CN1321014A - Orthogonal frequency-division multiplex signal receiving device - Google Patents

Orthogonal frequency-division multiplex signal receiving device Download PDF

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Publication number
CN1321014A
CN1321014A CN 01117184 CN01117184A CN1321014A CN 1321014 A CN1321014 A CN 1321014A CN 01117184 CN01117184 CN 01117184 CN 01117184 A CN01117184 A CN 01117184A CN 1321014 A CN1321014 A CN 1321014A
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output
signal
mentioned
subcarrier
orthogonal frequency
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井户纯
中山裕之
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
    • H04L25/023—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols
    • H04L25/0232—Channel estimation using sounding signals with direct estimation from sounding signals with extension to other symbols by interpolation between sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03375—Passband transmission
    • H04L2025/03414—Multicarrier
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03433—Arrangements for removing intersymbol interference characterised by equaliser structure
    • H04L2025/03439—Fixed structures
    • H04L2025/03522—Frequency domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03592—Adaptation methods
    • H04L2025/03598—Algorithms

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)
  • Circuits Of Receivers In General (AREA)

Abstract

To obtain an orthogonal frequency-division multiplexed signal receiver with improved receiving performance, by removing the inter-carrier interference component present in the Fourier transform 1 output, thus reducing the error probability in the recovered data. The frequency-domain signal output from the Fourier transform is filtered 3 to remove the inter-carrier interference component, and coefficients capable of removing the inter-carrier interference component are calculated 4 dynamically by an adaptive algorithm. The filtered output is then demodulated.

Description

Orthogonal frequency-division multiplex signal receiving device
The present invention relates to the receiving system of orthogonal frequency-division multiplex signal.
Figure 15 represents for example shadow mountain, Xi Cun, Ikeda work " the ground-wave digital broadcasting key technologies of receiver ", video information medium association will, the 52nd volume, o. 11th, the 1571st～1572 page, the block diagram of the signal demodulation section of the existing orthogonal frequency-division multiplex transmission of in November, 1998 record.In Figure 15, the 10th, the tuning portion of the signal that input is transmitted according to the orthogonal frequency-division multiplex mode, the 11st, import the output r of this tuning portion r, r iAnd the synchronizing regeneration portion of the output of FFT portion 1, the 1st, import the FFT portion of the output of this synchronizing regeneration portion 11, the 2nd, import the demodulation section of the output of this FFT portion 1, the output I ' of this demodulation section and Q ' they are the playback of data of the numerical data that sends or the playback of data of error correction coding.In addition, R RFThe signal that expression is transmitted according to the orthogonal frequency-division multiplex mode, r rAnd r iReal part and imaginary part when expression becomes the signal souvenir of predetermined band to pluralize signal the signal transformation that transmit according to the orthogonal frequency-division multiplex mode respectively, S rAnd S iReal part and imaginary part when expression will pluralize signal by the signal souvenir that synchronizing regeneration portion 11 has carried out frequency regeneration and clock regeneration respectively, real part and imaginary part when I and Q represent respectively that the output signal souvenir with FFT portion 1 pluralizes signal, real part and imaginary part when I ' and Q ' represent respectively that the output signal souvenir with demodulation section 2 pluralizes signal.
Secondly, working condition is described.The signal that tuning 10 input transmitted according to the orthogonal frequency-division multiplex mode is exported after it is transformed into predetermined band.11 these tuning 10 the output r of input of synchronizing regeneration portion r, r iAnd output signal I, the Q of FFT portion 1, carry out the synchronizing regeneration of frequency of orthogonal frequency-division multiplex signal and the synchronizing regeneration of clock, the signal S of output frequency regeneration and clock regeneration rAnd S i(hereinafter referred to as " timing definition territory signal ").The output of this synchronizing regeneration portion 11 of input of FFT portion 1 is time domain of definition signal, and output counting according to the rules carried out the signal I and the Q (hereinafter referred to as " frequency domain signal ") of Fourier transform processing to it.In demodulation section 2, incoming frequency domain of definition signal, according to the demodulation method corresponding with various modulation systems, each subcarrier of demodulation.The output of this demodulation section 2 is the playback of data of the numerical data that sends or the playback of data of error correction coding, sends data according to its regeneration.
In existing orthogonal frequency-division multiplex signal receiver, because directly demodulation is as the frequency domain signal of Fourier transform output, so interference (to call " inter-carrier interference " in the following text) component in synchronizing regeneration portion between residual each subcarrier that produces by inexpungible frequency error, the problem that exists the wrong probability of happening of playback of data to increase.
The present invention finishes in order to solve the above problems, and purpose is that the inter-carrier interference component that inexpungible frequency error in the synchronizing regeneration portion is caused removes, and obtains the orthogonal frequency-division multiplex signal receiving device with high receptivity.
The described orthogonal frequency-division multiplex signal receiving device of the application's first aspect is a kind of according to the orthogonal frequency-division multiplex signal, and regeneration sends the orthogonal frequency-division multiplex signal receiving device of data, it is characterized in that:
Have the Fourier transform device that the timing definition territory signal transformation that will receive becomes the frequency domain signal;
Coefficient calculation means;
Import the output of above-mentioned Fourier transform device and the output of above-mentioned coefficient calculation means, the filter that carries out filtering according to filter factor from the output of above-mentioned coefficient calculation means; And
Import the output of above-mentioned filter, the demodulating equipment that carries out demodulation according to the demodulation method corresponding with various modulation systems,
Above-mentioned coefficient calculation means is imported output, step value and the reference value of the output of above-mentioned filter, above-mentioned Fourier transform device, from the signal of above-mentioned filter output, upgrades one by one and export filter factor, so that inter-carrier interference is a minimum.
The described orthogonal frequency-division multiplex signal receiving device of second aspect is characterised in that, also has in first aspect:
Whether the output signal of output identification Fourier lens arrangement is the control timing signal generator of the timing signal of control carrier signal; And
Import the output of this control timing signal generator, export the step-length control device of the step parameter corresponding with timing signal,
Above-mentioned coefficient calculation means is imported the output of this step-length control device as above-mentioned step value, carries out the renewal one by one of above-mentioned filter factor according to it.
