CN102325105A - A kind of channel equalization method based on the threshold value sub-band division - Google Patents
A kind of channel equalization method based on the threshold value sub-band division Download PDFInfo
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- CN102325105A CN102325105A CN201110186267A CN201110186267A CN102325105A CN 102325105 A CN102325105 A CN 102325105A CN 201110186267 A CN201110186267 A CN 201110186267A CN 201110186267 A CN201110186267 A CN 201110186267A CN 102325105 A CN102325105 A CN 102325105A
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Abstract
The invention discloses a kind of channel equalization method based on the threshold value sub-band division; Comprise: because channel equalization error curve rate of convergence is relevant with signal autocorrelation matrix exgenvalue diffusance; Signal autocorrelation matrix exgenvalue diffusance is big more; Balancing error curve convergence speed is slow more, and balanced used filter weight coefficient upgrades slow more.Through sub-band division, each subband signal is reduced with respect to the autocorrelation characteristic value diffusance of full range band signal greatly, in each subband branch road, carry out equilibrium respectively then, to improve rate of convergence, fast updating filter weight coefficient makes weight coefficient reach optimum rapidly.The increase of number of sub-bands can make data processing amount increase, and takies multi-system resource; In addition, because sub-band division and merging are not complete ideal, carry out subband after subband signal is handled and merge; Number of sub-bands is many more, and signal after causing merging and the error of decomposing between preceding signal are big more.
Description
Technical field
The present invention relates to the comparatively serious wireless communication field of intersymbol interference, be specifically related to a kind of subband equalization methods that is used to eliminate intersymbol interference based on threshold value thought.
Background technology
In recent years, along with the raising of message transmission rate, the bandwidth of transmission signals constantly increases, and along with the increase of signal bandwidth, the probability that distortion takes place in the frequency band of signal frequency-selective channel will increase.At the receiving terminal of communication system, the frequency spectrum of signal more is prone to produce the deep fading, causes the frequency of signal to produce bigger fluctuations.When there was bigger fluctuations in signal spectrum, signal autocorrelation matrix exgenvalue diffusance will become big.When realizing channel equalization; Require the tap coefficient of channel equalizer more and more, this reduces the renewal rate of equalizer weight coefficient to a great extent, and the channel spectrum fluctuations is when bigger; Can further reduce convergence of algorithm speed again; Owing to above-mentioned two reasons, make that LMS algorithmic statement speed is very slow, performance reduces.
Using the sub-band division interface differential technique to collect mail number decomposes; Utilize the prewhitening effect of sub-band division; Reduce the autocorrelation matrix characteristic value diffusance of each subband signal, then each subband signal is carried out equilibrium respectively, realize that the purpose of the high rate of convergence of equalizer becomes a kind of method commonly used.
Chinese invention patent " frequency-domain equalizer of cutting apart based on subband "; Publication number 101340409 discloses a kind of balancing technique of cutting apart based on subband, has realized that subband to received signal cuts apart; Some subbands have been obtained; Remerge after in each subband, selecting to have the signal of optimal spectrum, combined signal has good spectral characteristic, has eliminated intersymbol interference; But this method is in the processing more complicated of selecting to have aspect the optimal spectrum signal, and the subband signal spectral characteristic after sub-band division not necessarily all possesses the condition of merging.
Summary of the invention
Problem to be solved by this invention is: in based on the equalizing system of sub-band division, introduce the sub-band division threshold condition; The decomposition number of restriction subband; Avoid the excessive decomposition of subband,, do not influence sub-band division post-equalization speed simultaneously in order to avoid take too much system resource.
Technical problem proposed by the invention is to solve like this: a kind of subband equalization methods based on threshold value thought is provided, it is characterized in that, may further comprise the steps:
A compares according to input signal characteristic value diffusance and setting threshold, surpasses to set threshold value, goes to the sub-band division stage, and signal is carried out sub-band division one time;
B compares according to input signal characteristic value diffusance and setting threshold, is not higher than when setting threshold value, and signal carries out balance stage, through iterative algorithm the equalization filter weight coefficient is upgraded.
Further, step is following:
Signal threshold value is state relatively, signal calculated autocorrelation matrix characteristic value diffusance, and compare with setting threshold, and comparative result is for greater than threshold value or be not more than threshold value;
At signal subband decomposing state, to use fully or be similar to complete reconfigurable filter signal is carried out the tree decomposition, produce the two-way subband signal each the decomposition;
At balance stage, use least mean square algorithm that the filter weight coefficient is upgraded.
A nearlyer step ground,
Requirement according to equalization filter weight coefficient renewal rate speed; Artificial or setting threshold automatically; Decomposition threshold is a numerical value, and its numerical value unit is same as input signal autocorrelation matrix diffusance, generally uses the percentage of signal autocorrelation matrix exgenvalue diffusion to represent; According to the threshold value comparative result, initialize signal is resolved into the plurality of sub band signal.
The resolution filter that sub-band division is used is complete reconstruct of two passages or approximate complete reconfigurable filter group, is input as one road signal, is output as two paths of signals, after each the decomposition, obtains two paths of signals by one road signal.
