CN107438040A - Leading symbol detects resolver and method - Google Patents
Leading symbol detects resolver and method Download PDFInfo
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- CN107438040A CN107438040A CN201610361958.2A CN201610361958A CN107438040A CN 107438040 A CN107438040 A CN 107438040A CN 201610361958 A CN201610361958 A CN 201610361958A CN 107438040 A CN107438040 A CN 107438040A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2656—Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2614—Peak power aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2662—Symbol synchronisation
- H04L27/2663—Coarse synchronisation, e.g. by correlation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2662—Symbol synchronisation
- H04L27/2665—Fine synchronisation, e.g. by positioning the FFT window
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2669—Details of algorithms characterised by the domain of operation
- H04L27/2671—Time domain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2669—Details of algorithms characterised by the domain of operation
- H04L27/2672—Frequency domain
Abstract
The invention provides a kind of leading symbol detection resolver and method, it is characterised in that including：Correlator, using the three-stage structure characteristic of leading symbol, to the frequency displacement of reception signal elder generation, front and rear correlation obtains correlation again；Peak detector, the peak value for searching for correlation calculate the rough position of leading symbol, and the phase angle of peak value correspondingly obtains fractional part of frequency offset value；Integer frequency offset and spectrum inversion discrimination module, characteristic is lifted using the effective sub-carrier power of the frequency domain of leading symbol, estimates the integer frequency offset and spectrum inversion characteristic of subcarrier spacing；The smart synchronization module of time domain timing, the data after removal frequency deviation are done with the exact position for synchronously obtaining leading symbol；Time-frequency domain decoder, the data after smart synchronization are decoded in time domain and frequency domain respectively；Signaling differentiates parsing module, parses signaling, if time-frequency domain decoding result is different, first signaling is differentiated and confirms that leading symbol decodes result again；If time-frequency domain decoding result is identical, show that leading symbol decodes result.
Description
Technical field
The present invention relates to preamble detecting, offset estimation and signaling information extraction in ofdm system, especially relate to
And the leading symbol detection means and method of a kind of DVB_T2 systems robust.
Background technology
European second generation Digital TV broadcasting standard for terrestrial《Digital Video Broadcasting
(DVB)；Frame structure channel coding and modulation for a second generation
digital terrestrial television broadcasting system(DVB-T2)》It is a kind of special to disclose
P1 symbols are as ofdm system frame head symbol, as shown in figure 1, leading symbol (is referred to P1 herein
Generation) using with frequency displacement circulation before and after sew structure C _ A_B structures.BBC is in patent document
The design advantage of P1 symbols is illustrated in 1:Do not disturbed, can resisted by serious continuous wave (CW)
" dangerous " multipath, is not influenceed by frequency deviation.P1 carries the Fourier change of signaling information instruction system simultaneously
(FFT) size is changed, protection interval (GI) scope is basic/to simplify (base/lite) pattern, single input list
Output/multiple input single output (SISO/MISO) pattern etc..
Leading symbol P1 uses suffix structures before the circulation with frequency displacement, and correlation is not by frequency deviation and continuous wave
The influence of interference, but under some multipath conditions, P1 detections still can fail.DVB-T2, which is realized, to be referred to
South《Digital Video Broadcasting(DVB)；Implementation guidelines for a second
generation digital terrestrial television broadcasting system(DVB-T2)》In P1 performances
It is 100% to show that P1 detects probability of failure under the multipath channel of two footpath constant amplitude opposite in phase in simulation result,
Signaling resolution probability of failure is 100%.Feelings of the patent document 2 in the case where not changing the fundamental characteristics of P1 structures
To realizing that the implementation method of guide has done two enhancings under condition, but signaling resolution does not make modification.P1
853 subcarriers are occupied in frequency domain, wherein 384 effective sub-carrier powers are higher, it is other untapped
Subcarrier is set to 0, as shown in Figure 2.Using this characteristic, can be with the frequency deviation of extraction system and identification frequency spectrum
No upset.The present invention proposes emphatically the P1 symbol detections and analytic method of a kind of robust, while increases frequency deviation
The scope of estimation, while whether the frequency spectrum of identifying system is overturn.
