CN101521652B - Reception apparatus and reception method - Google Patents

Reception apparatus and reception method Download PDF

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Publication number
CN101521652B
CN101521652B CN 200910118314 CN200910118314A CN101521652B CN 101521652 B CN101521652 B CN 101521652B CN 200910118314 CN200910118314 CN 200910118314 CN 200910118314 A CN200910118314 A CN 200910118314A CN 101521652 B CN101521652 B CN 101521652B
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transmission line
signal
frequency
circuit
interpolation
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CN101521652A (en
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川内豪纪
弓场廷昭
宫内俊之
横川峰志
冈本卓也
池田保
难波田康治
清水和洋
拉赫兰·布鲁斯·迈克尔
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Sony Corp
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Sony Corp
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Abstract

The present invention relates to a reception apparatus, a reception method and program thereof.A reception apparatus including an extraction section; a transmission line characteristic estimation section; an interpolation section; a compensation section; a detection section; and a selection section.

Description

Receiving equipment and method of reseptance
Technical field
The present invention relates to receiving equipment, method of reseptance and program.
Background technology
As one of modulator approach of earthwave (ground wave) digital broadcasting, proposed OFDM (OFDM) method, a large amount of quadrature carriers is used and by phase shift keying (PSK) or quadrature amplitude modulation (QAM) and modulated in the method.
A characteristic of OFDM method is: because whole transmission wave band is divided into a large amount of subcarriers, so the bandwidth of each subcarrier is narrower, although the transmission speed of each subcarrier is lower, total transmission speed equals the transmission speed of existing modulator approach.
Another characteristic of OFDM is: because a large amount of subcarrier of parallel transmission, so symbol rate is lower.Therefore, can reduce with a symbol the time long correlation the multipath duration.As a result, the OFDM method has the characteristic of the impact that can reduce multipath.
In addition, another characteristic of OFDM is: because data are assigned to a plurality of subcarriers, so can use contrary fast fourier transform (IFFT) the mathematical operation circuit of when modulation, carrying out inverse Fourier transform to configure transtation mission circuit, and can use fast fourier transform (FFT) the mathematical operation circuit at solution timing execution Fourier transform to configure receiving circuit.
Because above-mentioned these characteristics, the OFDM method by frequent application in the ground wave digital broadcasting that is subjected to multipath disturbance appreciable impact.Standard as the ground wave digital broadcasting that has adopted the OFDM method, for example, DVB-T (digital video broadcast-terrestrial), ISDB-T (integrated service DTB Digital Terrestrial Broadcasting) and ISDB-TSB (the integrated service DTB Digital Terrestrial Broadcasting that is used for sound radio) are arranged.
Fig. 1 shows the OFDM symbol.
According to the OFDM method, signal transmission is to carry out in the unit that is called the OFDM symbol.
Comprise a significant character and a protection interval with reference to 1, one OFDM symbol of figure, this significant character has the sigtnal interval that is performed IFFT when sending, and has copied the waveform of the part of significant character in the protection interval.Position before time shaft protection interval is inserted into significant character.
By insert protection interval, the interference between the OFDM symbol that the OFDM method can prevent from occuring in multi-path environment.
A plurality of this OFDM symbols are brought together to form an OFDM and send frame.For example, according to the ISDB-T standard, an OFDM frame is formed by 204 OFDM symbols.The insertion position of pilot signal is to determine with reference to the unit of OFDM transmission frame.
QAM type modulator approach is used as can being subject to when sending for the OFDM method of the modulator approach of subcarrier the interference of multipath etc.As a result, for each subcarrier, amplitude and phase place become different when sending when receiving.Therefore, the necessary executive signal of recipient is balanced, so that it is identical with amplitude and the phase place of transmitted signal with the phase potential energy to receive the amplitude of signal.
In the OFDM method, transmit leg is inserted into the pilot signal of predetermined amplitude and predetermined phase in the transmission symbol discretely.The frequency characteristic that the recipient determines transmission line based on amplitude and the phase place of pilot signal, and come the balanced reception signal based on the characteristic of determined transmission line.
The pilot signal that is used for calculating in this way transmission line property is known as disperses pilot signal (hereinafter being called the SP signal).Pattern of rows and columns of SP signal in the OFDM symbol that show Fig. 2 DVB-T standard or ISDB-T standard adopt.
Fig. 3 shows the block diagram of the example of the configuration that has the OFDM receiver now.
With reference to figure 3, shown in OFDM receiver 100 comprise that reception antenna 1, tuner 2, analog/digital (A/D) change-over circuit 3, orthogonal demodulation circuit 4, carrier wave produce circuit 5, fft circuit 6 and FFT interval control circuit 7.OFDM receiver 100 also comprises transmission line Distoriton compensating circuit 8, error correction circuit 9, postpones overview estimating circuit 10 and frequency interpolation filter selection circuit 11.
Tuner 2 converts the RF signal frequency that reception antenna 1 receives to the IF signal, and this IF signal is outputed to A/D change-over circuit 3.
3 pairs of A/D change-over circuits are carried out the A/D conversion from the IF signal that tuner 2 offers it, and the digital IF signal that will produce outputs to orthogonal demodulation circuit 4.
Orthogonal demodulation circuit 4 utilizes and produces carrier wave that circuit 5 offers it from carrier wave and carry out quadrature demodulation the IF signal acquisition baseband OFDM signal that comes from providing from A/D change-over circuit 3 is provided, and the ofdm signal that obtains of output.This baseband OFDM signal is to carry out FFT mathematical operation time-domain signal before.
In the following description, be called the OFDM time-domain signal with carrying out FFT mathematical operation baseband OFDM signal before.This OFDM time-domain signal is the complex signal as the quadrature demodulation result, and this complex signal comprises real axis component (I channel signal) and imaginary axis component (Q channel signal).Be provided for carrier wave generation circuit 5, fft circuit 6, FFT interval control circuit 7 and postpone overview estimating circuit 10 from the OFDM time-domain signal of orthogonal demodulation circuit 4 outputs.
Carrier wave produces circuit 5 based on the carrier wave that provides the OFDM time-domain signal that comes to produce the preset frequency synchronous with receiving signal from orthogonal demodulation circuit 4, and the carrier wave that produces is outputed to orthogonal demodulation circuit 4.
Fft circuit 6 removes signal in the protection interval based on the FFT trigger impulse that offers it from FFT interval control circuit 7 from the signal of an OFDM symbol, is extracted in the signal in the significant character length range.
In addition, fft circuit 6 is also carried out the FFT mathematical operation to the OFDM time-domain signal that extracts and is extracted data through quadrature modulation in the subcarrier.Particularly, the starting position of the FFT mathematical operation of fft circuit 6 be from Fig. 1 as the position A on the border of OFDM symbol to as the position in the scope of another position B on the border protection interval and the significant character.This FFT mathematical operation scope is called the FFT interval, and the starting position at this FFT interval is by provide the FFT trigger impulse that comes to specify from FFT interval control circuit 7.
The ofdm signal of the data that fft circuit 6 output representatives are extracted.This ofdm signal is the frequency-region signal of having carried out after the FFT mathematical operation.Ofdm signal after the FFT mathematical operation is called the OFDM frequency-region signal hereinafter.Be provided for SP extraction circuit 8-1 and the division circuit 8-4 of transmission line Distoriton compensating circuit 8 from this OFDM frequency-region signal of fft circuit 6 outputs.
FFT interval control circuit 7 is based on next OFDM time-domain signal being provided from orthogonal demodulation circuit 4 and determining the FFT interval by the delay overview that delay overview estimating circuit 10 estimates.Subsequently, FFT interval control circuit 7 will specify the FFT trigger impulse of the starting position at determined FFT interval to output to fft circuit 6.
Transmission line Distoriton compensating circuit 8 comprises that SP extracts circuit 8-1, time orientation transmission line property estimating circuit 8-2, frequency interpolation circuit 8-3 and division circuit 8-4.
SP extracts circuit 8-1 and extracts the SP signal from the OFDM frequency-region signal that offers it from fft circuit 6, and the modulation product that removes the SP signal is estimated the transmission characteristic of subcarrier at the position place of SP signal.SP extraction circuit 8-1 outputs to time orientation transmission line property estimating circuit 8-2 with the signal of the transmission line property that representative estimates.
Time orientation transmission line property estimating circuit 8-2 extracts the transmission characteristic that circuit 8-1 estimates based on SP, estimate in the position of each of the upper OFDM symbol arranged side by side of time orientation (that is, OFDM symbol direction), the transmission characteristic of having arranged the subcarrier of SP signal.In Fig. 2, vertical direction is time orientation, and horizontal direction is frequency direction.
For example, time orientation transmission line property estimating circuit 8-2 uses the SP signal SP of the Fig. 2 that is estimated by SP extraction circuit 8-1 1The transmission line property of position and another SP signal SP 2Another transmission line property of position, come the regional A of drawing for estimate 2 1In the transmission line property of subcarrier of distinct symbols position.
Owing to having inserted a SP signal at per 12 subcarriers of synchronization as shown in Figure 2, so time orientation transmission line property estimating circuit 8-2 is for the transmission line property of the subcarrier at an OFDM character position of per three sub-carrier estimation place.The signal of the transmission line property of per three subcarriers that time orientation transmission line property estimating circuit 8-2 output representative estimates.Be provided for frequency interpolation circuit 8-3 and postpone overview estimating circuit 10 from the signal of time orientation transmission line property estimating circuit 8-2 output.
Frequency interpolation circuit 8-3 carries out interpolation processing for interpolation transmission characteristic on frequency direction according to the transmission line property that per three subcarriers that come are provided from time orientation transmission line property estimating circuit 8-2, thereby estimates the transmission characteristic of subcarrier of the position of each OFDM symbol in frequency direction.Frequency interpolation circuit 8-3 comprises a plurality of interpolation filters with different filter wave bands, and utilizes these interpolation filters to carry out interpolation processing.
The transmission characteristic of subcarrier in the position of the OFDM symbol that for example, comprises among the regional A2 of frequency interpolation circuit 8-3 to Fig. 2, that not yet carry out the position of the OFDM symbol that transmission characteristic estimates is estimated.Transmission characteristic estimated to utilize extracted by SP that transmission characteristic that circuit 8-1 and time orientation transmission line property estimating circuit 8-2 estimated carries out.
As a result, estimated the transmission route characteristic of all subcarriers of the position of OFDM symbol.Frequency interpolation circuit 8-3 exports the signal of being carried out the interpolation processing acquisition by the interpolation filter of selecting circuit 11 to provide next filter to select the specified filter wave band of signal from the frequency interpolation filter by utilizing to division circuit 8-4, as the signal of the estimated result that represents transmission line property.
Division circuit 8-4 is from providing the OFDM frequency-region signal that comes is removed provides the transmission characteristic of all subcarriers of representative that come from frequency interpolation circuit 8-3 the component of signal from fft circuit 6, thereby removes the distortion component of transmission line from this OFDM frequency-region signal.The OFDM frequency-region signal that division circuit 8-4 will remove distortion component outputs to error correction circuit 9.
Signal that 9 pairs of transmit legs of error correction circuit interweave is carried out processings that deinterleave, and carry out sympathetic such as going (depuncture), Veterbi decoding, the processing spread signal removes and RS (Read-Solomon) decodes.Error correction circuit 9 is processed the data that obtain as decoded data to late-class circuit output through these.
The time resolution characteristics that postpone overview estimating circuit 10 definite transmission lines are estimated the delay overview of transmission line.For example, postponing transmission line property that 10 pairs of time orientation transmission line properties of overview estimating circuit estimating circuit 8-2 estimates carries out IFFT and comes the estimated delay overview.The transmission line property that is estimated by time orientation transmission line property estimating circuit 8-2 is frequency domain characteristic, is to postpone overview by the time resolution characteristics that this transmission line property execution IFFT is obtained therefore.
Representative is provided for FFT interval control circuit 7 and frequency interpolation filter selection circuit 11 by the signal of the time overview that delay overview estimating circuit 10 estimates.Note, as being used for postponing the method that overview is estimated, known its tap coefficient that utilizes in addition is to protect the matched filter (MF) of gap periods to come from the method for OFDM time-domain signal estimated delay overview.
The frequency interpolation filter selects circuit 11 based on the delay overview that is estimated by delay overview estimating circuit 10 (namely, position in the time shaft upper pathway) determines delay scope (delay spread), and from the filter wave band of the interpolation filter that offers frequency interpolation circuit 8-3, select the filter wave band corresponding with this delay scope.The frequency interpolation filter selects circuit 11 will specify the filter of institute's selecting filter wave band to select signal to export to frequency interpolation circuit 8-3.
Fig. 4 shows the example of the configuration of frequency interpolation circuit 8-3.
With reference to figure 4, frequency interpolation circuit 8-3 comprises frequency interpolation filter circuit 8-3a 0To 8-3a N-1, and selector circuit 8-3b.Be imported into 8-3a from the signal of the transmission characteristic of per three subcarriers of representative of time orientation transmission line property estimating circuit 8-2 output 0To 8-3a N-1In corresponding one, and select the filter of circuit 11 outputs to select signal to be imported into selector circuit 8-3b from the frequency interpolation filter.
Frequency interpolation filter circuit 8-3a 0To 8-3a N-1Utilization provides the interpolation filter that comes to carry out interpolation processing, and the signal that will represent interpolation result outputs to selector circuit 8-3b.In the example of Fig. 4, frequency interpolation filter circuit 8-3a 0Utilize the interpolation filter of filter wave band BW0 to carry out interpolation processing, frequency interpolation filter circuit 8-3a 1Utilize the interpolation filter of filter wave band BW1 to carry out interpolation processing.Frequency interpolation filter circuit 8-3a N-1Utilize the interpolation filter of filter wave band BW (N-1) to carry out interpolation processing.Fig. 5 shows the filter wave band BW0 to BW3 on the time shaft.
In the example of Fig. 5, filter wave band BW0 has maximum bandwidth, and filter wave band BW3 has minimum bandwidth.Empty leg-of-mutton position upwards represents the position at the center of filter wave band.Interpolation processing is performed so that the center of filter wave band becomes identical with the center that postpones scope.
Selector circuit 8-3b is from from frequency interpolation filter circuit 8-3a 0To 8-3a N-1In the signal that provides, select to select the interpolation filter of the specified filter wave band of signal to carry out the signal that interpolation processing obtains by utilizing by filter, and with the signals selected division circuit 8-4 that outputs to.
