JP2000278241A - Repeater for ofdm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an OFDM use repeater where the adjustment is easy and the characteristic of a transmission channel subject to change in seasons, weather and time can adaptively be compensated. SOLUTION: A compensation quantity detector 2 sequentially converts an RF input signal into an IF signal, a base band signal, and a frequency base signal to extract pilot signals at an interval of subcarriers arranged on a frequency base. Since the pilot signal for each subcarrier appears at a prescribed symbol period, interpolation processing is applied thereto in the direction of the time base. The amplitude phase characteristic in a transmission frequency band can be obtained by detecting the amplitude and phase characteristic of the pilot signal with a symbol period in each subcarrier obtained in this way. A signal with a characteristic inverse to this characteristic is generated and used for a compensation signal to compensate (3) the amplitude and phase characteristic of an IF signal that is a main signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing) repeater used for digital transmission, for example, a relay transmitter for medium-wave, short-wave, terrestrial / satellite / cable television.

[0002]

2. Description of the Related Art As a next-generation digital broadcasting system,
The development of digital terrestrial broadcasting using the TV band by the current terrestrial wave is being promoted. The transmission method is O
A scheme using FDM (Orthogonal Frequency Division Multiplexing) has already been adopted as a European standard scheme, and is considered to be a leading scheme in Japan. Further, the OFDM system is not limited to terrestrial waves, but is also considered to be applied to medium waves, short waves, digital broadcasting such as satellite and cable television.

[0003] In a broadcasting system, the use of a relay device is required for the purpose of expanding a broadcasting service area and eliminating a blind area. In conventional analog television broadcasting, to suppress distortion in the transmission path from the transmitter to the relay device, the transmission line characteristics are measured at the installation point of the relay device, and the transmission line characteristics opposite to those characteristics are measured. This is realized by adjusting the frequency characteristic of the filter in the IF stage of the relay device based on the above.

On the other hand, it is impossible to apply the analog system to the digital system. In the case of the digital system, it is required to more accurately compensate for transmission path distortion such as multipath. The preset compensation used in the analog method cannot be used in the digital method. This is because it is necessary to detect and compensate for changing transmission path characteristics.

[0005]

As described above, O
In the digital broadcasting according to the FDM system, when a relay device is used, it is necessary to accurately compensate for transmission line distortion from a transmission device. It has been difficult to adaptively compensate for transmission path characteristics that change with time.

SUMMARY OF THE INVENTION An object of the present invention is to provide an OFDM repeater which can be easily adjusted and can adaptively compensate for transmission path characteristics that change with season, weather, and time in order to solve the above problems. I do.

[0007]

To achieve the above object, an OFDM relay apparatus according to the present invention has the following characteristic configuration.

(1) A pilot signal having a known amplitude / phase characteristic is repeatedly carried on each subcarrier at a predetermined symbol period for amplitude / phase equalization in advance.
OF for relaying FDM (Orthogonal Frequency Division Multiplexing) transmission signal
In a relay device for DM, receiving / demodulating means for receiving and demodulating the OFDM transmission signal, domain converting means for converting a demodulated output of this means from a time domain signal to a frequency domain signal, and an output of the domain converting means. A pilot signal extracting means for extracting a pilot signal arranged on each subcarrier of an OFDM transmission signal from the apparatus; a frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a received signal from the pilot signal extracted by this means; A compensation amount calculating means for calculating an amplitude compensation amount and a phase compensation amount on the time axis from the characteristics detected by the means, and an amplitude and phase compensation of an OFDM transmission signal to be relayed in accordance with the compensation amount obtained by the means. And a compensating means for performing on the time axis.

(2) For amplitude / phase equalization, a pilot signal having a known amplitude / phase characteristic is repeatedly carried on each subcarrier at a predetermined symbol period.
OF for relaying FDM (Orthogonal Frequency Division Multiplexing) transmission signal
In the relay device for DM, demodulation means for demodulating a relay output of the OFDM transmission signal, domain conversion means for converting a demodulated output of this means from a time domain signal to a frequency domain signal, Pilot signal extracting means for extracting a pilot signal arranged on each subcarrier of an OFDM transmission signal; frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a relay output signal from the pilot signal extracted by this means; A compensation amount calculating means for calculating the amplitude compensation amount and the phase compensation amount on the time axis from the characteristics detected by the means, and the amplitude and phase compensation of the relay output signal in the time axis according to the compensation amount obtained by the means. And a compensation means for performing the above.