Prior art literature：
Patent document
Patent document 1：No. 200880024926.7 specification 101743731A of Chinese patent CN
Patent document 2：Chinese patent 201010196280.X specifications
Non-patent literature
[1]Digital Video Broadcasting(DVB)；Frame structure channel coding and
modulation for a second generation digital terrestrial television broadcasting
system(DVB-T2)；
[2]Digital Video Broadcasting(DVB)；Implementation guidelines for a second
generation digital terrestrial television broadcasting system(DVB-T2)。
The content of the invention
The present invention solves the problems, such as it is that leading symbol detects probability of failure under multipath channel in existing DVB-T2
It is low.
To solve the above problems, the embodiments of the invention provide a kind of leading symbol to detect resolver, bag
Include：Correlator is front and rear related again to the frequency displacement of reception signal elder generation using the three-stage structure characteristic of leading symbol
To correlation；Peak detector, the peak value for searching for correlation calculate the rough position of leading symbol, peak value
Phase angle correspondingly obtain fractional part of frequency offset value；Integer frequency offset and spectrum inversion discrimination module, utilization are leading
The effective sub-carrier power lifting characteristic of frequency domain of symbol, estimate the integer frequency offset and frequency spectrum of subcarrier spacing
Rollover characteristics；The smart synchronization module of time domain timing, the data after removal frequency deviation are done and synchronously obtain leading symbol
Exact position；Time-frequency domain decoder, the data after smart synchronization are decoded in time domain and frequency domain respectively；
Signaling differentiates parsing module, parses signaling, if time-frequency domain decoding result is different, first signaling is sentenced
Do not confirm that leading symbol decodes result again；If time-frequency domain decoding result is identical, show that leading symbol decodes
As a result.
Alternatively, wherein, the integer frequency offset estimation and spectrum inversion discrimination module include：Frequency domain
Carrier wave pretreatment unit：Amplitude limit is done to frequency domain exception subcarrier, removed with interior interference signal；Circulation is related
Unit：Consider spectrum inversion, related operation is replaced using Fourier and inversefouriertransform, to frequency domain
The processing of the pretreated signal of carrier wave and effective subcarrier obtains integer frequency offset estimation value.
Alternatively, wherein, integer frequency offset estimation and spectrum inversion discrimination module are run several times, every time
The leading symbol original position of selection is different.
Alternatively, wherein, the smart synchronization module of the time domain timing is confirmed before confirming while integer frequency offset
Lead symbol exact position.
Alternatively, wherein, the time-frequency domain decoder combination Time-domain decoding and decoding in frequency domain decode respectively,
Done during Time-domain decoding using the time domain related features and cross correlation and all leading symbols of leading symbol
Related realization Time-domain decoding；During decoding in frequency domain decoding in frequency domain is realized using frequency domain differential demodulation relevant way.
Alternatively, wherein, signaling differentiates parsing module to the decoding result different to time-frequency domain decoder
Do and confirm：First signaling is differentiated and confirms that leading symbol decodes result again.
Alternatively, wherein, signaling differentiates parsing module, Time-domain decoding and decoding in frequency domain is obtained leading
Symbol is related to the leading symbol sequence progress time domain received, obtains two groups of correlations, and search is any one
First three maximum of group correlation is summed and writes down the position of first three maximum, to another group of correlation pair
Answer three correlations of opening position to sum, compare size, the decoding result wherein corresponding to higher value is correct.
In addition, the embodiment of the present invention additionally provides a kind of leading symbol detection analytic method, including following step
Suddenly：Using the three-stage structure characteristic of leading symbol, to the frequency displacement of reception signal elder generation, front and rear correlation obtains correlation again；
The peak value for searching for correlation calculates the rough position of leading symbol, and the phase angle of peak value correspondingly obtains decimal frequency multiplication
Bias；Using the effective sub-carrier power lifting characteristic of the frequency domain of leading symbol, the whole of subcarrier spacing is estimated
Several times frequency deviation and spectrum inversion characteristic；Data after removal frequency deviation are done and synchronously obtain the accurate of leading symbol
Position；The data after smart synchronization are decoded in time domain and frequency domain respectively；Signaling is parsed, if time-frequency domain is translated
Code result is different, then first signaling is differentiated and confirm that leading symbol decodes result again；If time-frequency domain decodes
As a result it is identical, then show that leading symbol decodes result.