Complete reconfigurable filter; Be made up of analysis filterbank and composite filter group, analysis filtered resolves into plurality of sub band signal (being decomposed into two way band signals here) with one road input signal, and signal is through after the needed processing; Merge through the composite filter group; Signal before and after merging just differs a fixing multiple on amplitude, and relevant with a combined filter group exponent number in time time delay, and the bank of filters that adopts here is a FIR mirror filter group.
Signal adjustment: after the complete reconfigurable filter group in signal process N rank; There is delay in input signal in time with the output signal; Postpone relevant with filter order; And there is a fixing ratio in amplitude, therefore every through once decomposing and merging, need carry out suitable adjustment to the output and the input of bank of filters.
Merge: signal resolves into the plurality of sub band signal through analysis filterbank, in each branch road subband, signal is carried out the correlated equilibrium filter process, and each subband signal after will handling then is through the synthetic final signal of composite filter.Here the composite filter role is exactly the merging of subband signal.It is two input signals, an output signal.Decomposing and merging is the part of complete reconfigurable filter.
Beneficial effect of the present invention is: more existing balancing technique based on subband, can reduce the excessive decomposition of subband, and under less number of sub-bands, carry out equilibrium; Dwindle because the error that the subband excessive decomposition is brought; Reduce the taking of system resource reduced amount of calculation, guarantee the portfolio effect of using sub-band division to bring simultaneously again; Satisfy and save the speed that system resource can significantly improve the renewal of equalization filter weight coefficient simultaneously again, reach the purpose of real-time.
Description of drawings
Fig. 1 is the adaptive transversal filter sketch map as equalization filter;
Fig. 2 is to use the sketch map of the complete reconstruct quadrature mirror filter bank of secondary (PR-QMF banks);
Fig. 3 is a sub-band adaptive equalization filtering sketch map;
Fig. 4 is based on the balanced schematic flow sheet of sub-band adaptive of threshold value thought.
Embodiment
For making technical scheme of the present invention clearer, the present invention is further specified below in conjunction with accompanying drawing.
The inventive method embodiment comprises that input signal autocorrelation matrix characteristic value diffusance is estimated, setting threshold is confirmed the sub-band division structure, subband branch road adaptive equalization and subband signal merge, and is specific as follows:
1, adaptive equalizing filter is referring to Fig. 1.X among the figure (n) is the list entries signal, and d (n) is the training sequence signal, and y (n) is the output sequence signal of equalization filter, and e (n) is an error signal, e (n)=d (n)-y (n), and w (n) is the weight coefficient of equalization filter.
2, the weight coefficient of adaptive equalizing filter upgrades and uses the LMS algorithm, and this algorithm performance is stable, is easy to realize.Weight coefficient upgrades according to error feedback signal e (n), upgrades the result and makes error signal as far as possible little, that is: make equalization filter output signal y (n) and desired signal d (n) more approaching; The equalization filter weight coefficient of employing LMS algorithm more new formula is
; μ is a convergence factor, here
;
3, complete reconfigurable filter group, referring to Fig. 2, Fig. 2 is the sketch map that signal decomposition is become three way band signals, the structure in the empty frame is basic two passage sub-band division unit.
4, through after the sub-band division,, increase processing speed, before processing, data are carried out down-sampling, after handling, before subband signal merges, signal is carried out up-sampling for reducing data processing amount.
5, the setting of decomposition threshold, the threshold value that sets are a numerical value, and its numerical value unit is same as signal autocorrelation matrix diffusance, generally use the percentage of signal autocorrelation matrix exgenvalue diffusion to represent.Generally get below 1/2nd or 1/3rd of full range band signal autocorrelation matrix diffusance, make subband signal autocorrelation matrix characteristic value diffusance after the decomposition compare the full range band signal and reduce significantly.
6, based on the sub-band division of setting threshold thought, its method is following:
(1) input signal autocorrelation characteristic value diffusance estimated value and setting threshold are relatively; During greater than threshold value; Signal is carried out one time two passage sub-band division; Obtain the two-way subband signal, with two paths of signals autocorrelation matrix characteristic value once more when setting threshold value row relatively judge whether to carry out once more sub-band division;
(2) through after the sub-band division processing; Signal has delay on time domain, confirm the time delay line amplitude correction of going forward side by side, and the subband signal that need not decompose is carried out corresponding time delay; Here institute's time delay of doing and amplitude correction are in order to make the subband combined signal reach the result of anticipation;
7, Fig. 3 is for using the sketch map of sub-band division structure, and in the balancing procedure, input signal sequence x this moment (n) is identical with training sequence d (n).The sub-band division structure that they use is identical.Use the weight coefficient of LMS algorithm adjustment equalization filter, make signal x (n) obtain revising, make balanced output signal approach d (n), disturb the influence that brings between blanking code through signal after the intersymbol interference.
