JP3022854B1 - Delay profile analyzer and symbol synchronization method - Google Patents

Abstract

Abstract: In an OFDM transmission using a segment method, a precise delay profile is calculated, and at the same time, accurate symbol synchronization is established even in an environment such as fading. SOLUTION: A first symbol synchronization circuit 16 specifies a window position, and an FFT circuit 13 Fourier-transforms an OFDM signal, and then establishes frame synchronization. At this time,
The CP / DBPSK detection / complex division circuit 19 extracts the phase reference signals of the CP signal and the DBPSK signal in the first symbol of the frame synchronization, inserts zero in other carrier positions, and performs complex division using a known signal. Find the transmission path characteristics. This signal is subjected to inverse Fourier transform by the IFFT circuit 18 to obtain a delay profile. Also, based on the delay profile, the second symbol synchronization circuit 17 uses the FF which is the same as the transmission side or shifted by a predetermined position.
Set the T window.

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 (OFDM) transmission system, and more particularly to an orthogonal frequency division multiplexing signal decoding device used for digital broadcasting according to an orthogonal frequency division multiplexing (OFDM) transmission method.

[0002]

2. Description of the Related Art In recent years, digital audio broadcasting (DAB) for mobile objects and digital terrestrial television broadcasting have been increasingly used.
A transmission system using the FDM technology has attracted attention.

[0003] This OFDM system is a type of multicarrier modulation system in which transmission data is divided and assigned to a number of carriers orthogonal to each other with an effective symbol period length, and each carrier is subjected to multi-level modulation such as QAM for each symbol. Information on the amplitude and the phase using the inverse Fourier transform
The M signal is generated.

[0004] Since an OFDM signal uses a large number of carriers, the symbol length can be increased. Therefore, a period in which a part of the signal is cyclically copied and transmitted, that is, a so-called guard period can be provided. Since a delayed wave within the guard period is removed when performing FFT processing on the receiving side, there is a feature that intersymbol interference does not occur.

[0005] However, OFDM signals are susceptible to phase noise because the carrier spacing is very narrow. Further, since it is susceptible to nonlinear distortion, its receiving / demodulating technology is considered to be more difficult than the single carrier system.

[0006] At present, in Japan, as in Europe, the work of formulating a system called ISDB-T is in progress in consideration of the fact that the OFDM modulation system is suitable for terrestrial digital television broadcasting. The feature of this method is that the band is divided into 13 segments (1 segment = 108 carriers in the case of 2K mode), and transmission in up to three layers is possible, in addition to adopting the OFDM modulation method. QPS
It is possible to set a carrier modulation method such as K, 16QAM, or 64QAM. Also, considering mobile reception,
DQPSK is also employed as carrier modulation.

When 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.

In recent years, research on this OFDM has been carried out by various research institutions and manufacturers, and as a result, practical and practical reports on reception and demodulation techniques have been increasing. Therefore, these conventional reception demodulation techniques will be summarized.

[0009] OFDM is characterized in that a part of a signal is copied and transmitted during a guard period as described above. There are many reports on reception demodulation technology using this section.

First, a process called a guard correlation process will be described. The signal down-converted to the base band signal on the time axis is obtained by multiplying the signal itself with a signal delayed by an effective symbol period length. By sliding integrating this signal by the time width of the guard period, a triangular waveform can be obtained. Coarse synchronization of symbols is obtained from the peak position of this triangular waveform.
Symbol boundaries are extracted from the received data by symbol synchronization processing, and FFT processing is performed using the signals.

Using this guard correlation, a frequency error within a carrier interval is reproduced as reported in Television Technical Report vol.19, No.38, pp.13-18, Aug. be able to.

The data after the FFT processing is a signal from which a frequency error within a carrier interval has been removed, and has only an error per carrier interval. Since the CP signal and the TMCC signal are known on the receiving side, the error in the unit of the carrier interval is determined by correlating the known arrangement pattern with the received data to determine the frequency error in the unit of the carrier interval. . By feeding this back to the frequency error circuit within the carrier interval, the frequency error is corrected.

The sampling frequency synchronization is established as follows. Since the peak-to-peak period of the triangular waveform obtained by the above-described guard correlation processing is a symbol period, for example, when the guard interval length is 1/8 in the 2K mode, the symbol period is 2048 (1 + 1/8) = 2304. The above symbol period is set to 1
By dividing the frequency by / 2304, the sampling clock is reproduced, and the sampling frequency is synchronized.

As a result, symbol synchronization, frequency synchronization,
Sampling frequency synchronization is established.

[0015] Frame synchronization is established as follows. In the ISDB-T system, a synchronization signal is embedded in a TMCC signal. Since the synchronization signal is known on the receiving side, as in the case of the wideband AFC, by correlating the synchronization signal in the known TMCC signal with the received TMCC signal in the symbol time direction in the symbol time direction, Frame sync is played.

[0016]

SUMMARY OF THE INVENTION Thus, OFDM
The demodulation technique has been almost established, but the following problems occur in the case of reception in a multipath and fading environment.

First, under such an environment, the triangular waveform obtained by the above-described guard correlation processing is disturbed, and precise symbol synchronization cannot be achieved. In order to establish precise symbol synchronization, it is essential to find an impulse response.

Conventionally, in the European terrestrial digital television system (DVB-T), a method for achieving precise synchronization from an impulse response of an SP signal has been described. But,
In the Japanese method, when DQPSK is used for carrier modulation, the SP signal does not exist, so that method cannot be used. Further, even when CP signals are used, it is difficult to obtain an accurate impulse response because the number is small.

When all segments are synchronous segments, an SP signal can be used, and an impulse response can be obtained. However, when analyzing a delayed wave, whether it is a rear ghost or a front ghost is determined. There was a problem that identification was not possible.

In the analysis of a delayed wave, conventionally, a delay profile is measured using a reference symbol, and ITE'9
8: Reported at 1998 ITE Annual Convention pp17-18. However, in the ISDB-T method, since there is no reference symbol, it is difficult to measure a delay profile in the ISDB-T method.

However, with the introduction of digital terrestrial broadcasting, it is essential to evaluate a delay profile in order to plan a broadcasting station and a relay station. In order to obtain a precise delay profile and smoothly shift to digital broadcasting, the current ISDB-T format is effectively used without transmitting a special signal for delay profile evaluation, and a precise transmission path characteristic is obtained. Needs to be evaluated.

The present invention has been made in consideration of the above circumstances, and has as its first object to provide a delay profile analysis apparatus capable of analyzing and evaluating a delay profile without transmitting a special signal. A second object is to provide an OFDM receiver capable of precisely performing symbol synchronization using a delay profile.

[0023]

In order to solve the above-mentioned first problem, a delay profile analyzer according to the present invention has the following characteristic configuration.

(1) In a case where a DBPSK-modulated signal is allocated to the same specific carrier position for each symbol in the OFDM signal, and a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol, Symbol synchronization means for establishing symbol synchronization of an OFDM signal;
Fourier transform means for Fourier transforming the FDM signal, frame synchronization means for establishing frame synchronization of the OFDM signal, and a phase reference signal of the DBPSK-modulated signal transmitted from the synchronization frame established by the frame synchronization means. a particular symbol extracting means for extracting a particular symbol, and the phase reference signal extracting means for extracting all or part of the phase reference signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means, the Japanese
About the specific symbol extracted by the fixed symbol extraction means
The phase reference signal extracted by the phase reference signal extraction means.
Complex division of signal by carrier using known signal at receiving side
The phase reference signal is extracted by the phase reference signal extracting means.
The real and imaginary parts are set at carrier positions other than the
A specific symbol processing means for inserting a
Inverse Fourier transform means for obtaining a delay profile by inverse Fourier transforming the signal obtained by the signal processing means .

(2) In the OFDM signal, a continuous pilot signal and a DBPSK-modulated signal are allocated to the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol. In this case, the symbol synchronization means for establishing symbol synchronization of the OFDM signal, the Fourier transform means for performing Fourier transform on the OFDM signal, the frame synchronization means for establishing frame synchronization of the OFDM signal, and the frame synchronization means Specific symbol extracting means for extracting a specific symbol from which the phase reference signal of the DBPSK-modulated signal is transmitted from the synchronized frame, and the DBPSK-modulated phase reference signal and the continuous symbol based on the specific symbol extracted by the specific symbol extracting means. Phase reference signal for extracting all or part of the pilot signal And a continuous pilot signal extracting means and the specific symbols extracted by the specific symbol extracting means
The phase reference signal and the continuous pilot signal
Phase reference signal and continuous pilot extracted by extraction means
Complex division of the signal for each carrier using a known signal on the receiving side
Calculating the phase reference signal and the continuous pilot signal.
Phase reference signal and continuous pilot signal extracted in stage
Zero for both real and imaginary parts at carrier positions other than the carrier position
Specific symbol processing means to be inserted;
Inverse Fourier transform means for obtaining a delay profile by performing an inverse Fourier transform on the signal obtained by the logical means .

[0026]

[0027]

( 3 ) Among a plurality of carriers constituting the OFDM signal, a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal. Each segment is used for either synchronous detection or differential detection for each segment. In the differential detection segment, a continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol, The DBPSK
A phase reference signal of the modulated signal is allocated to a specific symbol. In the synchronous detection segment, in addition to the DBPSK-modulated signal, a carrier periodically dispersed in a symbol time and a carrier frequency direction is converted to a specific phase. And when a scattered pilot signal that modulates in amplitude is provided,
A symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, the frame synchronization means for establishing frame synchronization of OFDM signals, synchronization is established in the frame synchronization unit frame A scattered pilot signal extracting means for extracting a scattered pilot signal of the synchronous detection segment from the multiplexed detection signal segment; an interpolating means for interpolating the scattered pilot signal extracted by the scattered pilot signal extracting means in a symbol time direction; Sync frame
The phase reference signal of the DBPSK-modulated signal is transmitted from
Specific symbol extracting means for extracting a specific symbol to be sent
A phase reference signal and a continuous pilot signal extraction means for extracting the phase reference signal and the continuous pilot signal of the DBPSK modulation from the specific symbol extracted by the specific symbol extraction means; and a synchronization frame established by the frame synchronization means. Synthesizing means for extracting a dispersed pilot signal interpolated by the interpolating means from a specific symbol position and synthesizing the phase reference signal and the continuous pilot signal extracted by the phase reference signal and continuous pilot signal extracting means;
The specific symbol extracted by the specific symbol extracting means
The combined signal output from the combining means
And performs complex division for each carrier using a known signal.
Zero is inserted for both real and imaginary parts at carrier positions where there is no signal component.
Specific symbol processing means for inputting, and the specific symbol processing
And inverse Fourier transform means for obtaining a delay profile by inverse Fourier transforming the signal obtained by the means.