Compared with prior art, technical solution of the present invention has the advantages that：
Because resolver and method are detected according to leading symbol involved in the present invention, by robustly examining
The presence of header signal in DVB-T2 is surveyed, the characteristics of leading symbol P1 in itself is made full use of, accurately estimates
Frequency deviation value simultaneously identifies whether frequency spectrum overturns, and enters row decoding to P1 signalings in time-frequency domain respectively, and finally P1 is believed
Order is correctly parsed, and robust can be achieved detects leading symbol, and the scope of offset estimation is big, decoding
As a result more robust.
Brief description of the drawings
Fig. 1 is that leading symbol three-stage structure CAB structures are shown in DVB_T2 standards involved in the present invention
It is intended to；
Fig. 2 is the effective subcarrier of 8M system leading symbols point in DVB_T2 standards involved in the present invention
Butut；
Fig. 3 is leading symbol detection resolver schematic diagram in embodiment of the invention；
Fig. 4 is C_A_B correlator configurations schematic diagram in the present invention；
Fig. 5 is C_A_B peakvalue's checkings schematic diagram in the present invention；
Fig. 6 is the footpaths of 0db two that 1024 symbols are spaced in the present invention, the phase in Article 2 footpath respectively and
First footpath is identical, the C_A_B correlation figures under opposite one；
Fig. 7 is that once whole estimation partially and spectrum inversion identify schematic diagram in the present invention；
Fig. 8 is the synchronous schematic flow sheet of time domain essence in the present invention；
Fig. 9 is Time-domain decoding schematic flow sheet in the present invention；
Figure 10 is frequency domain decoding schematic flow sheet of the present invention；
Figure 11 is that decoding confirms schematic flow sheet in the present invention；And
Figure 12 is that leading symbol detects analytic method schematic diagram in the present invention.
Embodiment
It is understandable to enable the above objects, features and advantages of the present invention to become apparent, below in conjunction with the accompanying drawings
The embodiment of the present invention is described in detail.
It is an object of the invention to robustly detect the presence of DVB-T2 header signals, before making full use of P1
The characteristic of symbol in itself is led, frequency deviation value is accurately estimated and identifies whether frequency spectrum overturns, respectively in time-frequency domain
Row decoding is entered to leading symbol P1 signalings, finally leading symbol P1 signalings correctly parsed.
In the P1 symbol detection apparatus of the DVB_T2 system robusts of the present invention, C_A_B correlators are roots
Front and rear delay associative operation will be done after signal frequency shift according to the structure for the correlator announced in DVB_T2 standards,
After smoothing processing, it is multiplied after delay alignment, for finding leading symbol P1 signals and fractional part of frequency offset
Estimation.Frequency domain effective sub-carrier power of P1 symbols is utilized when integer frequency offset and spectrum inversion discrimination module
The integer frequency offset and frequency spectrum hair for lifting characteristic estimating 1K subcarrier spacings turn characteristic.Time domain timing essence is synchronous
Module is averagely got according to all P1 symbols (128 kinds of P1 that DVB-T2 agreements are used in this example)
Time domain related features accurately find P1 original positions, and then time domain and frequency domain decode to P1 symbols again
Completed by time-frequency domain decoder, because time-frequency domain decoding result is different, it is necessary to which signaling differentiates parsing module most
The confirmation that result is decoded to P1 is realized in judgement afterwards.
A kind of another object of the present invention, there is provided the leading symbol detection parsing of DVB_T2 systems robust
Method.The signal of reception is first done into C_A_B structures correlation, P1 substantially original position is found while estimates
Count fractional part of frequency offset；It is special using the effective sub-carrier power liftings of P1 in frequency domain in regional extent existing for P1
Property estimation 1K subcarrier spacings integer frequency offset and reversing spectrum characteristic, data are done after frequency deviation compensation again
Got according to 128 kinds of P1 Symbol averagesTime domain related features are utilized in substantially original position certain area
Accurate P1 original positions are found, P1 are decoded in time-frequency domain respectively after finding P1 exact positions, finally
Decoding result is done and confirmed.
