CN1286287C - Adaptive location method and device of autocorrelation sequence - Google Patents

Abstract

The present invention relates to a positioning method and a positioning device for the known autocorrelation sequence of a receiving signal in digital communication, which comprises an input signal storage, a correlator, a correlation value sequence storage, a search window controller and a correlation peak searcher, wherein the input signal storage stores a received signal sequence; the known self-adaptive sequence and the received signal sequence carry out correlation by the correlator and are successively shifted to obtain a correlation value sequence; the correlation value sequence is saved in the correlation value sequence storage; the search window controller controls the width of a search window for the judgment of reliability, and a search result is stored; the search window controller outputs the search result; according to the given width of the search window by the search window controller, the correlation peak searcher searches a maximum correlation peak and a secondary correlation peak in the correlation value sequence saved by the correlation value sequence storage. The present invention can effectively solve the problem looking for the position of an autocorrelation sequence under a multi-path condition. The present invention has the characteristics of accurate positioning and little false judgment possibility.

Description

Adaptive location method and device to autocorrelation sequence

Technical field

The present invention relates to the method that in the digital communication system autocorrelation sequence in the signal positioned, the method that known autocorrelation sequence in relating in particular in a kind of digital wireless communication to received signal positions the invention still further relates to a kind of positioner based on described method.

Background technology

In digital communication system, need in the signal that sends, to insert a known sequence with good autocorrelation performance, be convenient to receiver one side the information that receives is positioned, this locate mode is the technology that extensively adopts in radio communication and other communications fields; Wherein localization method can underdraw relevantly for using known autocorrelation sequence and the unknown nucleotide sequence that receives to be shifted one by one, by seeking maximum relevant peaks, determines the position of autocorrelation sequence in the unknown nucleotide sequence.But in radio communication, because wireless transmission, the signal that receives is actual to have comprised multipath and intersymbol interference, and relevant peaks can broadening like this, a plurality of peaks perhaps occur, searches for and just has certain difficulty.

In disclosed patent, the patent No. is that 95190253 " coherent detector and the coherence detection that are used for digital communication receiver " proposed using pilot signal estimation transfer function, use the transfer function of being estimated and carry out the interpolation coherent detection, the storage testing result is as dummy pilot signal, the method for estimating again for transfer function.The patent No. is the method that 95121337 " blind multipath corrections that are used for digital communication channel " propose to adopt a plurality of signal taps, and each tap response tap coefficient and time migration produce the digital output signal of multipath equilibrium.The patent No. is that 97103050 " synchronizers " propose to increase by second known mode in received signals.By the relevant treatment between first known mode and one second known mode, improve receiving the location.U.S. Pat 5402450: " signal time synchronously (Signal timing synchronizer) " proposes to adopt on the time independently second correlator, help to determine the influence of multipath signal, thereby realize accurate timing signal to auto-correlation function.More than these disclosed localization methods all have certain practicality, but all have the following disadvantages: most methods all claims to the coding and the modulation of signal, such as increase pilot signal, or increase by second known mode, this can only for example receive and dispatch at special equipment and be adopted by the equipment of same manufacturer production, for the equipment of producing according to industry standard, device fabrication person can't make an amendment to the coding and the modulator approach of standard; In addition, if adopt the method for a plurality of signal taps or a plurality of correlators, also can increase the cost and the complexity of equipment.

Summary of the invention

One object of the present invention is to provide a kind of adaptive location method of autocorrelation sequence, does not need the coding and the modulation of signal are made an amendment, and can handle effectively and under the multipath situation, seek the autocorrelation sequence position, accurate positioning, the erroneous judgement possibility is little; Another object of the present invention is, a kind of self adaptation positioner of the autocorrelation sequence based on said method is provided, and can make receiving system synchronous with emitter rapidly and accurately, improves receptivity, reduces the error rate.

Technical scheme provided by the invention is: a kind of localization method is provided, to be the sequence that will receive relevant one by one with known autocorrelation sequence obtains a series of correlation, when the maximum of search correlation, adopt adjustable length self-adapting window to search for, determine the threshold value of expression reliability of search result simultaneously according to characteristics of signals, in search procedure with Search Results and threshold, to obtain best Search Results.

