CN101453238A - Differential midamble acquiring and frequency bias estimation for TDMA communication system - Google Patents

Abstract

The invention provides a system and a method for obtaining a middle lead code and estimating frequency deviation in a TDMA communication system. The system comprises a local middle lead code signal generator, a difference correlation device, a frequency deviation estimator, a frequency deviation compensator and a correlative device, wherein the local middle lead code signal generator is used for generating a local middle lead code signal sequence meeting the specific TDMA standard; the difference correlation device carries out difference sliding correlation on a receiving signal sequence and the local middle lead code signal sequence, takes the position of related coefficient peak value obtained as first middle lead code timing of the receiving signal sequence and outputs the related coefficient peak value and the first middle lead code timing; the frequency deviation estimator carries out frequency deviation estimation based on the first middle lead code timing and the related coefficient peak value and outputs the frequency deviation obtained through estimation; the frequency deviation compensator utilizes the frequency deviation obtained through estimation to compensate the receiving signal sequence and outputs the compensated receiving signal sequence; and the correlative device carries out sliding correlation on the local middle lead code sequence and the compensated receiving signal sequence, thereby obtaining second middle lead code timing of the receiving signal sequence more accurately.

Description

Leading sign indicating number in the difference of tdma communication system obtains and frequency offset estimating

Technical field

The present invention relates to TDMA (time division multiple access) communication system, obtain and frequency offset estimating for leading sign indicating number in obtaining regularly that (timing) carry out synchronously in the tdma communication system.

Background technology

In the tdma communication system, particularly extremely short and when sending with high bit rate at sending duration, successful transmission and reception in order to ensure burst need obtain accurate timing synchronously, otherwise will produce unacceptable adverse consequences and/or inefficiency between transmitting terminal and receiving terminal.In the prior art, usually by in lead obtaining of sign indicating number (midamble) and realize regularly synchronously, leading sign indicating number in described is the part of burst frame (burst frame).But, when because Doppler effect etc. when making that very big frequency deviation takes place carrier frequency, is led sign indicating number in being difficult to obtain.This makes the timing simultaneous techniques of frequency offset resistant become the key technology of this area.

The known technology of leading sign indicating number in many obtaining that exists.For example, the applying date be Chinese patent application that March 29, application number in 2006 are No.CN200610025177.2 disclose a kind of use slide relevant (sliding correlation) directly obtains to lead a yard duplicate (template) in this locality and the correlation peak of the signal that received, thereby the method for leading in the acquisition yard.But this method is not considered the frequency deviation factor, therefore, obtains if adopt this method to lead sign indicating number in carrying out, and then slight frequency deviation just will cause intolerable mis-behave, even lead sign indicating number in can causing can't obtaining at all.

Again for example, publication number be US 20060165128 U.S. Patent Application Publication a kind of at first in time domain and frequency domain, the search to lead a sign indicating number rough estimate regularly, the method for carrying out frequency offset estimating and correction then in obtaining.But the search in two territories needs very huge amount of calculation, and this makes and has increased the weight of the burden of system and increased system complexity.And, since utilize that this method obtains in lead sign indicating number and regularly have error, so that the frequency offset estimating of carrying out also exists than mistake based on this.

Summary of the invention

In view of the above problems, one object of the present invention is to provide a kind of sign indicating number of leading that is used for tdma system to obtain system, and it comprises: lead the coded signal generator in this locality, be used for generating this locality that meets specific T DMA standard and lead the coded signal sequence; The difference relevant apparatus, the received signal sequence that meets described specific T DMA standard that this device receives from the outside system and leading from this locality is led the coded signal sequence and is carried out difference and slide relevant in this locality that the coded signal generator receives, the residing position of coefficient correlation peak value of getting relevant gained be the received signal sequence first in lead sign indicating number regularly, and export and lead sign indicating number in this coefficient correlation peak value and first regularly; Frequency offset estimator, its based on the difference relevant apparatus obtained first in lead sign indicating number regularly and the coefficient correlation peak value carry out frequency offset estimating, and the frequency deviation that obtains of output estimation; The compensate of frequency deviation device, its utilize the estimated frequency deviation that obtains of frequency offset estimator to come to received signal sequence compensates, and output is through the received signal sequence of compensate of frequency deviation; And relevant apparatus, this device to lead in this locality the coded signal sequence with slide from the described received signal sequence of compensate of frequency deviation device output through compensate of frequency deviation relevant, thereby obtain more accurately coefficient correlation peak value and received signal sequence second in lead sign indicating number regularly.

According to embodiments of the invention, can provide with lower amount of calculation more accurate frequency offset estimating and in lead sign indicating number regularly.In addition, described system can compensate the evaluated error of being introduced by timing error, thereby can overcome the timing error in the frequency offset estimation procedure.

According to the detailed description below in conjunction with accompanying drawing, above and other objects of the present invention, feature and advantage will become very clear.