( 4 ) Among a plurality of carriers constituting the OFDM signal, a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal. Each segment is used for either synchronous detection or differential detection for each segment, and the synchronous detection segment and the differential detection segment include a continuous pilot signal and a DBPSK-modulated signal at the same carrier position for each symbol. if they are arranged, the symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the frame
Signal extracting means for extracting the continuous pilot signal and the DBPSK-modulated signal from the synchronization frame established by the system synchronization means, and extracting the DBPSK-modulated signal.
That signal and error correcting means for correcting data errors of the extracted DBPSK modulated signal extracting means, differential to differential encoding a DBPSK modulated signal error corrected by the error correction <br/> means Encoding means and the frame synchronization means
For each symbol of the established synchronization frame, the signal
Pilot signal and DBP extracted by signal extraction means
The SK-modulated signal is converted to a continuous pilot known on the receiving side.
Signal and the signal differentially encoded by the differential encoding means.
And perform complex division for each carrier by
The pilot signal and the DBPSK modulated signal are extracted.
Zero for both real and imaginary parts at carrier positions other than the specified carrier position
Symbol processing means for inserting a symbol, and the symbol processing means
And inverse Fourier transform means for performing an inverse Fourier transform on the signal obtained in step (1) to obtain a delay profile.

( 5 ) Among a plurality of carriers constituting the OFDM signal, a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band-end pilot signal. Each segment is used for either synchronous detection or differential detection for each segment, and the synchronous detection segment modulates a carrier periodically dispersed in a symbol time and a carrier frequency direction with a specific phase and amplitude. A distributed pilot signal is arranged, a DBPSK-modulated signal is arranged at the same carrier position in the symbol direction, and in the differential detection segment, a DBPSK-modulated signal and a continuous pilot signal are arranged at the same carrier position for each symbol. The symbol synchronization of the OFDM signal. And Le synchronization means, Fourier transform means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the full
From the synchronization frame established by frame synchronizing means, the successive pilot signals, DBPSK modulated signal, and said signal extracting means for extracting a scattered pilot signal synchronous detection segment, the signal scattered pilots extracted by the extraction means and interpolating means for interpolating the signal in the symbol time direction, and the error correcting means for correcting data error in DBPSK modulated signal extracted by said signal extracting means, the erroneous
Differential to differential encoding a signal error correction Ri correcting means
Coding means, the continuous pilot signal and DBPSK
And combining means for combining the interpolated scattered pilot signals in the symbol direction by the interpolation means a modulated signal, the multiplexer
The continuous pilot signal synthesized by the
Received dispersed pilot signal and DBPSK modulated signal.
A known signal on the receiving side and differential encoding by the differential encoding means
Complex division for each carrier by the obtained signal,
The combined continuous pilot signal, DBPSK modulated
Signal, interpolated scattered pilot signal is placed
Zero is inserted for both real and imaginary parts at carrier positions other than the carrier position.
Receiving the combined signal processing means,
Configured by including an inverse Fourier transform means for obtaining a delay profile by performing inverse Fourier transform was signals.

( 6 ) In the case where a DBPSK-modulated signal is allocated to the same specific carrier position for each symbol in the OFDM signal, and a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol, Symbol synchronization means for establishing symbol synchronization of an OFDM signal;
Fourier transforming means for Fourier transforming an FDM signal, frame synchronizing means for establishing frame synchronization of the OFDM signal, and specifying that a phase reference signal of the DBPSK-modulated signal is transmitted from a synchronization frame established by the frame means. a particular symbol extracting means for extracting a symbol, and the phase reference signal extracting means for extracting all or part of the phase reference signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means, said specific sheet
For the specific symbol extracted by the symbol extraction means,
Receiving the phase reference signal extracted by the phase reference signal extracting means;
The receiving side performs complex division for each carrier using a known signal, and
The key from which the phase reference signal has been extracted by the phase reference signal extraction means.
Zero in both real and imaginary parts at carrier positions other than carrier position
Specific symbol processing means to be inserted into the extracted signal;
First inverse Fourier transform means for performing an inverse Fourier transform on the signal obtained by the specific symbol processing means, and an arrangement pattern obtaining means for obtaining an arrangement pattern on the transmission side of the DBPSK-modulated signal allocated to the specific symbol; , The arrangement pattern
Phase rotation of the arrangement pattern obtained by the
That the phase rotation means, the second inverse Fourier transform means for inverse Fourier transform the acquired arrangement pattern in the phase rotation unit, before Symbol said second opposite from the signal obtained in the first inverse Fourier transform unit Normalization operation processing means for normalizing the signal obtained by the Fourier transform means, and subtracting the normalized signal from the signal obtained by the first inverse Fourier transform means to obtain a delay profile. It is composed.

( 7 ) In the OFDM signal, a DBPSK-modulated signal and a continuous pilot signal are allocated to the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol. In this case, the symbol synchronization means for establishing symbol synchronization of the OFDM signal, the Fourier transform means for performing Fourier transform on the OFDM signal, the frame synchronization means for establishing frame synchronization of the OFDM signal, and the frame synchronization means A specific symbol extracting means for extracting a specific symbol in which the phase reference signal of the DBPSK-modulated signal is arranged from the synchronized frame, and the DBPSK extracting means for extracting the DBPSK from the specific symbol extracted by the specific symbol extracting means. Extract all or part of the modulation phase reference signal and continuous pilot signal Signal extraction means for extracting the specific symbol
The signal extraction is performed for the specific symbol extracted by the means.
Phase reference signal and continuous pilot signal
Complex division of signal by carrier using known signal at receiving side
And a phase reference signal and a continuous pilot signal by the signal extracting means.
To a carrier position other than the carrier position where the
Specific symbol processing means for inserting zeros for both the real and imaginary parts;
First inverse Fourier transform means for performing an inverse Fourier transform on the signal obtained by the specific symbol processing means, an arrangement pattern obtaining means for obtaining an arrangement pattern on the transmission side of a DBPSK-modulated signal allocated to the specific symbol, The placement pattern
A second inverse Fourier transform means for inverse Fourier transform the acquired arrangement pattern in over emissions acquisition means, the second inverse Fu
Phase rotation means for phase rotating the inverse Fourier transformed arranged pattern Fourier transform means, normalizing the signal obtained by the first from said signal obtained by the inverse Fourier transform means of the second inverse Fourier transform unit After that, normalization processing means for obtaining a delay profile by subtracting the normalized signal from the signal obtained by the first inverse Fourier transform means is provided.

( 8 ) In the OFDM signal, when a DBPSK-modulated signal is allocated to the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol, Symbol synchronization means for establishing symbol synchronization of an OFDM signal;
Fourier transform means for Fourier transforming the FDM signal, frame synchronization means for establishing frame synchronization of the OFDM signal, and a phase reference signal of the DBPSK-modulated signal from the synchronization frame established by the frame synchronization means are arranged. a particular symbol extracting means for extracting a specific symbol are a phase reference signal extracting means for extracting all or part of the phase reference signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means, wherein
The specific symbol extracted by the specific symbol extraction means
And the phase reference extracted by the phase reference signal extracting means.
Complex division of the signal for each carrier using a known signal on the receiving side
And a phase reference signal is extracted by the phase reference signal extracting means.
Real and imaginary parts at carrier positions other than the specified carrier position
A specific symbol processing means for inserting a zero,
Phase rotation means for rotating the phase of the signal obtained by the vol processing means, first inverse Fourier transform means for performing an inverse Fourier transform on the signal rotated by the phase rotation means, and a DBPSK-modulated signal of the specific symbol an arrangement pattern obtaining means for obtaining an arrangement pattern of the transmission side of the arrangement pattern
A second inverse Fourier transform unit for performing an inverse Fourier transform on the arrangement pattern acquired by the acquisition unit; and a signal obtained by the second inverse Fourier transform unit from a signal obtained by the first inverse Fourier transform unit. After the normalization, normalization operation processing means for obtaining a delay profile by subtracting the normalized signal from the signal obtained by the first inverse Fourier transform means is provided.

( 9 ) In the OFDM signal, a DBPSK-modulated signal and a continuous pilot signal are arranged at the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is arranged in a specific symbol. In this case, the symbol synchronization means for establishing symbol synchronization of the OFDM signal, the Fourier transform means for performing Fourier transform on the OFDM signal, the frame synchronization means for establishing frame synchronization of the OFDM signal, and the frame synchronization means a particular symbol extracting means for extracting a specific symbol phase reference signal is arranged in the frame sync DBPSK modulated signal, the specific symbol extracting
Wherein the specific symbol extracted by means out DBPSK
A signal extraction means for extracting all or part of the phase reference signal and a continual pilot signal modulation, the specific symbol extracting
Signal processing for the specific symbol extracted by the output means.
Phase reference signal and continuous pilot signal
Complex division of signal by carrier using known signal at receiving side
And a phase reference signal and a continuous pilot signal by the signal extracting means.
To a carrier position other than the carrier position where the
Specific symbol processing means for inserting zeros for both the real and imaginary parts;
Phase rotation means for rotating the phase of the signal obtained by the specific symbol processing means, first inverse Fourier transform means for performing an inverse Fourier transform on the signal rotated by the phase rotation means, and DBPSK modulation of the specific symbol. an arrangement pattern obtaining means for obtaining an arrangement pattern of the transmission side of the signal that, before
A second inverse Fourier transform unit for performing an inverse Fourier transform on the arrangement pattern acquired by the arrangement pattern acquisition unit, and a signal obtained by the first inverse Fourier transform unit, obtained by the second inverse Fourier transform unit. And a normalization operation processing means for obtaining a delay profile by subtracting the normalized signal from the signal obtained by the first inverse Fourier transform means.

In the configurations (1) to (3) and (7) to (9) , the specific symbol is a head symbol of the frame.

In order to solve the second problem,
The OFDM receiving apparatus according to the present invention has the following characteristic configuration.

( 10 ) A DBPSK-modulated signal is arranged at the same specific carrier position for each symbol.
When receiving the OFDM signal in which the phase reference signal of the K-modulated signal is allocated to a specific symbol, the OFD signal
First symbol synchronization means for establishing symbol synchronization of the M signal, Fourier transform means for performing Fourier transform on the OFDM signal, frame synchronization means for establishing frame synchronization of the OFDM signal, and the frame synchronization means. Specific symbol extracting means for extracting a specific symbol from which a phase reference signal of the DBPSK-modulated signal is transmitted from a synchronization frame; and a method of extracting the DBPSK-modulated phase reference signal from the specific symbol extracted by the specific symbol extracting means. Phase reference signal extracting means for extracting all or a part thereof, and the specific symbol extracted by the specific symbol extracting means.
Vol, extracted by the phase reference signal extraction means
A phase reference signal is used for each carrier using a signal known on the receiving side.
To the phase reference signal extraction means.
Real part at a carrier position other than the carrier position where the signal was extracted
Specific symbol processing means for inserting zeros in both imaginary parts,
And inverse Fourier transform means for inverse Fourier transform signals obtained by the specific symbol processing means, and precision symbol synchronization second symbol synchronization means on the basis of the peak position of the inverse Fourier transformed signal by said inverse Fourier transform means It comprises.

( 11 ) Receives an OFDM signal in which a continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is arranged in a specific symbol. when a first symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the frame
The frame sync established without synchronization means DBPS
A specific symbol extracting means phase reference signal of K modulated signal to extract the specific symbol to be transmitted, the specific thin
DBP from the specific symbol extracted by the bol extraction means
A phase reference signal and a continuous pilot signal extracting means for extracting all or part of the phase reference signal and a continuous pilot signal SK modulation extracted by the specific symbol extracting means
For the specified symbol, the phase reference signal and the continuous
The phase reference signal extracted by the
The pilot signal is carried by the receiver using a known signal.
A complex division is performed for each phase, and the phase reference signal and the continuous pilot
Signal reference means and continuous pilot signal
Is imaginary at a carrier position other than the extracted carrier position.
Specific symbol processing means for inserting zeros in both parts,
And inverse Fourier transform means for inverse Fourier transform signals obtained by the constant-symbol processing means, and precision symbol synchronization second symbol synchronization means on the basis of the peak position of the inverse Fourier transformed signal by said inverse Fourier transform means It comprises.