The step of localization method is as follows:

The first step: use correlator, known self adaptation sequence and the sequence that receives are carried out relevant, in the position range that sequence may be in, be shifted one by one and obtain a sequence of correlation values, comprising:

From prime received signal sequence, store;

According to the composition of signal and possible transmission deviation, determine the position range that received signal is possible, known self adaptation sequence and burst are carried out related operation;

In possible position range,, repeated for the 2nd step, all calculate correlation up to all possible position with the whole sequence displacement.

Second step: according to the characteristics of received signal and transmission channel, the scope of relevant peaks width is known.

At first the search window width is set to initial value, may further comprise the steps:

The beginning that search window is placed sequence of correlation values,

Calculate correlation in the associated window the mould value and, be designated as E (0)

Associated window is moved 1 numeral backward, double counting mould value and, arrive the sequence end up to associated window;

E (n) sequence that record obtains is obtained maximum Em wherein;

According to pre-determined algorithm, judge whether present maximum meets the confidence level thresholding, meets the requirements, the autocorrelation sequence starting point that output searches, otherwise record confidence level.

The 3rd step: the search window width is changed, repeated for second step,, changeed for the 4th step if the various of search window may value all be attempted.

The 4th step: choose the highest search window Search Results of confidence level.

The 5th step: the autocorrelation sequence starting point that output searches.

The self adaptation positioner of autocorrelation sequence provided by the invention is made up of following components: input signal holder, correlator, sequence of correlation values holder, search window controller, relevant peaks searcher; The input signal holder stores the burst that receives get off, and uses for correlator; Correlator carries out known self adaptation sequence and the sequence that receives relevant, and in the position range that sequence may be in, displacement obtains a sequence of correlation values one by one; Preserving this sequence uses for the relevant peaks searcher in the sequence of correlation values holder; The search window controller is responsible for controlling the search window width that search is used, and the Search Results that uses each width to obtain is carried out confidence level judge, stored search result simultaneously, if the confidence level of neither one search window reaches thresholding, just select one the most believable.Controller is responsible for Search Results is exported simultaneously; The search window width that the relevant peaks searcher provides according to the search window controller, the maximum and time big relevant peaks of search in the sequence of correlation values that the sequence of correlation values holder is preserved.

Realize adaptive location method and the device to autocorrelation sequence provided by the invention, utilize the characteristics of the multi-path influence in the wireless transmission own, adopt adaptive approach search autocorrelation sequence position, realize signal Synchronization; The inventive method (the method and apparatus list is compared with method, does not have comparativity) is compared with existing method, does not need the coding and the modulation of signal are made an amendment; Can handle the problem of under the multipath situation, seeking the autocorrelation sequence position effectively, compare, have accurate positioning, the little characteristics of erroneous judgement possibility with common search relevant peaks method; The method and the device that adopt the present invention to propose can correspondingly also improve receptivity so that receiving system is synchronous with emitter rapidly and accurately, have reduced the error rate.Whole devices that the present invention simultaneously proposes can realize that implementation cost is low on original receiving equipment basis.

Description of drawings

Fig. 1 is the flow chart of localization method of the present invention;

Fig. 2 is the structured flowchart of the self adaptation positioner of autocorrelation sequence of the present invention;

Fig. 3 is the schematic diagram of relevant peaks broadening when having multi-path influence;

Fig. 4 is the search error schematic diagram of search window width during greater than actual relevant peaks;

Fig. 5 is the search error schematic diagram of search window width during less than actual relevant peaks;

Fig. 6 is the search error schematic diagram when existing two relevant peaks of being separated by bigger;

Fig. 7 is the flow diagram of self-adaptive search algorithm.

Embodiment

As shown in Figure 1, the step of localization method of the present invention is as follows:

From prime received signal sequence, store;

According to the composition of signal and possible transmission deviation, determine the position range that received signal is possible, known self adaptation sequence and burst are carried out related operation;

In possible position range,, repeated for the 2nd step, all calculate correlation up to all possible position with the whole sequence displacement.