Fig. 1 is leading symbol three-stage structure C_A_B structures in DVB_T2 standards involved in the present invention
Schematic diagram；
As shown in figure 1, in the present embodiment, leading symbol three-stage structure C_A_B structures, part A 1K
(1024) OFDM symbol, C portion pass through frequency displacement f by preceding 542 sampled points of part ASH(one
Individual subcarrier spacing) obtain；Part B is obtained by rear 482 sampled points of part A by frequency displacement.
In 8MHz systems, the duration of P1 symbols is 224us (totally 2048 sampled points).Part A
Duration be 112us, C and B duration be respectively 59us (542 sampled points) and 53us
(482 and sampled point).
Fig. 2 is the effective subcarrier of 8M system leading symbols point in DVB_T2 standards involved in the present invention
Butut；
As shown in Fig. 2 in the present embodiment, there are 853 available subcarriers in 1K symbols, wherein 384
Subcarrier be can use, and other are set to 0.In 8MHz systems, signal bandwidth be 7.61MHz (occupy 0~
852 subcarriers), there are 766 carrier waves in useful 6.83MHz bandwidth, first is 44, finally
One is 809.
Fig. 3 is leading symbol detection resolver schematic diagram in embodiment of the invention；
As shown in figure 3, the leading symbol detection resolver in the present embodiment includes C_A_B correlators 11,
Leading symbol peak detector 12, integer frequency offset and spectrum inversion discrimination module 13, time domain timing essence
Synchronization module 14, time-frequency domain decoder 15, signaling differentiate parsing module 16.
C_A_B correlators 11 are that above-mentioned DVB-T2 realizes classical architecture in guide [2], and its is basic
Structure is exactly front and rear correlation after frequency displacement.
Fig. 4 is C_A_B correlator configuration figures in institute of the invention；
As shown in figure 4, frequency deviation rotary module 11A is used to remove C sections and A sections in three-stage structure C_A_B
Frequency deviation, the first Postponement module 11E and the second Postponement module 11B, the 3rd Postponement module 11F, respectively
Corresponding delay length is 542,482 and 1024.The conjugation of first conjugate multiplication module 11C and second
Frequency deviation is eliminated the signal conjugate multiplication after delay alignment, the first moving average by multiplication module 11G respectively
Module 11D and the second moving average module 11H does moving average processing to the result of multiplier, passes through
11F is multiplied to obtain correlation Z after postponing 1024 symbols by multiplication module 11I.Z peak angle pair
Answer fractional part of frequency offset.
Fig. 5 is C_A_B peakvalue's checkings schematic diagram in the present invention；
As shown in figure 5, in the present embodiment, leading symbol P1 peak detectors 12 are to C_A_B correlations
Make a decision, the peak value for searching for P1 calculates P1 rough position, and the phase angle of peak value corresponds to fractional part of frequency offset.
Suitable threshold value is set, because the data dependence and noise of non-P1 symbols are consistent, numeral electricity
Depending on there is AGC automatic growth controls module can be by letter power adjusting to necessarily in terrestrial broadcast reception system
On power level, the correlation of data division is not influenceed by the receiving power and channel situation of reception signal,
Appropriate threshold can be set, correlation continuously is considered as detecting leading symbol P1 more than the part of threshold value,
Thresholding call number s is crossed in Z absolute value with last for first1And s2, pass through s1And s2Midpoint
The position that P1 symbols occur can be calculated, as shown in figure 5, P1 thick sync bit P1_coarse_index
By below equation (1) extrapolate for：
In the formula (1), Δ0It is empirical value (additional calculations delay), na=1024, nc=542
Fractional part of frequency offset value is extrapolated by below equation (2)：Can be according to N near peakfPoint
Phase angle average determines.