(3) A data signal having a known amplitude / phase characteristic for each subcarrier (for example, a DBPSK modulated signal)
In an OFDM relay apparatus for relaying an OFDM (Orthogonal Frequency Division Multiplexing) transmission signal carrying
Receiving / demodulating means for receiving and demodulating a transmission signal; domain converting means for converting a demodulated output of this means from a time domain signal to a frequency domain signal;
Data signal extracting means for extracting a data signal having a known amplitude / phase characteristic in an FDM transmission signal, and frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a received signal from the data signal extracted by this means Compensation amount calculating means for calculating the amplitude compensation amount and phase compensation amount on the time axis from the characteristics detected by the means, and the amplitude and phase compensation of the OFDM transmission signal relayed according to the compensation amount obtained by the means. And compensating means for performing on the time axis.

(4) In an OFDM relay apparatus for relaying an OFDM (Orthogonal Frequency Division Multiplexing) transmission signal in which a data signal having a known amplitude / phase characteristic is carried on each subcarrier, a relay output of the OFDM transmission signal is transmitted. Demodulating means for demodulating the signal; domain converting means for converting a demodulated output of the means from a time domain signal to a frequency domain signal;
Data signal extracting means for extracting a data signal having a phase characteristic, frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a relay output signal from the data signal extracted by this means, Compensation amount calculating means for calculating the amplitude compensation amount and the phase compensation amount on the time axis from the characteristic, and compensation means for performing the amplitude and phase compensation of the relay output signal on the time axis in accordance with the compensation amount obtained by this means. It is characterized by having.

(5) In the configuration of (1) or (3), the OF is at least prior to demodulation by the receiving / demodulating means.
A filter for removing unnecessary wave components outside the DM transmission signal band is interposed.

(6) In the constitution of (2) or (4), a filter for removing unnecessary wave components outside the OFDM transmission signal band is interposed at least before demodulation by the demodulation means. .

(7) In the configuration of (1) or (2), when the OFDM transmission signal is transmitting a digital signal of a synchronous modulation system, the frequency characteristic detecting means includes:
A pilot signal of each subcarrier extracted by the pilot signal extracting means is interpolated in a time direction in a symbol unit to detect an entire amplitude / phase frequency characteristic.

(8) In the configuration of (1) or (2), when the OFDM transmission signal transmits a digital signal of a differential modulation system, the frequency characteristic detecting means:
The signal converted into the frequency domain is delay-detected in the frequency axis direction, the amount of change in amplitude and phase between adjacent subcarriers is obtained and integrated, and the relative amplitude and phase frequency characteristics of the subcarriers are obtained. The phase and amplitude of the pilot signal of each subcarrier extracted by the signal extracting means is added as a reference value to the integrated output to obtain the phase and amplitude frequency characteristics of all carriers.

(9) In the configuration of (1) or (2), when the OFDM transmission signal is divided into bands and hierarchized, and each layer employs a synchronous or differential modulation method, A frequency characteristic detecting unit, which interpolates a pilot signal of each subcarrier extracted by the pilot signal extracting unit in a time direction on a symbol basis in a time direction to detect a whole amplitude / phase frequency characteristic; The signal converted into the frequency domain is subjected to delay detection in the frequency axis direction, the amount of change in amplitude and phase between adjacent subcarriers is obtained and integrated, the relative amplitude and phase frequency characteristics of the subcarriers are obtained, and the pilot signal is obtained. The differential output is obtained by adding the integral output using the phase and amplitude of the pilot signal of each subcarrier extracted by the extraction means as a reference value to obtain the phase and amplitude frequency characteristics of all carriers. And a detection unit, the compensation amount calculation means may be used selectively switched in accordance with the contents of the hierarchy each detected result of the synchronous hierarchy characteristic detection section and the differential hierarchy characteristic detection section.