8, Fig. 4 is based on the balanced flow chart of sub-band adaptive of threshold value thought, and this flow chart may further comprise the steps
401: estimate input signal autocorrelation matrix characteristic value diffusance, setting threshold compares input signal autocorrelation matrix characteristic value diffusance and preset threshold, obtains two kinds of results, and the one, greater than preset threshold, the 2nd, be not more than preset threshold;
402: will carry out one time two passage sub-band division greater than the signal of setting threshold; Obtain subband signal, the signal that obtains repeated 401 and 402 go on foot, up to gained signal autocorrelation matrix exgenvalue diffusance be not more than set threshold value till; Be in two way signals of same level; If there is one road signal to be decomposed once more, when another road signal need not to decompose, road signal is wherein taked amplitude correction measure and necessary time delay.
403: the subband signal less than setting threshold that will obtain carries out the equilibrium treatment stage, adopts the LMS algorithm that weight coefficient is upgraded;
404: confirm the sub-band division filter bank structure, training sequence signal is decomposed with same sub-band division filter bank structure, decompose the sub band number that obtains similar number through the signal of intersymbol interference and desirable training sequence;
405: after each subband branch road equalization filtering, need use synthesis filter to merge processing to subband signal, finally generate one road signal, merging process and decomposable process be inverse process.
Claims (4)
1. the channel equalization method based on the threshold value sub-band division is characterized in that, may further comprise the steps:
A compares according to input signal characteristic value diffusance and setting threshold, surpasses to set threshold value, goes to the sub-band division stage, and signal is carried out sub-band division one time;
B compares according to input signal characteristic value diffusance and setting threshold, is not higher than when setting threshold value, and signal carries out equilibrium state, through iterative algorithm the equalization filter weight coefficient is upgraded.
2. the channel equalization method based on the threshold value sub-band division according to claim 1 is characterized in that:
At signal threshold value state relatively, signal calculated autocorrelation matrix characteristic value diffusance, and compare with setting threshold, comparative result is for greater than threshold value or be not more than threshold value;
At signal subband decomposing state, to use fully or be similar to complete reconfigurable filter signal is carried out the tree decomposition, produce the two-way subband signal each the decomposition;
In equilibrium state, use least mean square algorithm that the filter weight coefficient is upgraded.
3. the channel equalization method based on the threshold value sub-band division according to claim 1 and 2 is characterized in that:
According to the requirement of equalization filter weight coefficient renewal rate speed, artificial or setting threshold automatically, according to the threshold value comparative result, initialize signal is resolved into the plurality of sub band signal;
Subband minimal decomposition unit is complete reconfigurable filter, is input as one road signal, is output as two paths of signals, and every like this through once decomposing, one tunnel signal decomposition is two road signals.
4. the channel equalization method based on the threshold value sub-band division according to claim 2 is characterized in that:
Complete reconfigurable filter: form by analysis filterbank and composite filter group; Analysis filtered resolves into the plurality of sub band signal with one road input signal; Signal is through after the needed processing; Merge through the composite filter group, the signal before and after merging just differs a fixing multiple on amplitude, and relevant with a combined filter group exponent number in time time delay;
Signal adjustment: after the complete reconfigurable filter group in signal process N rank; There is delay in input signal in time with the output signal; Postpone relevant with filter order; And there is a fixing ratio in amplitude, therefore every through once decomposing merging, need carry out suitable adjustment to the output and the input of bank of filters;
Merge: signal resolves into the plurality of sub band signal through analysis filterbank, in each branch road subband, signal is carried out the correlated equilibrium filter process, and each subband signal after will handling then is through the synthetic final signal of composite filter.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105306396A (en) * | 2015-11-03 | 2016-02-03 | 西安烽火电子科技有限责任公司 | Optimization method for iterative equalization of wireless wideband communication channel |
| CN106161301A (en) * | 2015-03-30 | 2016-11-23 | 索尼公司 | Apparatus and method in wireless communication system and wireless communication system |
| CN106712836A (en) * | 2017-01-19 | 2017-05-24 | 清华大学 | Approximate precision reconstruction filter bank-based channelizer design method and apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101340409A (en) * | 2008-08-20 | 2009-01-07 | 中国电子科技集团公司第五十四研究所 | Frequency domain equalizer based on sub-band splitting |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101340409A (en) * | 2008-08-20 | 2009-01-07 | 中国电子科技集团公司第五十四研究所 | Frequency domain equalizer based on sub-band splitting |
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| Title |
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| 王鹏等: "用于宽带均衡的子带分解策略的分析", 《黑龙江科技信息》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106161301A (en) * | 2015-03-30 | 2016-11-23 | 索尼公司 | Apparatus and method in wireless communication system and wireless communication system |
| CN105306396A (en) * | 2015-11-03 | 2016-02-03 | 西安烽火电子科技有限责任公司 | Optimization method for iterative equalization of wireless wideband communication channel |
| CN105306396B (en) * | 2015-11-03 | 2018-11-09 | 西安烽火电子科技有限责任公司 | A kind of optimization method of wireless broadband communication channel iterations equilibrium |
| CN106712836A (en) * | 2017-01-19 | 2017-05-24 | 清华大学 | Approximate precision reconstruction filter bank-based channelizer design method and apparatus |
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