Description of drawings

Fig. 1 is the frame structure schematic diagram of TD-SCDMA system;

Lead sign indicating number during Fig. 2 shows according to an embodiment of the invention and obtain block diagram with the frequency offset estimating system;

Fig. 3 is the theory diagram of the difference engine in the system shown in Figure 2;

Fig. 4 is the block diagram that the configuration of the frequency offset estimator in the system shown in Figure 2 is shown;

Fig. 5 leads sign indicating number in the difference to obtain flow chart with frequency deviation estimating method according to an embodiment of the invention;

Fig. 6 illustrates according to an embodiment to carry out the flow chart of the relevant method of difference to leading coded signal sequence and received signal sequence in this locality; And

Fig. 7 illustrates the flow chart that the received signal sequence after leading the coded signal sequence in this locality and compensating is carried out relevant method according to an embodiment.

Embodiment

Describe the present invention below in conjunction with the accompanying drawings and the specific embodiments.

The present invention is an example with the TD-SCDMA system, by obtain in the TD-SCDMA frame (with reference to figure 1) in lead sign indicating number and carry out timing synchronously, but the present invention equally also is applicable to other tdma system, for example GSM/GPRS/EGPRS.As shown in Figure 1, be the schematic diagram of the frame structure of TD-SCDMA system.The chip of TD-SCDMA system (chip) speed is 1.28Mcps, and the length of each frame is 5ms, i.e. 6400 chips.Each TD-SCDMA frame is divided into 7 time slot TS0～TS6 again; the length of each time slot is 0.675ms; i.e. 864 chips, being the data segment DATA1 of 352 chips and DATA2, length between data segment DATA1 and DATA2 comprising two segment length is the middle guiding code sequence of 144 chips and protection that last length is 16 chips G at interval.Lead sign indicating number in described and comprise that again it is the intermediate code section 102 of 112 chips with sign indicating number section 103 and length that length is 16 chips sign indicating number section 101 identical from one another.Sign indicating number section 103 is repetitions of sign indicating number section 101, and the existing tdma system of this characteristic all has.

Lead sign indicating number during Fig. 2 shows according to an embodiment of the invention and obtain block diagram with frequency offset estimating system 200.As shown in the figure, system 200 comprises: lead coded signal generator 201 in this locality, be used for making up and export this locality according to the TD-SCDMA standard and lead coded signal sample sequence c (n); Difference relevant apparatus 207, its to from the received signal sample sequence s (n) that meets the TD-SCDMA standard of outside with from this locality, lead this locality that coded signal generator 201 receives in lead coded signal sample sequence c (n) and carry out difference and slide relevant, the residing position of coefficient correlation peak value of getting relevant gained be among the received signal sequence s (n) in lead the original position (leading sign indicating number in hereinafter being called regularly) of sign indicating number, and export this coefficient correlation peak value and in lead sign indicating number regularly; Frequency offset estimator 204, be used for based on from difference relevant apparatus 207 output lead sign indicating number regularly and the coefficient correlation peak value come the estimating received signal sequence in the frequency deviation led yard, just the frequency deviation f of received signal sequence _Offset, and export the frequency deviation f that estimation obtains _OffsetCompensate of frequency deviation device 205 utilizes the frequency offset estimator 204 estimated frequency deviation f that obtain _OffsetCompensate received signal sequence s (n), and the received signal sample sequence s after the output compensation _c(n); And relevant apparatus 206, be used for the received signal sample sequence s that leads this locality that coded signal generator 201 receives after coded signal sequence c (n) and the compensation that receives from compensate of frequency deviation device 205 leading from this locality _c(n) slide relevantly, and search obtains the coefficient correlation peak value, thereby leads sign indicating number in obtaining more accurately regularly, that is, the residing position of coefficient correlation peak value, and export that this accurately obtains in lead sign indicating number regularly.

In one embodiment, received signal sequence s (n) is that the analog receiving signal that system receives is sampled by ADC and the complex signal sample sequence through obtaining after Hilbert (Hilbert) conversion, and its length is N.N general corresponding a whole at least Frame, suppose that the every chip-spaced hits of ADC is n _s(that is n, _sSamples/chip), N=6400 * n then _s(referring to Fig. 1).The complex signal sample is made up of I (homophase) baseband signal sample and Q (quadrature) baseband signal sample.

In lead coded signal sample sequence c (n) length be M, code length and sample rate calculate M according to leading in the tdma frame, leading code length in for example stipulating in the TD-SCDMA standard is 144chips, this moment, sample rate was n _sSamples/chip, then length M=144 * n of sample sequence c (n) _s

In one embodiment, difference relevant apparatus 207 comprises: the first difference engine 202a is used for to received signal that sample sequence s (n) carries out difference (conjugate multiplication of promptly delaying time will be described after a while), thereby obtains and output differential received signal sequence s _d(n); The second difference engine 202b is used for carrying out difference to leading coded signal sample sequence c (n) this locality of leading coded signal generator 20l reception from this locality, thereby leads coded signal sequence c in acquisition and the output difference _d(n); And correlator 203, its differential received signal sequence s to receiving from the first difference engine 202a _d(n) with the difference that receives from the second difference engine 202b lead coded signal sequence c _d(n) slide relevant, and search obtain the coefficient correlation peak value and corresponding in lead sign indicating number regularly, i.e. a differential received signal sequence s _d(n) lead the original position of sign indicating number in, and output should in lead sign indicating number regularly and a coefficient correlation peak value.Should understand, described coefficient correlation peak value is differential received signal sample sequence s _d(n) lead from described in that sign indicating number regularly begins with difference in lead coded signal sequence c _d(n) corresponding part is with leading coded signal sequence c in this difference _d(n) coefficient correlation of relevant gained.

