodulating means, based on an output of the wideband carrier frequency error calculating means, controlling a local oscillation frequency of the quadrature demodulating means. An orthogonal frequency division multiplexing signal demodulator for correcting a carrier frequency.