( 12 ) Receives an OFDM signal in which a continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is arranged in a specific symbol. when a first symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the frame
The frame sync established without synchronization means DBPS
A specific symbol extracting means phase reference signal of K modulated signal to extract the specific symbol to be transmitted, the specific thin
DBP from the specific symbol extracted by the bol extraction means
Phase reference signal and a continuous pilot signal extraction means, said specific symbol extracting means for extracting all or part of the phase reference signal and a continual pilot signal SK modulation in complex form
The phase reference signal for the specific symbol extracted in
And complex form extracted by continuous pilot signal extraction means
Phase reference signal and continuous pilot signal for each carrier
To convert the phase reference signal and the continuous pi
Phase reference signal and continuous pilot by lot signal extraction means
Executes at a carrier position other than the carrier position where the signal was extracted.
Specific symbol processing means for inserting zeros in both the imaginary part and the
Serial and inverse Fourier transform means for inverse Fourier transform the resulting signals at a particular symbol processing means, the inverse Fourier transform means inverse Fourier transformed signal precision symbol synchronization second on the basis of the peak position of the symbol synchronization means And is provided.

( 13 ) Of a plurality of carriers constituting the OFDM signal, a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal, Each segment is used for either synchronous detection or differential detection for each segment, and in the differential detection segment,
A continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol.
A phase reference signal of the K-modulated signal is allocated to a specific symbol, and the DBPSK is used in the synchronous detection segment.
OFD in which, in addition to the modulated signal, a distributed pilot signal for modulating a carrier periodically dispersed in the symbol time and carrier frequency directions with a specific phase and amplitude is arranged.
First symbol synchronization means for establishing symbol synchronization of the OFDM signal when receiving the M signal;
Fourier transform means for Fourier transforming the M signal;
Frame synchronization means for establishing frame synchronization of the FDM signal; and a synchronization frame established by the frame synchronization means.
Transmits the phase reference signal of the DBPSK-modulated signal
Specific symbol extracting means for extracting a specific symbol to be extracted
And the specific symbol extracted by the specific symbol extracting means.
From the DBPSK-modulated phase reference signal and the continuous
A phase reference signal for extracting all or part of the lot signal and
And a continuous pilot signal extracting means, a distributed pilot signal extracting means for extracting the distributed pilot signal from the synchronous detection segment of the synchronization frame established by the frame synchronization means, and the distributed pilot signal extracting means Interpolating means for interpolating in the symbol time direction the scattered pilot signal extracted in
The phase reference signal and the continuous
A phase reference signal extracted by the pilot signal extracting means;
The continuous pilot signal is divided by the variance interpolated by the interpolation means.
Combining means for combining with the pilot signal;
The continuous pilot signal synthesized by
Scattered pilot signal, the phase reference signal is
Complex division is performed for each carrier using a signal, and the continuous pyro
Signal, interpolated scattered pilot signal, and phase
To a carrier position other than the carrier position where the quasi signal was extracted
Specific symbol processing means for inserting zeros for both the real and imaginary parts;
Wherein the inverse Fourier transform means for inverse Fourier transform signals obtained by the specific symbol processing means, the precision symbol synchronization on the basis of the peak position of the inverse Fourier transformed signal by said inverse Fourier transform hand <br/> stage And two symbol synchronization means.

( 14 ) Among a plurality of carriers constituting the OFDM signal, a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal. Each segment is used for either synchronous detection or differential detection for each segment, and in the synchronous detection segment,
A distributed pilot signal that modulates a carrier periodically dispersed in the symbol time and carrier frequency directions with a specific phase and amplitude is arranged, and a DBPSK-modulated signal is arranged at the same carrier position in the symbol direction, and the differential detection is performed. A first symbol synchronization unit for establishing symbol synchronization of the OFDM signal when receiving an OFDM signal in which a continuous pilot signal and a signal subjected to DBPSK modulation are arranged at the same carrier position; Fourier transform means for performing a Fourier transform, a frame synchronization means for establishing frame synchronization of the OFDM signal, and extracting the continuous pilot signal and the DBPSK-modulated signal from a synchronization frame established by the frame synchronization means, and Distributed pilot of detection segment A signal extraction means for extracting the items, before
Interpolating means for interpolating the scattered pilot signal extracted by the signal extracting means in the symbol direction, error correcting means for correcting a data error of the DBPSK modulated signal extracted by the signal extracting means, and error correcting means. Differential encoding means for differentially encoding an error-corrected DBPSK-modulated signal; a scattered pilot signal interpolated by the interpolation means; a continuous pilot signal extracted by the signal extraction means; Synthesizing means for synthesizing the DBPSK modulated signal differentially encoded by the means,
The combined pilot signal, the interpolated variance
A pilot signal and a DBPSK-modulated signal are received.
The receiver uses a known signal and a differentially encoded signal to
Complex division for each carrier, the continuous pilot signal, interpolation
Scattered pilot signal and DBPSK modulated
Executes at a carrier position other than the carrier position where the signal was extracted.
Symbol processing means for inserting zero in both the imaginary and imaginary parts;
And inverse Fourier transform means for inverse Fourier transform the signals processed by the symbol processing unit, and a fine symbol synchronization second symbol synchronization means on the basis of the peak position of the inverse Fourier transformed signal by said inverse Fourier transform means It is configured with.

( 15 ) The Fourier transform means performs Fourier transform processing at a fixed position with reference to the peak position obtained by the second symbol synchronization means.

( 16 ) The Fourier transform means performs a Fourier transform process by providing a window so that the power of the guard period width of the signal obtained from the output signal of the inverse Fourier transform means is maximized. I do.

In the constitutions ( 10 ), (12) to ( 13 ), the specific symbol is a head symbol of a frame.

That is, the evaluation of the delay profile according to the present invention is performed as follows.

In the ISDB-T system, for example, in the case of the 2K mode, if all the segments are of a differential system, the CP
There are 14 signals. The number of AC signals to be DBPSK is 78 and the number of TMCC signals is 65.

Here, in the CP signal, the same phase information for each symbol is transmitted as binary real part data by a specific PN sequence for each carrier position, and zero is transmitted for the imaginary part. Further, the TMCC signal is transmitted as binary real part data by a specific PN sequence for each carrier position only in the first symbol of the frame, and zero is transmitted for the imaginary part. Therefore, in the first symbol of the frame, the phase information of the AC signal and the TMCC can be handled as known information, like the CP signal. Therefore, the first symbol of the frame is 15
It can be considered that seven known signals are being transmitted. Therefore, by performing the inverse Fourier transform using only the first symbol, it is possible to obtain a delay profile with higher accuracy than when using other symbols.

In this case, the number of carriers 157 to be used is not essential, and the same result can be obtained even when the number of carriers to be used is small. However, the more the number of carriers used, the more accurate the determination can be made.

Hereinafter, a method of calculating the delay profile will be described.

The reference signal, CP signal and SP signal of DBPSK to be transmitted are denoted by Si, k, and the reference signal, CP signal and SP signal of DBPSK to be received are denoted by Ri, k. Assuming that the transmission path characteristic is Hi, k and the noise component added on the transmission path is Ni, k, these relationships are expressed by the following equations. Ri, k = Hi, k-Si, k + Ni, k ... (1) Therefore, the transmission path characteristic is expressed by Hi, k = Ri, k / Si, k-Ni, k / Si, k ... (2) . Since the noise is random in positive and negative directions, it can be approximated by Hi, k = Ri, k / Si, k (3). By this processing, the transmission path characteristics are obtained. On the receiving side, this complex operation is performed only at the position where the DBPSK reference signal and the CP signal are transmitted, and zeros are inserted in other portions. When the noise is large, the error increases, but the same processing is performed.

By subjecting the obtained Hi, k to the inverse Fourier transform, it is possible to analyze a delay profile. The display of the delay profile is representatively represented by a power obtained by squaring and adding the real part and the imaginary part obtained here.

Next, if all segments are synchronous, AC
One signal is 26 lines. The number of TMCC signals is 13. Therefore, the number of known signals at the first symbol of the frame is very small as compared with the case of the differential system. Therefore, in the case of the segment of the synchronous system, S
The P signal is used.

The SP signal is transmitted using one carrier for every 12 carriers and shifted by 3 carriers for each symbol. Therefore, if the interpolation is performed in the symbol direction, the reference signal is transmitted at three carrier intervals. Therefore, the number of carriers that can be used for obtaining the delay profile is 468, and a much more stable delay profile can be obtained.

However, aliasing components appear due to the interpolation processing. In the case of ISDB-T, the effective symbol length is 250 μ
Because of s, aliasing components appear at intervals of about 83 μs from 250/3. Therefore, if the ghost component is within about 83 μs, the delay profile can be obtained. However, when only this processing is performed, it is usually necessary to separate the ghost after 50 μs and the ghost before 33 μs due to the aliasing component. Can not. However, since the FFT window position is known by the symbol synchronization circuit, it is possible to separate the front ghost and the rear ghost based on the information.

When a differential segment and a synchronous segment are mixed, a delay profile can be obtained by using all of the SP signal and the CP signal. still,
Even in the case of only the synchronous segment, the SP signal and the CP
By using all the signals, a delay profile can be obtained.

Consider again the case where all the segments are of the differential type. In this case, there is a problem that a small ghost component is not detected because the number of carriers is smaller than that in a case where 157 carriers are used, all segments are synchronous systems, and interpolation processing is performed. Further, in symbols other than the head of the frame, usable signals are limited to only CP signals, and a delay profile cannot be obtained.

This can be solved by the method described below. For a DBPSK-modulated signal such as an AC signal or a TMCC signal, a reference phase is transmitted at the beginning of a frame. Therefore, the signal after error correction can be used as known data. After error correction of DBPSK-modulated data on the receiving side, differential encoding is performed in the same manner as when the data is processed on the transmitting side. This differentially encoded signal is (3)
This is Si, k in the formula. Ri, k is the received data vector. Therefore, the transmission path characteristic is obtained by the calculation of the equation (3). By performing an inverse Fourier transform on this signal, a delay profile can be obtained. With this method, it is possible to calculate a delay profile using all symbols.

In order to obtain the FFT window position on the transmitting side, the DBP of the AC signal, the TMCC signal, etc.
The FFT window position can be determined by subjecting the SK-modulated data to the square (doubling it on the complex plane) and performing the inverse Fourier transform. In this case, information on whether the ghost is a post-ghost or a pre-ghost is lost in the delay profile, but the FFT position on the transmission side can be accurately obtained.

When all segments are differentially coded, the number of carriers that can be used is 157, which is still insufficient when a precise delay profile is required for business use or the like. This is mainly due to the presence of pulse-like noise due to the arrangement pattern due to the small number of carriers used. This point can be obtained by subtracting the inverse Fourier transform of the arrangement pattern from the received data because the transmitted reference signal is known. As a result, a noise component caused by using a small number of carriers is removed.