The described orthogonal frequency-division multiplex signal receiving device of the third aspect is in first aspect, it is characterized in that:
Also have the output computation device that calculates and export the signal power of each subcarrier; And
Import the output of this output computation device, according to the step-length control device of its control and output step parameter,
Above-mentioned coefficient calculation means is imported the output of this step-length control device as above-mentioned step value, carries out the renewal one by one of above-mentioned filter factor according to it.
The described orthogonal frequency-division multiplex signal receiving device of fourth aspect is in the third aspect, it is characterized in that:
Above-mentioned output computation device is imported the output of above-mentioned Fourier lens arrangement, calculates and export the signal power of each subcarrier.
The described orthogonal frequency-division multiplex signal receiving device in the 5th aspect is in the third aspect, it is characterized in that:
Above-mentioned demodulating equipment is carrying out in the process of demodulation according to the transmission line property that each subcarrier is inferred, under the situation of calculating the physical quantity suitable with the average power of each subcarrier, and the above-mentioned output computation device of above-mentioned demodulating equipment double as,
Above-mentioned step parameter is controlled and exported to above-mentioned step-length control device input from the information of the above-mentioned average power of each subcarrier of expression of above-mentioned demodulating equipment output according to its.
The described orthogonal frequency-division multiplex signal receiving device in the 6th aspect is in first aspect, it is characterized in that:
Also have the output computation device that calculates and export the signal power of each subcarrier; And
Import the output of this output computation device, according to the reference control device of its control and output reference level value,
Above-mentioned coefficient calculation means import this with reference to the output of control device as above-mentioned step value, carry out the renewal one by one of above-mentioned filter factor according to it.
The described orthogonal frequency-division multiplex signal receiving device in the 7th aspect be aspect the 6th in, it is characterized in that:
Above-mentioned output computation device is imported the output of above-mentioned Fourier lens arrangement, calculates and export the signal power of each subcarrier.
The described orthogonal frequency-division multiplex signal receiving device of eight aspect be aspect the 6th in, it is characterized in that:
Above-mentioned demodulating equipment is carrying out in the process of demodulation according to the transmission line property that each subcarrier is inferred, under the situation of calculating the physical quantity suitable with the average power of each subcarrier, and the above-mentioned output computation device of above-mentioned demodulating equipment double as,
Above-mentioned reference value is controlled and exported to above-mentioned step-length control device input from the information of the above-mentioned average power of each subcarrier of expression of above-mentioned demodulating equipment output according to its.
Fig. 1 is the block diagram of the receiving system of expression example 1 of the present invention.
Fig. 2 is the block diagram of structure example of filtering portion 3 of the receiving system of expression example 1.
Fig. 3 is the block diagram of structure example of coefficient calculations portion 4 of the receiving system of expression example 1.
Fig. 4 is the block diagram of structure example of tap coefficient renewal portion 400 of the receiving system of expression example 1.
Fig. 5 is the block diagram of the receiving system of expression example 2 of the present invention.
Fig. 6 is the block diagram of the receiving system of expression example 3 of the present invention.
Fig. 7 is the block diagram of structure example of step-length control part 8 of the receiving system of expression example 3.
Fig. 8 is the block diagram of another structure example of step-length control part 8 of the receiving system of expression example 3.
Fig. 9 is the block diagram of the receiving system of expression example 4 of the present invention.
Figure 10 is the block diagram of structure example of synchronous modulation signal demodulation section 20 of the receiving system of expression example 4.
Figure 11 is the block diagram of the receiving system of expression example 5 of the present invention.
Figure 12 is the block diagram of structure example of reference control part 9 of the receiving system of expression example 5.
Figure 13 is the block diagram of another structure example of reference control part 9 of the receiving system of expression example 5.
Figure 14 is the block diagram of the receiving system of expression example 6 of the present invention.
Figure 15 is the block diagram of the existing receiving system of expression.
Example 1
Fig. 1 is the block diagram of the orthogonal frequency-division multiplex signal receiving device of expression example 1 of the present invention.In Fig. 1, the 1st, the signal transformation of transmitting according to the orthogonal frequency-division multiplex mode is become predetermined band and the input timing definition territory signal S as the signal of frequency regeneration and clock regeneration rAnd S iFFT portion, the 2nd, the demodulation section of the output of input filtering portion 3, the 3rd, input is as the filtering portion of the output of frequency domain signal I, the Q of the output of above-mentioned FFT portion 1 and coefficient calculations portion 4, the 4th, import the coefficient calculations portion of output, step value and the reference value of the output of this filtering portion 3, above-mentioned FFT portion 1, the output of above-mentioned demodulation section 2 is the playback of data of the numerical data that sends or the playback of data of error correction coding.In addition, in Fig. 1, C r, C iRepresent real part and imaginary part when output signal souvenir with coefficient calculations portion 4 pluralizes signal respectively, μ represents to be transfused to the step parameter in the coefficient calculations portion 4, R represents to be transfused to the reference level signal in the coefficient calculations portion 4, I ", Q " represent real part and imaginary part when output signal souvenir with filtering portion 3 pluralizes signal respectively.
Secondly, working condition is described.The domain of definition signal 1 input time S of FFT portion rAnd S i, counting according to the rules carried out exporting after the Fourier transform processing to it.Filtering portion 3 couples of frequency domain signal I, Q as the output of this FFT portion 1 are according to the filter factor C as the output of coefficient calculations portion 4 r, C iCarry out filtering.The output I of this filtering portion 3 ", Q " become the signal that inter-carrier interference component residual among frequency domain signal I, the Q is removed.Output, step value and the reference value of the output of these filtering portions 3 of input of coefficient calculations portion 4, above-mentioned FFT portion 1 are upgraded one by one and exports filter factor, so that reach minimum at inter-carrier interference component from the signal of filtering portion 3 outputs.In demodulation section 2, import the output of above-mentioned filtering portion 3, the demodulation method according to corresponding with various modulation systems carries out demodulation to each subcarrier.The output of this demodulation section 2 is the playback of data of the numerical data that is sent out or the playback of data of error correction coding, sends data according to its regeneration.