Fig. 3 is the first and second difference engine 202a shown in Figure 2 and the theory diagram of 202b, and the first and second difference engine 202a and 202b are referred to as difference engine 202 here.As shown in the figure, difference engine 202 comprises: time-delay part 301, be used for input signal sequence is delayed time, and the length of hypothesis time-delay here is n _DThe pairing time of individual sample; Conjugate moiety 302 is used for the input signal through time-delay that receives from time-delay part 301 is asked conjugation; And multiplier 303, be used for original input signal sequence and the input signal through the time-delay conjugation that receives from conjugate moiety 302 are multiplied each other, thereby obtain and the output differential signal.Wherein, if wish to catch big as far as possible frequency deviation, then should make n _DAs much as possible little, but n _DThe too little performance that then can influence correlator subsequently, therefore, n preferably _DGet the sample number of a chip (being a symbol) in GSM/GPRS/EGPRS, for example, if sample rate n _sBe 4samples/chip, then n _D=n _s=1 * 4=4, accordingly, the time-delay length of difference engine 202 is chip (symbol) cycle.

Should be noted that the length through the received signal sample sequence s (n) of the first difference engine 202a has reduced n _D, that is to say s _d(n) length is N-n _DSimilarly, the length of leading coded signal sample sequence c (n) in this locality through the second difference engine 202b has also reduced n _D, that is, and c _d(n) length is M-n _DIn addition, should understand, calculus of differences can be converted to frequency deviation the phase place rotation, thereby can not be subjected to the influence of receiving signal frequency offset in related operation subsequently, and can try to achieve frequency deviation at an easy rate.

Below will the operation principle of correlator shown in Figure 2 203 be described in detail.The maximum timing error of the long W1 of the search window of correlator 203 for when system design, defining, and its initial phase off-position is changed to the position of triggering the pairing received signal sequence of ADC sampling instant, supposes differential received signal sequence s _d(n) n sample is relevant original position, then this moment differential received signal sequence s _d(n) lead the coefficient correlation of leading the relevant gained of coded signal sequence in the corresponding part of coded signal sequence and this difference and be in in the difference:

$R_d\left(n\right)=\frac{\underset{k=0}{\overset{M-n_D-1}{\mathrm{\Σ}}}{\left(c_d\left(k\right)\right)}^{*}\·s_d(k+n)}{\sqrt{\underset{k=0}{\overset{M-n_D-1}{\mathrm{\Σ}}}{c}_d^2\left(k\right)\·\underset{k=0}{\overset{M-n_D-1}{\mathrm{\Σ}}}{s}_d^2(k+n)}}...\left(1\right)$

With n+1 sample is that starting point repeats above-mentioned related operation to obtain R _d(n+1), the related operation of all samples (sampled point) and try to achieve corresponding coefficient correlation in finishing whole search window.Search obtains the maximum in all these coefficient correlations then, supposes that this maximum appears at sample n _DmaxThe place then leads regularly n of sign indicating number in correlator 203 outputs _DmaxAnd corresponding coefficient correlation peak value R _d(n _Dmax).n _DmaxIndicated differential received signal sequence s _d(n) lead the original position of sign indicating number in the difference in, its also can regard as among the received signal sequence s (n) in lead the original position of coded signal sequence.

The operation principle of the relevant apparatus 206 among Fig. 2 is similar to correlator 203, but, and the n that relevant apparatus 206 will obtain in correlator 203 _DmaxIndividual sample position is set to initial relevant position, and with n _DmaxWorst error be set to the long W2 of corresponding search window, the long W2 of the search window here is in general much smaller than the long W1 of search window of correlator 203.In addition, n _DmaxWorst error depend on the service behaviour of difference relevant apparatus 207, particularly, the time-delay n of the difference engine 202 in the difference relevant apparatus 207 _DThe more little then n of value _DmaxError big more, otherwise n _DBig more then n _DmaxError more little, secondly, the minimum work signal to noise ratio of requirement of system design is low more, then n _DmaxError just big more.In one embodiment, the long W1 of the search window of correlator 203 is ± 30 chips, and the search window length of relevant apparatus 206 equals n _DmaxWorst error ± 1 chip.