(10) In the configuration of (1) to (4),
The compensation amount calculating means converts the amplitude / phase frequency characteristic detected by the frequency characteristic detecting means into a characteristic on a time axis and obtains an inverse characteristic thereof, thereby obtaining an amplitude compensation amount and a phase compensation amount on a time axis. Is calculated.

(11) In the configuration of (1) to (4),
The compensation amount calculating means obtains an inverse characteristic of the amplitude / phase frequency characteristic detected by the frequency characteristic detecting means, and converts the characteristic into a characteristic on the time axis, thereby obtaining an amplitude compensation amount and a phase on the time axis. The compensation amount is calculated.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows the configuration of a relay apparatus according to the present invention for terrestrial digital television broadcasting of the OFDM system. In FIG. 1, an RF input signal to be relayed is frequency-converted from a radio frequency band to an intermediate frequency band by a down converter 1 to become an IF signal. This IF signal is input to the compensation amount detector 2 and the compensator 3. The compensation amount detector 2 includes an A / D converter 21, a quadrature demodulator 22, an FFT calculator 23, a pilot signal extractor 24, an amplitude / phase frequency characteristic detector 25, an amplitude / phase compensation amount calculator 26, and an IFFT calculator. 27.

The IF signal input to the compensation amount detector 2 is
The signal is converted into a digital signal by the A / D converter 21,
The signal is orthogonally demodulated by the orthogonal demodulator 22 to become a baseband signal. This baseband signal is subjected to FFT processing by an FFT calculator 23, converted from a time axis signal to a frequency axis signal, and supplied to a pilot signal extractor 24.

The pilot signal extractor 24 has an FFT
From the frequency axis signal output from the arithmetic unit 23, only a pilot signal for amplitude / phase equalization, which is previously arranged on the frequency axis, is extracted. The pilot signal obtained here is the amplitude / phase frequency It is supplied to the characteristic detector 25. The amplitude / phase frequency characteristic detector 25 interpolates an input pilot signal for amplitude / phase equalization to generate and output a frequency characteristic signal.
It is supplied to the phase compensation amount calculator 26. The amplitude / phase compensation amount calculator 26 obtains the inverse characteristic of the output of the amplitude / phase frequency characteristic detector 25 and outputs the result as an amplitude (gain) / phase compensation signal for each subcarrier. This compensation signal is converted from a frequency axis signal to a time axis signal by the IFFT calculator 27 and supplied to the compensator 3 as a compensation signal having information on the amount of delay, gain, and phase.

The compensator 3 receives the IF signal and the compensation signal, compensates the amplitude / phase frequency characteristics of the IF signal on the time axis according to the compensation signal, and outputs the compensated IF signal. Here, the compensator 3 is specifically configured as shown in FIG.

In FIG. 2, the OFDM input signal is n + 1
The signals of the first line are directly supplied to the adder 32, and the signals of the second to (n + 1) th lines are supplied to the adder 32 via the signal processors 311 to 31n. The operation result of the adder 32 is output as a compensation result. Signal processors 311-
31n is configured by connecting a time delay unit A, a variable resistor B, and a phase adjuster C in series, and the time delay unit A, the variable resistor B, and the phase adjuster C are connected to the IFFT calculator 27, respectively. A delay amount compensation signal, a gain compensation signal, and a phase compensation signal are supplied.

That is, the compensator 3 shown in FIG.
The OFDM input signal is distributed to the lines, the signals on each line are shifted by a predetermined time by a time delay unit A, and the signals on the second to (n + 1) th lines are adjusted by a variable resistor B based on a gain compensation signal. After performing phase adjustment based on the phase compensation signal by the phase adjuster C,
The adder 32 outputs the result. In this configuration, real-time convolution processing is realized by an analog circuit, and amplitude and phase compensation can be performed on a time axis. I after compensation
The F signal is converted into an RF signal by the up-converter 4,
The signal is amplified by the amplifier 5 and becomes an output signal of the relay device.

By the way, in terrestrial digital television broadcasting in Japan, although it is a provisional system, OFDM
It is determined in advance that a pilot signal having a known amplitude / phase characteristic is repeatedly applied to each subcarrier at a fixed symbol period for amplitude / phase equalization in a transmission signal. FIG. 3 shows an example of arrangement of data symbols and pilot symbols in one frame.