Secondly, as the structure example of filtering portion 3, Fig. 2 shows the block diagram of the complex filter of M type.In Fig. 2, the 300th, make input signal postpone the delay portion of certain hour, the 301st, with the multiply each other multiplier of back output of two input signals, 302 is first signal addition portions, its input is from the signal of multiplier 301 output of plural number, the signal that these multiplier 301 inputs have postponed it as the input signal I of filtering portion 3 or by delay portion 300 and as the filter factor C of the input signal of filtering portion 3 r, the 303rd, secondary signal addition portion, its input is from the signal of multiplier 301 output of plural number, the signal that these multiplier 301 inputs have postponed it as the input signal I of filtering portion 3 or by delay portion 300 and as the filter factor C of the input signal of filtering portion 3 i, 304 is the 3rd signal addition portions, its input is from the signal of multiplier 301 output of plural number, the signal that these multiplier 301 inputs have postponed it as the input signal Q of filtering portion 3 or by delay portion 300 and as the filter factor C of the input signal of filtering portion 3 r, 305 is the 4th signal addition portions, its input is from the signal of multiplier 301 output of plural number, the signal that these multiplier 301 inputs have postponed it as the input signal Q of filtering portion 3 or by delay portion 300 and as the filter factor C of the input signal of filtering portion 3 i, the 306th, the signal subtraction portion of the output of input first signal addition portion 302 and the 4th signal addition portion 305, the 307th, the 5th signal addition portion of the output of input secondary signal addition portion 303 and the 3rd signal addition portion 304.In addition, in Fig. 2, C R, mAnd C I, mRepresent coefficient C respectively rAnd C iM (m=0,1 ..., M-1) coefficient value of type.
Secondly, the working condition of complex filter shown in Figure 23 is described.The signal that the delay of inverse that delay portion 300 will be equivalent to the FFT sample rate of FFT portion 1 gives frequency domain signal I, Q and they have been postponed.In multiplier 301, with the output signal of delay portion 300 with corresponding to various types of multiplication and output.The signal that the input of the first signal addition portion 302 will have been postponed it as the input signal I of filtering portion 3 or by delay portion 300 by multiplier 301 and as the filter factor C of the input signal of filtering portion 3 rSignal after multiplying each other will be exported after their additions.The signal that secondary signal addition portion 303 input will have been postponed it as the input signal I of filtering portion 3 or by delay portion 300 by multiplier 301 and as the filter factor C of the input signal of filtering portion 3 iSignal after multiplying each other will be exported after their additions.The signal that the input of the 3rd signal addition portion 304 will have been postponed it as the input signal Q of filtering portion 3 or by delay portion 300 by multiplier 301 and as the filter factor C of the input signal of filtering portion 3 rSignal after multiplying each other will be exported after their additions.The signal that the input of the 3rd signal addition portion 305 will have been postponed it as the input signal Q of filtering portion 3 or by delay portion 300 by multiplier 301 and as the filter factor C of the input signal of filtering portion 3 iSignal after multiplying each other will be exported after their additions.Signal subtraction portion 306 exports deduct the output of the 4th signal addition portion 305 from the output of the first signal addition portion 302 after.Export after the output addition of the 5th signal addition portion 307 with the output of secondary signal addition portion 303 and the 3rd signal addition portion 304.The output signal of the 5th signal addition portion 307 becomes the output signal Q of filtering portion 3 ", the output signal of above-mentioned signal subtraction portion 306 becomes the output signal I of filtering portion 3 ".At the signal from 4 outputs of FFT portion 1 and coefficient calculations portion is under the situation of complex signal by souvenir, and filter shown in Figure 2 is nothing but I " and Q " the FIR type complex filter of the M type of the real part of the complex signal that is output and imaginary part become.
Secondly, coefficient calculations portion 4 is described.In coefficient calculations portion 4, according to the output of FFT portion 1, filtering portion 3, in order to remove the inter-carrier interference component that comprises among frequency domain signal I, the Q, and the calculating optimum filter factor is exported to filtering portion 3.
Here, interference between the carrier wave in the signal of orthogonal frequency-division multiplex transmission is described.In the orthogonal frequency-division multiplex transmission means, because the skew between the transmitting-receiving of carrier frequency, and in the restituted signal that receiver side obtains, produce interference between the carrier wave, become the reason of receptivity deterioration.This frequency shift (FS) is because the residual frequency error that the synchronizing regeneration circuit of receiving system produces or the phase noise of tuner etc. cause, and the error rate when receiving increases and decreases along with the difference of situation.Represent that with formula 1 transmission line is the orthogonal frequency-division multiplex signal of the Ideal Transmission Line road equivalent low frequency system of having ignored noise.[formula 1] r ( t ) = Re [ Σ i = - ∞ ∞ Σ k = 0 N - 1 S k , i exp [ j 2 πk ( t - iT s ) t s ] f c ( t - iT s ) ]
In the formula, S K, iBe in the orthogonal frequency-division multiplex signal with the transmission complex data of k subcarrier transmission in first symbol, T sBe the symbol period that comprises guard interval, t sBe the symbol period of having removed guard interval, N is total number of sub.In addition, the length setting with guard interval is t s, f then cIt is the function of representing with formula 2.[formula 2] f c ( t ) = { 0 : otherwise 1 : - t g ≤ t ≤ t s
In receiving system, r (t) is carried out Fourier transform, each subcarrier of demodulation realizes sending the regeneration of data.At this moment, suppose to exist the error delta f of carrier frequency between transceiver, then the output of the Fourier transform of m subcarrier of i symbol as shown in Equation 3.[formula 3] x m , i = 1 t s ∫ iT s iT s + t s r ( t ) exp [ - j 2 π ( f m + δf ) ( t - iT s ) ] dt
In the formula, f mBe m original subcarrier frequency.With formula 1 substitution formula 3, then can obtain formula 4.[formula 4] x m , i = S m , i sin c ( δf t s ) exp [ - jπ δft s ] + Σ k = 0 , k ≠ m N - 1 S k , i exp [ jπ ( k - m - δft s ) ] sin c [ ( k - m - δft s ) ]
In the formula, sinc (x) is the decreasing function of representing with formula 5.[formula 5] sin c ( x ) = sin ( πx ) πx
In formula 4, first expression be with the signal component of m subcarrier transmission, the interference component between second expression carrier wave.From formula 4 as can be known, the interference component between the carrier wave has increased gain and the phase place rotation that is determined by the frequency interval with the subcarrier that is equivalent to principal component, the signal of their expression linear, additive with respect to each subcarrier.Therefore,, carry out linear signal with linear filters such as complex filters and handle, can remove the interference component between the carrier wave by to the frequency domain signal behind the Fourier transform.