Suppose that the coefficient correlation that relevant apparatus 206 calculates is R (n), and hypothesis coefficient correlation peak value appears at n _MaxThe sample place, in one embodiment, relevant apparatus 206 is also to n _MaxThe power ‖ R (n of the coefficient correlation at sample place _Max) ‖ ²Compare with predetermined threshold, if judge ‖ R (n _Max) ‖ ²More than or equal to this threshold value, then can think and successfully lead sign indicating number in the acquisition, and this n _MaxBe exactly accurately obtain in lead sign indicating number regularly.Otherwise, if ‖ R is (n _Max) ‖ ²Less than this threshold value, lead sign indicating number in then and obtain failure.Wherein, described threshold value is the number between 0～1, and the selection of its occurrence is relevant with the minimum SNR of system, mainly obtains an empirical value by emulation and is used as this threshold value.The method that obtains this threshold value by emulation is well known in the art, does not give unnecessary details here.

Fig. 4 is the block diagram that the configuration of the frequency offset estimator 204 among Fig. 2 is shown.As mentioned above, frequency offset estimator 204 is based on the differential received signal sequence s of 207 outputs of the difference relevant apparatus from Fig. 2 _d(n) lead original position (in the lead sign indicating number regularly) n of sign indicating number in the difference in _DmaxWith corresponding coefficient correlation peak value R _d(n _Dmax) come the frequency deviation f of estimating received signal sequence _OffsetParticularly, as shown in Figure 4, frequency offset estimator 204 comprises thick frequency offset estimator 401, smart frequency offset estimator 402 and frequency offset processing device 403.At first, thick 401 couples of R of frequency offset estimator _d(n _Dmax) carry out arg[] computing, just ask plural R _d(n _Dmax) the phase place of radian form:

φ _dmax＝arg[R _d(n _dmax)]...(2)

φ wherein _DmaxValue between ± π.Those of ordinary skills should understand, according to φ _Dmax, be easy to just can obtain:

$f_{\mathrm{raw}}=\frac{f_s\·{\mathrm{\φ}}_{d\max }}{2\mathrm{\π}\·n_D}...\left(3\right)$

Wherein, f _sBe the ADC sample rate, unit is Hz.As seen, the frequency offset estimation range of this moment exists from formula (3)

Between, f _RawIt is thick frequency offset estimating value.

Then, carry out obtaining of accurate frequency bias by smart frequency offset estimator 402.As shown in Figure 1, the sign indicating number section 101 of leading sign indicating number among the TD-SCDMA is identical with sign indicating number section 103, sign indicating number section 101 and sign indicating number section 103 128 chips of being separated by.Based on the original position of leading sign indicating number among the difference relevant apparatus 207 resulting received signal sequence s (n), we can obtain among the s (n) with in lead the corresponding part of coded signal sequence c (n), just can find then in this part and sign indicating number section 101 and 103 corresponding two sign indicating number sections, respectively these two code segment tables are shown s here ₁₀₁(n) and s ₁₀₃(n).Suppose n _16chips=16n _s, n _128chips=128n _s, then can get:

s ₁₀₁(n)＝s(n)，n＝n _dmax，…，n _dmax+n _16chips-1...(4)

s ₁₀₃(n)＝s(n)，n＝n _dmax+n _128chips，…，n _dmax+n _128chips+n _16chips-1...(5)

By calculating s ₁₀₁(n) and s ₁₀₃(n) phase place poor just can estimate to obtain smart frequency deviation f _Fine:

$f_{\mathrm{fine}}\text{=}\frac{f_s\·\arg [\underset{n}{\mathrm{\Σ}}\left(s_{101}\left(n\right)\right)*\·s_{103}\left(n\right)]}{2\mathrm{\π}\·n_{128\mathrm{chips}}}$

$=\frac{f_s\·\arg [\underset{k=0}{\overset{n_{16\mathrm{chips}}-2n_{\mathrm{\Δ}}-1}{\mathrm{\Σ}}}{\left(s(n_{d\max }+n_{\mathrm{\Δ}}+k)\right)}^{*}\·s(n_{d\max }+n_{128\mathrm{chips}}+n_{\mathrm{\Δ}}+k)]}{2\mathrm{\π}\·n_{128\mathrm{chips}}}...\left(6\right)$

Wherein, f _FineUnit be Hz; f _sBe the ADC sample rate, unit also is Hz; Arg[Z] be phase bit arithmetic to the radian form of plural Z, value is between ± π; n _△Be used for eliminating received signal sequence s (n) in lead the adverse effect that the code position evaluated error brings for smart frequency offset estimating, n _△Be to obtain in the following way: the n that obtains by correlator 203 in the time of at first can knowing difference signal (the workable minimum SNR (signal to noise ratio) of this system that defines during system design, corresponding with minimum SNR is exactly difference signal) by emulation and theory analysis _DmaxThe worst error that exists adds received signal intersymbol (ISI) degree of depth of crosstalking then, just can obtain final n _△For example, in one embodiment, n _DmaxWorst error be ± 1 chip, the ISI degree of depth of the TD-SCDMA signal that receives is 2 chips, then n _△=2+1=3 chip.