In order to perform such a method, it is necessary that precise frequency synchronization and symbol synchronization have been obtained before obtaining a delay profile. A precise AFC has been established by using the technology described in the section of the prior art. Symbol synchronization will be described in detail in an embodiment of the present invention. Even when the sampling phase is shifted, a precise delay profile can be obtained by incorporating a phase adjustment circuit.

When this calculation is performed, if the processing section of the FFT is the same as that of the transmission side, the peak of the impulse response observed as the main wave appears at the same position in transmission and reception. Is corrected, the inversely Fourier-transformed signal A is normalized using the inverse-Fourier-transformed signal B of a known arrangement pattern such as CP, AC, and TMCC. Assuming that the obtained signal is C, a delay profile can be obtained by subtracting B from C.

If the transmission path is ideal, all the components become zero by this operation. Therefore,
If you want to observe the transmission path response including the main wave, only the impulse part of the main wave is not subtracted.
The components of the main wave and the delayed wave can be obtained.

Even if the FFT processing section on the receiving side is shifted from the transmitting side, the position of the FFT window on the receiving side becomes the same as that on the transmitting side by performing the precise synchronization processing.
In this case, only the sampling phase shift remains, and the noise pattern of the impulse floor differs from the noise pattern of the impulse floor on the transmission side. Therefore, a detailed delay profile can be obtained by rotating the phase on the receiving side to align the phases, and then performing the subtraction processing. Also in this case, no subtraction is performed only for the peak position.

The delay profile obtained by the above method can be used to determine the FFT processing window on the receiving side. OFDM has the advantage that the power of the signal component delayed within the guard period can be used. Therefore, by setting a window of the guard period width and shifting the window, the total power within a certain period can be obtained. If the method of setting the point where the power becomes maximum as the synchronous position of the Fourier transform is used, a signal can be reproduced without any problem even when a large number of delayed waves are present or a previous ghost exists.

[0065]

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

(First Embodiment) FIG. 1 shows an OFDM having a delay profile analysis function when all segments are differentially coded as a first embodiment according to the present invention.
FIG. 3 is a block diagram illustrating a configuration of a receiving device. In the present embodiment, the delay profile is obtained using only the head of the frame.

In FIG. 1, a received OFDM signal is down-converted to a baseband signal, and then supplied to a frequency error calculation circuit 11 and a frequency correction circuit 12, and at the same time, to a first symbol synchronization circuit 16 to be described later. You.

Although not shown in detail, the frequency error calculation circuit 11 calculates a frequency error within a carrier interval in a time domain from an input OFDM signal, and a frequency after Fourier transform from an FFT circuit 13 described later. A circuit for calculating a frequency error per carrier interval in the area. Frequency synchronization within the carrier interval
l.19, No.38, pp.13-18, Aug.1995. In the frequency synchronization on a carrier interval basis, the CP component and the DBPSK modulated carrier are extracted by differentially demodulating the data after FFT, passing through a squaring circuit, and passing through an inter-symbol filter. On the receiving side, since this arrangement pattern is known in advance, a frequency error in a unit of a carrier interval is calculated by correlating with this arrangement pattern.

The frequency correction circuit 12 corrects the frequency of the OFDM signal by using the frequency error obtained by the frequency error calculation circuit 11, and outputs the output of the FFT circuit 1.
3 is supplied. The FFT circuit 13 determines a Fourier transform period based on a signal from a second symbol synchronization circuit 17 described later, performs an FFT operation, and converts the signal from the time domain to the frequency domain. Is supplied to the above-described frequency error calculation circuit 11 and is also supplied to the frame synchronization circuit 14 and the detection circuit 15.

The frame synchronization circuit 14 detects a TMCC synchronization signal included in the OFDM signal and establishes frame synchronization. Further, the detection circuit 15 includes an FF
The data after T is subjected to delay detection processing to obtain a reception output.

Since the information of the reference phase is transmitted to the first symbol of the frame, the T
DBP of MCC signal and AC (AC1, AC2) signal etc.
Hereinafter, data to be SK-modulated will be generally referred to as a DBPSK signal.

The first symbol synchronization circuit 16 is specifically configured as shown in FIG. Here, the operation of the first symbol synchronization circuit 16 will be described with reference to FIG.

First, as shown in FIG. 3A, the OFDM signal has a symbol consisting of a guard period and an effective symbol period, and the guard period is obtained by cyclically copying the rear part of the effective symbol. First symbol synchronization circuit 1
In FIG. 6, the effective symbol period delay circuit 161 operates as shown in FIG.
As shown in (b), the OFDM signal is delayed by an amount corresponding to the effective symbol period, and the multiplier 162 multiplies the OFDM signal before and after the delay. Since the delayed signal component matches the signal component of the path without delay in the guard period, a correlation value is obtained, and no correlation appears in other sections.

The sliding averaging circuit 163 slide-integrates the correlation signal for a guard period length. As a result, as shown in FIG. 3C, a triangular waveform having a peak at a symbol boundary in a signal of a path without delay is obtained. The symbol filter circuit 164 averages the waveform of FIG. 3C between symbols. Since the period from the peak to the peak of this triangular waveform matches the symbol length, the position of the window for performing the Fourier transform can be roughly determined from the position of this triangle.

The window position information determined by the first symbol synchronization circuit 16 is sent to a second symbol synchronization circuit 17 together with window position information from an IFFT circuit 18 described later.

Next, the CP / DBPSK detection / complex division circuit 19 is specifically configured as shown in FIG. In FIG. 4, the CP / DBPSK signal extraction circuit 19
1 extracts the complex signal at the carrier position of the CP signal of the first symbol of the frame and the DBPSK-modulated signal from the data after the FFT. The CP / DBPSK signal generation circuit 192 outputs the CP signal at the head of the frame and the DBPS
A known signal of the K signal is generated. The complex division circuit 193 is
This is a circuit for complexly dividing the signal extracted by the CP / DBPSK signal extraction circuit 191 by the signal generated by the CP / DBPSK signal generation circuit 192, and includes CP and DBPSK.
Find the transmission path characteristics of the signal. Zeros are inserted into the remaining carrier positions. This is sent to the IFFT circuit of FIG.

The IFFT circuit 18 uses the CP / DB
The signal output from the PSK detection / complex division circuit 19 is subjected to an inverse Fourier transform, and the output is supplied to a second symbol synchronization circuit 17.

The second symbol synchronization circuit 17 is specifically configured as shown in FIG. In FIG. 5, a power calculation circuit 171 is a circuit that squares a real part and an imaginary part of an IFFT signal and then adds the squared parts. The peak position detection circuit 172 detects a peak of the output of the power calculation circuit 171. Note that an absolute value circuit is used instead of the power calculation circuit 171, and the FFT is performed using the peak position of the output.
The window position may be determined. However, a power calculation circuit is required to calculate the delay profile. The FFT window position determination circuit 173 corrects the FFT window position sent from the first symbol synchronization circuit 16 with the signal sent from the peak position detection circuit 172, and sets the FFT window position as a new FFT window position.
Output to the circuit 18.

Here, the FFT window position will be described with reference to FIG. FIG. 6A shows received OFDM.
Here, symbols are shown, and it is assumed here that there is no positional deviation from the section subjected to IFFT on the transmission side. FIG.
The impulse response of the signal shown in (a) appears at the position shown in FIG. 6C (for the sake of explanation, when the DC component is subjected to inverse Fourier transform, the impulse appears at the center). The FFT window position at this time is as shown in FIG.

However, when a position shift occurs in the OFDM symbol as shown in FIG. 6B, the position of the impulse also shifts and appears at the position shown in FIG. 6D. Therefore, the position of the window to be Fourier-transformed is shifted by an amount corresponding to the shift from the originally appearing position (FIG. 6C). In the case of FIG. 6, by changing the position of the window to be Fourier-transformed to the position shown in FIG. 6 (f), the impulse component of the main wave appears at the center. The FFT window position is determined in this manner. When an impulse appears as shown in FIG. 6D, the FFT window is moved to a position fixedly shifted to half of the guard period as shown in FIG. You can also set windows.

The output of the delay profile can be obtained even when the FFT window is set at the position shown in FIG.
Even when the position is set to the position shown in (g), the normal FFT window position is fixedly output as the center. Thereby, the front ghost and the rear ghost can be confirmed.

FIG. 7A shows a delay profile when there is a rear ghost, and FIG. 7B shows a delay profile when there is a front ghost. That is, in the case of FIG. 7A, an impulse located behind the position of the impulse of the main wave at the center can be identified as a rear ghost, and time A can be measured as a delay time of the rear ghost. In the case of FIG. 7B, it is possible to identify a preceding impulse as a preceding ghost from the position of the main wave impulse at the center, and measure the time B as the preceding ghost delay time.

Therefore, according to the present embodiment, it is possible to analyze and evaluate a delay profile without transmitting a special signal, and furthermore, it is possible to discriminate between a front ghost and a rear ghost with a normal receiving device configuration. Symbol synchronization can be precisely performed.

(Second Embodiment) FIG. 8 is a block diagram showing a configuration of an OFDM receiver having a delay profile analysis function when all segments are synchronous segments according to a second embodiment of the present invention. is there. In the present embodiment, a delay profile is obtained using all symbols. In FIG. 8, the same parts as those in FIG. 1 are denoted by the same reference numerals, and different parts will be described here.

In FIG. 8, the received OFDM signal is down-converted to a baseband signal,
, And is subjected to a first symbol synchronization process. The first symbol synchronization process is the same as in the first embodiment. Further, the frequency error calculation circuit 11, the frequency correction circuit 12, the FFT circuit 13, and the frame synchronization circuit 14 all perform the same processing as in the first embodiment.

The present embodiment is characterized in that an SP detection / complex division / interpolation circuit 20 is used instead of the CP / DBPSK detection / complex division circuit 19 shown in FIG.
The details of the SP detection / complex division / interpolation circuit 20 are shown in FIG.

In FIG. 9, an SP signal extraction circuit 201 extracts an SP signal whose position is specified from a frame synchronization signal from data after FFT. The SP signal generation circuit 202 generates a known SP signal. The complex division circuit 203 divides the received SP signal by a known SP signal to obtain a transmission path characteristic at each SP position. Since the SP signal is shifted by three carriers for each symbol, interpolation is performed in the symbol direction using the symbol filter 204. Zeros are inserted into the remaining carrier positions and sent to the IFFT circuit 18.

The IFFT circuit 18 in FIG. 8 determines the FFT window position by performing an inverse Fourier transform on the data sent from the SP detection / complex division / interpolation circuit 20. In the second symbol synchronization circuit 17, the same processing as in the first embodiment is performed.

The processing operation of the above configuration will be described below.

FIG. 10 shows a delay profile. When all segments are synchronous segments, as shown in FIG. 10A, the main signal impulse is observed at three places by the SP signal. Therefore, as shown in FIG. 10B, when a delayed wave is observed at the point C, it is not known whether the delayed wave is a rear ghost or a front ghost. However, the information from the first symbol synchronization circuit 16 makes it possible to distinguish between a pre-ghost and a post-ghost. This is shown in FIG.

FIG. 11A shows an FFT of the same section as the transmitting side.
This is the case. In this case, since only the rear ghost is observed as the delay profile, it can be seen that the ghost component shown in FIG. 11A is the rear ghost. On the other hand, when the section as shown in FIG. 11 (c) is subjected to the FFT processing, the impulse of the main wave is observed at the last part of the observation region, and the zero point of the time, that is, the distance from the center to the main wave. A delayed wave is observed.