Japanese Patent Laid Open Publication No.2006-311385 discloses for detection of the quality of the signal after the equilibrium and in response to the technology of detected quality to controlling from the optimal filter coefficients in a plurality of filter coefficients.
Summary of the invention
As mentioned above, the delay overview that estimates is selected circuit 11 to be used for the selective filter wave band by the frequency interpolation filter.
Therefore, in the multi-path environment that comprises the path that not to be detected owing to surpassing detection limit, sometimes selected mistakenly the filter wave band.Owing to may not compensate fully transmission path distortion, this causes receptivity to worsen.
An example of the delay overview that provides in three ripples (three-wave) environment is provided Fig. 6.In Fig. 6, transverse axis is time shaft, and the longitudinal axis represents the power in path.
In the example of Fig. 6, there are path P, another paths Q and another paths R three paths.In these paths, only can detect path P and path Q, and can not being delayed overview estimating circuit 10, path R detects, because its power is lower.
In this example, because only path P and path Q are the paths that detects, although therefore the delay scope in fact with path P and path R between the corresponding range scope of distance in exist, but judge the delay scope only with path P and path Q between the corresponding amount of distance exist, and based on this judgement selective filter wave band.
In the example of Fig. 6, selected filter wave band BW3, the filter wave band of filter wave band BW3 can hold path P and path Q when being set to same position in the center of the center of path P and path Q and filter wave band.The mass ratio of the OFDM frequency-region signal behind the final transmission line distortion compensation that obtains has the filter wave band that can also hold path R by utilization interpolation filter carries out interpolation and the quality that compensates the OFDM frequency-region signal that obtains is carried out in the transmission line distortion low to transmission line property.
If typically selected to be similar to the filter wave band of wider bandwidth of the filter wave band BW0 of Fig. 5, then can carry out interpolation with the form that also comprises the path that not to be detected.But the low noise of power of the path R of a lot of power ratio Fig. 6 is included in the filter wave band, and has carried out interpolation in this state.Therefore, but the filter wave band preferably includes all path width as far as possible near the wave band of the width of delay scope.
Therefore, expectation provides a kind of receiving equipment, method of reseptance and program that may prevent that receptivity from worsening.
According to embodiments of the invention, a kind of receiving equipment is provided, this receiving equipment comprises: extraction element is used for extracting pilot signal from the OFDM frequency-region signal; The transmission line property estimation unit is used for estimating transmission line property based on the pilot signal of being extracted by extraction element at time orientation; Interpolating apparatus, be used for to utilize a plurality of interpolation filters with the filter wave band that differs from one another, based on carrying out the interpolation processing of on frequency direction, transmission line property being carried out interpolation by the transmission line property on the estimated time orientation that goes out of transmission line property estimation unit, thereby produce a plurality of signals of the transmission line property that represents all subcarriers; Compensation arrangement is used for the signal of the transmission line property of all subcarriers of representative of producing based on the OFDM frequency-region signal with by interpolating apparatus, produces a plurality of signals through the transmission line distortion compensation of the component of the distortion that has removed the respective transmissions circuit; Checkout gear is for detection of the quality through the signal of transmission line distortion compensation that is produced by compensation arrangement; And choice device, be used for selecting the signal through the transmission line distortion compensation through the signal of transmission line distortion compensation that produced by compensation arrangement based on the detected result of checkout gear.
Choice device can be selected the signal through the transmission line distortion compensation that has best quality in the signal of transmission line distortion compensation that produced by compensation arrangement.
Interpolating apparatus can comprise: the first interpolating apparatus is used for utilizing the interpolation filter of the first filter wave band to carry out described interpolation processing; And second interpolating apparatus, be used for utilizing the interpolation filter of the second filter wave band to carry out described interpolation processing; And compensation arrangement can comprise: the first compensation arrangement is used for producing signal through the transmission line distortion compensation based on the OFDM frequency-region signal with by the signal that the first interpolating apparatus produces; And second compensation arrangement, be used for producing signal through the transmission line distortion compensation based on the OFDM frequency-region signal with by the signal that the second interpolating apparatus produces.
This receiving equipment can also comprise control device, this control device is used for the filter wave band of the interpolation filter that will be used by interpolating apparatus is controlled, thereby change the filter wave band of the interpolation filter of this interpolating apparatus use, signal with the transmission line property that produces following all subcarriers of representative: based on these signals that represents the transmission line property of all subcarriers, produced the signal through the transmission line distortion compensation that device selected is not selected.
According to another embodiment of the invention, a kind of method of reseptance is provided or has made computer carry out the program of processing, the method and processing may further comprise the steps: extract pilot signal from the OFDM frequency-region signal; Estimate transmission line property based on the pilot signal of extracting at time orientation; Utilization have the filter wave band that differs from one another a plurality of interpolation filters, carry out the interpolation processing of on frequency direction, transmission line property being carried out interpolation based on the transmission line property on the estimated time orientation that goes out, thereby produce a plurality of signals of the transmission line property that represents all subcarriers; Based on the signal of OFDM frequency-region signal with the transmission line property of all subcarriers of representative that produce, produce a plurality of signals through the transmission line distortion compensation of the component of the distortion that has removed the respective transmissions circuit; Detect the quality through the signal of transmission line distortion compensation produce; And based on to select a signal through the transmission line distortion compensation in the signal of transmission line distortion compensation through the testing result of the quality of the signal of transmission line distortion compensation.
According to still another embodiment of the invention, provide a kind of receiving equipment, this equipment comprises: FFT mathematical operation device is used for the OFDM time-domain signal is carried out the FFT mathematical operation; The pilot signal extraction element is used for the OFDM frequency-region signal extraction pilot signal that obtains from by carried out the FFT mathematical operation by FFT mathematical operation device; Estimation unit, be used for to estimate the characteristic of the transmission line corresponding with each pilot signal and on time orientation the characteristic to transmission line carry out interpolation, determine the transmission line property of every predetermined number subcarrier; Control device, be used for width and center that control will be used for the passband of the interpolation filter that frequency interpolation processes, this frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and is carried out that filtering is next carries out interpolation to transmission line property on frequency direction; Interpolating apparatus, be used in width and center for the passband that changes interpolation filter according to the OFDM frequency-region signal that represents prosign under the control of transmission line property at control device of definite every predetermined number subcarrier, utilize this interpolation filter to carry out the transmission line property of determining all subcarriers for the processing of carrying out the frequency interpolation processing; Distortion calibration device is used for utilizing the distortion of proofreading and correct the OFDM frequency-region signal that represents prosign by the transmission line property of determined all subcarriers of interpolating apparatus; Calculation element is used for the quality that the OFDM frequency-region signal of distortion has been proofreaied and correct in calculating; Choice device is used for selecting to obtain one the interpolation filter that OFDM frequency-region signal after the distortion correction shows best quality based on the quality that is calculated by calculation element; The variable coefficient interpolating apparatus, be used for to utilize the interpolation filter that for the width of passband and center, has with by the characteristic identical characteristics of the selected interpolation filter of choice device to process carrying out frequency interpolation by the transmission line property of the determined every predetermined number subcarrier of estimation unit, thus the transmission line property of definite all subcarriers; And balancer, thereby be used for utilizing the transmission line property by determined all subcarriers of variable coefficient interpolating apparatus to come the execution equilibrium is proofreaied and correct in the distortion of OFDM frequency-region signal.
This interpolating apparatus can utilize the bandwidth of passband and the concurrent execution frequency interpolation of interpolation filter that the center differs from one another to process.
This control device can change the center of the passband of interpolation filter in following ranges: be centered close to signal in the mulitpath that form to postpone overview and arrive the earliest pre-position between a paths on institute edge and another paths that this signal arrives the institute edge recently, and extend round about half amount that equates with the width of the passband of this interpolation filter from this center.
According to another embodiment of the invention, a kind of method of reseptance is provided or has made computer carry out the program of processing, the method and processing may further comprise the steps: the OFDM time-domain signal is carried out the FFT mathematical operation; From the OFDM frequency-region signal extraction pilot signal that obtains by carrying out the FFT mathematical operation; Estimate the characteristic of the transmission line corresponding with each pilot signal and on time orientation the characteristic to transmission line carry out interpolation, determine the transmission line property of every predetermined number subcarrier; Control will be used for width and the center of the passband of the interpolation filter that frequency interpolation processes, and this frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and carried out that filtering is next carries out interpolation to transmission line property on frequency direction; For according to the OFDM frequency-region signal that represents prosign and when the transmission line property of definite every predetermined number subcarrier changes the width and center of passband of interpolation filter, utilize this interpolation filter to carry out for the transmission line property of carrying out processing that frequency interpolation processes and determine all subcarriers; The distortion that utilizes the transmission line property of all subcarriers to proofread and correct the OFDM frequency-region signal of this representative prosign; Calculate the quality of the OFDM frequency-region signal of having proofreaied and correct distortion; Select to obtain to show in the described OFDM frequency-region signal after the distortion correction one interpolation filter of best quality based on the quality that calculates; Utilization has interpolation filter with the characteristic identical characteristics of selected interpolation filter and comes that the transmission line property of every predetermined number subcarrier is carried out frequency interpolation and process for the width of passband and center, thereby determines the transmission line property of all subcarriers; And the transmission line property that utilizes determined all subcarriers comes thereby the execution equilibrium is proofreaied and correct in the distortion of OFDM frequency-region signal.
According to still a further embodiment, provide a kind of receiving equipment, this receiving equipment comprises: FFT mathematical operation device is used for the OFDM time-domain signal is carried out the FFT mathematical operation; The pilot signal extraction element is used for the OFDM frequency-region signal extraction pilot signal that obtains from by carried out the FFT mathematical operation by FFT mathematical operation device; Estimation unit is used for estimating the characteristic of the transmission line corresponding with each pilot signal and on time orientation this characteristic being carried out interpolation, to determine the transmission line property of every predetermined number subcarrier; Control device, be used for the center that control will be used for the passband of the interpolation filter that frequency interpolation processes, this frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and is carried out that filtering is next carries out interpolation to transmission line property on frequency direction; Interpolating apparatus, be used in the center for the passband that changes interpolation filter according to the OFDM frequency-region signal that represents prosign under the control of transmission line property at control device of definite every predetermined number subcarrier, utilize this interpolation filter to carry out the transmission line property of determining all subcarriers for the processing of carrying out the frequency interpolation processing; Distortion calibration device is used for utilizing the distortion of proofreading and correct the OFDM frequency-region signal of described representative prosign by the transmission line property of determined all subcarriers of interpolating apparatus; Calculation element is used for the quality that the OFDM frequency-region signal of distortion has been proofreaied and correct in calculating; Choice device is used for selecting to obtain one the interpolation filter that OFDM frequency-region signal after the distortion correction shows best quality based on the quality that is calculated by calculation element; And delay overview estimation unit, be used for to determine postpone overview, this delays overview be by in by the path in the frequency domain that the market demand IFFT that represents the transmission line property of the estimated every predetermined number subcarrier that goes out by estimation unit is obtained, be included in and be centered close to and formed by the path in the predetermined frequency band of identical position, the center of the passband of the selected interpolation filter of choice device.
The width of this predetermined frequency band can equal the width of the passband of interpolation filter.
According to still a further embodiment, a kind of method of reseptance is provided or has made computer carry out the program of processing, the method and processing may further comprise the steps: the OFDM time-domain signal is carried out the FFT mathematical operation; From the OFDM frequency-region signal extraction pilot signal that obtains by carrying out the FFT mathematical operation; Estimate the characteristic of the transmission line corresponding with each pilot signal and on time orientation, this characteristic is carried out interpolation, to determine the transmission line property of every predetermined number subcarrier; Control will be used for the center of the passband of the interpolation filter that frequency interpolation processes, and this frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and carried out that filtering is next carries out interpolation to transmission line property on frequency direction; For according to the OFDM frequency-region signal that represents prosign and when the transmission line property of definite every predetermined number subcarrier changes the center of passband of interpolation filter, utilize this interpolation filter to carry out for the transmission line property of carrying out processing that frequency interpolation processes and determine all subcarriers; The distortion that utilizes the transmission line property of determined all subcarriers to proofread and correct the OFDM frequency-region signal that represents prosign; Calculate the quality of the OFDM frequency-region signal of having proofreaied and correct distortion; Select to obtain to show in the described OFDM frequency-region signal after the distortion correction one interpolation filter of best quality based on the quality that calculates; And determine to postpone overview, this delay overview be by in the path in the frequency domain that obtains by the market demand IFFT to the transmission line property that represents the estimated every predetermined number subcarrier that goes out, the path that is included in the predetermined frequency band that is centered close to the position identical with the center of the passband of selected interpolation filter forms.
In this receiving equipment, method of reseptance and program, pilot signal is extracted from OFDM frequency-region signal signal, and estimates transmission line property on the time orientation based on the pilot signal that extracts.Subsequently, utilization have the filter wave band that differs from one another a plurality of interpolation filters, carried out the interpolation processing of on frequency direction, transmission line property being carried out interpolation based on the transmission line property on the estimated time orientation that goes out, thereby produced a plurality of signals of the transmission line property that represents all subcarriers.In addition, based on the signal of OFDM frequency-region signal with the transmission line property of all subcarriers of representative that produce, a plurality of signals through the transmission line distortion compensation of the component of the distortion that has removed the respective transmissions circuit have been produced.After this, detect the quality through the signal of transmission line distortion compensation that produces, and based on to selected a signal through the transmission line distortion compensation in the signal of transmission line distortion compensation through the testing result of the signal of transmission line distortion compensation.
In this receiving equipment, method of reseptance and program, the OFDM time-domain signal is carried out the FFT mathematical operation, and extract pilot signal from the OFDM frequency-region signal that obtains by execution FFT mathematical operation.Subsequently, estimate the characteristic of the transmission line corresponding with each pilot signal, and the characteristic to transmission line is carried out interpolation on time orientation, to determine the transmission line property of every predetermined number subcarrier.Then, control will be used for width and the center of the passband of the interpolation filter that frequency interpolation processes, and this frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and carried out that filtering is next carries out interpolation to transmission line property on frequency direction.Subsequently, for according to the OFDM frequency-region signal that represents prosign and when the transmission line property of definite every predetermined number subcarrier changes the width and center of passband of interpolation filter, carry out and utilize this interpolation filter to carry out the transmission line property that all subcarriers are determined in processing that frequency interpolation processes.In addition, utilize the transmission line property of all subcarriers to proofread and correct the distortion of the OFDM frequency-region signal of this representative prosign, and calculate the quality of the OFDM frequency-region signal of having proofreaied and correct distortion.Subsequently, based on the quality that calculates, selected to be used for to obtain to show in the described OFDM frequency-region signal after the distortion correction one interpolation filter of best quality.In addition, utilization has the interpolation filter with the characteristic identical characteristics of selected interpolation filter for the width of passband and center, transmission line property to every predetermined number subcarrier has been carried out the frequency interpolation processing, thereby determines the transmission line property of all subcarriers.Subsequently, utilize the transmission line property of determined all subcarriers to proofread and correct the distortion of OFDM frequency-region signal, thereby carried out equilibrium.