At last, the f that obtains by 403 pairs of thick frequency offset estimators 401 estimations of frequency offset processing device _RawEstimate the f that obtains with smart frequency offset estimator 402 _FineCarry out combined treatment.From formula (6) as can be seen, f _FineEstimation range exist

Between.But if frequency deviation drops on outside this scope, then there is the uncertainty of 2 π in the phase bit arithmetic of formula (6), and this will cause estimating existing between the frequency deviation that the frequency deviation that obtains and expectation obtain integral multiple

Difference, that is, and the expectation frequency deviation be

(L is an integer) rather than f _FineFortunately, as mentioned above, n _DUsually than n _128chipsLittle a lot, therefore can utilize f _RawFind the solution integer L, this utilizes f _RawThe method of finding the solution integer L document " FANG Xiaoqing; XU Peixia and LI Hui; " A New Phase-unwrapping MethodUsed in the Single Frequency Estimation; " ICSP2004 Beijing, Sept.2004 " etc. in have a detailed description, just repeat no more here.At last, can obtain the output of frequency offset estimator 204:

$f_{\mathrm{offset}}=f_{\mathrm{fine}}+\frac{f_s}{n_{128\mathrm{chips}}}\·\mathrm{round}[\frac{n_{128\mathrm{chips}}}{f_s}\·(f_{\mathrm{raw}}-f_{\mathrm{fine}})]...\left(7\right)$

Wherein, round[a] be rounding up of real number a.From formula (7) f as can be seen _OffsetEstimation range and f _RawIdentical, also drop on

Between, but f _OffsetEstimated accuracy and f _FineIdentical.

Lead sign indicating number during Fig. 5 shows according to an embodiment of the invention and obtain flow chart with frequency deviation estimating method.Symbolic representation with Fig. 2 identical implication identical employed in figure 5 with Fig. 2.In step 501, generate according to the TD-SCDMA standard and to lead coded signal sample sequence c (n) in this locality.

In step 502, the received signal sequence s (n) that led coded signal sequence c (n) during step 501 generated and meet the TD-STDMA standard is carried out the difference related operation, and search obtains the coefficient correlation peak value, get the residing position of this peak value and be among the received signal sequence s (n) in lead sign indicating number regularly.

Fig. 6 shows according to an embodiment and carries out the flow chart of the relevant method of difference to leading coded signal sequence c (n) and received signal sequence s (n) in this locality.Described method is from step 601, in this step, carries out calculus of differences (the time-delay conjugate multiplication, time-delay length is n leading coded signal sequence c (n) (length is M) in this locality _D), lead coded signal sequence c thereby generate in the difference _d(n), its length is M-n _DThen, in step 602, sequence s (n) (length is N) carries out the calculus of differences identical with step 601 to received signal, thereby generates differential received signal sequence s _d(n), its length is N-n _D

In step 603, to leading coded signal sequence c in the difference that in step 601, generates _d(n) the differential received signal sequence s that generates and in step 602 _d(n) slide relevant (for example, the performed operation of first relevant apparatus 203 shown in Figure 2).Particularly, the position of at first triggering the pairing received signal sequence of ADC sampling instant is set to initial relevant position; Secondly, the maximum timing error of system is set to the long W1 of search window of associative operation; Slide relevant based on set initial relevant position and the long W1 of search window then and calculate the coefficient R at each sample position place _d(n), thus lead sign indicating number regularly in the search.Then, processing advances to step 604.

In step 604,, can search for and obtain coefficient correlation peak value R based on the coefficient correlation at each sample position place that step 603 calculated, in the search window _d(n _Dmax) and residing position n _Dmax(in lead sign indicating number regularly).Wherein, n _DmaxIndicated differential received signal sequence s _d(n) lead the original position of sign indicating number in the difference in, its also can regard as among the received signal sequence s (n) in lead the original position of coded signal.Then, described method finishes.

Turn back to Fig. 5, in step 503, what carry out is that frequency offset estimating is handled.At first, try to achieve the coefficient correlation peak value R that in step 502, obtains _d(n _Dmax) phase _Dmax, then according to φ _DmaxCalculate thick frequency deviation value f _Raw(with reference to formula 3), the frequency offset estimation range of this moment exists

Between.Then, according to the identical characteristic of the sign indicating number section 101 of leading sign indicating number among the TD-SCDMA and sign indicating number section 103 (participate in Fig. 1, sign indicating number section 101 and sign indicating number section 103 be separated by 128 chips), based in step 502, detect among the received signal sequence s (n) that obtains in lead a regularly n of sign indicating number _DmaxFind sign indicating number section 101 and sign indicating number section 103, by calculating sign indicating number section s ₁₀₁(n) and s ₁₀₃The phase place of each respective sample (n) poor, and the phase difference of the gained that adds up, promptly

Can in the hope of in lead the sign indicating number accurate frequency bias f _Fine(with reference to formula 6), the frequency offset estimation range of this moment exists Between.At last, for big frequency deviation being estimated accurately through type (7) is to f _RawAnd f _FineMerge, thereby obtain final frequency deviation f _Offsetf _OffsetEstimation range and f _RawIdentical, but f _OffsetBut have and f _FineIdentical estimated accuracy.The operation of step 503 leaves it at that, and handles to advance to step 504.