As a result, a delay profile that can be observed up to about 83 μs before and after the SP signal can be obtained. However, the amplitude of the delayed wave exceeding the guard period length is observed to be small.

(Third Embodiment) FIG. 12 is a block diagram showing a configuration of an OFDM receiver having a delay profile analysis function when a synchronous segment and a differential segment coexist as a third embodiment. . In the present embodiment, the delay profile is obtained using only the head of the frame. 12, the same parts as those in FIG. 1 are denoted by the same reference numerals, and different parts will be described here.

In FIG. 12, a received OFDM signal is down-converted to a baseband signal, and then input to a first symbol synchronization circuit 16, where a first symbol synchronization process is performed. The first symbol synchronization process is the same as in the first embodiment. The frequency error calculation circuit 11, frequency correction circuit 12, FFT circuit 13, and frame synchronization circuit 14 all perform the same processing as in the first embodiment.

The feature of this embodiment is that instead of the CP / DBPSK detection / complex division circuit 19 shown in FIG. 1, SP detection / complex division / interpolation and CP / DBPSK detection / complex detection are performed.
The point is that the complex division circuit 21 is used. FIG. 13 shows details of the SP detection / complex division / interpolation and CP / DBPSK detection / complex division circuit 21.

In FIG. 13, a CP / DBPSK signal detection circuit 211 extracts a CP signal and a DBPSK signal of a head symbol of a frame from an output signal of the FFT circuit 13. The CP / DBPSK signal generation circuit 212 uses a known CP
/ DBPSK signal. The complex division circuit 213 performs complex division of the received CP / DBPSK signal by the CP / DBPSK signal from the CP / DBPSK signal generation circuit 212. The SP signal extraction circuit 214 extracts an SP signal for each symbol from the output signal of the FFT circuit 13. The SP signal generation circuit 215 generates a known SP signal. The complex division circuit 216 converts the received SP signal into an SP signal generation circuit 21.
Complex divide by the known SP signal from 5 The symbol filter 218 interpolates the complex-divided signal in the symbol direction.

The combining circuit 217 combines the CP / DBPSK signal, which has been subjected to complex division at the head symbol position of the frame, and the interpolated SP signal once per frame at the frame head position, and inserts zeros into the remaining portions. , IFFT circuit 1
8

The IFFT circuit 18 shown in FIG.
The data transmitted from the complex division / interpolation and CP / DBPSK detection / complex division circuit 21 is subjected to inverse Fourier transform.
The second symbol synchronization circuit 17 performs the same processing as in the first embodiment.

According to the above configuration, even when the synchronous segment and the differential segment are mixed, the SP and the CP / DBPS are used.
K can be detected together, and the FFT window position can be changed based on the detection result, and a delay profile observable up to about 83 μs before and after can be obtained as in the second embodiment.

In the present embodiment, the case where the synchronous segment and the differential segment coexist has been described. However, the present invention can be applied to the case where only the synchronous segment is used.

(Fourth Embodiment) FIG. 14 shows an OFDM having a delay profile analysis function when all segments are differential segments as a fourth embodiment according to the present invention.
FIG. 3 is a block diagram illustrating a configuration of a receiving device. However, in the present embodiment, a case will be described in which all segments are differential segments, but the same processing can be performed on CPs and DBPSKs of synchronous segments even when synchronous segments are included. In FIG. 14, the same parts as those in FIG. 1 are denoted by the same reference numerals, and different parts will be described here.

In FIG. 14, a received OFDM signal is down-converted to a baseband signal, and then input to a first symbol synchronization circuit 16, where a first symbol synchronization process is performed. The first symbol synchronization process is
This is the same as the first embodiment. The frequency error calculation circuit 11, frequency correction circuit 12, FFT circuit 13, and frame synchronization circuit 14 all perform the same processing as in the first embodiment.

This embodiment is characterized in that a CP detection / complex division and DBPSK detection / error correction / complex division circuit 22 is used in place of the CP / DBPSK detection / complex division circuit 19 shown in FIG. It is in. This CP detection / complex division and DBPSK detection / error correction / complex division circuit 22
Are shown in FIG.

In FIG. 15, a DBPSK signal extraction circuit 221 extracts a DBPSK signal from the output signal of the FFT circuit 13. The FEC decoder circuit 222 has a DBPSK
Error correction processing. The differential encoding circuit 223 performs the same differential encoding process performed on the transmission side on the basis of the error-corrected data. CP signal generation circuit 2
24 generates a known CP signal. The combining circuit 225 combines the signals from the differential encoding circuit 223 and the CP signal generating circuit 224, and inserts zero into the remaining carrier part.

The CP / DBPSK signal extraction circuit 226 outputs F
Extract the CP and DBPSK signals from the data after FT,
Zero is substituted for the remaining carrier part. Delay circuit 22
7 is the DBPSK signal detection circuit 221 to the synthesis circuit 22
The delay processing is performed only for the time required up to 5. The complex division circuit 228 performs a complex division process by dividing the signal sent from the delay circuit 227 by the signal output from the synthesis circuit 225. The symbol filter 229 filters the data subjected to the complex division processing in the symbol direction, and then sends the data to the IFFT circuit 18. Note that the symbol filter 229 may not be provided.

The IFFT circuit 18 shown in FIG.
The data transmitted from the complex division and DBPSK detection / error correction / complex division circuit 21 is subjected to inverse Fourier transform. In the second symbol synchronization circuit 17, the same processing as in the first embodiment is performed.

According to the above configuration, even when all segments are differential segments, a delay profile can be obtained using all symbols, and noise can be suppressed by using a symbol filter. Note that even if a part of the synchronous segment is included, DBPSK of the synchronous segment can be used.

(Fifth Embodiment) FIG. 16 is a block diagram showing a configuration of an OFDM receiver according to a fifth embodiment of the present invention when all segments are differential segments. In FIG. 16, the same portions as those in FIG. 1 are denoted by the same reference numerals, and different portions will be described here.

In FIG. 16, a received OFDM signal is down-converted to a baseband signal, and then input to a first symbol synchronization circuit 16, where a first symbol synchronization process is performed. The first symbol synchronization process is
This is the same as the first embodiment. Further, the frequency error calculation circuit 11, the frequency correction circuit 12, the FFT circuit 13, and the frame synchronization circuit 14 all perform the same processing as in the first embodiment.

The present embodiment is characterized in that a CP / DBPSK detection / squaring circuit 23 is used in place of the CP / DBPSK detection / complex division circuit 19 shown in FIG. The difference between this embodiment and the first embodiment is that although only the first symbol of a frame can be used in the first embodiment, precise synchronization can be achieved using all symbols in the present embodiment. However, a delay profile cannot be obtained.

FIG. 17 shows the details of the CP / DBPSK detection / squaring circuit 23. In FIG. 17, CP / DBP
The SK signal extraction circuit 231 extracts the CP signal and the DBPSK signal of the signal from the FFT circuit 13, and inserts zeros in other portions. The squaring circuit 232 uses the extracted CP
And the DBPSK signal are squared. Symbol filter 23
3 filters this signal in the symbol direction,
A signal is sent to the FT circuit 18.

The IFFT circuit 18 shown in FIG.
The signal from the PSK detection / squaring circuit 23 is subjected to inverse Fourier transform. The second symbol synchronization circuit 17 is the same as in the first embodiment. However, because of the squaring process, it is not possible to distinguish between the front ghost and the rear ghost, and no delay profile is obtained.

(Sixth Embodiment) FIG. 18 shows an OFD having a delay profile analysis function when all segments are differential segments as a sixth embodiment according to the present invention.
FIG. 3 is a block diagram illustrating a configuration of an M receiving device. Note that FIG.
Since the configuration other than the second symbol synchronization circuit 25 and the delay profile generation circuit 26 is the same as in the first embodiment, the same parts as those in FIG. 1 are denoted by the same reference numerals, and different parts will be described here. .

In FIG. 18, in the case of the first embodiment, the second symbol synchronization circuit 25 may set the FFT window position to be the same as the IFFT window position on the transmitting side, or it may be fixedly shifted. In the case of the present embodiment, synchronization is performed so that the FFT window position is always the same as that of the transmitting side. As a result, when symbol synchronization converges, the output of the IFFT circuit 18 does not deviate from the position where the peak of the delay profile appears when converted to power, but it can be considered that only the sampling phase is deviated.

FIG. 19 shows this state. FIG. 19A shows a case where no phase shift has occurred. The signal after IFFT has a component only in the real part, and the imaginary part is zero. FIG. 19B shows a case where a phase shift of 90 degrees occurs. The signal after the IFFT has a component only in the imaginary part, and the real part is zero. Here, in FIGS. 19A and 19B,
The peak position of the impulse displayed in the IQ plane is shown at the bottom. That is, the rotation of this phase can be controlled by looking at the peak position of the impulse.

FIG. 20 shows a specific configuration of the delay profile generation circuit 26. In FIG. 20, CP / DBPS
The K generation circuit 261 generates a CP / DBPSK component on the transmission side. The phase rotation circuit 262 determines the phase of the peak position in the impulse of the data sent from the IFFT circuit 18 and rotates the phase of the CP / DBPSK signal. IFFT circuit 263 performs IFFT processing on data output from phase rotation circuit 262.

The normalization circuit 264 converts the data input from the IFFT circuit 18 and the data input from the IFFT circuit 263 of FIG. 18 into electric power, respectively, and then normalizes the data so that the peak values are the same for both. I do. Thereafter, the normalized output and the IFFT circuit 263 are output from the subtraction circuit 265.
Subtraction with the output of Then, the peak of the main wave disappears at the input of the synthesis circuit 266, and only the delayed wave component appears. In order to simultaneously show the main wave as a delay profile, the synthesis circuit 266 adds only the center point of the impulse output from the normalization circuit 264.

As a result, a precise delay profile is obtained in which the influence of noise due to the CP / DBPSK arrangement pattern is eliminated.

In the present embodiment, the processing up to the input of the delay profile generation circuit 26 uses the configuration of the first embodiment. However, the second to second processings are performed according to the segment configuration of the input OFDM signal. Any of the four embodiments can be used.

(Seventh Embodiment) FIG. 21 is a block diagram showing a configuration of an OFDM receiving apparatus having a delay profile analysis function according to a seventh embodiment of the present invention. In FIG. 21, components other than the phase rotation circuit 27 and the delay profile generation circuit 28 are the same as those in the sixth embodiment, and the same parts as those in FIG. 18 are denoted by the same reference numerals, and different parts will be described here.

Also in the case of the present embodiment, the second symbol synchronization circuit 25, as in the case of the sixth embodiment, always has the same FFT window position as that of the transmitting side, that is, the impulse is displayed at the center. Is synchronized. The phase rotation circuit 27 controls the phase rotation so that the real part of the impulse after the IFFT becomes maximum and the imaginary part becomes zero, as shown in FIG. This control is based on IFFT
This is performed after a later power peak appears at the center.

FIG. 22 shows details of the delay profile generation circuit 28. In FIG. 22, a CP / DBPSK generation circuit 281 generates a CP / DBPSK component on the transmission side. IFFT circuit 282 performs IFFT processing on data output from CP / DBPSK generation circuit 281. still,
Since the processing of the CP / DBPSK generation circuit 281 and the IFFT circuit 282 has a fixed pattern depending on the segment configuration, the processing may be stored in the ROM 283 in a lump.