Second step: according to the characteristics of received signal and transmission channel, the scope of relevant peaks width is known.

At first the search window width is set to initial value, may further comprise the steps:

The beginning that search window is placed sequence of correlation values,

Calculate correlation in the associated window the mould value and, be designated as E (0)

Associated window is moved 1 numeral backward, double counting mould value and, arrive the sequence end up to associated window;

E (n) sequence that record obtains is obtained maximum Em wherein;

According to pre-determined algorithm, judge whether present maximum meets the confidence level thresholding, meets the requirements, the autocorrelation sequence starting point that output searches, otherwise record confidence level.

The 3rd step: the search window width is changed, repeated for second step,, changeed for the 4th step if the various of search window may value all be attempted.

The 4th step: choose the highest search window Search Results of confidence level.

The 5th step: the autocorrelation sequence starting point that output searches.

As shown in Figure 2, positioner provided by the invention comprises input signal holder, correlator, sequence of correlation values holder, search window controller and relevant peaks searcher; The input signal holder receives the burst of prime and stores, and carries out related operation by correlator and known auto-correlation synchronizing sequence, and the sequence of correlation values that obtains leaves in the sequence of correlation values holder.

The search window controller is the core of whole device, is responsible for selecting current suitable search window width, is issued to the relevant peaks searcher, is searched for by the sequence of correlation values that the relevant peaks searcher is preserved the sequence of correlation values memory according to this search window width.Search Results is transmitted back to the search window controller by the relevant peaks searcher, and the search window controller is differentiated Search Results, determines whether next step adopts another window to search for.

Meet the threshold value requirement if the search window controller is differentiated certain Search Results, perhaps all windows have all attempted having determined later an optimum.Just search result corresponding is sent to back level processing unit.

For ease of localization method provided by the invention is described, the present invention defines the method for expressing of following burst:

The burst A0 (n) that needs transmission, n=0,1,2 ... N.

Sequence S (m) with good autocorrelation performance, m=0,1,2 ... M.

With the K position that S inserts A0, obtain a new sequence A (l), l=0,1,2 ..., L.L＝M+N。

A (i)=A0 (i) works as i=0 ..., K-1.

A (i)=S (i-K) works as i=K ..., K+M-1.

A (i)=A0 (i-(K+M)) works as i=K+M ..., M+N.

A (i) is actual sequence by Channel Transmission.

Receiver one side, the burst that receives is Y (j), j=0,1,2, J, J=L+TAM, TAM (time advance max) are that the time of reception of system's permission is poor, that is to say, the starting point of the actual correspondence position of useful sequence A (l) in Y (j) may be Y (0), Y (1) ... among the Y (TAM) one.

Introducing autocorrelation sequence S is exactly that clearly, the starting point of the correspondence position of S (m) in Y (j) should be Y (K) in order to address this problem ..., among the Y (K+TAM) one.

Utilize the autocorrelation performance of S (m), each possible among S (m) and the Y (j) corresponding sequence is carried out related operation, obtain sequence of correlation values X (p), p=0,1,2 ..., TAM.

X(0)＝S(0)*Y(K)+S(1)*Y(K+1)+…………+S(M)*Y(K+M)

X(1)＝S(0)*Y(K+1)+S(1)*Y(K+2)+…………+S(M)*Y(K+M+1)

X(2)＝S(0)*Y(K+2)+S(1)*Y(K+3)+…………+S(M)*Y(K+M+2)

………………………………

X(TAM-1)＝S(0)*Y(K+(TAM-1))+S(1)*Y(K+1+(TAM-1))+…………+S(M)*Y(K+M+(TAM-1))

X(TAM)＝S(0)*Y(K+TAM)+S(1)*Y(K+1+TAM)+…………+S(M)*Y(K+M+TAM)。

If the interference in not considering to transmit so only need be selected maximum X (TA)=Xmax in X (p), TA is exactly the physical location of S (m) so.