In receiving equipment, method of reseptance and program, the OFDM time-domain signal is carried out the FFT mathematical operation, and extracted pilot signal from the OFDM frequency-region signal that obtains by execution FFT mathematical operation.Subsequently, estimate the characteristic of the transmission line corresponding with each pilot signal and this characteristic is carried out interpolation in the time on by direction, to determine the transmission line property of every predetermined number subcarrier.Subsequently, control will be used for the center of the passband of the interpolation filter that frequency interpolation processes, and this frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and carried out that filtering is next carries out interpolation to transmission line property on frequency direction.Subsequently, for according to the OFDM frequency-region signal that represents prosign and when the transmission line property of definite every predetermined number subcarrier changes the center of passband of interpolation filter, utilize this interpolation filter to carry out to be used for and carry out the transmission line property that all subcarriers are determined in processing that frequency interpolation processes.Subsequently, utilize the transmission line property of determined all subcarriers to proofread and correct the distortion of the OFDM frequency-region signal that represents prosign, and calculate the quality of the OFDM frequency-region signal of having proofreaied and correct distortion.Subsequently, select to be used for to obtain to show in the described OFDM frequency-region signal after the distortion correction one interpolation filter of best quality based on the quality that calculates.Subsequently, determine the delay overview, this delay overview be by in the path in the frequency domain that obtains by the market demand IFFT to the transmission line property that represents the estimated every predetermined number subcarrier that goes out, the path that is included in the predetermined frequency band that is centered close to the position identical with the center of the passband of selected interpolation filter forms.
Utilize this receiving equipment, method of reseptance and program, can prevent the deterioration of receptivity.
To know by reference to the accompanying drawings above and other purpose, the feature and advantage of embodiments of the invention from following description and appended claims, similarly part and element are represented by similar label in the accompanying drawings.
Description of drawings
Fig. 1 shows the diagram of OFDM symbol;
Fig. 2 shows the diagram of an example of the arrangement of SP signal;
Fig. 3 shows the block diagram of an example of the configuration that has the OFDM receiver now;
Fig. 4 shows the block diagram of an example of the configuration of the frequency interpolation circuit shown in Fig. 3;
Fig. 5 shows the diagram of an example of filter wave band;
Fig. 6 shows the diagram of an example that postpones overview;
Fig. 7 shows the block diagram according to an example of the configuration of the OFDM receiver of first embodiment of the invention;
Fig. 8 shows the block diagram of an example of the configuration of the signal quality testing circuit shown in Fig. 7;
Fig. 9 shows the diagram of the Selective sequence in the OFDM receiver of Fig. 7;
Figure 10 to 12 shows the diagram by the different examples of the selected filter wave band of the control circuit shown in Fig. 7;
Figure 13 shows the flow chart of OFDM demodulation process of the OFDM receiver of Fig. 7;
Figure 14 shows the signal of the step S12 place of Figure 13 carrying out and selects the flow chart processed;
Figure 15 shows the block diagram of another example of configuration of modification of the OFDM receiver of Fig. 7;
Figure 16 A to 16D, 17A to 17D and 18A to 18B show the diagram of the different examples of signal quality;
Figure 19 shows the block diagram of an example of the configuration of OFDM receiver according to a second embodiment of the present invention;
Figure 20 shows the block diagram of an example of the configuration of the frequency interpolation circuit shown in Figure 19;
Figure 21 shows the diagram of time orientation characteristic estimating data;
Figure 22 is similar diagram but shows frequency direction characteristic interpolated data;
Figure 23 shows the diagram that 0 value is inserted the example of the data in the time domain of performance data;
Figure 24 shows the block diagram of an example that the optimal filter coefficients shown in Figure 19 is selected the configuration of circuit;
Figure 25 shows the flow chart of reception ﹠ disposal of the OFDM receiver of Figure 19;
Figure 26 shows the filter coefficient of the step S58 place of Figure 25 carrying out and selects the flow chart processed;
Figure 27 shows the block diagram of another example that the optimal filter coefficients shown in Figure 19 is selected the configuration of circuit;
Figure 28 shows the block diagram of an example of configuration of modification of the OFDM receiver of Figure 19;
Figure 29 shows the block diagram of an example that the optimal filter coefficients shown in Figure 28 is selected the configuration of circuit;
Figure 30 A and 30B show the diagram of an example of mobility scale of center of the passband of the interpolation filter shown in Figure 28;
Figure 31 shows the block diagram of an example of configuration of another modification of the OFDM receiver of Figure 19;
Figure 32 shows the block diagram of an example that the optimal filter coefficients shown in Figure 31 is selected the configuration of circuit;
Figure 33 A to 33D shows the diagram of the estimation that postpones overview; And
Figure 34 is the block diagram of an example of the configuration of personal computer.
Embodiment
The＜the first embodiment 〉
Fig. 7 shows an example according to the configuration of the OFDM receiver of the embodiment of the invention.
With reference to figure 7, shown in OFDM receiver 101 comprise that reception antenna 1, tuner 2, analog/digital (A/D) change-over circuit 3, orthogonal demodulation circuit 4, carrier wave produce circuit 5, fft circuit 6, FFT interval control circuit 7, transmission line Distoriton compensating circuit 8, error correction circuit 9, postpone overview estimating circuit 10, the frequency interpolation filter selects circuit 11 and optimal frequency interpolation filter to select circuit 21.OFDM receiver 101 is that with OFDM receiver 100 differences shown in Fig. 3 it also additionally comprises optimal frequency interpolation filter selection circuit 21.
Tuner 2 converts the RF signal frequency that reception antenna 1 receives to the IF signal, and this IF signal is outputed to A/D change-over circuit 3.
3 pairs of A/D change-over circuits are carried out the A/D conversion from the IF signal that tuner 2 offers it, and the digital IF signal that will produce outputs to orthogonal demodulation circuit 4.
Orthogonal demodulation circuit 4 utilizes and produces carrier wave that circuit 5 offers it from carrier wave and carry out quadrature demodulation the IF signal acquisition OFDM time-domain signal that comes from providing from A/D change-over circuit 3 is provided, and the OFDM time-domain signal that obtains of output.Be provided for carrier wave generation circuit 5, fft circuit 6, FFT interval control circuit 7 and postpone overview estimating circuit 10 from the OFDM time-domain signal of orthogonal demodulation circuit 4 outputs.
Carrier wave produces circuit 5 based on the carrier wave that provides the OFDM time-domain signal that comes to produce preset frequency from orthogonal demodulation circuit 4, and the carrier wave that produces is outputed to orthogonal demodulation circuit 4.
Fft circuit 6 removes signal in the protection interval based on the FFT trigger impulse that offers it from FFT interval control circuit 7 from the signal of an OFDM symbol, is extracted in the signal in the significant character length range.
In addition, fft circuit 6 is also carried out the FFT mathematical operation to the OFDM time-domain signal that extracts and is extracted data through quadrature modulation in the subcarrier, and the OFDM frequency-region signal of the data extracted of output representative.Be provided for the SP extraction circuit 8-1 of transmission line Distoriton compensating circuit 8 and the division circuit 21-4 of division circuit 8-4 and optimal frequency interpolation filter selection circuit 21 from this OFDM frequency-region signal of fft circuit 6 outputs.
FFT interval control circuit 7 is determined the FFT interval based on the OFDM time-domain signal that provides from orthogonal demodulation circuit 4 with by the delay overview that delay overview estimating circuit 10 estimates, and will specify the FFT trigger impulse of the starting position at determined FFT interval to output to fft circuit 6.
In the situation that determine the FFT interval with the OFDM time-domain signal; FFT interval control circuit 7 is determined the correlation of latter half of different piece to this significant character in the copy source that is used as the protection interval in the OFDM time-domain symbol of the significant character of OFDM symbols, and will have the part of high correlation and detect and be the protection interval.FFT interval control circuit 7 is defined as the boundary position of detected protection interval and this significant character the starting position at FFT interval.
On the other hand, when determining the FFT interval with the delay overview, FFT interval control circuit 7 will postpone the starting position that the overview significant character that represents and the boundary position of protecting the interval are defined as the FFT interval by this.
Transmission line Distoriton compensating circuit 8 comprises that SP extracts circuit 8-1, time orientation transmission line property estimating circuit 8-2, frequency interpolation circuit 8-3 and division circuit 8-4.
SP extracts circuit 8-1 and extracts the SP signal from the OFDM frequency-region signal that offers it from fft circuit 6, and the modulation product that removes the SP signal is estimated the transmission characteristic of subcarrier at the position place of SP signal.SP extraction circuit 8-1 outputs to time orientation transmission line property estimating circuit 8-2 with the signal of the transmission line property that representative estimates.
Time orientation transmission line property estimating circuit 8-2 extracts the transmission characteristic that circuit 8-1 estimates based on SP, estimate each the position, the transmission characteristic of having arranged the subcarrier of SP signal in the upper OFDM symbol arranged side by side of time orientation (that is, OFDM symbol direction).The signal of the transmission line property of per three subcarriers that time orientation transmission line property estimating circuit 8-2 output representative estimates.Be provided for the frequency interpolation circuit 21-3 that frequency interpolation circuit 8-3, delay overview estimating circuit 10 and optimal frequency interpolation filter are selected circuit 21 from the signal of time orientation transmission line property estimating circuit 8-2 output.
Frequency interpolation circuit 8-3 carries out interpolation to transmission characteristic according to the transmission line property that per three subcarriers that come are provided from time orientation transmission line property estimating circuit 8-2 on frequency direction, thereby estimates the transmission characteristic of subcarrier of the position of each OFDM symbol in frequency direction.
Frequency interpolation circuit 8-3 has the configuration identical with the configuration shown in Fig. 4.Frequency interpolation circuit 8-3 is according to one the signal that provides next filter selection signal to select to represent the interpolation result that utilizes a plurality of interpolation filters acquisitions with the different filter wave bands shown in Fig. 5 from control circuit 21-2.Frequency interpolation circuit 8-3 outputs to division circuit 8-4 with the signal of signals selected estimated result as representing transmission line property.
Division circuit 8-4 is from providing the OFDM frequency-region signal that comes is removed provides the transmission characteristic of all subcarriers of representative that come from frequency interpolation circuit 8-3 the component of signal from fft circuit 6, thereby removes the distortion component of transmission line from this OFDM frequency-region signal.Division circuit 8-4 exports the OFDM frequency-region signal behind the transmission line distortion compensation that has removed distortion component.OFDM frequency-region signal behind the transmission line distortion compensation of division circuit 8-4 output is imported into selection circuit 21-1 and the signal quality testing circuit 21-5 that the optimal frequency interpolation filter is selected circuit 21.
The OFDM frequency-region signals that 9 pairs of error correction circuits select the selection circuit 21-1 of circuit 21 to offer it from the optimal frequency interpolation filter are carried out processings that deinterleave, and carry out, Veterbi decoding sympathetic such as going, the processing spread signal removes and RS decodes.Error correction circuit 9 is processed the data that obtain as decoded data to late-class circuit output through these.
Postpone time resolution characteristics that overview estimating circuit 10 determines transmission lines and estimate the delay overview of transmission line, and the signal of the estimated delay overview that goes out of output representative.Be provided for FFT interval control circuit 7 and frequency interpolation filter selection circuit 11 from the signal that postpones 10 outputs of overview estimating circuit.
The frequency interpolation filter selects circuit 11 based on determining the delay scope by postponing the delay overview that overview estimating circuit 10 estimates, and the filter selection signal that will represent the filter wave band corresponding with this delay scope outputs to the control circuit 21-2 of optimal frequency interpolation filter selection circuit 21.
The optimal frequency interpolation filter is selected circuit 21 to comprise and is selected circuit 21-1, control circuit 21-2, frequency interpolation circuit 21-3, division circuit 21-4 and signal quality testing circuit 21-5.Select in the assembly of circuit 21 at the optimal frequency interpolation filter, therefore the processing that frequency interpolation circuit 21-3 execution is identical with the processing of the frequency interpolation circuit 8-3 of transmission line Distoriton compensating circuit 8, can always be embodied as single circuit with them.Simultaneously, because the division circuit 21-4 execution processing identical with the processing of the division circuit 8-4 of transmission line Distoriton compensating circuit 8, so also they always can be embodied as single circuit.
Select circuit 21-1 according to the selection signal that comes is provided from control circuit 21-2, select OFDM frequency-region signal after division circuit 8-4 provides a transmission line distortion compensation coming and the OFDM frequency-region signal after division circuit 21-4 provides another transmission line distortion compensation of coming.Subsequently, select circuit 21-1 that the selected OFDM frequency-region signal is outputed to error correction circuit 9.
Control circuit 21-2 is based on provide the information of coming to one selection signal selecting to show the circuit 21-1 output indication OFDM frequency-region signal better quality from signal quality testing circuit 21-5.The information of the information of the quality of the OFDM frequency-region signal that provides representative to carry out the transmission line distortion compensation by division circuit 8-4 from signal quality testing circuit 21-5 to control circuit 21-2 and obtain and the quality of the OFDM frequency-region signal that representative is obtained by division circuit 21-4 execution transmission line distortion compensation.Control circuit 21-2 selects signal to output to frequency interpolation circuit 8-3 and frequency interpolation circuit 21-3 in filter.
Frequency interpolation circuit 21-3 carries out interpolation to transmission line property according to the transmission line property that per three subcarriers that come are provided from the time orientation transmission line property estimating circuit 8-2 of transmission line Distoriton compensating circuit 8 on frequency direction, thereby estimates the transmission line property of subcarrier of the position of each OFDM symbol in frequency direction.
In addition, frequency interpolation circuit 21-3 has the configuration identical with the configuration shown in Fig. 4.The signal of the interpolation result that a plurality of interpolation filters that frequency interpolation circuit 21-3 selects signal to select to represent to utilize to have different filter wave bands as shown in Figure 5 according to the filter that provides from control circuit 21-2 obtain one.Frequency interpolation circuit 21-3 outputs to division circuit 21-4 with the signal of signals selected estimated result as representing transmission line property.