In the present invention, focusing on this pilot signal,
In the compensation amount detector 2, the RF input signal is sequentially converted into an IF signal, a baseband signal, and a frequency axis signal to extract pilot signals at subcarrier intervals arranged on the frequency axis. Since the pilot signal of each subcarrier appears at a constant symbol period, interpolation processing is performed in the time axis direction. By detecting the amplitude / phase characteristics of the pilot signal of the symbol period in each subcarrier obtained in this way, the amplitude / phase characteristics in the transmission frequency band can be obtained. Therefore, a signal having a characteristic opposite to this characteristic is created, and the amplitude / phase characteristic of the main IF signal is compensated on the frequency axis by using the signal as a compensation signal.

Therefore, in the relay apparatus having the above configuration, the compensation signal for correcting the transmission line distortion based on the amplitude / phase characteristics is created by using the pilot signal carried on the OFDM transmission signal. Adjustment can be easily performed without using a special measuring instrument or the like.
In addition, since the amplitude and phase change of the pilot signal can be obtained for each symbol, it is possible to adaptively compensate for transmission path characteristics that change with season, weather, and time.

(Second Embodiment) FIG. 4 shows the configuration of a second embodiment of the repeater for terrestrial digital television broadcasting based on the OFDM method. In FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In this repeater, the output of the down converter 1 is inputted to the compensation amount detector 2 in the first embodiment, whereas the output of the amplifier 5 is inputted to the compensation amount detector 2. I have. However, the compensation amount detector 2 in this case is
Since the output of the amplifier 5 is up-converted, it is necessary to add a down-converter 20 to the input stage and convert the input signal to baseband.

In the configuration of the present embodiment, the compensation is performed by the feedback loop, whereas the first embodiment compensates by the feedforward loop. For this reason, it is inferior to the configuration of the first embodiment in the speed of following the transmission line distortion, but is controlled in terms of the output result, which is advantageous in terms of accuracy.

(Third Embodiment) FIG. 5 shows the configuration of a third embodiment of the terrestrial digital television broadcasting relay apparatus according to the OFDM system. In FIG. 5, the same parts as those in FIGS. 1 and 4 are denoted by the same reference numerals, and the description thereof is omitted here.

In this relay device, an intermediate frequency filter 6 is further interposed between the down converter 2 and the compensator 3 in the configuration of the second embodiment, and an output filter 7 is interposed in the output stage. It is characterized in that external unnecessary waves are removed. Incidentally, the insertion position of the intermediate frequency filter 6 may be at a stage subsequent to the compensator 3. Thus, by interposing the intermediate frequency filter 6 and the output filter 7,
Unnecessary wave components outside the baseband band can be removed, and deterioration of frequency characteristics generated by the intermediate frequency filter 6 and the output filter 7 can be compensated.

Also in the first embodiment, the intermediate frequency filter 6 and the output filter 7
, The same effect as in the third embodiment can be obtained.

(Fourth Embodiment) FIG. 6 shows the configuration of a fourth embodiment of the terrestrial digital television broadcasting relay apparatus according to the OFDM method. In FIG. 6, the same parts as those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof will be omitted.

This repeater is an amplitude / phase frequency characteristic detector 2 of the compensation amount detector 2 in the configuration of the third embodiment.
5 is used for the synchronization layer, and a differential layer amplitude / phase frequency characteristic detector 27 is additionally provided. This differential hierarchy amplitude / phase frequency characteristic detector 28
Inputs the output of the FFT operation unit 23 and
1 performs delay detection in the frequency axis direction. Next, the amount of change in amplitude and phase between adjacent carriers is obtained by the phase and amplitude change amount detector 282, and then integrated by the integrator 283 to obtain the relative amplitude and phase characteristics of the carrier.