Wherein, z (i) is correlation result, as shown in figure 4,
Formula (1) is applied to awgn channel, C_A_B peak value under different multipath conditions amplitude and
Shape has very big difference, how to be exactly crucial by the presence and position of peakvalue's checking to P1.On
State DVB-T2 and realize that leading symbol P1 Performance Simulation Results show, two footpaths isometrical in 0dB in guide [2]
Postpone as (two footpath signal phases differ 180 degree) under 1024 symbols, P1 detection probabilities of failure
For 100%.
Fig. 6 is the footpaths of 0db two that 1024 symbols are spaced in the present invention, the phase in Article 2 footpath respectively and
First footpath is identical, the C_A_B correlation figures under opposite one；
As shown in fig. 6, be 1024,0dB intervals symbol two footpath channels under correlation, wherein, even
What continuous lines represented is symbol identical situation, and what dotted lines represented is the opposite situation of symbol, can be with
Find out, two footpath symbols are identical, the peak value of the C_A_B in the case that symbol is opposite, peak amplitude and shape
Shape has the opposite 0db channels of very big difference, particularly symbol, and the actual position in footpath is deviateed in the position of peak value
About 1000 symbols are put, integer frequency offset is done in the P1 positions obtained according to peak value can cause integer
The failure of times offset estimation, and then leading symbol P1 decoding failures.In addition to this special channels of Fig. 5,
Under other multipath channels, the scope that C_A_B correlations exceed threshold value is very wide, and the thick sync bits of P1 are forbidden.
In order to solve the problems, such as that the thick sync bits of P1 are inaccurate, it can must arrive position in formula (1) and move left and right one
Determine scope, attempt search P1 position, this search procedure is differentiated by integer frequency offset and spectrum inversion
Module 13, the smart synchronization module 14 of time domain timing are completed jointly.
Fig. 7 is that once whole estimation partially and spectrum inversion identify schematic diagram in the present invention；
In the present embodiment, as shown in Fig. 2 there was only 384 effective subcarriers in leading symbol P1, remain
469 subcarriers of remaininging are 0, and known to distribution.Local frequency domain sequence length is that 1024,384 sons carry
The position of ripple is 1, and its remaining sub-carriers is 0, as shown in fig. 7, by 13A steps to three in P1
A sections symbol (1024 points) in segment structure is FFT, and the frequency domain sequence shown in Fig. 2 does energy phase
Close, the position correspondence maximum frequency deviation of peak value.Consider to be likely to occur spectrum inversion simultaneously, effectively son carries
Ripple specular.As shown in fig. 7, in the present embodiment, found in peakvalue's checking
The thick sync bits of P1_coarse_index, take thick synchronization of the later data of fractional part of frequency offset with leading symbol
A segment signals in the C_A_B three-stage structures that position P1_coarse_index starts do integer frequency offset and estimated
Meter, fractional part of frequency offset compensation are similar to 11A modules.13B steps calculate the energy (I of each subcarrier2+Q2
Represent the quadratic sum of real and imaginary parts), it is contemplated that the influence with interior interference signal, 13C steps are to energy
Abnormal subcarrier does amplitude limit.Step 13F~13I realizes circulation associative operation using FFT mode,
Circulation is related to set rational cycle-index according to system frequency deviation scope, and FFT realizes that related mode avoids
This point.Step 13D and 13E are that spectrum inversion module is overturn, do not overturn.Step 13D
It is to ask for circulating correlation when frequency spectrum is not overturn with 13F~I, step 13E and 13F~I are to ask for frequency
Circulate correlation during spectrum inversion, in Fig. 7 for after 13E the step of content identical with 13F~I in figure
Omission is drawn, and step 13J searches for the maximum and subscript of correlation, and subscript correspond to whole inclined estimate.
Compare maximum, obtain spectrum inversion mark.The thick sync bit of subsequent leading symbol respectively
P1_coarse_index or so moves certain limit, in the present embodiment, mobile 1000 symbols.Repeat Fig. 7
Shown calculating process.Three groups of integer frequency bias, correlation and spectrum inversion mark are finally obtained,
Three groups of maximums are ranked up, obtain first two groups of integer frequency bias and spectrum inversion mark, if this two groups
Frequency deviation value it is consistent, second group of frequency deviation value is added 1.