But, in the communication environment of reality, exist multipath and disturb, so X (p) not necessarily presenting well unimodally, maximal correlation is not a point, but the relevant peaks that a plurality of high value is formed.As shown in Figure 3, the width of relevant peaks is 6, if select maximum simply, may cause to be 6 error to the maximum.

Clearly, in order to obtain TA accurately under situation shown in Figure 3, reasonable method is to adopt the superposition value of several correlations of continuous adjacent.In the following description, the present invention is called one " window " with the position that the Several Parameters of continuous adjacent accounts for, and asks the method for TA to change into to obtain the left margin of mould value and maximum window.As shown in Figure 3, when window width was identical with the relevant peaks width, the inventive method was quite accurately.

But in most of the cases,, be difficult to determine in advance suitable search window width because the situation of wireless transmission environment is quite complicated.If the width of window width and the relevant peaks worth situation that differs, still may have error.

About above-mentioned error, can be furthermore bright in conjunction with the accompanying drawings:

Fig. 4 shows when the width of the search window situation greater than the relevant peaks actual size; The width of relevant peaks is 3 among the figure, is 6 search window and adopted size, and in this case, Search Results is actually by the noise size decision around the search peak.In the worst case, the error of TA can reach 3.

Fig. 5 shows when the width of the search window situation less than the actual size of relevant peaks; The width of relevant peaks is 6 among the figure, is 3 search window and adopted size, and in this case, Search Results is actually by the size decision of each point in the search peak; In the worst case, the error of TA also can reach 3.

Fig. 6 shows another special circumstances, and relevant peaks is split into two parts, and the distance at two peaks is bigger with respect to the width at peak; Specifically, if the width of search window is M0, and the distance of two relevant peaks is Md, if M0+Md＞TAM, just belong to this situation, please note in this case, can not exist an enough big search window (Breadth Maximum is TAM) to comprise this two relevant peaks simultaneously, also can mention this point in the back.

In general, if the width of search window is M0, the width of actual relevant peaks is M1, and the max value of error of TA is so | M0-M1|.

Eliminate this error, the best way is to adopt adaptive method to determine the width of search window, so just must find a kind of definite certain search window width whether to be suitable for the method for current relevant peaks.Be described in detail the positioning principle of this method below:

Still be example with situation shown in Figure 4, the position that the search window shown in the figure may draw is TA, TA-1, TA-2, TA-3 is on this several position, search window all can comprise whole relevant peaks, so specifically searches which position, only depends near the noise that relevant peaks is.These noises are compared with the search peak, and numerical value is very little.Like this, on above-mentioned several position, the result of search window should be more approaching, and simultaneously compared with other positions, it is bigger that the result then differs.

As shown in Figure 5, the position that search window may draw is TA, TA+1, TA+2, TA+3; On this several position, search window all can comprise the part of relevant peaks, so specifically searches which position, depends on the size of each point of inside of relevant peaks; Same, on these positions, the result of search window is more approaching, compares with other positions, it is bigger that the result then differs.

By top analysis, can draw the method whether a kind of definite current search window is suitable for current relevant peaks width.Just the accumulation result of search window in each position being compared, is not only the taking-up maximum, determines also that simultaneously whether this maximum compare with other accumulation result and have remarkable advantages.

Too complicated for fear of algorithm, can adopt a kind of like this method: when using some search window width to search for, not only write down maximum Xmax, write down second largest value Xmax2 simultaneously.After search finishes,, determine whether current search window width is suitable by whether observing Xmax significantly greater than Xmax2.

Further specify localization method of the present invention below in conjunction with flow diagram shown in Figure 7:

At first, search window controller initial search window is set to 1; Relevant peaks searcher initialization computing intermediate variable Xmax, Xmax2, T0, T02, K; Use search window then, along sequence search maximum and second largest value.

After search finishes, maximum, second largest value is kept at Xmax, and among the Xmax2, corresponding correlation position is left T0 in, among the T02.