The normalization circuit 284 converts both the data input from the IFFT circuit 18 and the data input from the IFFT circuit 282 into power, and then normalizes the peak values so that both become the same. I do. afterwards,
Subtraction processing is performed by the subtraction circuit 285. Then, the peak of the main wave disappears at the input of the synthesis circuit 286, and only the delayed wave component appears. In order to simultaneously show the main wave as a delay profile, the synthesis circuit 286 adds only the center point of the impulse output from the normalization circuit 284. As a result, a precise delay profile in which the influence of noise due to the arrangement pattern of CP / DBPSK is removed can be obtained.

Although the present embodiment has been described based on the first embodiment, a precise delay profile can be similarly obtained in any of the second to fourth embodiments.

(Eighth Embodiment) A method of determining an FFT window position using the circuit of the first embodiment will be described. In the case as shown in FIG. 7A, the first delayed wave is behind the position of the delay profile,
As described in the embodiment, F is determined based on the position of the peak of the main wave.
Determining the FT window position does not cause a problem. However, in the case of a three-station SFN or the like, a so-called front ghost component in which a signal component arrives earlier in time than the main wave may appear. In this case, when the FFT window position is determined based on the main wave, the previous ghost component causes intersymbol interference.

This situation is shown in FIG. In FIG. 23, (a) shows the main wave, and (b) shows the front ghost component. Here, when the FFT window position is adjusted to the main wave as shown in (c), the pre-ghost component shown in (b) causes intersymbol interference. Therefore, if there is a previous ghost component, the FFT window position is determined at a position including the previous ghost component as shown in FIG. By providing the FFT period in this way, it is possible to reproduce a signal without intersymbol interference.

When a large number of delayed waves arrive, IFF
In the delay profile output from the T circuit 18,
As shown in FIG. 23D, the FFT window position is determined at a position where the power within the guard period is maximized. As a result, the power of the ghost component can be used to the utmost, and even under an environment where a previous ghost exists, it is possible to reproduce a signal that is less affected by intersymbol interference.

In each of the above embodiments, when displaying the delay profile analysis result, it is preferable to display the main wave at the center regardless of whether a front ghost exists or a rear ghost exists.

[0129]

As described above, according to the present invention, even when the number of CP signals, DBPSK signals, etc. is small, the FFT window position can be determined accurately, and the delay profile can be obtained accurately. Even when only the SP signal is transmitted, the front ghost and the rear ghost can be distinguished. Further, by providing the FFT window position at the position where the power within the guard period in the delay profile is maximum, the transmitted signal can be used to the maximum,
Even when a previous ghost exists, the influence of intersymbol interference can be eliminated.

Therefore, it is possible to provide a delay profile analyzer which can analyze and evaluate a delay profile without transmitting a special signal, which is the first problem, and further, which is a second problem, which is a normal problem. Thus, it is possible to identify a pre-ghost or a post-ghost by the configuration of the receiving device, and thereby provide a symbol synchronization method capable of precisely performing symbol synchronization.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a configuration of an OFDM receiver having a delay profile analysis function according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a first symbol synchronization circuit according to the first embodiment of the present invention.

FIG. 3 is a timing waveform chart for explaining the operation of the first symbol synchronization circuit according to the first embodiment of the present invention.

FIG. 4 shows a CP / DBP according to the first embodiment of the present invention.
FIG. 3 is a block circuit diagram showing details of an SK detection / complex division circuit.

FIG. 5 is a block circuit diagram showing details of a second symbol synchronization circuit according to the first embodiment of the present invention.

FIG. 6 is a timing waveform chart for explaining a symbol synchronization method according to the first embodiment of the present invention.

FIG. 7 is a timing waveform chart for explaining a delay profile according to the first embodiment of the present invention.

FIG. 8 is a block circuit diagram showing a configuration of an OFDM receiver having a delay profile analysis function according to a second embodiment of the present invention.

FIG. 9 is a block circuit diagram showing details of an SP detection / complex division / interpolation circuit according to a second embodiment of the present invention.

FIG. 10 is a timing waveform chart for explaining a delay profile according to the second embodiment of the present invention.

FIG. 11 is a timing waveform chart for explaining a delay profile observation method according to the second embodiment of the present invention.

FIG. 12 is a block circuit diagram showing a configuration of an OFDM receiver having a delay profile analysis function according to a third embodiment of the present invention.

FIG. 13 is a diagram showing SP detection and detection according to the third embodiment of the present invention.
FIG. 3 is a block circuit diagram showing details of a complex division / interpolation and CP / DBPSK detection / complex division circuit.

FIG. 14 is a block circuit diagram showing a configuration of an OFDM receiver having a delay profile analysis function according to a fourth embodiment of the present invention.

FIG. 15 is a block diagram showing CP detection and detection according to a fourth embodiment of the present invention.
FIG. 2 is a block circuit diagram showing details of a complex division and DBPSK detection / error correction / complex division circuit.

FIG. 16 is a block circuit diagram showing a configuration of an OFDM receiver according to a fifth embodiment of the present invention.

FIG. 17 shows a CP / DB according to the fifth embodiment of the present invention.
FIG. 3 is a block circuit diagram showing details of a PSK detection / squaring circuit.

FIG. 18 is a block circuit diagram showing a configuration of an OFDM receiver having a delay profile analysis function according to a sixth embodiment of the present invention.

FIG. 19 is a view for explaining a phase rotation method according to the sixth embodiment of the present invention.

FIG. 20 is a block circuit diagram showing details of a delay profile generation circuit according to a sixth embodiment of the present invention.

FIG. 21 is a block circuit diagram showing a configuration of an OFDM receiver having a delay profile analysis function according to a seventh embodiment of the present invention.

FIG. 22 is a block circuit diagram showing details of a delay profile generation circuit according to a seventh embodiment of the present invention.

FIG. 23 is a timing waveform chart for explaining a symbol synchronization method according to the eighth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 11 frequency error calculating circuit 12 frequency correcting circuit 13 FFT circuit 14 frame synchronizing circuit 15 detecting circuit 16 first symbol synchronizing circuit 161 effective symbol period delay circuit 162 multiplier multiplier 163 sliding averaging circuit 164 Symbol filter circuit 17 second symbol synchronization circuit 171 power calculation circuit 172 peak position detection circuit 173 FFT window position determination circuit 18 IFFT circuit 19 CP / DBPSK detection / complex division circuit 191 CP / DBPSK signal extraction Circuit 192 CP / DBPSK signal generation circuit 193 Complex division circuit 20 SP detection / complex division / interpolation circuit 201 SP signal extraction circuit 202 SP signal generation circuit 203 complex division circuit 204 symbol filter 21 SP detection / Complex division / interpolation and C / DBPSK
Detection / complex division circuit 211 ... CP / DBPSK signal detection circuit 212 ... CP / DBPSK signal generation circuit 213 ... Complex division circuit 214 ... SP signal extraction circuit 215 ... SP signal generation circuit 216 ... Complex division circuit 217 ... Synthesis circuit 218 ... Symbol Filter 22 CP detection / complex division and DBPSK detection / error correction / complex division circuit 221 DBPSK signal extraction circuit 222 FEC decoder circuit 223 Differential encoding circuit 224 CP signal generation circuit 225 Synthesis circuit 226 CP / DBPSK signal extraction circuit 227 delay circuit 228 complex division circuit 229 symbol filter 23 CP / DBPSK detection / squaring circuit 231 CP / DBPSK signal extraction circuit 232 square circuit 233 symbol filter 25 second symbol Synchronous circuit 26 ... Delay File generation circuit 261 CP / DBPSK generation circuit 262 Phase rotation circuit 263 IFFT circuit 264 Normalization circuit 265 Subtraction circuit 266 Synthesis circuit 27 Phase rotation circuit 28 Delay profile generation circuit 281 CP / DBPSK generation circuit 282 IFFT circuit 283 ROM 284 Normalization circuit 285 Subtraction circuit 286 Synthesis circuit

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tomohiro Kimura 5-2-8 Akasaka, Minato-ku, Tokyo Inside the Next Generation Digital Television Broadcasting System Research Laboratories (72) Inventor Kenichiro Hayashi Akasaka, Minato-ku, Tokyo 5-2-2, Next Generation Digital Television Broadcasting System Laboratories, Inc. (72) Inventor Sadaji Kageyama 5-2-2-8, Akasaka, Minato-ku, Tokyo Research on Next-Generation Digital Television Broadcasting Systems In-house (72) Inventor Shigeru Soga 5-2-2-8 Akasaka, Minato-ku, Tokyo Inside the Next Generation Digital Television Broadcasting System Research Laboratories (72) Inventor Seiji Sakashita 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Within Sangyo Co., Ltd. (56) References JP-A-5-75568 (JP, A) Transmission method-Transmission characteristics in fixed reception and mobile reception-", STRL Open Lectures and Proceedings, NHK Engineering Services, May 22, 1998, p. 67-72 Technical Report of the Institute of Image Information and Television Engineers vol. 21, No. 73, p. 37-42 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04J 11/00

Claims (18)