On the other hand, the pilot signal extractor 284 extracts only pilot signals of known phase and amplitude, which are arranged on the frequency axis, from the output signal of the FFT operator 23, and the adder 285 outputs the pilot signal of the pilot signal. phase·
The output of the integrator 283 is added using the amplitude as a reference value. As a result, the phase and amplitude characteristics of all carriers are obtained. Finally, the LPF 286 performs filtering in the time axis direction to remove the influence of noise and the like received on the transmission path, and outputs the result to the amplitude / phase compensation amount calculator 26. The amplitude / phase compensation amount calculator 26 selectively uses each detection result of the synchronous hierarchical amplitude / phase frequency characteristic detector 25 and the differential hierarchical amplitude / phase frequency characteristic detector 26 for use.

In the above configuration, the technical background and processing contents will be described below.

At present, in Japan, work is in progress to formulate a system called ISDB-T for the standardization of digital terrestrial television broadcasting. The feature of this method is that
In addition to adopting the FDM method,
Divided into 3 segments (realizing a hierarchy by combining segments) (1 segment = 10 in the case of 2K mode)
(8 carriers), and transmission on up to three layers is possible, and a carrier modulation scheme such as QPSK, 16QAM, or 64QAM can be set for each layer. DQPSK is also employed as carrier modulation in consideration of mobile reception.

The carrier modulation is QPSK, 16QAM, 6
In a synchronous segment such as 4QAM, an SP (Scattered Pilot) signal (a signal obtained by modulating a carrier periodically dispersed in the symbol time and carrier frequency directions with a specific phase and amplitude) for equalization processing on the receiving side. Is transmitted. On the other hand, in the differential system segment using DQPSK as carrier modulation, the SP signal is unnecessary. Therefore, in the synchronous segment and the differential segment, C
P (Continual Pilot) signal (the same pilot signal for each symbol at a specific carrier position), AC (Auxiliary Chan
nel) signal (AC1 and AC2 are defined by signals for transmitting additional information) and TMCC (Transmission
Mode Configuration Control) signals (signals for transmitting control information) are different. In the case of mode 1,
The synchronous segment has nine SP signals, two AC1 signals, and one TMCC signal, whereas the differential segment has one CP signal, two AC1 signals,
There are four AC2 signals and five TMCC signals.

As described above, in the relay apparatus, it is necessary to perform processing while distinguishing between the synchronous system segment and the differential system segment. Therefore, in the relay device of the present embodiment, F
The output of the FT arithmetic unit 23 is distributed to two systems, one for the synchronous system segment, and the other for the differential system segment. However, for the synchronous system segment,
Since it is possible to deal with the processing contents described in the above embodiment,
Reference numeral 5 denotes a synchronous hierarchical amplitude / phase frequency characteristic detector. Here, the differential hierarchical amplitude / phase frequency characteristic detector 28 will be described.

That is, the differential hierarchical amplitude / phase frequency characteristic detector 28 delay-detects the output of the FFT calculator 23 in the direction of the frequency axis, finds the amplitude / phase variation between adjacent carriers, integrates them, and performs carrier integration. The relative amplitude and phase characteristics of are calculated. On the other hand, from the output signal of the FFT calculator 23, only the pilot signal whose phase and amplitude are known, which is arranged on the frequency axis, is extracted, and the integrated output is added using the phase and amplitude as a reference value, and all carriers are added. Find phase and amplitude characteristics. Finally, filtering is performed in the time axis direction to remove the influence of noise or the like received on the transmission path, and the result is output to the amplitude / phase compensation amount calculator 26. Amplitude / phase compensation calculator 26
Uses the detection results of the synchronous hierarchical amplitude / phase frequency characteristic detector 25 and the differential hierarchical amplitude / phase frequency characteristic detector 26 selectively in accordance with the contents of the hierarchy (segment).

According to the above configuration, the transmission band is divided and hierarchized, and the pilot signal of each layer is adaptively extracted even when different modulation schemes of a synchronous system and a differential system are employed in each layer. The amplitude / phase compensation amount can be obtained as described above, and the adjustment can be easily performed without using a special measuring instrument or the like, as in the above-described embodiment, and changes with season, weather, and time. The transmission path characteristics can be adaptively compensated. However, when the OFDM transmission signal has only one of the synchronous system and the differential system, it is needless to say that only the corresponding detector may be provided.

In the fourth embodiment, the configuration based on the feedback loop has been described. However, as in the first embodiment, the output of the down converter 1 is compensated by eliminating the down converter 20 of the compensation amount detector 2. A /
If the signal is input to the D converter 21, it can be constituted by a feedforward loop.