Division circuit 21-4 is from providing the OFDM frequency-region signal that comes is removed provides the transmission line property of all subcarriers of representative that come from frequency interpolation circuit 21-3 the component of signal from fft circuit 6, thereby removes the distortion component of transmission line from this OFDM frequency-region signal.Division circuit 21-4 will remove OFDM frequency-region signal behind the transmission line distortion compensation of distortion component and output to and select circuit 21-1 and signal quality testing circuit 21-5.
The quality of the OFDM frequency-region signal after signal quality testing circuit 21-5 detects and the quality of the OFDM frequency-region signal behind the transmission line distortion compensation that comes to be provided and the transmission line distortion compensation that comes is provided from division circuit 21-4 from division circuit 8-4, and the signal quality information that will represent detected quality outputs to control circuit 21-2.For example, quality is by the definition of the amount of noise, and signal quality testing circuit 21-5 detects the amount of the noise in the OFDM frequency-region signal that is included in behind the transmission line distortion compensation.
Fig. 8 shows an example of the configuration of signal quality testing circuit 21-5.
With reference to figure 8, signal quality testing circuit 21-5 comprises hard decision circuit 21-5a, subtraction circuit 21-5b, square mathematical operation circuit 21-5c, carrier wave orientation average circuit 21-5d and time orientation average circuit 21-5e.OFDM frequency-region signal behind the transmission line distortion compensation of division circuit 8-4 or division circuit 21-4 output is provided for hard decision circuit 21-5a and subtraction circuit 21-5b.
Hard decision circuit 21-5a is according to the hard decision of the execution of the modulator approach such as PSK or QAM to the signal behind the transmission line distortion compensation.Hard decision circuit 21-5a outputs to subtraction circuit 21-5b with the hard decision value as the result of this judgement.
Difference between the value of the OFDM frequency-region signal of subtraction circuit 21-5b after with hard decision value and transmission line distortion compensation outputs to a square mathematical operation circuit 21-5c.The poor noisiness that represents between hard decision value and the OFDM.
Square mathematical operation circuit 21-5c carries out square converting noisiness to power to the noisiness that is calculated by subtraction circuit 21-5b.Square mathematical operation circuit 21-5c will be by square power stage of the determined noise of mathematical operation to carrier wave orientation average circuit 21-5d.
Carrier wave orientation average circuit 21-5d averages to put forward high-power accuracy to the power of being determined by square mathematical operation circuit 21-5c on the carrier wave direction.Carrier wave orientation average circuit 21-5d outputs to time orientation average circuit 21-5e with the mean value of the power on the carrier wave direction.
Select signal to be applied in the situation of a plurality of symbols at a filter, can calculate at time orientation average.In this example, time orientation average circuit 21-5e calculate be included in the noise when the OFDM frequency-region signal behind the transmission line distortion compensation that when the identical filter of control circuit 21-2 output is selected signal, produces power on time orientation on average, and the average information output on the time orientation that representative is calculated is to control circuit 21-2.When filter selected signal to be changed at every turn, reset signal was imported into time orientation average circuit 21-5e, and this reset signal is used for cancellation and is used for until be somebody's turn to do the information of mathematical operations constantly.
Here, described control circuit 21-2 selective filter wave band and select the transmission line distortion compensation after the sequence of OFDM frequency-region signal.
Fig. 9 shows the example of Selective sequence.
With reference to figure 9, represent the character representation shown in each ellipse of different conditions and select signal from the filter that control circuit 21-2 outputs to frequency interpolation circuit 8-3 and frequency interpolation circuit 21-3; And the content of the condition that near the character representation that illustrates the arrow mark of representative from a state to the change of another state should changes generation and the signal of this moment exporting from control circuit 21-2.In near the character that illustrates each arrow mark, those character representations in slash (/) left side change condition (action lists), and the content of those expression signals of right side, that is, and the state of the destination of this change.
In the following description, represent to output to from control circuit 21-2 the filter selection signal of frequency interpolation circuit 8-3 with FLT_A, and represent to output to from control circuit 21-2 the filter selection signal of frequency interpolation circuit 21-3 with FLT_B.In addition, the quality representation of the OFDM frequency-region signal that will obtain by the transmission line distortion compensation of division circuit 8-4 is signal quality information NPWR_A, and the quality representation of the OFDM frequency-region signal that will obtain by the transmission line distortion compensation of division circuit 21-4 is signal quality information NPWR_B.
In addition, select circuit 11 based on postponing the estimated selected filter wave band of delay overview that goes out of overview estimating circuit 10 with BWX (X=0 to 3) expression by the frequency interpolation filter.Select this filter wave band of signal indication BWX from the filter that the frequency interpolation filter selects circuit 11 to offer control circuit 21-2.Note, postpone overview and here have as top with reference to figure 6 described states.Particularly, comprise three paths: path P, path Q and path R, and in this three paths, only path P and path Q can be delayed overview estimating circuit 10 and detect, and path R can not be detected, because its power is lower.
State s0 is initial condition, FLT_A=BWX and FLT_B=BW0 in this state.In state s0, be used for selecting the instruction based on postponing the selected filter wave band of overview to be provided for frequency interpolation circuit 8-3.When FLT_A=BWX and FLT_B=BW0, control circuit 21-2 compares the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 8-4 and the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 21-4 based on signal quality information NPWR_A and NPWR_B.
Shown in the top among Figure 10, in the situation of BWX=BW3, owing to there being the path R not yet be detected, so division circuit 8-4 can not the distortion of full remuneration transmission line, thereby the receptivity deterioration has occured.On the contrary, shown in the bottom among Figure 10, frequency interpolation circuit 21-3 utilizes the interpolation filter of the filter wave band BW0 also comprise the path R that not yet is detected to carry out interpolation, and division circuit 21-4 distortion compensates to transmission line based on the result's who represents this interpolation signal.
With reference to figure 9, provide the signal quality information that comes to become NPWR_A＞=NPWR_B from signal quality testing circuit 21-5 again, and because X=3, so the state of control circuit 21-2 changes to another state s1 from state s0.In the higher situation of the value of signal quality information, the amount of noise is larger, and lower based on its quality of OFDM frequency-region signal of amount that detects noise.
This moment, select signal to change to FLT_A=BW2 to the filter of frequency interpolation circuit 8-3.In addition, indication should select selection signal SEL=FLT_B from the OFDM frequency-region signal of division circuit 21-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
In state s1, FLT_A=BW2 and FLT_B=BW0.When FLT_A=BW2 and FLT_B=BW0, control circuit 21-2 compares the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 8-4 and the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 21-4 based on next signal quality information NPWR_A and NPWR_B is provided from signal quality testing circuit 21-5.
Owing to also there being the visible path R that not yet is detected from the top of Figure 11 in state s1, so division circuit 8-4 can not the distortion of full remuneration transmission line, thereby the receptivity deterioration has occured.On the contrary, shown in the bottom among Figure 11, frequency interpolation circuit 21-3 utilizes the interpolation filter of the filter wave band BW0 also comprise the path R that not yet is detected to carry out interpolation, and division circuit 21-4 distortion compensates to transmission line based on the result's who represents this interpolation signal.
Provide the signal quality information that comes to become NPWR_A＞=NPWR_B from signal quality testing circuit 21-5, and because X=3, so the state of control circuit 21-2 changes to another state s3 from state s1.
This moment, select signal to change to FLT_A=BW2 to the filter of frequency interpolation circuit 8-3.In addition, indication should select selection signal SEL=FLT_B from the OFDM frequency-region signal of division circuit 21-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
In state s3, FLT_A=BW1 and FLT_B=BW0.When FLT_A=BW1 and FLT_B=BW0, control circuit 21-2 compares the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 8-4 and the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 21-4 based on next signal quality information NPWR_A and NPWR_B is provided from signal quality testing circuit 21-5.
Owing to also there being the path R that as seen not yet is detected from the top of Figure 12 in state s3, so division circuit 8-4 can not the distortion of full remuneration transmission line, thereby the receptivity deterioration has occured.On the contrary, shown in the bottom among Figure 12, frequency interpolation circuit 21-3 utilizes the interpolation filter of the filter wave band BW0 also comprise the path R that not yet is detected to carry out interpolation, and division circuit 21-4 distortion compensates to transmission line based on the result's who represents this interpolation signal.
Provide the signal quality information that comes to become NPWR_A＞=NPWR_B from signal quality testing circuit 21-5, and because X=3, so the state of control circuit 21-2 changes to state s0 from state s3.In addition, when X=2, the state of control circuit 21-2 changes to state s0 similarly from state s3.
This moment, select signal to change to FLT_A=BWX to the filter of frequency interpolation circuit 8-3.In addition, indication should select selection signal SEL=FLT_B from the OFDM frequency-region signal of division circuit 21-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
Like this, equally OFDM receiver 101 be in exist the path R that exceeds the detection limit that postpones overview estimating circuit 10 and division circuit 8-4 can not the situation of full remuneration transmission line distortion in, because according to selecting signal SEL=FLT_B to select the OFDM frequency-region signal that is produced by division circuit 21-4, so the result of the performed transmission line distortion compensation that also comprises path R can be offered error correction circuit 9.Thereby can prevent the deterioration of receptivity.
In addition in other situations, appropriate change like the state class of control circuit 21-2.For example, in the situation of NPWR_A＜NPWR_B in state s0, keep state s0.
On the other hand, in the situation of NPWR_A＞=NPWR_B and X=2 in state s0, the state of control circuit 21-2 changes to state s3 from state s0.This moment, select signal to change to FLT_A=BW1 to the filter of frequency interpolation circuit 8-3.In addition, indication should select selection signal SEL=FLT_B from the OFDM frequency-region signal of division circuit 21-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
In the situation of NPWR_A＜NPWR_B and X=3 in state s1, the state of control circuit 21-2 changes to another state s2 from state s1.This moment, select signal to change to FLT_B=BW3 to the filter of frequency interpolation circuit 21-3.In addition, indication should select selection signal SEL=FLT_A from the OFDM frequency-region signal of division circuit 8-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
In state s2, FLT_A=BW2 and FLT_B=BW3.When FLT_A=BW2 and FLT_B=BW3, control circuit 21-2 compares the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 8-4 and the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 21-4 based on next signal quality information NPWR_A and NPWR_B is provided from signal quality testing circuit 21-5.
In the situation of NPWR_A＜NPWR_B and X=3 in state s2, the state of control circuit 21-2 changes to state s1 from state s2.This moment, select signal to change to FLT_B=BW0 to the filter of frequency interpolation circuit 21-3.In addition, indication should select selection signal SEL=FLT_A from the OFDM frequency-region signal of division circuit 8-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
On the other hand, in the situation of NPWR_A＞=NPWR_B and X=3 in state s2, the state of control circuit 21-2 changes to state s0 from state s2.This moment, select signal to change to FLT_A=BWX to the filter of frequency interpolation circuit 8-3, and select signal to change to FLT_B=BW0 to the filter of frequency interpolation circuit 21-3.In addition, indication should select selection signal SEL=FLT_B from the OFDM frequency-region signal of division circuit 21-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
In the situation of NPWR_A＜NPWR_B and X=2 in state s3 or 3, the state of control circuit 21-2 changes to another state s4 from state s3.This moment, select signal to change to FLT_B=BW2 to the filter of frequency interpolation circuit 21-3.In addition, indication should select selection signal SEL=FLT_A from the OFDM frequency-region signal of division circuit 8-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
In state s4, FLT_A=BW1 and FLT_B=BW2.When FLT_A=BW1 and FLT_B=BW2, control circuit 21-2 compares the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 8-4 and the amount that is included in the noise in the OFDM frequency-region signal that is produced by division circuit 21-4 based on next signal quality information NPWR_A and NPWR_B is provided from signal quality testing circuit 21-5.
In the situation of NPWR_A＜NPWR_B and X=2 in state s4 or 3, the state of control circuit 21-2 changes to state s3 from state s4.This moment, select signal to change to FLT_B=BW0 to the filter of frequency interpolation circuit 21-3.In addition, indication should select selection signal SEL=FLT_A from the OFDM frequency-region signal of division circuit 8-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
On the other hand, in the situation of NPWR_A＞=NPWR_B and X=2 in state s4 or 3, the state of control circuit 21-2 changes to state s0 from state s4.This moment, select signal to change to FLT_A=BWX to the filter of frequency interpolation circuit 8-3, and select signal to change to FLT_B=BW0 to the filter of frequency interpolation circuit 21-3.In addition, indication should select selection signal SEL=FLT_B from the OFDM frequency-region signal of division circuit 21-4 output as being exported from control circuit 21-2 to the selection signal SEL that selects circuit 21-1.
Above-mentioned Selective sequence can work when OFDM receiver 101 is carried out reception ﹠ disposal, therefore, generally can select optimum OFDM frequency-region signal.In other words, even OFDM receiver 101 also has higher reinforcing property in the environment that overview fluctuates continuously.
In addition, can be adaptively the filter wave band of the interpolation filter that uses in two frequency interpolation circuit be controlled, and can be in the situation that do not cause error in data to prevent that receptivity from worsening.Basically, the filter wave band is adaptively controlled, and is used for determining the filter wave band of the frequency interpolation circuit of following transmission line property with change: produced the signal through the transmission line distortion compensation that selected circuit 21-1 selects based on this transmission line property.
The processing of the OFDM receiver 101 with above-mentioned configuration is described below.The processing at the step place of following flow diagram can be carried out according to the order of step number, perhaps also can suitably carry out concurrently with the processing at another step place.
The OFDM demodulation process of OFDM receiver 101 at first, is described with reference to Figure 13.
At step S1, the RF signal that tuner 2 frequency inverted are received by reception antenna 1, and the IF signal that produces outputed to A/D change-over circuit 3.
At step S2,3 pairs of these IF signals of A/D change-over circuit are carried out the A/D conversion, and the digital IF signal that produces is outputed to orthogonal demodulation circuit 4.
At step S3, orthogonal demodulation circuit 4 is carried out quadrature demodulation, and the OFDM time-domain signal that produces is outputed to carrier wave generation circuit 5, fft circuit 6, FFT interval control circuit 7 and postpones overview estimating circuit 10.
At step S4, fft circuit 6 arranges the FFT interval based on the FFT trigger impulse that provides from FFT interval control circuit 7, and carries out the FFT mathematical operation.Fft circuit 6 will output to by the OFDM frequency-region signal that the FFT mathematical operation obtains SP and extract circuit 8-1, division circuit 8-4 and division circuit 21-4.