(57) [Claims] 1. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. , A DBPSK-modulated signal is arranged at the same specific carrier position for each symbol,
When a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol, a delay profile analysis device that analyzes a delay profile thereof, wherein: a symbol synchronization unit that establishes symbol synchronization of the OFDM signal; Fourier transforming means for Fourier transforming the signal; frame synchronizing means for establishing frame synchronization of the OFDM signal; and a phase reference signal of the DBPSK-modulated signal transmitted from the synchronization frame established by the frame synchronizing means. Specific symbol extracting means for extracting the symbols of the following symbols; phase reference signal extracting means for extracting all or a part of the phase reference signal of the DBPSK modulation from the specific symbols extracted by the specific symbol extracting means; Specific symbols extracted by means
The phase reference extracted by the phase reference signal extraction means.
The quasi-signal is complexed for each carrier using a known signal on the receiving side.
The phase reference signal is extracted by the phase reference signal extracting means.
The real and imaginary parts are placed at carrier positions other than the issued carrier position.
A delay profile analysis apparatus comprising: a specific symbol processing unit that inserts zero into the signal; and an inverse Fourier transform unit that performs an inverse Fourier transform on the signal obtained by the specific symbol processing unit to obtain a delay profile. 2. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. In the case where a continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is arranged in a specific symbol,
In a delay profile analysis device for analyzing the delay profile, symbol synchronization means for establishing symbol synchronization of the OFDM signal, Fourier transformation means for performing Fourier transform on the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal A specific symbol extracting means for extracting a specific symbol from which a phase reference signal of the DBPSK-modulated signal is transmitted from the synchronization frame established by the frame synchronizing means; and a specific symbol extracted by the specific symbol extracting means. A phase reference signal and a continuous pilot signal extracting means for extracting all or a part of the phase reference signal and the continuous pilot signal of the DBPSK modulation, and a specific symbol extracted by the specific symbol extracting means.
Extracting the phase reference signal and the continuous pilot signal.
Phase reference signal and continuous pilot signal extracted by means
Complex division of each carrier using a known signal on the receiving side
And said phase reference signal and continuous pilot signal extracting means.
The key from which the phase reference signal and the continuous pilot signal
Zero is inserted for both the real and imaginary parts at carrier positions other than the carrier position.
A delay profile analysis device , comprising: a specific symbol processing unit for inputting a signal; and an inverse Fourier transform unit for obtaining a delay profile by performing an inverse Fourier transform on a signal obtained by the specific symbol processing unit . 3. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period, and comprising an OFDM signal of the transmission system. Among a plurality of carriers, a predetermined number of carriers are assigned to one or more segments as one unit, one or more carriers are assigned to a band end pilot signal, and the one or more segments are respectively used for synchronous detection for each segment, In the differential detection segment, a continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol, and the DBPSK-modulated signal is used in the differential detection segment. The phase reference signal of the detected signal is allocated to a specific symbol, and in the synchronous detection segment, When a dispersed pilot signal that modulates a carrier periodically dispersed in the symbol time and carrier frequency directions with a specific phase and amplitude is provided in addition to the DBPSK-modulated signal, a delay for analyzing the delay profile thereof in profile analysis device, a symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, in the frame synchronization means A distributed pilot signal extracting means for extracting a distributed pilot signal of the synchronous detection segment from the established synchronous frame; an interpolating means for interpolating the distributed pilot signal extracted by the distributed pilot signal extracting means in a symbol time direction; Established by frame synchronization means Before from the frame synchronization
The phase reference signal of the DBPSK-modulated signal is transmitted.
A specific symbol extracting unit for extracting a specific symbol, a phase reference signal and a continuous pilot signal extracting unit for extracting the DBPSK-modulated phase reference signal and the continuous pilot signal from the specific symbol extracted by the specific symbol extracting unit, removed scattered pilot signal interpolated by said interpolating means from the <br/> specific symbol position of the synchronous frame established by the frame synchronizing means, phase reference signal extracted by the phase reference signal and a continuous pilot signal extracting means and Combining means for combining with a continuous pilot signal; and a specific symbol extracted by the specific symbol extracting means.
The combined signal output from the combining means
And performs complex division for each carrier using a known signal.
Zero is inserted for both real and imaginary parts at carrier positions where there is no signal component.
A delay profile analysis device , comprising: a specific symbol processing unit for inputting a signal; and an inverse Fourier transform unit for obtaining a delay profile by performing an inverse Fourier transform on a signal obtained by the specific symbol processing unit . 4. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period, and comprising an OFDM signal of the transmission system. Among a plurality of carriers, a predetermined number of carriers are assigned to one or more segments as one unit, one or more carriers are assigned to a band end pilot signal, and the one or more segments are respectively used for synchronous detection for each segment, Used in a system of a system used as one of differential detection, a continuous pilot signal and a DBPSK-modulated signal are arranged at the same carrier position for each symbol in the synchronous detection segment and the differential detection segment. In case,
In a delay profile analysis device for analyzing the delay profile, symbol synchronization means for establishing symbol synchronization of the OFDM signal, Fourier transformation means for performing Fourier transform on the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal Signal extracting means for extracting the continuous pilot signal and the DBPSK-modulated signal from the synchronization frame established by the frame synchronizing means; and DBPSK-modulated signal extracted by the signal extracting means for extracting the DBPSK-modulated signal. Error correcting means for correcting the data error of the received signal, differential encoding means for differentially encoding the DBPSK-modulated signal error-corrected by the error correcting means, and a synchronous frame established by the frame synchronizing means. Each
For the symbol, the continuous pattern extracted by the signal extraction means is used.
Receiving the pilot signal and the DBPSK modulated signal on the receiving side
A continuous pilot signal and the differential encoding means
Performs complex division for each carrier with the signal differentially encoded in the stage,
The signal extracting means uses a continuous pilot signal and DBPSK.
Carriers other than the carrier position where the modulated signal was extracted
Symbol processing means for inserting a real part and an imaginary part zero at a position
And an inverse Fourier transform unit for performing an inverse Fourier transform on the signal obtained by the symbol processing unit to obtain a delay profile. 5. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period, and comprising an OFDM signal of the transmission system. Among a plurality of carriers, a predetermined number of carriers are assigned to one or more segments as one unit, one or more carriers are assigned to a band end pilot signal, and the one or more segments are respectively used for synchronous detection for each segment, Used in a system of the type used as one of the differential detection, In the synchronous detection segment, a scattered pilot signal that modulates a carrier periodically dispersed in the symbol time and the carrier frequency direction with a specific phase and amplitude. And DBPS at the same carrier position in the symbol direction.
A K-modulated signal is arranged, and in the differential detection segment, when a DBPSK-modulated signal and a continuous pilot signal are arranged at the same carrier position for each symbol, a delay profile analyzer for analyzing a delay profile thereof A symbol synchronization unit for establishing symbol synchronization of the OFDM signal; a Fourier transform unit for performing a Fourier transform on the OFDM signal; a frame synchronization unit for establishing a frame synchronization of the OFDM signal; and a frame synchronization unit. From the sync frame,
The continuous pilot signal, a DBPSK modulated signal,
Signal extracting means for extracting a scattered pilot signal of the segment for synchronous detection; interpolating means for interpolating the scattered pilot signal extracted by the signal extracting means in the symbol time direction; and DBPSK modulation extracted by the signal extracting means. and error correcting means for correcting data errors in the signal, and the differential encoding means for differentially encoding the signal error correction at the error correction means, said interpolating the successive pilot signals and DBPSK modulated signal Means for combining with the dispersed pilot signal interpolated in the symbol direction by the means, and the continuous pilot signal synthesized by the combining means.
During variance pilot signals, DBPSK modulated signal
Signal on the receiving side and differential with the differential encoding means
Complex division is performed for each carrier by the encoded signal,
The continuous pilot signal synthesized by the means, DBPSK
Modulated signal, interpolated scattered pilot signal arranged
Real and imaginary parts
A delay profile analysis device , comprising: synthesized signal processing means for inserting a b; and inverse Fourier transform means for obtaining a delay profile by inverse Fourier transforming the signal obtained by the synthesized signal processing means . 6. An orthogonal frequency division multiplexing (OFDM) transmission system that modulates a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period and transmits digital information, and uses the OFDM signal of the transmission system. , A DBPSK-modulated signal is arranged at the same specific carrier position for each symbol,
When a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol, a delay profile analysis device that analyzes a delay profile thereof, wherein: a symbol synchronization unit that establishes symbol synchronization of the OFDM signal; a Fourier transforming means for Fourier-converts the signal, the frame synchronization means for establishing frame synchronization of the OFDM signal, the frame sync established by said frame means D
Specific symbol extracting means for extracting a specific symbol to which a phase reference signal of the BPSK-modulated signal is transmitted; and all or part of the DBPSK-modulated phase reference signal from the specific symbol extracted by the symbol extracting means. Phase reference signal extracting means for extracting, and the specific symbol extracted by the specific symbol extracting means.
The phase reference extracted by the phase reference signal extraction means.
The quasi-signal is complexed for each carrier using a known signal on the receiving side.
The phase reference signal is extracted by the phase reference signal extracting means.
The real and imaginary parts are placed at carrier positions other than the issued carrier position.
Specific symbol processing for inserting zero into the extracted signal
Means, first inverse Fourier transform means for performing an inverse Fourier transform on the signal obtained by the specific symbol processing means, and an arrangement pattern for obtaining an arrangement pattern on the transmission side of a DBPSK-modulated signal allocated to the specific symbol Acquisition means, and an arrangement pattern obtained by the arrangement pattern acquisition means
Said phase rotation means for phase rotation, an arrangement pattern in which the obtained phase rotation means and the second inverse Fourier transform means for inverse Fourier transform, from the obtained signal in the previous SL first inverse Fourier transform unit first Normalization processing means for normalizing the signal obtained by the second inverse Fourier transform means and subtracting the normalized signal from the signal obtained by the first inverse Fourier transform means to obtain a delay profile And a delay profile analysis device. 7. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. In the case where a DBPSK-modulated signal and a continuous pilot signal are arranged at the same specific carrier position for each symbol and the phase reference signal of the DBPSK-modulated signal is arranged at a specific symbol, the delay profile is in the delay profile analysis apparatus analyzing for the symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the frame the frame sync established by the synchronization means Specific symbol extracting means and the phase reference signal and a continual pilot signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means for extracting a specific symbol phase reference signal BPSK-modulated signal are arranged Signal extracting means for extracting all or a part of the symbol , and a specific symbol extracted by the specific symbol extracting means.
For the phase reference signal extracted by the signal extraction means
And a continuous pilot signal using a known signal on the receiving side.
Complex division is performed for each carrier, and the signal
Carrier position from which signal and continuous pilot signal were extracted
Identification to insert zero for both real and imaginary parts at carrier positions other than
Symbol processing means, first inverse Fourier transform means for performing an inverse Fourier transform on the signal obtained by the specific symbol processing means, and an arrangement for obtaining an arrangement pattern on the transmission side of a DBPSK-modulated signal allocated to the specific symbol Pattern acquisition means, second inverse Fourier transform means for performing an inverse Fourier transform on the arrangement pattern acquired by the arrangement pattern acquisition means, and phase rotation of the arrangement pattern inversely Fourier transformed by the second inverse Fourier transform means Phase rotation means, and after normalizing the signal obtained by the second inverse Fourier transform means from the signal obtained by the first inverse Fourier transform means, the normalized signal is converted to the first inverse Fourier transform means. And a normalization operation processing means for obtaining a delay profile by subtracting from a signal obtained by the Fourier transform means. Le analyzer. 8. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. In the case where a DBPSK-modulated signal is allocated to the same specific carrier position for each symbol and a phase reference signal of the DBPSK-modulated signal is allocated to a specific symbol, a delay profile analysis for analyzing the delay profile is performed. In the apparatus, symbol synchronization means for establishing symbol synchronization of the OFDM signal, Fourier transform means for performing Fourier transform on the OFDM signal, frame synchronization means for establishing frame synchronization of the OFDM signal, and the frame synchronization means DBPSK modulated signal from the synchronized frame A particular symbol extracting means for extracting a specific symbol phase reference signal is arranged, a phase reference for extracting all or part of the phase reference signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means Signal extracting means, a specific symbol extracted by the specific symbol extracting means,