In order to remove the interference component between the carrier wave, need make the coefficient optimization of complex filter, so that the interference component between the carrier wave in the complex filter output becomes minimum.This can upgrade filter coefficient and realize one by one by for example utilizing steepest descent method.Therefore, in coefficient update portion 4, the filter factor of filtering portion 3 is calculated and exported to the appropriate algorithm that the usage factor optimization is used one by one.
Secondly, coefficient update method when using CMA (Constant Modulus Algorithm) in the appropriate algorithm of coefficient update portion 4 uses be described.In CMA, upgrade filter factor one by one, so that the quadratic power mean error of the output signal of filter and its ideal signal reaches minimum.I tap coefficient C during moment n I, nMore as shown in Equation 6 new-type.[formula 6] C L, n+1=C L, n-μ (| y n| 2-R) y nx * I, n
In the formula, x I, nI tap input signal when being moment n, y nFilter output when being moment n, μ is a step parameter, and R is a reference level signal, and * represents conjugate complex number.The ideal signal of filter output was a when in addition, R was moment n nThe time constant represented with formula 7.[formula 7] R = E [ | a u | 1 ] E [ | a R | 2 ]
Secondly,, the appropriate algorithm of using as the coefficient optimization has been shown in Fig. 3 and Fig. 4, the block diagram when adopting the CMA algorithm as the structure example of coefficient calculations portion 4.In Fig. 3, the 400th, input is as the frequency domain signal of the input signal of filtering portion 3 or by the tap coefficient renewal portion of delay portion 401 in the coefficient calculations portion with output signal, reference level signal and the step parameter of its signal that has postponed, filtering portion 3, and the 401st, input is as the frequency domain signal of the input signal of filtering portion 3 or with delay portion in the coefficient calculations portion of its signal that has postponed.
In addition, in Fig. 3, x is as the complex signal souvenir of the frequency domain signal of the output of FFT portion 1, represents with formula 8.
[formula 8]
x=I+jQ
In addition, in Fig. 3, y is the complex signal souvenir of the output signal of filtering portion 3, represents with formula 9.
[formula 9]
y=I”+jQ”
In addition, C mBe filtering portion 3 m (m=0,1 ..., M-1) the complex signal souvenir of individual tap coefficient.
In Fig. 4, the 4000th, input is as the frequency domain signal of the input signal of filtering portion 3 or by the complex conjugate portion of delay portion 401 in the coefficient calculations portion with its signal that has postponed, the 4001st, import the complex multiplication portion of the output of the output of this complex conjugate portion 4000 and filtering portion 3, the 4002nd, the power calculation portion of the output of input filtering portion 3, the 4003rd, import the output of this power calculation portion 4002 and first subtraction portion of reference level signal, the 4004th, import the output of this first subtraction portion 4003 and first multiplier of step parameter, the 4005th, import second multiplier of the output of this first multiplier 4004 and above-mentioned complex multiplication portion 4001, the 4006th, import second subtraction portion of the output of this second multiplier 4005 and delay portion 4007, the 4007th, import the delay portion of the output of this second subtraction portion 4006, the output of this delay portion 4007 is the output of tap coefficient renewal portion 400 and is the output of coefficient calculations portion 4 simultaneously.
Secondly, working condition is described.Tap coefficient renewal portion 400 input as the frequency domain signal of the input signal of filtering portion 3 or by delay portion 401 in the coefficient calculations portion with its signal that has postponed, output signal, reference level signal and the step parameter of filtering portion 3, upgrade one by one and export, so that the filter factor optimization of each tap of filtering portion 3.Delay portion 401 input is as the frequency domain signal of the input signal of filtering portion 3 or with the signal that it has postponed in the coefficient calculations portion, is equivalent to the delay of inverse of the FFT sampling rate of FFT portion 1.
Secondly, the working condition of tap coefficient renewal portion 400 is described with Fig. 4.4000 outputs of complex conjugate portion are with respect to the complex signal of the complex signal conjugation of input.Complex multiplication portion 4001 imports the output of these complex conjugate portions 4000 and the output of filtering portion 3, output after these complex signals are multiplied each other.The output of 4002 input filtering portions 3 of power calculation portion, the quadratic power value and the output of calculating the amplitude of this complex signal.In first subtraction portion 4003, deduct reference level signal and output from the output of this power calculation portion 4002.In first multiplier 4004, with the back output of multiplying each other of the output of this first subtraction portion 4003 and step parameter.The output of this first multiplier 4004 becomes scalar value.Second multiplier 4005 is exported after the scalar value of the output of this first multiplier 4004 be multiply by complex signal as the output of above-mentioned complex multiplication portion 4001.Second subtraction portion 4006 is exported deduct the output of this second multiplier 4005 from the output of delay portion 4007 after.The output of delay portion 4007 these second subtraction portion 4006 of input is equivalent to the delay of inverse of the FFT sampling rate of FFT portion 1.
Owing to as above constitute coefficient calculations portion 4, can utilize the optimization device of realizing filter factor by the CMA of formula 6 expressions.