At step S5, SP extracts circuit 8-1 and extracts the SP signal from this OFDM frequency-region signal and estimate transmission line property at the subcarrier of the position of each SP signal.SP extraction circuit 8-1 outputs to time orientation transmission line property estimating circuit 8-2 with the signal of the transmission line property that representative estimates.
At step S6, time orientation transmission line property estimating circuit 8-2 estimates transmission line property for per three subcarriers at time orientation, and the signal of the transmission line property that representative is estimated outputs to frequency interpolation circuit 8-3, postpones overview estimating circuit 10 and frequency interpolation circuit 21-3.
At step S7, postpone overview estimating circuit 10 estimated delay overviews, and should postpone overview and output to FFT interval control circuit 7 and frequency interpolation filter selection circuit 11.
At step S8, the frequency interpolation filter selects circuit 11 to determine the delay scope based on the delay overview that is estimated by delay overview estimating circuit 10, and selects the filter wave band corresponding with this delay scope.The frequency interpolation filter selects circuit 11 to select signal to the filter that control circuit 21-2 output is used to specify institute's selecting filter wave band.
At step S9, FFT interval control circuit 7 is determined the FFT interval based on the OFDM time-domain signal that provides from orthogonal demodulation circuit 4 with by the delay overview that postpones 10 estimations of overview estimating circuit, and is used to specify the FFT trigger impulse at determined FFT interval to fft circuit 6 outputs.
At step S10, frequency interpolation circuit 8-3 carries out interpolation to transmission characteristic according to the transmission line property that per three subcarriers that come are provided from time orientation transmission line property estimating circuit 8-2 on frequency direction, thereby estimate transmission line property at the subcarrier of the position of each OFDM symbol in frequency direction, and the signal that will represent the result of this estimation outputs to division circuit 8-4.Representing a signal that should be output as the result that representative estimates transmission line property in a plurality of signals of result of interpolation is based on from control circuit 21-2 and provides the filter that comes to select signal FLT_A to select.
At step S11, division circuit 8-4 removes the component that has been caused distortion by transmission line based on next signal is provided from frequency interpolation circuit 8-3 from the OFDM frequency-region signal that comes is provided from fft circuit 6.The OFDM frequency-region signal that division circuit 8-4 will remove distortion component outputs to selection circuit 21-1 and signal quality testing circuit 21-5.
At step S12, carry out the signal selection processing that will output to the OFDM frequency-region signal of error correction circuit 9 for selection.Signal is selected to process and will be described with reference to Figure 14 below.
At step S13,9 pairs of error correction circuits from the OFDM frequency-region signals of selecting circuit 21-1 and providing carry out, Veterbi decoding sympathetic such as deinterleaving, going, spread signal removes and the RS decoding various processing, and the decoded data that produces outputed to late-class circuit.
Repetition is carried out in 101 pairs of above-mentioned processing of OFDM receiver when OFDM receiver 101 receives signal.
Now, being described in the signal of carrying out among the step S12 of Figure 13 with reference to Figure 14 selects to process.
When executive signal received, the processing of Figure 14 was normally carried out in the processing of OFDM receiver 101 and Figure 13 concurrently.
At step S21, control circuit 21-2 selects signal FLT_A to output to frequency interpolation circuit 8-3 in filter, and selects signal FLT_B to output to frequency interpolation circuit 21-3 in filter.Filter selects signal FLT_A and FLT_B to select according to top Selective sequence with reference to figure 9 descriptions.
At step S22, frequency interpolation circuit 21-3 carries out interpolation to transmission line property according to the transmission line property that per three subcarriers that come are provided from time orientation transmission line property estimating circuit 8-2 on frequency direction, thereby estimates the transmission line property of subcarrier of the position of each OFDM symbol in frequency direction.Subsequently, the frequency interpolation circuit 21-3 signal that will represent the result of this estimation outputs to division circuit 21-4.Representing a signal that should be output as the result that representative estimates transmission line property in a plurality of signals of result of interpolation is based on from control circuit 21-2 and provides the filter that comes to select signal FLT_B to select.
At step S23, division circuit 21-4 removes the component that has been caused distortion by transmission line based on next signal is provided from frequency interpolation circuit 21-3 from the OFDM frequency-region signal that comes is provided from fft circuit 6.The OFDM frequency-region signal that division circuit 21-4 will remove the component of distortion outputs to selection circuit 21-1 and signal quality testing circuit 21-5.Note, in step S10, carried out the interpolation of frequency interpolation circuit 8-3 to transmission line property, and in step S11, carried out the compensation of division circuit 8-4 to the transmission line distortion.
At step S24, signal quality testing circuit 21-5 detects the amount that is included in the noise from the OFDM frequency-region signal behind the transmission line distortion compensation that division circuit 8-4 provides, and signal quality information NPWR_A is outputed to control circuit 21-2.
At step S25, signal quality testing circuit 21-5 detects the amount that is included in the noise from the OFDM frequency-region signal behind the transmission line distortion compensation that division circuit 21-4 provides, and signal quality information NPWR_B is outputed to control circuit 21-2.
At step S26, signal SEL is selected in control circuit 21-2 output, and this selection signal SEL is to selecting circuit 21-1 index signal quality information NPWR_A and NPWR_B to be compared to each other and should detecting one that has better quality in the OFDM frequency-region signal signal.
At step S27, select circuit 21-1 according to next selection signal is provided from control circuit 21-2, from next OFDM frequency-region signal being provided from division circuit 8-4 and providing the OFDM frequency-region signal that comes to select the OFDM frequency-region signal with better quality from division circuit 21-4.Subsequently, select circuit 21-1 that the selected OFDM frequency-region signal is outputed to error correction circuit 9.After this, process the step S11 turn back to Figure 13 and carry out processing in the step that begins with step S11.
By above-mentioned processing, can prevent the deterioration of receptivity.
＜revise
Figure 15 shows an example of the configuration of modified OFDM receiver.
With reference to Figure 15, to select the circuit 11 except not comprising the frequency interpolation filter, this modified OFDM receiver 102 OFDM receiver 101 with Fig. 7 aspect configuration is identical.Particularly, in the OFDM of Fig. 7 receiver 101, according to top Selective sequence with reference to figure 9 descriptions, select signal from selecting circuit 21-1 suitably to export a filter, this filter select signal designation should select with selected by the frequency interpolation filter circuit 11 based on postponing the delay overview that overview estimating circuit 10 estimates the identical filter wave band of the filter wave band of selecting.But in modified OFDM receiver 102, the filter wave band is normally selected by control circuit 21-2 oneself.Control circuit 21-2 oneself is that reference signal quality information NPWR_A and NPWR_B carry out to the selection of filter wave band.
In addition, in this mode, do not provide the frequency interpolation filter to select circuit 11, can be based on quality from from an OFDM frequency-region signal of division circuit 8-4 output with between another OFDM frequency-region signal of division circuit 21-4 output, select optimum OFDM frequency-region signal.As a result, can prevent the deterioration of receptivity.
Although the above has described frequency interpolation circuit 8-3 and frequency interpolation circuit 21-3 and can have been realized and division circuit 8-4 and division circuit 21-4 also can be realized by single circuit by single circuit, on the contrary, also can realize for detection of the signal quality testing circuit of the quality of the OFDM frequency-region signal that is produced by division circuit 8-4 with for detection of another signal quality testing circuit of the quality of the OFDM frequency-region signal that is produced by division circuit 21-4 with circuit separated from one another.
Particularly, if carry out interpolation processing with a plurality of interpolation filters with different filter wave bands, can obtain a plurality of transmission line properties for all subcarriers, if and carried out the transmission line distortion compensation based on these a plurality of transmission line properties, the signal behind a plurality of transmission line distortion compensations then could be obtained.In addition, if the quality of the signal behind each transmission line distortion compensation can be detected, then can realize frequency interpolation circuit, division circuit and signal quality testing circuit with arbitrary form.
In addition, compensation or balanced signal and the signal after the error correction after the transmission line distortion can be as the echo signals of quality testing.
In addition, for generation of the signal behind two transmission line distortion compensations and select the method for one of these two signals and for generation of three or more signals and one the method for selecting to have first water in these signals can use.
The＜the second embodiment 〉
Although the description of front relates to the situation that the filter wave band of the width of passband or interpolation filter is adjusted to improve signal quality, except the width of passband, can also adjust center or the centre frequency of passband.
Figure 16 A to 16D shows the signal quality in the situation of the width of variable passband in the center of the fixing passband of interpolation filter.
In Figure 16 A to 16D, horizontal direction direction instruction time, the power in vertical direction indication path.Empty triangle upwards represents the position at center of the passband of interpolation filter.
Figure 16 A shows the example of the distribution (profile) that receives signal.Receiving signal receives by path P, Q and R.
If adopt the interpolation filter in the passband that may some path be included in it, shown in Figure 16 B or 16C, then the mass ratio of the OFDM frequency-region signal behind the final transmission line distortion compensation that obtains comprises that in employing the signal quality in the situation of interpolation filter in all paths is low.
Figure 16 D shows the example that adopts all paths to be included in the interpolation filter in the passband.The quality of the OFDM frequency-region signal behind this transmission line distortion compensation be utilize in the signal quality that the interpolation filter of wave band BW3, BW2 and BW1 obtains best.
Figure 17 A to 17D shows when the center of the passband of interpolation filter is variable the signal quality in the fixing situation of the width of passband.
Figure 17 A shows and identical path P, Q and the R shown in Figure 16 A.
If adopt interpolation filter so that the position p1 shown in Figure 17 B can become the center of passband, then this passband does not comprise path R.
If adopt interpolation filter so that be positioned at the center that p1 slightly right position p2 in position can become passband shown in Figure 17 C, then path P, Q and R are included in this passband.Be set to the signal quality that shown in Figure 17 B not all path all is included in the replacement situations such as position in this passband with center in passband and compare, improved the quality of the OFDM frequency-region signal behind the transmission line distortion compensation.
If adopt interpolation filter so that be positioned at the center that p2 slightly right position p3 in position can become passband shown in Figure 17 D, then path P is excluded outside this passband.
But but the width of the passband shown in fixing and Figure 17 A to 17D is fixing in variable these two kinds of situations in center of passband, depend on that the adjustment mode can be included in the passband in all paths usually in the center of the variable passband of passband width of the interpolation filter shown in Figure 16 A to 16D.
Figure 18 A and 18B show the two signal quality in the variable situation of the width of passband of interpolation filter and center.
Figure 18 A shows and adopts interpolation filter so that the width of passband is the center of BW1 and passband is the example of position p11.
Figure 18 B shows and adopts interpolation filter so that the width of passband is that the center of BW2 and passband is in position p11 another example of right position p12 slightly.
Although all paths can be included in the passband of interpolation filter of Figure 18 A and 18B, if will utilize the quality of the OFDM frequency-region signal after the distortion correction that these interpolation filters obtain mutually to compare, then the signal quality in the situation of the interpolation filter that uses Figure 18 B is better.
This be because as Figure 18 A and the 18B white noise that as seen in fact superposeed in whole zone, so hope arranges the least possible interpolation filter that comprises this white noise of its passband.If the interpolation filter of the interpolation filter of comparison diagram 18A and Figure 18 B, the amount that then is included in the white noise in the passband of interpolation filter of Figure 18 B have lacked the amount that is included in the white noise in the scope that the dotted line that replaces with length centers on.
In the receiver that is described below, interpolation filter is provided so that its passband comprises that all paths still comprise white noise as few as possible.
Figure 19 shows an example according to the configuration of the OFDM receiver 103 of second embodiment of the invention.
Referring to Figure 19, the configuration of OFDM receiver 103 and the top OFDM receiver 101 of describing with reference to figure 7 but to be configured in main aspect similar different again, OFDM receiver 103 does not comprise frequency interpolation filter selection circuit 11, and comprises that replacing the optimal frequency interpolation filter selects the optimal filter coefficients of circuit 21 to select circuit 31.In addition, thereby transmission line Distoriton compensating circuit 8 also comprises the frequency interpolation circuit 32 for the width of the passband that changes interpolation filter according to coefficient and the processing of center execution frequency interpolation, as being used for carrying out the circuit that is used on frequency direction transmission line property being carried out the frequency interpolation processing of interpolation.
Tuner 2 converts the RF signal frequency that reception antenna 1 receives to the IF signal, and this IF signal is outputed to A/D change-over circuit 3.
3 pairs of these IF signals of A/D change-over circuit are carried out the A/D conversion, and the digital IF signal that will produce outputs to orthogonal demodulation circuit 4.
Orthogonal demodulation circuit 4 utilizations are obtained the OFDM time-domain signal from the carrier wave execution quadrature demodulation that carrier wave generation circuit 5 offers it, and export the OFDM time-domain signal that obtains.
Carrier wave produces the carrier wave that circuit 5 produces preset frequency, and the carrier wave that produces is outputed to orthogonal demodulation circuit 4.
Fft circuit 6 arranges the FFT interval based on the FFT trigger impulse that offers it from FFT interval control circuit 7, and in this FFT interval the OFDM time-domain signal is carried out the FFT mathematical operation.Fft circuit 6 will represent the OFDM frequency-region signal through the data of quadrature modulation in the subcarrier that extracts by the FFT mathematical operation and output to that SP extracts circuit 8-1, division circuit 8-4 and optimal filter coefficients is selected circuit 31.
FFT interval control circuit 7 is determined the FFT interval based on the delay overview that is estimated by delay overview estimating circuit 10, and the FFT trigger impulse is outputed to fft circuit 6.
The SP of transmission line Distoriton compensating circuit 8 extracts circuit 8-1 and extracts the SP signal from the OFDM frequency-region signal, and estimates the transmission characteristic corresponding with this SP signal.SP extraction circuit 8-1 outputs to time orientation transmission line property estimating circuit 8-2 with the transmission line property data of the transmission line property that representative estimates.
Time orientation transmission line property estimating circuit 8-2 estimate in the OFDM symbol arranged side by side on time orientation each the position, arranged the transmission line property of the subcarrier of SP signal.The time orientation characteristic estimating data that time orientation transmission line property estimating circuit 8-2 will represent the transmission line property of per three subcarriers output to optimal filter coefficients selection circuit 31, frequency interpolation circuit 32 and postpone overview estimating circuit 10.
Frequency interpolation circuit 32 is processed to carry out frequency interpolation based on width and the center of selecting circuit 31 to provide the coefficient that comes to change the passband of interpolation filter from optimal filter coefficients.