Fig. 8 is the synchronous schematic flow sheet of time domain essence in the present invention；
Integer frequency offset and spectrum inversion discrimination module 13 have drawn two kinds of frequency deviation values, and time domain timing essence is synchronously
Module 14 is done to frequency deviation to be confirmed, while finds P1 exact position.As shown in figure 8, in 14A steps
After removing integral multiple and fractional part of frequency offset, in the P1 positions near zone essence that P1 peak detectors 12 obtain
Really search P1 positions, using the equal value sequence for eliminating the sequence after frequency deviation and all P1, used in this example
With the leading symbol average of 128 kinds of P1 defined in DVB-T2 agreements(Pk is
P1 sequences) correlation is done, the leading symbol averageThere is correlation with any P1 sequences, peak value is most
Big position correspondence P1 exact timing position.Comprising multipath as long as possible, P1 or so 1K are taken to accord with
Number amount to 4K data plus 3k symbol of ontology data, to the 4K data using FFT realize withPhase
Close, realize correlation computations using FFT/IFFT, process is as shown in Figure 8.In step 14A, several times are rounded
4K data are done by first group of frequency deviation and frequency deviation overturning mark in frequency deviation and spectrum inversion discrimination module 13
Frequency deviation compensation includes fractional part of frequency offset and integer frequency offset, if spectrum inversion, the data imaginary part after compensation takes
Instead.14B~14D replaces correlation computations with FFT/IFFT computings, and 14B is 4K's to the data for going frequency deviation
FFT, 14C do conjugate multiplication to two FFT sequences, one be frequency deviation data 4K length FFT sequences
Row, another isThe FFT sequences of 4K length；14D is IFFT to the conjugate multiplication result of 4K length
Obtain correlation；14E calculates the amplitude of correlation.Due to integer frequency offset and spectrum inversion discrimination module
13 have drawn two kinds of frequency deviation value differences, and correlation is influenceed by frequency deviation, and correct frequency deviation correlation is big, wrong
Correlation corresponding to frequency deviation small by mistake, and the maximum of two groups of correlations meets certain ratio condition, then recognizes
Correct for P1 peaks, offset estimation is correct, the same the end of the step of essence, the position correspondence of correlation maximum
P1 exact positions, C_A_B correlators can be stopped.Otherwise P1 peakvalue's checkings are done again, until
Smart synchronous result meets condition.
Fig. 9 is Time-domain decoding schematic flow sheet in the present invention；
Behind the position for accurately finding the mono- strong footpaths of P1, the autocorrelation peak of P1 symbols is very high, cross-correlation peak
It is worth relatively low, in the time domain related features and cross correlation using P1 symbols, and 128 kinds of P1 do
Correlation, peak value maximum correspond to real P1 sequences.Time-domain decoding can solve the problems, such as overlength multipath,
P1 sequence lengths are longer, and correlation is not influenceed by signal to noise ratio, and Time-domain decoding anti-noise ability is strong.But
Under many channel conditions in nearly footpath, because P1 cross correlation is poor, Time-domain decoding result is inaccurate.Frequency domain
Decoding use difference relevant way, can overcome the influence in nearly footpath, under overlength multipath channel, frequency domain load
More, the decoding in frequency domain poor performance of ripple decline.The advantages of time domain and frequency domain can be combined, decode respectively, if
It is identical to decode result, then it is successfully decoded, if time-frequency domain decoding result is different, it is necessary to be done really to decoding result
Recognize.
As shown in figure 9, in the present embodiment, the handling process bag of the Time-domain decoding in time-frequency domain decoder 15
Containing following steps：
Step 15A1：Take the signal (being compensated through overdeviation) and 128 of P1 symbol part As after the smart synchronization of timing
Kind P1 part A is correlation, step 15B1：Find the maximum of every kind of P1 correlations, step 15C1：
Judge whether correlation computations terminate, the related traversal of 128 kinds of P1 terminate after by step 15D1 compare this 128
Individual peak value, maximum correspond to correct P1 sequences.