The search window controller is judged above result, one of meets the following conditions, and stops search:

1, search window length has expanded maximum, just TAM to; The search window controller is in all Search Results, and a confidence level maximum of selection with corresponding T0 TA output as a result of.

If (Xmax, Xmax2)＞threshold value, (Xmax is exactly above-mentionedly to judge that whether maximum compare the function with clear superiority with second largest value Xmax2) to F1 to 2 F1 herein.Under general situation, can directly get F1 (Xmax, Xmax2)=| Xmax|/| as final result TA output, threshold value can obtain by the test to real system with T0 in the Search Results that satisfies condition for Xmax2|, search window controller.

3, M0+|T0-T02|＞TAM is corresponding to the be separated by situation of bigger relevant peaks of two of existence shown in Figure 6; The search window controller is exported T0 in the Search Results that satisfies condition as final result TA.

If above condition does not satisfy, the search window controller increases by 1 with search window length, is searched for by the relevant peaks searcher again.

If above condition satisfies, then search procedure finishes.

If above-mentioned required treatment step for using system, is not very important, also can adopt the method for simplification, dispense deterministic process to the 2nd, the 3 step.That is to say all the time all possible search window length is searched for, in all results, seek the highest result of confidence level then.

Adopt such method for simplifying, on the one hand can be so that the relatively work of the searching appropriate threshold of difficulty has been avoided in the easier realization of system.On the other hand, can guarantee that also the search window that finds is optimum.

Adopting the shortcoming of method for simplifying is if the value of TAM is bigger, needs the long time that all probable values are searched for, and increases the processing time.

Adopt method and apparatus provided by the present invention, can effectively exist multipath at wireless channel and pass In the defeated situation, accurately utilize the characteristic location of auto-correlation sequence, thereby realize that signal is synchronous. With Prior art is compared, and does not need special coding and modulator approach, has widely applicability; Simultaneously All device can by revising software or logic realization able to programme, provide cost savings.

Claims (3)

1, a kind of adaptive location method to autocorrelation sequence is characterized in that, comprises the steps:

1) use correlator, known self adaptation sequence and the sequence that receives are carried out related operation, in the position range that sequence may be in, displacement obtains a sequence of correlation values one by one;

2) according to the characteristics of received signal and transmission channel, in the scope of relevant peaks width, the search window width is set to initial value; Search window is placed the beginning of sequence of correlation values; Calculate correlation in the search window the mould value and, be designated as E (O); Search window is moved 1 numeral backward, repeat to measure the mould value and, arrive the sequence end up to search window; E (n) sequence that record obtains is obtained maximum Em wherein; According to pre-determined algorithm, judge whether present maximum meets the confidence level thresholding, if meet the requirements, directly export the autocorrelation sequence starting point that searches, otherwise the record confidence level;

3) change search window width, repeating step 2), if the various of search window may value all be attempted, choose the highest search window Search Results of confidence level;

4) export the autocorrelation sequence starting point that searches.

2, according to the adaptive location method of the described a kind of autocorrelation sequence of claim 1, it is characterized in that, comprise the steps: in the described step 1)

From prime received signal sequence and storage;

According to the composition of signal and possible transmission deviation, determine the position range that received signal is possible; Known self adaptation sequence and burst are carried out related operation;

In possible position range,, repeat related operation, all possible position is all calculated correlation the whole sequence displacement.

3, a kind of self adaptation positioner of autocorrelation sequence is characterized in that, comprises input signal holder, correlator, sequence of correlation values holder, search window controller and relevant peaks searcher; Described input signal holder stores the burst that receives get off, described correlator carries out relevant with the sequence that receives known self adaptation sequence, in the position range that sequence may be in, displacement obtains a sequence of correlation values one by one, and preserve this sequence and in the sequence of correlation values holder, use for the relevant peaks searcher, the width of described search window controller control search window, and the Search Results that each width obtains is carried out confidence level judge, while stored search result, controller is exported Search Results, the search window width that the relevant peaks searcher provides according to the search window controller, the maximum and time big relevant peaks of search in the sequence of correlation values that the sequence of correlation values holder is preserved.

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