In step 504, utilize the estimated frequency deviation f that obtains of step 503 _OffsetCompensate received signal sequence s (n), thus the received signal sequence s after being compensated _c(n):

$s_c\left(n\right)=s\left(n\right)\·\exp (-2\mathrm{\π}\·\frac{f_{\mathrm{offset}}\·n}{f_s})...\left(8\right)$

Then, processing advances to step 505.

In step 505, to the received signal sequence s after the compensation of leading coded signal sequence c (n) in this locality that in step 501, generates and in step 504, obtaining _c(n) carry out related operation, thereby lead sign indicating number in obtaining more accurately regularly.

Fig. 7 show according to an embodiment to lead in this locality coded signal sequence c (n) and the compensation after received signal sequence s _cThe flow chart of the method for (n) being correlated with (for example, the performed operation of relevant apparatus shown in Figure 2 206).Described method is from step 701, in this step, with above-mentioned n _DmaxThe residing position of individual sample is set to the original position of associative operation; In step 702, with n _DmaxWorst error be set to the long W2 of search window of associative operation, in general W2 is much smaller than W1 (as mentioned above); In step 703, utilize in the step 701 the long W2 of search window that is provided with in the initial relevant position that is provided with and the step 702 come to lead coded signal sequence c (n) in this locality and compensate after received signal sequence s _c(n) coefficient R (n) of sliding and being correlated with and calculating each sample position place in the search window.Then, processing advances to step 704.

In step 704,, can search for and obtain coefficient correlation peak value R (n based on the coefficient correlation of each position in the search window that step 703 calculated _Max) and residing position n _Max(that is leading sign indicating number, regularly).Then, in step 705, judge ‖ R (n _Max) ‖ ²Whether more than or equal to predetermined threshold (as mentioned above).If ‖ R is (n _Max) ‖ ²Less than described threshold value, it illustrates that leading sign indicating number in this obtains failure, then handles the step 502 that turns back among Fig. 5, and leads a yard acquisition process in restarting.If ‖ R is (n _Max) ‖ ²More than or equal to described threshold value, lead sign indicating number in its explanation and obtain success, then handle advancing to step 706, lead regularly n of sign indicating number during output is accurately obtained in step 706 _Max, promptly among the received signal sequence s (n) in lead a yard original position (n _MaxCompare nd _MaxMore accurate).So far, described method finishes.

Obtain and the frequency offset estimating System and method for according to leading sign indicating number in the aforesaid difference, in difference is relevant, lead the coded signal sequence at first to received signal in sequence and this locality and carry out difference, then to lead in differential received signal sequence and difference this locality the coded signal sequence slide relevant, thereby obtain in the received signal in lead sign indicating number regularly.But, alternately, can be by leading coded signal sequence conjugate multiplication in received signal sequence and this locality, the result to the conjugate multiplication gained carries out difference then, and the burst that obtains after the difference added up the coefficient R in this accumulated value and said system and the method _d(n) be equivalent.

It will be understood by those skilled in the art that the system and the processing method of description can utilize the combination of hardware, software or hardware and software to realize in this manual.And, those that comprise that various processing in this manual are not limited to carry out in chronological order according to the description process are handled, and it can also be on demand or comes simultaneously or carry out above-mentioned various processing individually according to the disposal ability of the device that is suitable for realizing this processing.In addition, the system of mentioning in this manual comprises the logical set zoarium of being made up of multiple arrangement, and wherein, the device of forming each aggregate is not limited to be included in those devices in the same housing.

It will be understood by those skilled in the art that in the scope of claims or its equivalent and can carry out various modifications, combination, sub-portfolio and variation according to design needs or other factors.

Claims (22)

1. the sign indicating number of leading that is used for tdma system obtains system, comprising:

Lead the coded signal generator in this locality, be used for generating this locality that meets specific T DMA standard and lead the coded signal sequence;

The difference relevant apparatus, the received signal sequence that meets described specific T DMA standard that this device receives from the outside described system and leading from described this locality is led the coded signal sequence and is carried out difference and slide relevant in described this locality that the coded signal generator receives, the residing position of coefficient correlation peak value of getting relevant gained be described received signal sequence first in lead sign indicating number regularly, and export and lead sign indicating number in described coefficient correlation peak value and described first regularly;

Frequency offset estimator, be used for based on obtain by described difference relevant apparatus described first lead sign indicating number regularly and described coefficient correlation peak value carry out frequency offset estimating, and the frequency deviation that obtains of output estimation;

The compensate of frequency deviation device be used to utilize the frequency deviation that is obtained by described frequency offset estimator estimation to come described received signal sequence is compensated, and output is through the received signal sequence of compensate of frequency deviation; And

Relevant apparatus, this device is to leading the coded signal sequence and slide relevant from the described received signal sequence through compensate of frequency deviation of described compensate of frequency deviation device output by leading in described this locality in described this locality that the coded signal generator generates, thereby obtain more accurately coefficient correlation peak value and described received signal sequence second in lead sign indicating number regularly, and export and lead sign indicating number in described second regularly.