Figure 10 is decoding in frequency domain schematic diagram, in the present embodiment, the decoding in frequency domain in time-frequency domain decoder 15
Handling process comprise the steps of：
Step 15A2 and step 15B2 obtains effective subcarrier sequence in 384 subcarriers of frequency domain extraction
Active_Seq, step 15C2 do difference to two neighboring subcarrier；Difference formula is Active_Seq (i+1)
* conj (Active_Seq (i), does difference, totally 128 difference sequences, 15D2 to the local effective subcarrier of P1 frequency domains
The difference sequence of reception is done to 128 difference sequences related, compare maximum, maximum correspond to correctly
P1 sequences by 15D2~15G2 complete.
Figure 11 is that decoding confirms schematic flow sheet in the present invention；
As shown in figure 11, in the present embodiment, if time-frequency domain decoding result is different, signaling discrimination module 16
Do that time domain is related by comparing two sequences to the P1 sequences received, according to the size of correlation, judge
Which kind of P1 decodings result is more reliable.Step 16A takes the P1 positioned after smart synchronization or so 1K data,
This partial data has compensated all frequency deviations, and the data after compensating for frequency offset are 4KFFT by step 16B, when
P1 sequences are 4KFFT corresponding to decoding in frequency domain, and the P1 sequences that time domain, decoding in frequency domain are drawn are done respectively
4KFFT；16C is by 16B result and two kinds of P1 4K frequency domain sequence conjugate multiplications, 16D pairs of step
4K sequence is IFFT after multiplication, obtains 4K correlations, the calculating of this process and timing essence synchronization
Journey is the same, is all to realize related operation using FFT and IFFT.Step 16E calculates the amplitude of correlator,
Respectively obtain that Time-domain decoding correlation is denoted as peak_td, decoding in frequency domain correlation is denoted as peak_fd.Step
16F searches for first three maximum of Time-domain decoding correlation peak_td and position, calculate first three maximum it
And peak_td_sum, the value of peak_fd at peak_td first three maximum value position is found, calculates these three
It is worth sum peak_fd_sum, step 16G compares peak_td_sum and peak_fd_sum sizes, big
Corresponding correctly decoding result.
Figure 12 is that leading symbol detects analytic method schematic diagram in the present invention.
As shown in figure 12, in the present embodiment, Figure 12 is the P1 symbol rates according to preferred embodiment of the present invention
Detection method schematic flow sheet.Start step S51 and C_A_B correlations are done to the signal received, then
Step S52 makes a decision to correlation, has detected whether peak value appearance, P1 is calculated if peak value is detected
Original position, according to the small several times estimation of deviation of the angle calculation of peak value.Obtain the rough original positions of P1
After fractional part of frequency offset, step S53 fractional part of frequency offset is compensated after P1 symbols select three it is different
The whole estimations partially of step S54 are done in position and spectrum inversion judges, the larger integer frequency of two groups of peak values before record
Inclined and spectrum inversion mark, confirm whether frequency deviation value and frequency spectrum overturn by S55 essences synchronization module, step
The synchronous peak value of S56 essences meets that condition then provides the accurate original positions of P1, otherwise detects C_A_B again
Peak value.Next step carries out time-frequency domain decoding by step S57, and step S58 judges whether decode result
Identical, if both decodings are consistent, leading symbol P1 detections terminate, and do signaling if inconsistent by S59 and sentence
Certainly, it is final to confirm decoding result.
Although the present invention is disclosed as above with preferred embodiment, it is not for limiting the present invention, appointing
What those skilled in the art without departing from the spirit and scope of the present invention, may be by the disclosure above
Methods and technical content makes possible variation and modification to technical solution of the present invention, therefore, every not take off
From the content of technical solution of the present invention, the technical spirit according to the present invention is made any to above example
Simple modification, equivalent variation and modification, belong to the protection domain of technical solution of the present invention.