Figure 20 shows an example of the configuration of frequency interpolation circuit 32.
Referring to Figure 20, frequency interpolation circuit 32 comprises three times of up-samplings (triple up sampling) circuit 41 and interpolation filter circuit 42.
Three times of up-sampling circuit 41 for example insert two zero as new sampled value between per two neighbouring sample values that the time orientation characteristic estimating data of coming are provided from time orientation transmission line property estimating circuit 8-2.Three times of up-sampling circuit 41 are to interpolation filter circuit 42 these time orientation characteristic estimating data of output, and the number of the sampled value of this data estimator has been increased to three times of number of the sampled value of initial data.
Interpolation filter circuit 42 is included in the low pass filter (LPF) that on the frequency direction interpolation of transmission line property is carried out filtering, and the time orientation characteristic estimating data from three times of up-sampling circuit 41 are carried out filtering.Be used for the width of passband of the LPF of this filtering or interpolation filter and center and be utilizing the coefficient adjustment selecting circuit 31 to provide to come from optimal filter coefficients.
The controlled interpolation filter in the width of interpolation filter circuit 42 usefulness passbands and center is carried out filtering removing by inserting zero and the reflecting component (reflection component) that produces in time orientation characteristic estimating data, thereby determines the transmission line property of interpolation on frequency direction.The frequency direction characteristic interpolated data that interpolation filter circuit 42 will represent the transmission line property (that is, the transmission line property in the frequency direction interpolation of the transmission characteristic of all subcarriers) of interpolation on frequency direction outputs to division circuit 8-4.
If represent significant character length with Tu, this length is the length that has removed the interval behind the protection interval from symbol, then for example than with about Tu/3[second] width that corresponding width is little is used as the width of the passband of interpolation filter.
The width of the passband of interpolation filter is described now.
Figure 21 shows time orientation characteristic estimating data.
This time orientation characteristic estimating data shown in Figure 21 be by time orientation transmission line property estimating circuit 8-2 utilize about with Fig. 2 in the transmission line property data of the SP signal arranged of identical mode determine.Referring to Figure 21, open circles and by subcarrier or the transmission symbol of the circle expression ofdm signal shown in the oblique line.Simultaneously, be illustrated in the transmission symbol that has estimated its transmission line property after time orientation transmission line property estimating circuit 8-2 processes with the circle shown in the oblique line.
The estimation utilization of transmission line property is performed each OFDM symbol of transmission line property determine to(for) per three subcarriers about the transmission line property data of SP signal at time orientation, as shown in figure 21.The time orientation characteristic estimating data of this representative transmission line property shown in Figure 21 are provided to frequency interpolation circuit 32 from time orientation transmission line property estimating circuit 8-2.
Figure 22 shows frequency direction characteristic interpolated data.
Frequency interpolation circuit 32 utilizes representative as the time orientation characteristic estimating data of the transmission line property of per three subcarriers of subcarrier number direction, has determined by the application among Figure 22 the transmission line property of the subcarrier of the OFDM symbol that the scope of oblique line is indicated.
Particularly, three times of up-sampling circuit 41 insert two zero between per two neighbouring sample values of time orientation characteristic estimating data, produce three times the time orientation characteristic estimating data that sampling quantity is added to the sampling quantity of initial data.
The time orientation characteristic estimating data that are input to three times of up-sampling circuit 41 are the sampled value sequences that represent the transmission line property of per three subcarriers shown in Figure 21.Therefore, in time orientation characteristic estimating data, estimating two subcarriers that do not estimate its transmission characteristic of existence between per two adjacent sub-carriers of its transmission characteristic.Therefore, three times of up-sampling circuit 41 insert two zero, these two zero sampled points that form the transmission line property corresponding with these two subcarriers that do not estimate its transmission line property.
Note, zero the number that insert depends on that the time orientation characteristic estimating data representation that obtained by time orientation transmission line property estimating circuit 8-2 is for the transmission line property of every what subcarriers.
In the situation between two zero per two the neighbouring sample values that are inserted in this way time orientation characteristic estimating data, the time orientation characteristic estimating data that obtain as the result of this insertion comprise reflecting component in time domain.In the following description, insert zero time orientation characteristic estimating data and suitably be called null value interpolation performance data.
The reason that time orientation characteristic estimating data comprise reflecting component is described below.
Time orientation characteristic estimating data are from OFDM frequency-region signal established data, and also are the data in the frequency domain.
Therefore, time orientation characteristic estimating data with all be the signal identical with analog signal by null value interpolation performance data that zero insertion is obtained in the time directional characteristic data estimator.Data in the time domain of time orientation characteristic estimating data comprise identical frequency component with data in the time domain of null value interpolation performance data.
In addition, time orientation characteristic estimating data are sampled value sequences of the transmission characteristic of per three subcarriers of representative.If use Tu[second] expression significant character length and utilize Fc[Hz] distance between the expression subcarrier, then satisfy expression formula Fc=1/Tu[Hz].Therefore, be 3Fc=3/Tu[Hz as the distance between the sampled value of time orientation characteristic estimating data of the sampled value sequence of the transmission line property of per three subcarriers of representative].
Therefore, be Fc=1/Tu[Hz by the distance between the sampled value of inserting two zero null value interpolation performance datas that obtain between per two neighbouring sample values of time orientation characteristic estimating data].
Simultaneously, the distance between the sampled value is 3Fc=3/Tu[Hz] time orientation characteristic estimating data in time domain, be 1/3Fc=Tu/3[second for its one-period] data.
Distance between the sampled value is Fc=1/Tu[Hz] null value interpolation performance data to have its one-period in time domain be 1/Fc=Tu[second] data, that is, its one-period is three times of cycle of time orientation characteristic estimating data.
Like this, comprise frequency component that the frequency component of the data in the time domain with time orientation characteristic estimating data is identical and its one-period is that data comprise three times repetition to data in the time domain of time orientation characteristic estimating data in the time domain of three times null value interpolation performance data of frequency of the data in the time domain data of time orientation characteristic estimating data.
Figure 23 shows an example of the data in the time domain of null value interpolation performance data.
The situation that description is existed main ripple and delay ripple two paths here.In Figure 23, transverse axis represents the time, and the longitudinal axis represents the power level in path.
Be Tu[second when the cycle of checking in time domain] null value interpolation performance data the time, they comprise that with the cycle be Tu/3[second] the treble of the corresponding multipath of time orientation characteristic estimating data multiple.
Now, if hypothesis is extracted by the multipath that is positioned at central authorities shown in the oblique line among Figure 23 as frequency direction characteristic interpolated data, then must remove other multipaths in order to obtain the expectation multipath corresponding with this frequency direction characteristic interpolated data.
Therefore, 42 pairs of null value interpolation of interpolation filter circuit performance data is carried out filtering and is removed except the multipath of expectation the multipath, thereby extracts the expectation multipath corresponding with this frequency direction characteristic interpolated data.
Note, null value interpolation performance data is the data in the frequency domain, so the filtering of 42 pairs of null value interpolation of interpolation filter circuit performance data is to the filter coefficient of interpolation filter with as the convolution of the null value interpolation performance data of the data in the frequency domain.
Because this convolution in the frequency domain is the window function that multiply by in the frequency domain, in time domain, can be expressed as null value interpolation performance data is multiplied each other with the window function corresponding with the passband of interpolation filter circuit 42 so null value interpolation performance data is carried out filtering.The window function that represents with thick line among Figure 23 represents the function corresponding with the passband of interpolation filter circuit 42, and it is used to multiply each other when null value interpolation performance data is carried out filtering.
The cycle that repeats three times multipath is Tu/3[second].Therefore, for example, if it is the cycle T u/3[second that width equals the multipath of three times of repetitions that interpolation filter is set to its passband], the LPF of the wave band from-Tu/6 to+Tu/6, then can extract the expectation multipath corresponding with frequency direction characteristic interpolated data.
The width Tu/3 of the passband of suitably used interpolation filter depends on by can determine the transmission line property of every what subcarriers at time orientation estimation transmission line property in the interpolation filter circuit 42 in this mode.
Interpolation filter circuit 42 will be processed the division circuit 8-4 that the estimated result to the estimation of the transmission line property of all subcarriers who goes out outputs to Figure 19 by frequency interpolation.
With reference to Figure 19, division circuit 8-4 proofreaies and correct to carry out equilibrium based on the transmission characteristic that all subcarriers that come are provided from frequency interpolation circuit 32 to the distortion that is included in the OFDM frequency-region signal again.Division circuit 8-4 has proofreaied and correct the OFDM frequency-region signal of distortion to error correction circuit 9 outputs, that is, and and the OFDM frequency-region signal behind the transmission line distortion compensation.
The distortion from generations such as multipaths that ofdm signal stands in transmission line is multiplying each other to ofdm signal.It is by the actual ofdm signal that receives is realized divided by transmission line property that the distortion that OFDM is stood in transmission line is proofreaied and correct.
Error correction circuit 9 will use various processing and the data that obtain output to late-class circuit as decoded data.
Postpone overview estimating circuit 10 and estimate the delay overview of transmission lines, and should postpone overview and output to FFT interval control circuit 7.
Optimal filter coefficients is selected circuit 31 attempt frequency interpolation processing under the multiple condition of the width that the utilizes passband interpolation filter different with the center.For example, optimal filter coefficients select circuit 31 the center of the passband of the filter wave band BW0 to BW3 of for example Fig. 5 by the various conditions of continuous displacement preset width under the attempt frequency interpolation processing.
In addition, optimal filter coefficients selects circuit 31 also based on the transmission characteristic by determined all subcarriers of attempt frequency interpolation, comes providing the distortion of OFDM frequency-region signal to proofread and correct from fft circuit 6.Optimal filter coefficients is selected circuit 31 quality of OFDM frequency-region signal of distortion of having gone back calculation correction.
Optimal filter coefficients selects circuit 31 option tables to reveal the interpolation filter of best quality, and will represent the width of passband of selected interpolation filter and the coefficient of center outputs to frequency interpolation circuit 32.
Particularly, optimal filter coefficients selects circuit 31 for example to determine to be used for to obtain width and the center of passband of interpolation filter of the signal of best quality for each symbol.
Figure 24 shows the example that optimal filter coefficients is selected the configuration of circuit 31.
Referring to Figure 24, optimal filter coefficients selects circuit 31 controls to the write and read of memory 52 and 53, with data and the data that read the same-sign of being stored of storage same-sign.In addition, controller 51 test coefficient that will represent the width of passband of the interpolation filter that is used for test and center outputs to frequency interpolation circuit 54 and optimal value is selected circuit 57.
Memory 52 is stored the OFDM frequency-region signal that a symbol that comes is provided from fft circuit 6 under the control of controller 51.The OFDM frequency-region signal that is stored in a symbol in the memory 52 is read by transmission line distortion correction circuit 55.
Memory 53 is stored the OFDM time-domain signal of a symbol under the control of controller 51, these OFDM time-domain signals are the data that represent the transmission line property of per three subcarriers that estimated by time orientation transmission line property estimating circuit 8-2.The time orientation characteristic estimating data that are stored in a symbol in the memory 53 are read by frequency interpolation circuit 54.
The configuration of the frequency interpolation circuit 32 of the configuration of frequency interpolation circuit 54 and Figure 20 is similar.Frequency interpolation circuit 54 is three times of the sampled value up-samplings of these time orientation characteristic estimating data, and utilizes and carry out frequency interpolation according to the interpolation filter of the width that provides the test coefficient that comes to adjust passband from controller 51 and center and process.
Frequency interpolation circuit 54 will output to transmission line distortion correction circuit 55 by the transmission line property that frequency interpolation is processed all subcarriers that obtain.
The width of 54 pairs in the frequency interpolation circuit passband by repeatedly changing interpolation filter and center and carry out frequency interpolation from the data that same symbol obtains and process, and the transmission characteristic that obtains is processed in output by these frequency interpolation.Owing to depending on that width and center one paths of the passband of interpolation filter may be included also and may not be included in this passband, correspondingly be different so process the transmission line property of determining by frequency interpolation for controller 51 each set test coefficient as mentioned above.
When providing transmission line property from frequency interpolation circuit 54, transmission line distortion correction circuit 55 is just proofreaied and correct the transmission line distortion the OFDM frequency-region signal that is included in a symbol of reading from memory 52 at every turn.The OFDM frequency-region signal that transmission line distortion correction circuit 55 will have been proofreaied and correct distortion outputs to signal quality counting circuit 56.
When the OFDM frequency-region signal of every next symbol is provided to signal quality counting circuit 56 from transmission line distortion correction circuit 55, signal quality counting circuit 56 just calculates the quality of OFDM frequency-region signal, and the quality that calculates is outputed to optimal value selection circuit 57 as result of the test.For example, signal quality counting circuit 56 calculates the power that is included in the noise in the OFDM frequency-region signal, and the value of power output.
The quality that optimal value selects circuit 57 Coutinuous stores to be calculated by signal quality counting circuit 56 is until for the test of having finished as the width of the OFDM frequency-region signal of a symbol of the target passband by changing interpolation filter and center all patterns.
When optimal value selected circuit 57 to get access to the result of the test of all patterns, it selected to be used for producing the interpolation center of the OFDM frequency-region signal with best quality, and specifies width and the center of the passband of selected interpolation filter.Thereby optimal value selects circuit 57 for the width of specifying the transmission wave band of employed interpolation processing to have as the OFDM frequency-region signal of a symbol of target and the position that should be elected to be the center of passband, in order to obtain the signal of best quality.
Optimal value selects circuit 57 will represent the width of passband of selected interpolation filter and the coefficient of center outputs to frequency interpolation circuit 32.
In the following description, the interpolation filter that is used for producing the OFDM frequency-region signal of best quality suitably is called optimal filter.Frequency interpolation circuit 32 uses the interpolation filter that has the characteristic identical with the characteristic of optimal filter for the width of passband and center,, has the interpolation filter of the passband of same widths and same central position that is.
[operation of receiver]
The operation of the OFDM receiver 103 with above-mentioned configuration is described now.
The reception ﹠ disposal of OFDM receiver 103 at first, is described with reference to Figure 25.
These processing at the step place of flow chart can by the order of step number carry out or also can with another step in processing executed in parallel suitably.
At step S51, the RF signal that tuner 2 frequency inverted are received by reception antenna 1, and the IF signal that produces outputed to A/D change-over circuit 3.
At step S52,3 pairs of these IF signals of A/D change-over circuit are carried out the A/D conversion, and export the digital IF signal that produces.