2. lead sign indicating number in as claimed in claim 1 and obtain system, wherein, described difference relevant apparatus comprises:

First difference engine is used for the received signal sequence of described system is carried out difference, and output differential received signal sequence;

Second difference engine is used for carrying out difference to leading the coded signal sequence in the described this locality of being led the generation of coded signal generator by described this locality, and leads the coded signal sequence in output difference this locality; And

Correlator, be used for sliding relevant in the hope of coefficient correlation to leading the coded signal sequence with the described difference this locality of exporting from described second difference engine from the described differential received signal sequence of described first difference engine output, and detect the peak value loca of the coefficient correlation tried to achieve, get then this peak value loca as described received signal sequence first in lead sign indicating number regularly, and export and lead sign indicating number in described first regularly and a described coefficient correlation peak value.

3. lead sign indicating number in as claimed in claim 2 and obtain system, wherein, be set to initial relevant position with triggering the corresponding position of ADC sampling instant in the described received signal sequence of described correlator, and the maximum timing error of system to be set to first search window long.

4. lead sign indicating number in as claimed in claim 3 and obtain system, wherein, lead sign indicating number in the described relevant apparatus described first and regularly be set to initial relevant position in a residing position, and leading yard worst error of timing in described first, to be set to second search window long.

5. lead sign indicating number in as claimed in claim 4 and obtain system, wherein, described first search window is grown up long in described second search window.

6. lead sign indicating number in as claimed in claim 1 and obtain system, wherein, described frequency offset estimator comprises:

Thick frequency offset estimator is used for based on the thick frequency deviation of estimating and export described received signal sequence from the described coefficient correlation peak value of described difference relevant apparatus output;

Smart frequency offset estimator is used for according to leading the smart frequency deviation that described received signal sequence is regularly estimated and export to sign indicating number by described first of described difference relevant apparatus acquisition; And

The frequency offset processing device is used for carrying out combined treatment from the described thick frequency deviation of described thick frequency offset estimator output with from the described smart frequency deviation of described smart frequency offset estimator output, and the frequency deviation of output after handling.

7. lead sign indicating number in as claimed in claim 6 and obtain system, wherein, described smart frequency offset estimator utilize lead in described first sign indicating number regularly find in the described received signal sequence in lead two same code sections of coded signal, and estimate the smart frequency deviation of described received signal sequence by the phase difference that calculates described two same code sections.

8. lead sign indicating number as in the claim 1 to 7 any one in described and obtain system, wherein, described relevant apparatus has set in advance a threshold value, and described coefficient correlation peak value that accurately obtains and described threshold value compared, if comparative result is that the described coefficient correlation peak value that accurately obtains is more than or equal to described threshold value, lead sign indicating number in then judging and obtain success, obtain failure, and detect again by described difference relevant apparatus and to lead sign indicating number in described first regularly otherwise lead sign indicating number in judging.

9. frequency deviation estimation device that is used for tdma system comprises:

Lead the coded signal generator in this locality, be used for generating this locality that meets specific T DMA standard and lead the coded signal sequence;

The difference relevant apparatus, the received signal sequence that meets described specific T DMA standard that this device receives from the outside described frequency deviation estimation device and leading from described this locality is led the coded signal sequence and is carried out difference and slide relevant in described this locality that the coded signal generator receives, the residing position of coefficient correlation peak value of getting relevant gained be described received signal sequence in lead sign indicating number regularly, and export described coefficient correlation peak value and described in lead sign indicating number regularly; And

Frequency offset estimator, be used for based on obtain by described difference relevant apparatus described lead sign indicating number regularly and described coefficient correlation peak value carry out frequency offset estimating, and the frequency deviation that obtains of output estimation, described frequency offset estimator comprises:

Thick frequency offset estimator is used for based on the thick frequency deviation of estimating and export described received signal sequence from the described coefficient correlation peak value of described difference relevant apparatus output;

Smart frequency offset estimator is used for according to the described yard smart frequency deviation of regularly estimating and export described received signal sequence of leading that is obtained by described difference relevant apparatus; And

The frequency offset processing device is used for carrying out combined treatment from the described thick frequency deviation of described thick frequency offset estimator output with from the described smart frequency deviation of described smart frequency offset estimator output, and the frequency deviation of output after handling.

10. frequency deviation estimation device as claimed in claim 9, wherein, described smart frequency offset estimator utilize lead in described sign indicating number regularly find in the described received signal sequence in lead two same code sections of coded signal, and estimate the smart frequency deviation of described received signal sequence by the phase difference that calculates described two same code sections.