Claims (8)
1. a kind of leading symbol detects resolver, it is characterised in that including：
Correlator, using the three-stage structure characteristic of leading symbol, to the frequency displacement of reception signal elder generation, front and rear correlation obtains again
Correlation；
Peak detector, the peak value for searching for correlation calculate the rough position of leading symbol, the phase angle pair of peak value
Fractional part of frequency offset value should be obtained；
Integer frequency offset and spectrum inversion discrimination module, carried using the effective sub-carrier power of the frequency domain of leading symbol
Characteristic is risen, estimates the integer frequency offset and spectrum inversion characteristic of subcarrier spacing；
The smart synchronization module of time domain timing, the data after removal frequency deviation are done with the accurate position for synchronously obtaining leading symbol
Put；
Time-frequency domain decoder, the data after smart synchronization are decoded in time domain and frequency domain respectively；
Signaling differentiates parsing module, parses signaling, if time-frequency domain decoding result is different, first signaling is carried out
Differentiation confirms that leading symbol decodes result again；If time-frequency domain decoding result is identical, show that leading symbol is translated
Code result.
2. leading symbol as claimed in claim 1 detects resolver, it is characterised in that
Wherein, the integer frequency offset estimation and spectrum inversion discrimination module include：
Subcarrier in frequency domain pretreatment unit：Amplitude limit is done to frequency domain exception subcarrier, removed with interior interference signal；
Circulate correlation unit：Consider spectrum inversion, related operation replaced using Fourier and inversefouriertransform,
Processing to the pretreated signal of subcarrier in frequency domain and effective subcarrier obtains integer frequency offset estimation value.
3. leading symbol as claimed in claim 2 detects resolver, it is characterised in that
Wherein, integer frequency offset estimation and spectrum inversion discrimination module are run several times, before choosing every time
Lead symbol original position difference.
4. leading symbol as claimed in claim 1 detects resolver, it is characterised in that
Wherein, the smart synchronization module of the time domain timing confirms to confirm leading symbol essence while integer frequency offset
True position.
5. leading symbol as claimed in claim 1 detects resolver, it is characterised in that
The time-frequency domain decoder combination Time-domain decoding and decoding in frequency domain decode respectively, before utilizing during Time-domain decoding
The time domain related features and cross correlation and all leading symbols for leading symbol do related realization time domain and translated
Code；During decoding in frequency domain decoding in frequency domain is realized using frequency domain differential demodulation relevant way.
6. leading symbol as claimed in claim 1 detects resolver, it is characterised in that
Wherein, signaling differentiates that parsing module does to the decoding result different to time-frequency domain decoder and confirmed：
First signaling is differentiated and confirms that leading symbol decodes result again.
7. leading symbol as claimed in claim 1 detects resolver, it is characterised in that
Signaling differentiates parsing module, the leading symbol that Time-domain decoding and decoding in frequency domain are obtained and before receiving
Lead symbol sebolic addressing and carry out time domain correlation, obtain two groups of correlations, searching for any one group of correlation, first three is individual most
Big value is summed and writes down the position of first three maximum, to three phases of another group of correlation corresponding position
Pass value summation, compares size, the decoding result wherein corresponding to higher value is correct.
8. a kind of leading symbol detects analytic method, it is characterised in that comprises the following steps：
Using the three-stage structure characteristic of leading symbol, to the frequency displacement of reception signal elder generation, front and rear correlation obtains correlation again；
The peak value for searching for correlation calculates the rough position of leading symbol, and the phase angle of peak value correspondingly obtains small several times
Frequency deviation value；
Characteristic is lifted using the effective sub-carrier power of the frequency domain of leading symbol, estimates the integral multiple of subcarrier spacing
Frequency deviation and spectrum inversion characteristic；
Data after removal frequency deviation are done with the exact position for synchronously obtaining leading symbol；
The data after smart synchronization are decoded in time domain and frequency domain respectively；
Signaling is parsed, if time-frequency domain decoding result is different, first signaling is differentiated and confirms leading symbol again
Decode result；If time-frequency domain decoding result is identical, show that leading symbol decodes result.
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| CN107438042A (en) | 2017-12-05 |
| CN107438042B (en) | 2020-09-29 |
| CN107438040B (en) | 2020-09-29 |
| CN107438043A (en) | 2017-12-05 |
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