In addition, in the structure example of coefficient update portion 4 shown in Figure 3, though will import signal after the frequency domain signal delay of tap coefficient renewal portion 400 as the output signal of delay portion 401 in the coefficient calculations portion, but also can replace like this, i.e. input is as the output signal of the delay portion 300 in the filtering portion 3 of the signal equivalent with it.
In addition, though with CMA is that example shows the appropriate algorithm that the coefficient optimization is used, also can adopt LMS (Least Mean Squares) algorithm or RLS (Recursive Least Squares) algorithm except DD (Decision Directed) algorithm, DAMA (Decision AdjustedModulus Algorithm) etc.
As mentioned above, because the frequency domain signal as Fourier transform output is carried out filtering, as this filter factor, can utilize appropriate algorithm to calculate the coefficient that to remove the interference component between the carrier wave, separate interference between the carrier wave of timing so can reduce signal, can reduce the wrong probability of happening of playback of data.
In addition, owing to adopt the optimized algorithm of appropriate algorithm as filter factor, so can suitably follow the tracks of the variation of the interference situation between the carrier wave.
Example 2
In above example 1, when carrying out the optimization of filter factor, though coefficient calculation means is carried out identical work to whole sub-carrier information, the following control carrier signal example that carries out specific work that will provide to regulation.
Fig. 5 is the block diagram of the orthogonal frequency-division multiplex signal receiving device of expression example 2 of the present invention.In Fig. 5,1～4 identical with shown in the example 1.But the step-size parameter mu that is transfused in the coefficient calculations portion 4 is the output of step-length control part 6.The 5th, control timing signal generating unit, the 6th, import the step-length control part that this controls the output of timing signal generating unit 5.
Secondly, working condition is described.The work of FFT portion 1, demodulation section 2, filtering portion 3 and coefficient calculations portion 4 identical with shown in the example 1.Undertaken under the situation of signal transmission by orthogonal frequency-division multiplex transmission, its purpose is for example to improve the net synchronization capability of receiving system sometimes, with a plurality of particular subcarriers as the control carrier signal.At this moment, in receiving system, the transmission data of control carrier signal are known, so when asking filter factor in coefficient calculations portion 4, compare the faster and optimization that can seek coefficient accurately of speed with the situation of using other subcarriers.Therefore, in example 2,, compare, can increase the size of step parameter, overlapping when can control coefrficient upgrading with situation in addition for the control carrier signal.For this reason, whether 5 outputs of control timing signal generating unit are signals of control carrier signal in order to the output signal of identification filtering portion 3.In addition, in step-length control part 6, output and the corresponding step parameter of exporting from this control timing signal generating unit 5 of control timing signal.For example, represent that at the control timing signal output of filtering portion 3 is under the situation of control carrier signal, as step parameter, the big value of value of output ratio situation in addition.
In addition, in step-length control part 6, except control timing signal represent the output of filtering portion 3 be control carrier signal situation, the value that also can make step parameter is 0.
As mentioned above,, can increase step parameter during coefficient update, so the filter factor the interference of removing between the carrier wave can be tried to achieve at high speed the time owing to, compare with situation in addition for the control carrier signal.
In addition, owing to use the information of using when controlling carrier signal, remove device so can realize the higher inter-carrier interference of precision as coefficient update.
Example 3
In above example 2, though the step parameter in the time switching update coefficients with control carrier signal and carrier wave in addition, the following example that will provide according to the power level control step parameter of frequency domain signal.
Fig. 6 is the block diagram of the orthogonal frequency-division multiplex signal receiving device of expression example 3 of the present invention.In Fig. 6,1～4 identical with shown in the example 1.But the step-size parameter mu that is transfused in the coefficient calculations portion 4 is the output of step-length control part 8.The 7th, the power calculation portion of the output of input FFT portion 1, the 8th, import the step-length control part of the output of this power calculation portion 7.In addition, in Fig. 6, P is the output of power calculation portion 7, represents the instantaneous power signal of each subcarrier.
Secondly, working condition is described.The work of FFT portion 1, demodulation section 2, filtering portion 3 and coefficient calculations portion 4 identical with shown in the example 1.The signal of orthogonal frequency-division multiplex transmission is under the situation of multipath transmission, and each subcarrier of reception is decayed along with the difference of transmission path or amplified.In the case, in the subcarrier of subcarrier of decaying and amplification, signal power is to the noise power ratio difference, a side who is exaggerated does not allow to be subject to The noise, information reliability height during as coefficient update, the carrier wave of decay is subjected to The noise big, and the reliability of the information during as coefficient update is low.Therefore, control like this: calculate the signal power of each subcarrier,, the little subcarrier of power is reduced the value of step parameter the value of high-power subcarrier increase step parameter.In power calculation portion 7, import the output of FFT portion 1, calculate and export the power of each subcarrier.The output of step-length control part 8 these power calculation portions 7 of input, according to the power level of input, control and output step parameter.
Here, as the structure example of step-length control part 8, illustrated among Fig. 7 according to the output of power calculation portion 7 and selected and the such structured flowchart of output step parameter.In Fig. 7, the 800th, input is selected the signal generating unit as the step-length of the power information of the output of power calculation portion 7, the 801st, import that this step-length is selected the output of signal generating unit 800 and as the step-length selection portion of the step parameter candidate value that is plural number of the mutually different real constant of numerical value, the output of this step-length selection portion 801 is the output of step-length control part 8, is step parameter.In addition, in Fig. 7, μ k(k=1,2 ..., K) expression step parameter candidate value.
Secondly, working condition is described.Step-length selects signal generating unit 800 that the size of the power information of input is divided into K grade, and its result is selected signal output as step-length.At this moment, classify like this: power is big more, selects big value more as step parameter.In step-length selection portion 801, according to the signal of selecting 800 inputs of signal generating unit from step-length, select in K the step parameter candidate value, export the step parameter corresponding with the output of filtering portion 3.