At step S53, orthogonal demodulation circuit 4 is carried out quadrature demodulation, and exports the OFDM time-domain signal that produces.
At step S54, fft circuit 6 is carried out the FFT mathematical operation under the control of FFT interval control circuit 7, and the output OFDM frequency-region signal.
At step S55, SP extracts circuit 8-1 and extracts the transmission line property that the SP signal is estimated the subcarrier corresponding with each SP from this OFDM frequency-region signal.
At step S56, time orientation transmission line property estimating circuit 8-2 estimates the transmission line property of per three subcarriers, and output time directional characteristic data estimator.
At step S57, postpone overview estimating circuit 10 and come the estimated delay overview based on these time orientation characteristic estimating data.
At step S58, optimal filter coefficients is selected circuit 31 to carry out filter coefficient and is selected processing.Select the coefficient of processing selecting to be output to frequency interpolation circuit 32 by this filter coefficient.Filter coefficient is selected to process and will be described with reference to Figure 26 below.
At step S59, the FFT mathematical operation of FFT interval control circuit 7 control fft circuits 6.
At step S60, the sampled value of 32 pairs of time orientation characteristic estimating of frequency interpolation circuit data is carried out up-sampling, and has utilized based on the coefficient adjustment of selecting processing selecting by filter coefficient the interpolation filter of the width of passband and center to carry out frequency interpolation and processed.
At step S61, division circuit 8-4 comes the distortion that is included in the OFDM frequency-region signal is proofreaied and correct based on the transmission characteristic of processing all subcarriers that obtain by frequency interpolation.
At step S62,9 pairs of error correction circuits have been proofreaied and correct the processing of OFDM frequency-region signal execution such as error correction of distortion, and export the decoded data that produces.
Repetition is carried out in 103 pairs of above-mentioned processing of OFDM receiver when OFDM receiver 103 is carried out the reception of signal.
Now, being described in the filter correction of carrying out among the step S58 of Figure 25 with reference to Figure 26 selects to process.
This processing during at the OFDM frequency-region signal of reading a symbol from memory 52 and from time orientation characteristic estimating data that memory 53 is read a symbol.The OFDM frequency-region signal of reading from memory 52 and are signal and data about same symbol from the time orientation characteristic estimating data that memory 53 is read.
At step S71, controller 51 is selected width and the center of interpolation filter, and the test coefficient of the output selected width of representative and center.
At step S72,54 utilizations of frequency interpolation circuit have adjusted the width of passband according to this test coefficient and the interpolation filter of center is carried out the frequency interpolation processing.
At step S73, transmission line distortion correction circuit 55 comes the transmission line distortion that is included in the OFDM frequency-region signal is proofreaied and correct based on processing the transmission line property of determining by this frequency interpolation.
At step S74, signal quality counting circuit 56 calculates the quality of the OFDM frequency-region signal of having proofreaied and correct distortion.The quality that optimal value selects circuit 57 storages to be calculated by signal quality counting circuit 56.
At step S75, signal quality counting circuit 56 judges in as the symbol of target whether process by the width of testing the passband that changes interpolation filter and the frequency interpolation that all patterns have been carried out in the center.Not yet carry out the frequency interpolation of all patterns and process if in step S75, judge this test, then process turning back to step S71, in this step, repeat above-mentioned processing sequence by the width of change passband and at least one in the center.
On the other hand, if in step S75, judge this test executed the frequency interpolation of all patterns process, then optimal value selects circuit 57 to select optimal filter based on the result to the test of all patterns in step 76.Optimal value selects circuit 57 to export the width of the passband that represents optimal filter and the coefficient of center.
After this, process the step S58 turn back to Figure 25 and carry out processing in the step that begins with step S58.
By above-mentioned processing, frequency interpolation circuit 32 can utilize following interpolation filter to carry out frequency interpolation and process, and utilizes the OFDM frequency-region signal after the width of passband of this interpolation filter and center can finally obtain to have the distortion compensation of best quality.Therefore, utilize this all paths are included in its passband but may comprise less closely that again the interpolation filter of white noise carried out the frequency interpolation processing shown in Figure 18 B.
In the situation of the passband of determining optimal filter by the top processing sequence of describing with reference to figure 9, require the integration of enough number of times in order to obtain correct the solution.This be because, in fixing reception environment, reception situation change about white noise etc. is small, and if the data of distinct symbols are carried out the processing such as frequency interpolation processing, distortion correction treatment and the signal quality of result of the test is compared to each other, phenomenon then may take a turn for the worse.Reversing phenomenon is so a kind of phenomenon: although an interpolation filter can provide quality the signal high than the signal quality of other interpolation filters, and affecting it and also may provide quality the signal lower than the signal quality of other interpolation filters owing to accepting state.
Therefore, width and the center of the passband by selecting in the above described manner interpolation filter are compared with the replacement situation of the processing sequence of execution graph 9, can reduce the time that obtains before correct the solution.
In addition, can also reduce lock in time, even and OFDM receiver 103 are mobile agent and reception environment changing environments when being, also can provide enough reinforcing properties with respect to environmental turbulence.
In addition, because to comparing by quality that in multiple condition, carry out to process the signal that obtains for prosign, so even the reception situation changes in time, comparative result also can keep stablizing and the change that do not received situation affects.
＜revise 1 〉
Figure 27 shows the block diagram through modification that optimal filter coefficients is selected circuit 31.
Referring to Figure 27, shown modified optimal filter coefficients selects circuit 31 to comprise the assembly identical with the assembly of the optimal filter coefficients selection circuit 31 shown in Figure 24.
But frequency interpolation circuit 54 comprises frequency interpolation circuit 54-1 to 54-N, and transmission line distortion correction circuit 55 comprises transmission line distortion correction circuit 55-1 to 55-N.In addition, signal quality counting circuit 56 comprises signal quality counting circuit 56-1 to 56-N.
Test coefficient 1 to N is outputed to frequency interpolation circuit 54-1 to 54-N with controller 51 and optimal value is selected circuit 57, and each test coefficient represents width and the center of the passband of interpolation filter.Test coefficient 1 to N represents the different qualities of interpolation filter.
Among the frequency interpolation circuit 54-1 to 54-N each used according to the corresponding test coefficient that offers it from controller 51 and adjusted the width of passband and the interpolation filter of center, carries out frequency interpolation and processes.Frequency interpolation under the different condition is processed by the concurrent execution of frequency interpolation circuit 54-1 to 54-N.
The transmission line property of all subcarriers that frequency interpolation circuit 54-1 to 54-N will obtain by the corresponding frequencies interpolation processing outputs to respectively transmission line distortion correction circuit 55-1 to 55-N.
Transmission line distortion correction circuit 55-1 to 55-N uses from frequency interpolation circuit 54-1 to 54-N the transmission line property that comes is provided respectively, proofreaies and correct the distortion of the transmission line the OFDM frequency-region signal that is included in a symbol of reading from memory 52.The OFDM frequency-region signal of transmission line distortion correction circuit 55-1 to 55-N after with distortion correction outputs to respectively signal quality counting circuit 56-1 to 56-N.
When the OFDM frequency-region signal of every next symbol is provided to respectively signal quality counting circuit 56-1 to 56-N from transmission line distortion correction circuit 55-1 to 55-N, signal quality counting circuit 56-1 to 56-N calculates the quality of these OFDM frequency-region signals, and the quality that calculates is outputed to optimal value selection circuit 57.
The quality that optimal value selects circuit 57 storages to be calculated by signal quality counting circuit 56-1 to 56-N.Optimal value selects circuit 57 to select optimal filter based on the result of the test of all patterns, and will represent the width of passband of this optimal filter and the coefficient of center outputs to frequency interpolation circuit 32.
Because frequency interpolation is processed, be used for proofreading and correct the processing of distortion of transmission line and the processing concurrent execution under different condition that is used for calculating signal quality, so can reduce coefficient is outputed to the required time of frequency interpolation circuit 32.
Optimal filter coefficients selects circuit 31 can be configured to not make in frequency interpolation circuit 54, transmission line distortion correction circuit 55 and the signal quality counting circuit 56 each to comprise as shown in figure 27 a plurality of circuit, but only frequency interpolation circuit 54 comprises a plurality of circuit and in transmission line distortion correction circuit 55 and the signal quality counting circuit 56 each comprises single circuit.
＜revise 2 〉
Figure 28 shows the block diagram of an example of the configuration of modified OFDM receiver 104.
Referring to Figure 28, the modified OFDM receiver 104 that illustrates comprises the assembly identical with the assembly of the modified OFDM receiver 104 shown in Figure 19.
OFDM receiver 104 among modified OFDM receiver 104 among Figure 28 and Figure 19 different are that the information about the position of center of gravity is provided to optimal filter coefficients and selects circuit 31 from FFT interval control circuit 7.
FFT interval control circuit 7 is determined the FFT interval based on the delay overview that is estimated by delay overview estimating circuit 10, and output FFT trigger impulse.In addition, the information about the position of center of gravity also will be for example determined based on following formula (1) of FFT interval control circuit 7:
Position=the ∑ of center of gravity (path power * path arrival times)/∑ (path power) ... (1) outputs to optimal filter coefficients and select circuit 31.The time of advent of every paths and power represent by postponing the estimated delay overview that goes out of overview estimating circuit 10.
Note, utilize the interval at protection interval when paying close attention to a certain symbol and the interval in copy source to have this fact of identical signal, determine separately to postpone overview based on the interval at protection interval for the correlation at other intervals.Definite method of position of centre of gravity also can suitably change.
Optimal filter coefficients selects circuit 31 to carry out the frequency interpolation processing by width and the center of the passband of change interpolation filter.Therefore, the optimal filter coefficients center of selecting circuit 31 that the center of passband is provided with respect to the position of the center of gravity of being determined by FFT interval control circuit 7 only changes preset range and carries out processing.
Figure 29 shows the example that the optimal filter coefficients shown in Figure 28 is selected the configuration of circuit 31.
The optimal filter coefficients of Figure 29 is selected circuit 31 to comprise with the optimal filter coefficients of Figure 24 and is selected the identical assembly of the assembly of circuit 31, but is imported into controller 51 from different being that the optimal filter coefficients of Figure 24 is selected circuit 31 from the information about the position of center of gravity of FFT interval control circuit 7 outputs.
Controller 51 control is read and to they write from memory 52 and 53, and will represent the width of passband of interpolation filter and the test coefficient of center outputs to frequency interpolation circuit 54 and 57.
Figure 30 A and 30B show the example of mobility scale of center of the passband of interpolation filter.
Figure 30 A shows and has three paths P, Q and R, and the real triangle that makes progress represents to be confirmed as the position of the position of center of gravity.
In this example, if represent the position of center of gravity and represent the width of the passband of interpolation filter with BWX with gp, then optimal filter coefficients selects circuit 31 in the center that the scope-BWX/2+gp shown in Figure 30 B changes the passband of interpolation filter to the+BWX/2+gp, carries out frequency interpolation and processes.
The mobility scale of the center of the passband by limiting in this way interpolation filter is carried out the replacement situation that frequency interpolation processes and is compared with change the center in hard-core situation, can reduce the number of times of the test that will carry out.
Although the above has described the benchmark that the position of center of gravity is used as mobility scale, but as long as the optional position is included in the scope of position of another paths that position to the signal that arrives the earliest the path on institute edge from signal arrives the institute edge recently, then this position can be used as benchmark.
For example, can mobility scale be set to such scope: centered by based on the center between the position that postpones the determined signal of overview and arrive the earliest the position in path on institute edge and another paths that signal arrives the institute edge recently, and extend BWX/2 to front side and rear side.
＜revise 3 〉
Figure 31 shows an example of the configuration of OFDM receiver 105.
Referring to Figure 31, OFDM receiver 105 is the modifications to the OFDM receiver 103 shown in Figure 19, and difference is that being selected circuit 31 to feed back to about the information of the center of the passband of optimal filter from optimal filter coefficients postpones overview estimating circuit 10.
In addition, in the interpolation filter that frequency interpolation circuit 32 will use, the width of passband is fixed to Tu/3[second], and the center variable of passband only.In addition, at the interpolation filter that is used for test that optimal filter coefficients selects circuit 31 to use in frequency interpolation is processed, the width of passband also is fixed to Tu/3[second], and the center variable of passband only.
Figure 32 shows the example that the optimal filter coefficients shown in Figure 31 is selected the configuration of circuit 31.
Referring to Figure 32, it is modifications of top optimal filter coefficients with reference to Figure 24 description being selected circuit 31 that shown optimal filter coefficients is selected circuit 31, difference is that frequency interpolation circuit 54 equals Tu/3[second according to the width that provides the test coefficient that comes to passband from controller 51] the center of passband of interpolation filter adjust, and carry out frequency interpolation and process.
In addition, optimal value selects circuit 57 to select optimal filter based on the result of the test of all patterns, and the coefficient of center that will represent the passband of this optimal filter outputs to frequency interpolation circuit 32.
In addition, optimal value selects circuit 57 also to export the information of the center of the passband that represents optimal filter.Select this information of circuit 57 outputs to be imported into from optimal value and postpone overview estimating circuit 10.
Delay overview estimating circuit 10 shown in Figure 31 comes the estimated delay overview based on the time orientation characteristic estimating data come being provided from time orientation transmission line property estimating circuit 8-2 and selecting circuit 31 to offer the information of center of passband of its representative optimal filter from optimal filter coefficients.
Figure 33 A to 33D shows postponing the estimation of overview.
Equally, Figure 33 A shows and has three paths P, Q and R.
Postpone 10 pairs of time orientation characteristic estimating of overview estimating circuit market demand IFFT and determine to postpone overview.According to the characteristic of IFFT, the path is reflected every Tu/3 and is occurred once, and wherein Tu/3 is the inverse of the distance (referring to Fig. 2) between the SP signal, shown in Figure 33 B.
Although the configuration of the expected path that goes out from the whole path extraction in the path that comprises reflecting component is to postpone overview, if but only check the result of IFFT, then postpone overview estimating circuit 10 and can not judge that the path R ' that is positioned at before the path P is path or the Actual path of reflecting component.
Therefore, need a kind ofly be used to judging the whether countermeasure in the path of reflecting component of every paths, and the center of the passband of optimal filter is used as this judgement.
As mentioned above, if be not that all paths all are included in the passband of interpolation filter, then the OFDM frequency-region signal behind the distortion compensation does not have satisfied quality.
In addition, the path of non-existent reflecting component is included in the situation in the passband of interpolation filter actually, and the OFDM frequency-region signal does not have satisfied quality yet.