For the phase extracted by the phase reference signal extraction means.
The reference signal is duplicated for each carrier using a signal known on the receiving side.
Elementary division, and the phase reference signal is extracted by the phase reference signal extracting means.
Real and imaginary parts at carrier positions other than the extracted carrier position
Specific symbol processing means for both inserting zero, phase rotation means for phase-rotating the signal obtained by the specific symbol processing means, and first inverse Fourier transform for inversely Fourier-transforming the signal phase-rotated by the phase rotation means converting means and said the arrangement pattern acquisition means for obtaining the arrangement patterns of the transmitting side of the DBPSK modulation the signal of the particular symbol, the second inverse Fourier transform means for inverse Fourier transform the acquired arrangement pattern in the arrangement pattern acquiring means After normalizing the signal obtained by the second inverse Fourier transform means from the signal obtained by the first inverse Fourier transform means, and converting the normalized signal into the first inverse Fourier transform means And a normalization operation processing means for obtaining a delay profile by subtracting from the signal obtained in (1). 9. An orthogonal frequency division multiplexing (OFDM) transmission system for modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period and transmitting digital information, and the OFDM signal of the transmission system is used. In the case where a DBPSK-modulated signal and a continuous pilot signal are arranged at the same specific carrier position for each symbol, and a phase reference signal of the DBPSK-modulated signal is arranged in a specific symbol, its delay profile is in the delay profile analysis apparatus analyzing for the symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the frame before the synchronization frame established by the synchronization means A particular symbol extracting means for extracting a specific symbol phase reference signal DBPSK modulated signal are arranged, the phase reference signal and a continual pilot signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means Signal extracting means for extracting all or a part of the symbol , and the specific symbol extracted by the specific symbol extracting means.
The phase reference signal extracted by the signal processing means and
And a continuous pilot signal using a known signal on the receiving side.
Complex division for each carrier, and the signal
Signal and the continuous pilot signal
A specific system that inserts zeros for both the real and imaginary parts at the outer carrier position
A symbol processing unit, and phase rotation means for phase rotation of the signal obtained by said specific symbol processing means, a first inverse Fourier transform means for inverse Fourier transform on the signal phase-rotated by said phase rotating means, the specific An arrangement pattern obtaining means for obtaining an arrangement pattern on the transmission side of a DBPSK-modulated signal of a symbol, a second inverse Fourier transform means for performing an inverse Fourier transform on the arrangement pattern acquired by the arrangement pattern acquisition means, After normalizing the signal obtained by the second inverse Fourier transform means from the signal obtained by the inverse Fourier transform means, the normalized signal is subtracted from the signal obtained by the first inverse Fourier transform means. A delay profile analysis device for obtaining a delay profile. 10. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. An OFDM receiver that receives an OFDM signal in which a DBPSK-modulated signal is arranged at a position and a phase reference signal of the DBPSK-modulated signal is arranged in a specific symbol, wherein a symbol synchronization of the OFDM signal is established. Symbol synchronization means, Fourier transform means for Fourier-transforming the OFDM signal, frame synchronization means for establishing frame synchronization of the OFDM signal, and a signal modulated by the DBPSK from a synchronization frame established by the frame synchronization means. Extract specific symbols that carry the phase reference signal That a specific symbol extracting means, and the phase reference signal extracting means for extracting all or part of the phase reference signal of the DBPSK modulation from specific symbols extracted by the specific symbol extracting means, is extracted by the specific symbol extracting means Specific symbol
The phase reference extracted by the phase reference signal extraction means.
The quasi-signal is complexed for each carrier using a known signal on the receiving side.
The phase reference signal is extracted by the phase reference signal extracting means.
The real and imaginary parts are placed at carrier positions other than the issued carrier position.
Specific symbol processing means for inserting zero into the signal, an inverse Fourier transform means for performing an inverse Fourier transform on the signal obtained by the specific symbol processing means, and a peak position of the signal subjected to the inverse Fourier transform by the inverse Fourier transform means. An OFDM receiving apparatus comprising: a second symbol synchronization unit for performing precise symbol synchronization. 11. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. A continuous pilot signal and a DBPSK-modulated signal are arranged at the position,
An OFDM receiving apparatus for receiving an OFDM signal in which a phase reference signal of a K-modulated signal is allocated to a specific symbol, comprising: first symbol synchronization means for establishing symbol synchronization of the OFDM signal; Fourier transforming means for converting; frame synchronizing means for establishing frame synchronization of the OFDM signal; and extracting a specific symbol to which a phase reference signal of the DBPSK-modulated signal is transmitted from the synchronization frame established by the frame synchronizing means. a particular symbol extracting means for a phase reference signal and a continuous pilot signal extracting means for extracting all or part of the DBPSK modulation phase reference signal and the continual pilot signals from specific symbols extracted by the specific symbol extracting means, wherein To the specific symbol extracted by the specific symbol extraction means
Extracting the phase reference signal and the continuous pilot signal.
Phase reference signal and continuous pilot signal extracted by means
Complex division of each carrier using a known signal on the receiving side
And said phase reference signal and continuous pilot signal extracting means.
The key from which the phase reference signal and the continuous pilot signal
Zero is inserted for both the real and imaginary parts at carrier positions other than the carrier position.
A specific symbol processing means for entering said reverse Fourier transform means for inverse Fourier transform the resulting signals at a particular symbol processing means, precise symbol synchronization on the basis of the peak position of the inverse Fourier transformed signal by said inverse Fourier transform means And a second symbol synchronizing means for obtaining the OFDM signal. 12. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period. A continuous pilot signal and a DBPSK-modulated signal are arranged at the position,
An OFDM receiving apparatus for receiving an OFDM signal in which a phase reference signal of a K-modulated signal is allocated to a specific symbol, comprising: first symbol synchronization means for establishing symbol synchronization of the OFDM signal; Fourier transforming means for converting; frame synchronizing means for establishing frame synchronization of the OFDM signal; and extracting a specific symbol to which a phase reference signal of the DBPSK-modulated signal is transmitted from the synchronization frame established by the frame synchronizing means. Specific symbol extracting means, and a phase reference signal and a continuous pilot signal extracting means for extracting all or a part of the phase reference signal and the continuous pilot signal of the DBPSK modulation from the specific symbol extracted by the specific symbol extracting means in a complex form. When the specific extracted by the specific symbol extracting means The symbol
Extracting the phase reference signal and the continuous pilot signal.
Complex phase reference signal and continuous pi extracted by means
The lot signal is squared for each carrier and phase-converted.
Phase reference signal extraction means and continuous pilot signal extraction means
Carrier position from which quasi-signal and continuous pilot signal were extracted
Zero is inserted for both real and imaginary parts at carrier positions other than
Constant symbol processing means, inverse Fourier transform means for performing inverse Fourier transform on the signal obtained by the specific symbol processing means, and precise symbol synchronization based on the peak position of the signal subjected to inverse Fourier transform by the inverse Fourier transform means An OFDM receiving apparatus comprising: a second symbol synchronization unit. 13. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period, and comprising an OFDM signal of the transmission system. Among a plurality of carriers, a predetermined number of carriers are assigned to one or more segments as one unit, one or more carriers are assigned to a band end pilot signal, and the one or more segments are respectively used for synchronous detection for each segment, In the differential detection segment, a continuous pilot signal and a DBPSK-modulated signal are arranged at the same specific carrier position for each symbol, and the DBPSK-modulated signal is used in the differential detection segment. The phase reference signal of the detected signal is allocated to a specific symbol, and in the synchronous detection segment, OF of the DBPSK In addition to modulated signal, for receiving an OFDM signal scattered pilot signal is arranged to modulate periodically dispersed carrier in symbol time and carrier frequency direction in a specific phase and amplitude
In DM receiving device, a first symbol synchronization means for establishing symbol synchronization of the OFDM signal, a Fourier transforming means for Fourier transforming the OFDM signal, and frame synchronization means for establishing frame synchronization of the OFDM signal, the frame Before the synchronization frame established by the synchronization means
The phase reference signal of the DBPSK-modulated signal is transmitted.
A specific symbol extracting unit for extracting a specific symbol, and a specific symbol extracted by the specific symbol extracting unit .
The phase reference signal of DBPSK modulation and the continuous pilot
Phase reference signal for extracting all or part of the
And continue the pilot signal extraction means, the frame and the scattered pilot signal extracting means for extracting the scattered pilot signal from the synchronous detection segment sync frames established by the synchronization means, the scattered pilots said extracted with scattered pilot signal extracting means Interpolating means for interpolating the signal in the symbol time direction, and a specific symbol extracted by the specific symbol extracting means.
Extracting the phase reference signal and the continuous pilot signal.
Phase reference signal and continuous pilot signal extracted by means
With the scattered pilot signal interpolated by the interpolation means.
Synthesizing means, and the continuous pilot signal synthesized by the synthesizing means.
Signal, interpolated scattered pilot signal, said phase reference signal
Complex division of each carrier using a known signal on the receiving side
And the continuous pilot signal, the interpolated distributed pilot
Signal and the phase reference signal are extracted from the carrier position
A specific system that inserts zeros for both the real and imaginary parts at the outer carrier position
A symbol processing unit, wherein the inverse Fourier transform means for inverse Fourier transform the resulting signals at a particular symbol processing means, the precision symbol synchronization on the basis of the peak position of the inverse Fourier transformed signal by said inverse Fourier transform means 2. An OFDM receiving apparatus comprising: two symbol synchronization units. 14. An orthogonal frequency division multiplexing (OFDM) transmission system for transmitting digital information by modulating a plurality of carriers having a frequency relationship orthogonal to each other for each symbol period, and comprising an OFDM signal of the transmission system. Among a plurality of carriers, a predetermined number of carriers are assigned to one or more segments as one unit, one or more carriers are assigned to a band end pilot signal, and the one or more segments are respectively used for synchronous detection for each segment, Used in a system of the type used as one of the differential detection, In the synchronous detection segment, a scattered pilot signal that modulates a carrier periodically dispersed in the symbol time and the carrier frequency direction with a specific phase and amplitude. And DBPSK at the same carrier position in the symbol direction.
A modulated signal is arranged. In the differential detection segment, a continuous pilot signal and a DBP are placed at the same carrier position.
In an OFDM receiving apparatus that receives an OFDM signal on which an SK-modulated signal is arranged, a first symbol synchronization unit that establishes symbol synchronization of the OFDM signal; a Fourier transform unit that performs a Fourier transform of the OFDM signal; Frame synchronization means for establishing frame synchronization of an OFDM signal; extracting the continuous pilot signal and the DBPSK-modulated signal from a synchronization frame established by the frame synchronization means; and extracting a dispersed pilot signal of the synchronous detection segment. a signal extraction means, and interpolation means for interpolating a scattered pilot signal extracted by said signal extracting means in the symbol direction, and error correcting means for correcting data error in DBPSK modulated signal extracted by said signal extracting means, The DBPSK modulated error corrected by the error correcting means. Differential encoding means for differentially encoding the extracted signal, scattered pilot signals interpolated by the interpolation means, continuous pilot signals extracted by the signal extraction means, and differential encoding by the differential encoding means. Synthesizing means for synthesizing the DBPSK-modulated signal, and the continuous pilot signal synthesized by the synthesizing means.
Signal, interpolated scattered pilot signal, and DBPSK transformation
The modulated signal is converted to a known signal and differentially encoded
Complex division for each carrier using the
The pilot signal, the interpolated scattered pilot signal, and D
Other than the carrier position where the BPSK modulated signal was extracted
Symbol that inserts zero in both the real and imaginary parts at the carrier position of
Processing means, an inverse Fourier transform means for performing an inverse Fourier transform on the signal into which zero has been inserted by the symbol processing means, and a precision symbol synchronization based on a peak position of the signal subjected to the inverse Fourier transform by the inverse Fourier transform means. 2. An OFDM receiving apparatus comprising: two symbol synchronization units. 15. The Fourier transform unit, any one of claims 10 to 14, wherein the performing the Fourier transform processing in a fixed position relative to the peak position obtained by the second symbol synchronization means The OFDM receiver according to any one of the preceding claims. 16. The Fourier transform unit performs a Fourier transform process by providing a window so that the power of the guard period width of a signal obtained from the output signal of the inverse Fourier transform unit is maximized. Claims 10 through
15. The OFDM receiving apparatus according to any one of 14 . 17. The method of claim 1 to 3, 7, wherein said the specific symbol is a first symbol of a frame
10. The delay profile analyzer according to any one of claims 9 to 9 . 18. The method of claim 10, 12乃, wherein said the specific symbol is a first symbol of a frame
14. The OFDM receiver according to any one of to 13 .