Secondly,, transforming function transformation function according to the rules has been shown among Fig. 8, the output level of power calculation portion 7 is transformed into step parameter and exports such structured flowchart as another structure example of step-length control part 8.In Fig. 8, the 802nd, input is as the step-length map table portion of the power information of the output of power calculation portion 7, and the output of this step-length map table portion 802 is the output of step-length control part 8, is step parameter.
Secondly, working condition is described.Step-length map table portion 802 transforming function transformation function according to the rules is transformed into step parameter with the power level of importing, and exports the step parameter corresponding with the output of filtering portion 3.
For example, the example of formula 10 expression transforming function transformation functions.In formula 10, P represents power level, and α represents real constant.
[formula 10]
μ=αP
In addition, the example of formula 11 another transforming function transformation functions of expression.In formula 11, P represents power level, and β, γ represent positive real constant.
[formula 11] μ = β γP
If utilize formula 10 or formula 11 to carry out conversion, then power is big more, and step parameter is also big more.
As mentioned above, owing to constitute like this, promptly according to the watt level of subcarrier, the step parameter that uses when can control coefrficient upgrading is so also can suitably remove interference between the carrier wave to the orthogonal frequency-division multiplex signal that influenced by multipath.In addition, owing to output signal calculated power,, therefore can have the ground of hysteresis and do not carry out the renewal one by one of filter factor so can promptly carry out power calculation according to FFT portion 1.
Example 4
In above example 3, though the instantaneous power of calculating each subcarrier as power information, and according to it control step parameter, the following average power information that will provide according to the transmission channel of each subcarrier, control step parameter example.
Fig. 9 is the block diagram of the orthogonal frequency-division multiplex signal receiving device of expression example 4 of the present invention.In Fig. 9,1,3,4,8 identical with shown in example 1 and the example 3.But the input signal of step-length control part 8 is the average power signals from 20 outputs of synchronous modulation signal demodulation section.In addition, the 20th, the synchronous modulation signal demodulation section of the output of input filtering portion 3, the output of this synchronous modulation signal demodulation section 20 is the playback of data of the numerical data that sends or the playback of data behind the error correction coding.In addition, in Fig. 9, P ' expression average power signal.
Secondly, working condition is described.In Fig. 9, the work of FFT portion 1, filtering portion 3, coefficient calculations portion 4 and step-length control part 8 identical with shown in example 1 and the example 3.Modulation system as each subcarrier of orthogonal frequency-division multiplex transmission, when adopting QPSK (QuadraturePhase Shift Keying) or QAM (Quadrature AmplitudeModulation), mostly adopt and separate the control carrier signal of calling, signal demodulation in this case for example can realize with synchronous modulation signal demodulation section 20 such devices shown in Figure 10.In synchronous modulation signal demodulation section 20 shown in Figure 9, in the time of with the demodulation of the subcarrier that carries out above-mentioned modulation system, the average power information of each subcarrier that output is tried to achieve in its process.In step-length control part 8, importing this average power information is average power signal P ', the control step parameter.
Here, with Figure 10 synchronous modulation signal demodulation section 20 is described.In Figure 10, the 200th, input is as the I of the output of filtering portion 3 " and Q " synchronous demodulation with control carrier signal demodulation section, the 201st, import the transmission channel deduction portion of this synchronous demodulation with the output of control carrier signal demodulation section 200, the 202nd, import the complex conjugate portion of the output of this transmission channel deduction portion 201, the 203rd, input is as the I of the output of filtering portion 3 " and Q " delay portion, the 204th, import the complex multiplication portion of the output of this delay portion 203 and above-mentioned complex conjugate portion 202, the 205th, import the power calculation portion of the output of above-mentioned transmission channel deduction portion 201, the 206th, import the division portion of the output of this power calculation portion 205 and above-mentioned complex multiplication portion 204, the output of this multiplier 206 is the playback of data of the numerical data that sends during as the output of synchronous modulation signal demodulation section 20 or the playback of data of error correction coding, average power signal P ' when in addition, the output of above-mentioned power calculation portion 205 is output as synchronous modulation signal demodulation section 20.
Secondly, working condition is described.Synchronous demodulation is with the I of control carrier signal demodulation section 200 inputs as the output of filtering portion 3 " and Q ", extract the control carrier signal that the synchronous demodulation that wherein comprises is used out, it is exported after divided by the known signal corresponding with it.This synchronous demodulation becomes the signal of the transmission characteristic of the transmission channel of representing respectively to control carrier signal with the output of control carrier signal demodulation section 200.In transmission channel deduction portion 201, import the output of this synchronous demodulation with control carrier signal demodulation section 200, by carrying out the interpolation of time orientation and frequency direction, infer and export the transmission channel characteristic of whole subcarriers.Its complex conjugate signal is exported in the output of 202 these transmission channel deduction portions 201 of input of complex conjugate portion.Delay portion 203 makes the I as the output of filtering portion 3 " and Q " postpone, this delays with above-mentioned synchronous demodulation with control carrier signal demodulation section 200 and above-mentioned transmission channel deduction portion 201 in the delay of generation be equal to, and export.Therefore, become corresponding to signal from the signal of above-mentioned complex conjugate portion 202 outputs from the subcarrier of these delay portion 203 outputs.In complex multiplication portion 204, import the output of this delay portion 203 and above-mentioned complex conjugate portion 202, they are carried out exporting behind the complex multiplication operation.The output of the above-mentioned transmission channel deduction of 205 inputs portion of power calculation portion 201, the quadratic power value and the output of calculating the amplitude of these complex signals.In division portion 206, with the output of above-mentioned complex multiplication portion 204 divided by the scalar value and the output of calculating by this power calculation portion 205.Therefore, the complex signal that obtains as the output of this division portion 206 becomes the playback of data of numerical data of transmission or the playback of data behind the error correction coding.In addition, the output of above-mentioned power calculation portion 205 becomes the average power information of each subcarrier.