In other words, caused selecting not path with any reflecting component to be included in interpolation filter in its passband to the selection of optimal filter.Considered and in the passband of optimal filter, comprised all in esse paths but the path that does not comprise reflecting component.
This is delayed overview estimating circuit 10 and is used for the estimated delay overview.
Particularly, postpone the path (as Figure 33 C shown in) of overview estimating circuit 10 deletions except those paths in the scope from-Tu/6 to+Tu/6 around the position identical with the center of the passband of optimal filter, thereby extract this expected path shown in Figure 33 D.The configuration in the path of Figure 33 D is identical with the configuration of the Actual path shown in Figure 33 A.
The center of the passband by utilizing in this way optimal filter, can prevent the following wrong understanding to the time relationship in path: although in fact signal arrives the earliest along a paths, there is another paths but but judge, more early arrives along this signal of this path.In the situation of the time relationship of correctly recognizing the path, can strengthen the accuracy of the estimated result that postpones overview.
Although available hardware is carried out above-mentioned processing sequence, also available software is carried out separately.In carry out these situations of processing sequence with software, the program that consists of this software can is installed in the computer that is attached to the specialized hardware from program recorded medium or for example in the general purpose personal computer, general purpose personal computer can be carried out various functions by various programs are installed.
Figure 34 shows an example of hardware configuration of carrying out the computer of above-mentioned processing sequence according to program.
Referring to Figure 34, the computer that illustrates comprises by bus 74 CPU connected to one another (CPU) 71, read-only memory (ROM) 72 and random access memory (RAM) 73.
In addition, input/output interface 75 is connected to bus 74.The input block 76 that comprises keyboard, mouse, microphone etc., the output block 77 that comprises display unit, loud speaker etc., the memory unit 78 that is formed by hard disk drive, nonvolatile memory etc., the communication component 79 that is formed by network interface etc., and the driver 80 that is used for driving the removable media 81 such as CD or semiconductor memory all is connected to input/output interface 75.
In the computer of above-mentioned configuration, CPU 71 is loaded among the RAM 73 by the program that input/output interface 75 and bus 74 will for example be stored in the memory unit 78, and carries out this program and carry out above-mentioned processing sequence.
The program that CPU 71 carries out is to be provided in the state that is recorded in the removable media 81, perhaps be provided by wired or wireless transmission medium such as local area network (LAN), internet or digital broadcasting, and be installed in the hard disk drive that is built in the memory unit 78.
Note, can be performed according to time sequencing according to disclosed order among the application by the program that computer is carried out, perhaps can walk abreast or for example when being called, be performed according to the timing of necessity.
Although utilize particular term to describe the preferred embodiments of the present invention, this description is to be understood that to make in the situation of the spirit and scope that do not break away from appended claims to change and change for illustration purpose.
The application comprises the theme with disclosed Topic relative in following application: the Japan that submitted to the Japan special permission Room on September 26th, 2008 is patent application JP 2008-247909 formerly, and the Japan that submitted to the Japan special permission Room on February 29th, 2008 patent application JP 2008-049890 formerly, the full content of these applications is incorporated herein by reference.
Those skilled in the art should be understood that can be depended on designing requirement and other factors and make various modifications, combination, sub-portfolio and change, as long as they drop within the scope of claims or its equivalent.

Claims (11)

1. receiving equipment comprises:
Extraction element is used for extracting pilot signal from the OFDM frequency-region signal;
The transmission line property estimation unit is used for estimating transmission line property based on the described pilot signal of being extracted by described extraction element at time orientation;
Interpolating apparatus, be used for to utilize a plurality of interpolation filters with the filter wave band that differs from one another, based on carrying out the interpolation processing of on frequency direction, transmission line property being carried out interpolation by the transmission line property on the estimated time orientation that goes out of described transmission line property estimation unit, thereby produce a plurality of signals of the transmission line property that represents all subcarriers;
Compensation arrangement, the signal that is used for the transmission line property of all subcarriers of representative of producing based on described OFDM frequency-region signal with by described interpolating apparatus produces a plurality of signals through the transmission line distortion compensation of the component of the distortion that has removed the respective transmissions circuit;
Checkout gear is for detection of the quality of the described signal through the transmission line distortion compensation that is produced by described compensation arrangement; And
Choice device is used for selecting based on the detected result of described checkout gear the signal through the transmission line distortion compensation with best quality of the described signal through the transmission line distortion compensation that produced by described compensation arrangement.
2. receiving equipment according to claim 1, wherein, described interpolating apparatus comprises:
The first interpolating apparatus is used for utilizing the interpolation filter of the first filter wave band to carry out described interpolation processing; And
The second interpolating apparatus is used for utilizing the interpolation filter of the second filter wave band to carry out described interpolation processing; And
Described compensation arrangement comprises:
The first compensation arrangement is used for producing signal through the transmission line distortion compensation based on described OFDM frequency-region signal with by the signal that described the first interpolating apparatus produces; And
The second compensation arrangement is used for producing signal through the transmission line distortion compensation based on described OFDM frequency-region signal with by the signal that described the second interpolating apparatus produces.
3. receiving equipment according to claim 1, also comprise control device, this control device is used for the filter wave band of the interpolation filter that will be used by described interpolating apparatus is controlled, thereby change the filter wave band of the interpolation filter of described interpolating apparatus use, signal with the transmission line property that produces following all subcarriers of representative: based on these signals that represents the transmission line property of all subcarriers, produced the described signal through the transmission line distortion compensation of not selected by described choice device.
4. method of reseptance may further comprise the steps:
Extract pilot signal from the OFDM frequency-region signal;
Estimate transmission line property based on the described pilot signal of extracting at time orientation;
Utilization have the filter wave band that differs from one another a plurality of interpolation filters, carry out the interpolation processing of on frequency direction, transmission line property being carried out interpolation based on the transmission line property on the estimated time orientation that goes out, thereby produce a plurality of signals of the transmission line property that represents all subcarriers;
Based on the signal of described OFDM frequency-region signal with the transmission line property of all subcarriers of representative that produce, produce a plurality of signals through the transmission line distortion compensation of the component of the distortion that has removed the respective transmissions circuit;
Detect the quality through the signal of transmission line distortion compensation produce; And
Select a described signal through the transmission line distortion compensation with best quality in the signal of transmission line distortion compensation based on the testing result to the quality of described signal through the transmission line distortion compensation.
5. receiving equipment comprises:
Fast fourier transform mathematical operation device is used for the OFDM time-domain signal is carried out the fast fourier transform mathematical operation;
The pilot signal extraction element is used for the OFDM frequency-region signal extraction pilot signal that obtains from by carried out the fast fourier transform mathematical operation by described fast fourier transform mathematical operation device;
Estimation unit, be used for to estimate the characteristic of the transmission line corresponding with each described pilot signal and on time orientation the characteristic to described transmission line carry out interpolation, determine the transmission line property of every predetermined number subcarrier;
Control device, be used for width and center that control will be used for the passband of the interpolation filter that frequency interpolation processes, described frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and is carried out that filtering is next carries out interpolation to described transmission line property on frequency direction;
Interpolating apparatus, be used in width and center for the passband that changes described interpolation filter according to the OFDM frequency-region signal that represents prosign under the control of transmission line property at described control device of definite every predetermined number subcarrier, utilize described interpolation filter to carry out the transmission line property of determining all subcarriers be used to the processing of carrying out described frequency interpolation processing;
Distortion calibration device is used for utilizing the distortion of proofreading and correct the OFDM frequency-region signal of described representative prosign by the transmission line property of determined all subcarriers of described interpolating apparatus;
Calculation element is used for the quality that a plurality of OFDM frequency-region signals of distortion have been proofreaied and correct in calculating;
Choice device is used for selecting to obtain the interpolation filter that described OFDM frequency-region signal after the distortion correction shows an OFDM frequency-region signal of best quality based on the described quality that is calculated by described calculation element;
The variable coefficient interpolating apparatus, be used for to utilize the interpolation filter that for the width of passband and center, has with by the characteristic identical characteristics of the selected interpolation filter of described choice device to process carrying out frequency interpolation by the transmission line property of the determined every predetermined number subcarrier of described estimation unit, thus the transmission line property of definite all subcarriers; And
Balancer, thus be used for utilizing the transmission line property by determined all subcarriers of described variable coefficient interpolating apparatus to come the execution equilibrium is proofreaied and correct in the distortion of described OFDM frequency-region signal.
6. receiving equipment according to claim 5, wherein, described interpolating apparatus utilizes the bandwidth of passband and the described frequency interpolation of the concurrent execution of interpolation filter that the center differs from one another to process.
7. receiving equipment according to claim 5, wherein, described control device changes the center of the passband of described interpolation filter in following ranges: be centered close to signal in the mulitpath that form to postpone overview and arrive the earliest pre-position between a paths on institute edge and another paths that this signal arrives the institute edge recently, and extend round about half amount that equates with the width of the passband of described interpolation filter from described center.
8. method of reseptance may further comprise the steps:
The OFDM time-domain signal is carried out the fast fourier transform mathematical operation;
From the OFDM frequency-region signal extraction pilot signal that obtains by carrying out described fast fourier transform mathematical operation;
Estimate the characteristic of the transmission line corresponding with each described pilot signal and on time orientation the characteristic to described transmission line carry out interpolation, determine the transmission line property of every predetermined number subcarrier;
Control will be used for width and the center of the passband of the interpolation filter that frequency interpolation processes, and described frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and carried out that filtering is next carries out interpolation to described transmission line property on frequency direction;
For according to the OFDM frequency-region signal that represents prosign and when the transmission line property of definite every predetermined number subcarrier changes the width and center of passband of described interpolation filter, utilize described interpolation filter to carry out be used to the transmission line property of carrying out processing that described frequency interpolation processes and determine all subcarriers;
The distortion that utilizes the transmission line property of described all subcarriers to proofread and correct the OFDM frequency-region signal of described representative prosign;
Calculate the quality of the OFDM frequency-region signal of having proofreaied and correct distortion;
Select to obtain to show in the described OFDM frequency-region signal after the distortion correction interpolation filter of an OFDM frequency-region signal of best quality based on the described quality that calculates;
Utilization has interpolation filter with the characteristic identical characteristics of selected interpolation filter and comes that the transmission line property of described every predetermined number subcarrier is carried out described frequency interpolation and process for the width of passband and center, thereby determines the transmission line property of all subcarriers; And
The transmission line property that utilizes determined all subcarriers comes thereby the execution equilibrium is proofreaied and correct in the distortion of described OFDM frequency-region signal.
9. receiving equipment comprises:
Fast fourier transform mathematical operation device is used for the OFDM time-domain signal is carried out the fast fourier transform mathematical operation;
The pilot signal extraction element is used for the OFDM frequency-region signal extraction pilot signal that obtains from by carried out the fast fourier transform mathematical operation by described fast fourier transform mathematical operation device;
Estimation unit is used for estimating the characteristic of the transmission line corresponding with each described pilot signal and on time orientation described characteristic being carried out interpolation, to determine the transmission line property of every predetermined number subcarrier;
Control device, be used for the center that control will be used for the passband of the interpolation filter that frequency interpolation processes, described frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and is carried out that filtering is next carries out interpolation to described transmission line property on frequency direction;
Interpolating apparatus, be used in the center for the passband that changes described interpolation filter according to the OFDM frequency-region signal that represents prosign under the control of transmission line property at described control device of definite every predetermined number subcarrier, utilize described interpolation filter to carry out the transmission line property of determining all subcarriers be used to the processing of carrying out described frequency interpolation processing;
Distortion calibration device is used for utilizing the distortion of proofreading and correct the OFDM frequency-region signal of described representative prosign by the transmission line property of determined all subcarriers of described interpolating apparatus;
Calculation element is used for the quality that the OFDM frequency-region signal of distortion has been proofreaied and correct in calculating;
Choice device is used for selecting to obtain the interpolation filter that described OFDM frequency-region signal after the distortion correction shows an OFDM frequency-region signal of best quality based on the described quality that is calculated by described calculation element; And
Postpone the overview estimation unit, be used for to determine postpone overview, this delays overview be by in the path in the frequency domain that obtains against fast fourier transform by the market demand to representative transmission line property of the estimated every predetermined number subcarrier that goes out by described estimation unit, be included in and be centered close to and formed by the path in the predetermined frequency band of identical position, the center of the passband of the selected interpolation filter of described choice device.
10. receiving equipment according to claim 9, wherein, the width of described predetermined frequency band equals the width of the passband of described interpolation filter.
11. a method of reseptance may further comprise the steps:
The OFDM time-domain signal is carried out the fast fourier transform mathematical operation;
From the OFDM frequency-region signal extraction pilot signal that obtains by carrying out the fast fourier transform mathematical operation;
Estimate the characteristic of the transmission line corresponding with each described pilot signal and on time orientation, described characteristic is carried out interpolation, to determine the transmission line property of every predetermined number subcarrier;
Control will be used for the center of the passband of the interpolation filter that frequency interpolation processes, and described frequency interpolation is processed the transmission line property that is used for every predetermined number subcarrier and carried out that filtering is next carries out interpolation to described transmission line property on frequency direction;
For according to the OFDM frequency-region signal that represents prosign and when the transmission line property of definite every predetermined number subcarrier changes the center of passband of described interpolation filter, utilize described interpolation filter to carry out be used to the transmission line property of carrying out processing that described frequency interpolation processes and determine all subcarriers;
The distortion that utilizes the transmission line property of determined all subcarriers to proofread and correct the OFDM frequency-region signal of described representative prosign;
Calculate the quality of the OFDM frequency-region signal of having proofreaied and correct distortion;
Select to obtain to show in the described OFDM frequency-region signal after the distortion correction interpolation filter of an OFDM frequency-region signal of best quality based on the described quality that calculates; And
Determine to postpone overview, this delays overview be by in the path in the frequency domain that obtains against fast fourier transform by the market demand to the transmission line property that represents the estimated every predetermined number subcarrier that goes out, the path that is included in the predetermined frequency band that is centered close to the position identical with the center of the passband of selected interpolation filter forms.
CN 200910118314 2008-02-29 2009-02-27 Reception apparatus and reception method Expired - Fee Related CN101521652B (en)

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JP2008-049890 2008-02-29
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JP2008247909A JP4600559B2 (en) 2008-02-29 2008-09-26 Receiving device, receiving method, and program
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CN101095297A (en) * 2005-01-05 2007-12-26 Atc科技有限责任公司 Adaptive beam forming with multi-user detection and interference reduction in satellite communication systems and methods

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