In each of the embodiments described above, OFD
Although the description has been made assuming that the M transmission signal includes a pilot signal whose amplitude and phase are known, for example, in the case of the DBPSK modulation method, the amplitude / phase frequency characteristics are detected using data even if the pilot signal is not used. The compensation amount can be detected by calculating the inverse characteristic of the characteristic.

[0046]

As described above, according to the present invention, it is possible to provide an OFDM relay apparatus which can be easily adjusted and can adaptively compensate for transmission path characteristics that change with season, weather, and time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an OFDM terrestrial digital television broadcasting relay device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of the compensator of the embodiment.

FIG. 3 is an exemplary view showing an example of arrangement of pilot signals used in the embodiment;

FIG. 4 is a block diagram showing a configuration of an OFDM terrestrial digital television broadcast relay device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an OFDM terrestrial digital television broadcasting relay device according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an OFDM terrestrial digital television broadcasting relay device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Down converter 2 ... Compensation amount detector 20 ... Down converter 21 ... A / D converter 22 ... Quadrature demodulator 23 ... FFT arithmetic unit 24 ... Pilot signal extractor 25 ... (Synchronous hierarchy) amplitude / phase frequency characteristic detector 26 ... Amplitude / phase compensation amount calculator 27 ... IFFT calculator 28 ... Differential layer amplitude / phase frequency characteristic detector 281 ... Delay detector 282 ... Phase / amplitude change amount detector 283 ... Integrator 284 ... Pilot signal extractor 285 ... Adder 286 LPF 3 Compensator 311 to 31n Signal processor 32 Adder 4 Upconverter 5 Amplifier 6 Intermediate frequency filter 7 Output filter

Claims (11)