Therefore, separating timing, can in this demodulating process, obtain the average power information of each subcarrier of transmission channel to be equal to the subcarrier that step system mode modulates according to QPSK or QAM.Therefore, in example 4, as shown in Figure 9, and according to the average power signal P ' of such acquisition, the control step parameter.And also described identical with example 3 even in this case, power is big more, makes step parameter also big more.
As mentioned above, owing to constitute like this, can be according to the average power of the transmission channel of each subcarrier, the step parameter that uses when control coefrficient upgrades, so do not change the signal level that sends data, just can suitably remove interference between the carrier wave to the orthogonal frequency-division multiplex signal that influenced by multipath.In addition, because the power calculation function that can utilize demodulation section 20 to have originally, so, do not need to increase newly circuit for rated output.
Example 5
In example 3, the instantaneous power of calculating each subcarrier is controlled step parameter as power information according to it, but following will providing according to this instantaneous power information, the example of the reference level signal of using when control coefrficient upgrades.
Figure 11 is the block diagram of the orthogonal frequency-division multiplex signal receiving device of expression example 5 of the present invention.In Figure 11,1～4,7 identical with shown in the example 3.But in coefficient calculations portion 4, the fixing step value of input is as step parameter, uses output with reference to control part 9 as the reference level signal.The 9th, the reference control part of the output of input power calculating part 7.
Secondly, working condition is described.The work of FFT portion 1, demodulation section 2, filtering portion 3, coefficient calculations portion 4 and power calculation portion 7 identical with shown in the example 3.The signal of orthogonal frequency-division multiplex transmission is under the situation of multipath transmission, and each subcarrier of reception is decayed along with the difference of transmission path or amplified.In the case, when even the interference between the carrier wave does not take place, the signal level of each subcarrier in the frequency domain signal also changes in each subcarrier, so according to this point, the value of the reference level signal R that uses in the time of can thinking coefficient update and its change accordingly.Therefore, in reference control part 9,, select and the output reference value according to instantaneous power signal P from 7 outputs of power calculation portion.
Here,, the output according to power calculation portion 7 has been shown among Figure 12, has selected and the such block diagram that constitutes of output reference level signal as the structure example of reference control part 9.In Figure 12, the 900th, input is selected the signal generating unit as the reference value of the power information of the output of power calculation portion 7, the 901st, import output and the mutually different a plurality of reference value selection portions of numerical value that this reference value is selected signal generating unit 900 with reference to candidate value as real constant, the output of this reference value selection portion 901 is the output with reference to control part 9, is reference level signal.In addition, in Figure 12, R k(k=1,2 ..., K) expression with reference to candidate value.
Secondly, working condition is described.Reference value selects signal generating unit 900 that the size of the power information of input is divided into K grade, and its result is selected signal output as the reference value.At this moment, classify like this: power is big more, selects big value more as the reference level signal.In reference value selection portion 901, according to the signal of selecting 900 inputs of signal generating unit from reference value, select K with reference to one in the candidate value, export output corresponding reference level signal with filtering portion 3.
Secondly,, transforming function transformation function according to the rules has been shown among Figure 13, the output level of power calculation portion 7 is transformed into reference level signal and exports such structured flowchart as another structure example of reference control part 9.In Figure 13, the 902nd, input is as the reference value map table portion of the power information of the output of power calculation portion 7, and the output of this reference value map table portion 902 is the output with reference to control part 9, is reference level signal.
Secondly, working condition is described.Reference value map table portion 902 transforming function transformation function according to the rules is transformed into reference level with the power level of importing, the output corresponding reference level signal of output and filtering portion 3.
For example, the example of formula 12 expression transforming function transformation functions.In formula 12, P is a power level, η and R 0Be positive real constant, putative signal is consistent with the right of formula 7 by the right of desirable transmission channel transmission up-to-date style 12
[formula 12]
R=ηP+R 0
If carry out conversion with formula 12, then power is big more, and reference level is also big more.
As mentioned above, owing to constitute like this, can be according to the power of each subcarrier, the reference level signal of using when control coefrficient upgrades is so can suitably remove interference between the carrier wave to the orthogonal frequency-division multiplex signal that influenced by multipath.In addition, owing to output signal calculated power,, therefore can have the ground of hysteresis and do not carry out the renewal one by one of filter factor so can promptly carry out power calculation according to FFT portion 1.
Example 6
In above example 5, though the instantaneous power of calculating each subcarrier is as power information, and according to its control reference level signal, but the following average power information that will provide according to the transmission channel of each subcarrier, the example of control reference level signal.
Figure 14 is the block diagram of the orthogonal frequency-division multiplex signal receiving device of expression example 6 of the present invention.In Figure 14,1,3,4,9,20 identical with shown in example 1, example 4 and the example 5.But the input signal to reference control part 9 is the average power signal of exporting from synchronous modulation signal demodulation section 20.
Secondly, working condition is described.In Figure 14, FFT portion 1, filtering portion 3, coefficient calculations portion 4, identical with reference to shown in work and example 1, example 4 and the example 5 of control part 9 and demodulation section 20.As the modulation system of each subcarrier of orthogonal frequency-division multiplex transmission, when adopting QPSK or QAM, the demodulation of signal can realize with synchronous modulation signal demodulation section 20 such devices, so can obtain the average power information of each subcarrier thus.Therefore, as the input signal of reference control part 9, using its average power information is average power signal P ', the control reference level signal.And also described identical with example 5 in the case, power is big more, makes reference level also big more.
As mentioned above, since constitute like this, can be according to the average power of each subcarrier, the reference level signal of using when control coefrficient upgrades, so do not change the signal level that sends data, just can suitably remove interference between the carrier wave to the orthogonal frequency-division multiplex signal that influenced by multipath.In addition, because the power calculation function that can utilize demodulation section 20 to have originally, so, do not need to increase newly circuit for rated output.
If employing a first aspect of the present invention is then because to the frequency as Fourier transform output Domain of definition signal carries out filtering, as its filter factor, can utilize suitable algorithm calculate carrier wave it Between the coefficient that can remove of interference component, so have doing between the carrier wave that reduces signal solution timing Relate to, reduce the effect of the wrong probability of happening of playback of data.
In addition, owing to adopt suitable algorithm as the optimized algorithm of filter factor, so have Can suitably follow the tracks of the effect of the variation of the interference situation between the carrier wave.
If whether employing a second aspect of the present invention is then owing to according to being the control carrier signal, control The step parameter that uses during coefficient update processed is removed inter-carrier interference so have to try to achieve at high speed The time the effect of filter factor.
In addition, owing to adopt the information of using when controlling carrier signal as coefficient update, so tool The effect that can realize that the higher inter-carrier interference of precision is removed device is arranged.
If employing a third aspect of the present invention is then owing to can according to the power of subcarrier, control system The step parameter that uses when number upgrades can be to the orthogonal frequency-division multiplex that affected by multi-path so have Signal is suitably removed the effect of the interference between the carrier wave.
If employing a fourth aspect of the present invention is then owing to the output meter according to Fourier transform device Calculate signal power, so can promptly carry out the calculating of power, therefore can not have the ground of hysteresis and carry out filtering The one by one renewal of coefficient.
If employing a fifth aspect of the present invention is then because the merit that can utilize demodulating equipment originally to have The rate computing function is not so for rated output, need to increase newly circuit. In addition, owing to use Average power so do not change the signal level that sends data, just can stably carry out filtering system The one by one renewal of number.
If employing a sixth aspect of the present invention is then owing to can according to the power of subcarrier, control system The reference level signal of using when number upgrades can be to the orthogonal frequency division that affected by multi-path so have Multiple signals are suitably removed the effect of the interference between the carrier wave.
If employing a seventh aspect of the present invention is then owing to the output meter according to Fourier transform device Calculate signal power, so can promptly carry out the calculating of power, therefore can not have the ground of hysteresis and carry out filtering The one by one renewal of coefficient.
If employing a eighth aspect of the present invention is then because the merit that can utilize demodulating equipment originally to have The rate computing function is not so for rated output, need to increase newly circuit. In addition, owing to use Average power so do not change the signal level that sends data, just can stably carry out filtering system The one by one renewal of number.

Claims (8)

1. orthogonal frequency-division multiplex signal receiving device, it is according to the orthogonal frequency-division multiplex signal, regeneration sends the orthogonal frequency-division multiplex signal receiving device of data, it is characterized in that, has:
The timing definition territory signal transformation that receives is become the Fourier transform device of frequency domain signal;
Coefficient calculation means;
Import the output of above-mentioned Fourier transform device and the output of above-mentioned coefficient calculation means, the filter that carries out filtering according to filter factor from the output of above-mentioned coefficient calculation means; And
Import the output of above-mentioned filter, the demodulating equipment that subcarrier is carried out demodulation according to the demodulation method corresponding with various modulation systems,
Above-mentioned coefficient calculation means is imported output, step value and the reference value of the output of above-mentioned filter, above-mentioned Fourier transform device, from the signal of above-mentioned filter output, suitably upgrade one by one and export filter factor, so that the interference between the carrier wave is minimum.
2. orthogonal frequency-division multiplex signal receiving device according to claim 1 is characterized in that also having:
Whether the output signal of output identification Fourier lens arrangement is the control timing signal generator of the timing signal of control carrier signal; And
Import the output of this control timing signal generator, export the step-length control device of the step parameter corresponding with timing signal,
Above-mentioned coefficient calculation means is imported the output of this step-length control device as above-mentioned step value, carries out the renewal one by one of above-mentioned filter factor according to it.
3. orthogonal frequency-division multiplex signal receiving device according to claim 1 is characterized in that also having:
Calculate and export the output computation device of the signal power of each subcarrier; And
Import the output of this output computation device, according to the step-length control device of its control and output step parameter,
Above-mentioned coefficient calculation means is imported the output of this step-length control device as above-mentioned step value, carries out the renewal one by one of above-mentioned filter factor according to it.
4. orthogonal frequency-division multiplex signal receiving device according to claim 3 is characterized in that:
Above-mentioned output computation device is imported the output of above-mentioned Fourier lens arrangement, calculates and export the signal power of each subcarrier.
5. orthogonal frequency-division multiplex signal receiving device according to claim 3 is characterized in that:
Above-mentioned demodulating equipment is carrying out in the process of demodulation according to the transmission line property that each subcarrier is inferred, under the situation of calculating the physical quantity suitable with the average power of each subcarrier, and the above-mentioned output computation device of above-mentioned demodulating equipment double as,
Above-mentioned step parameter is controlled and exported to above-mentioned step-length control device input from the information of the above-mentioned average power of each subcarrier of expression of above-mentioned demodulating equipment output according to its.
6. orthogonal frequency-division multiplex signal receiving device according to claim 1 is characterized in that also having:
Calculate and export the output computation device of the signal power of each subcarrier; And
Import the output of this output computation device, according to the reference control device of its control and output reference level value,
Above-mentioned coefficient calculation means import this with reference to the output of control device as above-mentioned reference value, carry out the renewal one by one of above-mentioned filter factor according to it.
7. orthogonal frequency-division multiplex signal receiving device according to claim 6 is characterized in that:
Above-mentioned output computation device is imported the output of above-mentioned Fourier lens arrangement, calculates and export the signal power of each subcarrier.
8. orthogonal frequency-division multiplex signal receiving device according to claim 6 is characterized in that:
Above-mentioned demodulating equipment is carrying out in the process of demodulation according to the transmission line property that each subcarrier is inferred, under the situation of calculating the physical quantity suitable with the average power of each subcarrier, and the above-mentioned output computation device of above-mentioned demodulating equipment double as,
Above-mentioned reference value is controlled and exported to above-mentioned step-length control device input from the information of the above-mentioned average power of each subcarrier of expression of above-mentioned demodulating equipment output according to its.
CN 01117184 2000-04-25 2001-04-25 Orthogonal frequency-division multiplex signal receiving device Pending CN1321014A (en)

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