[Claims] 1. An OFD in which a pilot signal having a known amplitude / phase characteristic is repeatedly carried on each subcarrier at a predetermined symbol period for amplitude / phase equalization in advance.
OFDM relaying M (orthogonal frequency division multiplexing) transmission signal
A receiving / demodulating means for receiving and demodulating the OFDM transmission signal; a domain converting means for converting a demodulated output of this means from a time domain signal to a frequency domain signal; Pilot signal extracting means for extracting a pilot signal arranged on each subcarrier of an OFDM transmission signal; frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a received signal from the pilot signal extracted by this means; Compensation amount calculating means for calculating an amplitude compensation amount and a phase compensation amount on the time axis from the characteristics detected by this means; and time and amplitude compensation and phase compensation of an OFDM transmission signal relayed according to the compensation amount obtained by this means. A repeater for OFDM, comprising: an on-axis compensator. 2. An OFD in which a pilot signal having a known amplitude / phase characteristic is repeatedly applied to each subcarrier at a predetermined symbol period for amplitude / phase equalization in advance.
OFDM relaying M (orthogonal frequency division multiplexing) transmission signal
A demodulating means for demodulating a relay output of the OFDM transmission signal; a domain converting means for converting a demodulated output of the means from a time domain signal to a frequency domain signal; Pilot signal extracting means for extracting a pilot signal arranged on each subcarrier of the transmission signal; frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a relay output signal from the pilot signal extracted by this means; Compensation amount calculating means for calculating the amplitude compensation amount and phase compensation amount on the time axis from the characteristics detected by this means; and the amplitude and phase compensation of the relay output signal on the time axis according to the compensation amount obtained by this means. And a compensating means. 3. An OFDM relay apparatus for relaying an OFDM (Orthogonal Frequency Division Multiplexing) transmission signal in which a data signal having a known amplitude / phase characteristic is carried on each subcarrier, wherein the OFDM transmission signal is received and demodulated. Reception / demodulation means; domain conversion means for converting the demodulated output of this means from a time domain signal to a frequency domain signal; and data having a known amplitude / phase characteristic in an OFDM transmission signal from the output of this domain conversion means. Data signal extracting means for extracting a signal; frequency characteristic detecting means for detecting an amplitude frequency characteristic and a phase frequency characteristic of a received signal from the data signal extracted by this means; and a time axis based on the characteristic detected by this means. Compensation amount calculating means for calculating the amplitude compensation amount and the phase compensation amount of the OFDM transmission signal to be relayed according to the compensation amount obtained by this means. A relay device for OFDM, comprising: a compensator that performs amplitude and phase compensation on a time axis. 4. An OFDM relay apparatus for relaying an OFDM (Orthogonal Frequency Division Multiplexing) transmission signal in which a data signal having a known amplitude / phase characteristic is carried on each subcarrier, wherein a relay output of the OFDM transmission signal is demodulated. Demodulation means for converting the demodulated output of the means from a time-domain signal to a frequency-domain signal; and a data signal having a known amplitude / phase characteristic in an OFDM transmission signal from the output of the domain conversion means. Data signal extracting means for extracting the data signal, frequency characteristic detecting means for detecting the amplitude frequency characteristic and the phase frequency characteristic of the relay output signal from the data signal extracted by this means, and a time axis based on the characteristic detected by this means. Compensation amount calculating means for calculating the amplitude compensation amount and the phase compensation amount, and the amplitude and the position of the relay output signal in accordance with the compensation amount obtained by this means. And a compensating means for performing phase compensation on a time axis. 5. The OFDM relay according to claim 1, wherein a filter for removing unnecessary wave components outside the OFDM transmission signal band is interposed at least before demodulation by the receiving / demodulating means. apparatus. 6. The OFDM repeater according to claim 2, wherein a filter for removing unnecessary wave components outside the OFDM transmission signal band is interposed at least before demodulation by said demodulation means. 7. When the OFDM transmission signal is transmitting a digital signal of a synchronous modulation scheme, the frequency characteristic detecting means converts a pilot signal of each subcarrier extracted by the pilot signal extracting means into a symbol unit. 3. The OFDM repeater according to claim 1, wherein the whole amplitude / phase frequency characteristic is detected by interpolation in a time direction. 8. When the OFDM transmission signal is transmitting a digital signal of a differential modulation system, the frequency characteristic detecting means delay-detects the signal converted into the frequency domain in a frequency axis direction, and detects adjacent signals. The amount of change in amplitude and phase between subcarriers is obtained and integrated, and the relative amplitude and
Determining a phase frequency characteristic, adding the integral output using the phase and amplitude of the pilot signal of each subcarrier extracted by the pilot signal extracting means as a reference value, and determining the phase and amplitude frequency characteristics of all carriers. Claim 1
Or the relay device for OFDM according to 2. 9. When the OFDM transmission signal is band-divided and hierarchized, and each hierarchy employs a synchronous or differential modulation scheme, the frequency characteristic detecting means includes a pilot signal extracting means. A pilot signal of each extracted subcarrier is interpolated in the time direction on a symbol basis, and a synchronization layer characteristic detection unit for detecting the entire amplitude / phase frequency characteristic, and the signal converted to the frequency domain is converted in the frequency axis direction. Delay detection, find the amount of change in amplitude and phase between adjacent subcarriers, integrate,
Find the relative amplitude and phase frequency characteristics of the subcarrier,
A differential hierarchy characteristic detection unit that adds an integrated output using the phase and amplitude of the pilot signal of each subcarrier extracted by the pilot signal extraction unit as a reference value, and obtains the phase and amplitude frequency characteristics of all carriers, 3. The compensation amount calculation unit according to claim 1, wherein each of the detection results of the synchronous layer characteristic detecting section and the differential layer characteristic detecting section is selectively switched and used according to the contents of the layer. Relay device for OFDM. 10. The compensation amount calculating means converts the amplitude / phase frequency characteristic detected by the frequency characteristic detecting means into a characteristic on a time axis and obtains an inverse characteristic thereof, thereby obtaining amplitude compensation on a time axis. The OFDM repeater according to any one of claims 1 to 4, wherein the amount and the phase compensation amount are calculated. 11. The compensation amount calculating means obtains an inverse characteristic of the amplitude / phase frequency characteristic detected by the frequency characteristic detecting means, and converts the characteristic into a characteristic on a time axis to thereby obtain a characteristic on the time axis. 5. The OFDM repeater according to claim 1, wherein the amplitude compensation amount and the phase compensation amount are calculated.