11. frequency deviation estimation device as claimed in claim 9, wherein, described difference relevant apparatus comprises:

First difference engine is used for described received signal sequence is carried out difference, and output differential received signal sequence;

Second difference engine is used for carrying out difference to leading the coded signal sequence in the described this locality of being led the generation of coded signal generator by described this locality, and leads the coded signal sequence in output difference this locality; And

Correlator, be used for sliding relevant in the hope of coefficient correlation to leading the coded signal sequence with the described difference this locality of exporting from described second difference engine from the described differential received signal sequence of described first difference engine output, and the peak value loca that detects the coefficient correlation tried to achieve is as leading sign indicating number regularly in the described received signal sequence, and exports and lead sign indicating number in described regularly and a described coefficient correlation peak value.

12. yard acquisition methods of leading that is used for tdma system may further comprise the steps:

Generation meets the step of leading the coded signal sequence in this locality of specific T DMA standard;

The difference correlation step, carry out difference and slide relevant leading the coded signal sequence the received signal sequence that meets described specific T DMA standard that receives from the outside and described this locality, the residing position of coefficient correlation peak value of getting relevant gained be described received signal sequence first in lead sign indicating number regularly, and export and lead sign indicating number in described coefficient correlation peak value and described first regularly;

The frequency offset estimating step, based in described difference correlation step, obtain described first in lead sign indicating number regularly and described coefficient correlation peak value carry out frequency offset estimating, and the frequency deviation that obtains of output estimation;

The compensate of frequency deviation step utilize the frequency deviation that estimation obtains in described frequency offset estimating step to come described received signal sequence is compensated, and output is through the received signal sequence of compensate of frequency deviation; And

Correlation step, slide relevant to leading the coded signal sequence in described this locality with the described received signal sequence of in described compensate of frequency deviation step, exporting through compensate of frequency deviation, thereby obtain more accurately coefficient correlation peak value and described received signal sequence in lead sign indicating number regularly, in second, lead sign indicating number regularly, and export and lead sign indicating number in described second regularly.

13. lead a yard acquisition methods in as claimed in claim 12, wherein, described difference correlation step comprises:

The first difference step is carried out calculus of differences to described received signal sequence, thereby obtains the differential received signal sequence;

The second difference step is carried out calculus of differences to leading the coded signal sequence in described this locality, thereby obtains leading in difference this locality the coded signal sequence; And

The related operation step, slide relevant to leading the coded signal sequence in the described differential received signal sequence that in the described first difference step, obtains and the described difference this locality that in the described second difference step, obtains in the hope of coefficient correlation, and detect the peak value loca of the coefficient correlation tried to achieve, get then this peak value loca as described received signal sequence first in lead sign indicating number regularly, and export and lead sign indicating number in described first regularly and a described coefficient correlation peak value.

14. lead a yard acquisition methods in as claimed in claim 13, wherein, in described related operation step, be set to initial relevant position with triggering the corresponding position of ADC sampling instant in the described received signal sequence, and the maximum timing error of system to be set to first search window long.

15. lead a yard acquisition methods in as claimed in claim 14, wherein, in described correlation step, lead sign indicating number in described first and regularly be set to initial relevant position in a residing position, and a worst error of leading the sign indicating number timing in described first to be set to second search window long.

16. lead a yard acquisition methods in as claimed in claim 15, wherein, described first search window is grown up long in described second search window.

17. lead a yard acquisition methods in as claimed in claim 12, wherein, described frequency offset estimating step comprises:

Thick frequency offset estimating step is estimated the thick frequency deviation of described received signal sequence based on the described coefficient correlation peak value that obtains in described difference correlation step;

Smart frequency offset estimating step, according in described difference correlation step, obtain described first in lead the smart frequency deviation that sign indicating number is regularly estimated described received signal sequence; And

The frequency offset processing step is carried out combined treatment to described thick frequency deviation of estimating to obtain and the described smart frequency deviation that estimation obtains in described smart frequency offset estimating step in described thick frequency offset estimating step, thus the frequency deviation after obtaining handling.

18. lead a yard acquisition methods in as claimed in claim 17, wherein, in described smart frequency offset estimating step, utilize lead in described first sign indicating number regularly find in the described received signal sequence in lead two same code sections of coded signal, and estimate the smart frequency deviation of described received signal sequence by the phase difference that calculates described two same code sections.

19. lead a yard acquisition methods as in the claim 12 to 18 any one in described, wherein, in described correlation step, also comprise:

Set in advance the step of threshold value; And

The step that described threshold value and the described coefficient correlation peak value that accurately obtains are compared, if comparative result is that the described coefficient correlation peak value that accurately obtains is more than or equal to described threshold value, lead sign indicating number in then judging and obtain success, obtain failure otherwise lead sign indicating number in judging, and return described difference correlation step.

20. a frequency deviation estimating method that is used for tdma system may further comprise the steps:

Generation meets the step of leading the coded signal sequence in this locality of specific T DMA standard;

The difference correlation step, carry out difference and slide relevant leading the coded signal sequence the received signal sequence that meets described specific T DMA standard that receives from the outside and described this locality, the residing position of coefficient correlation peak value of getting relevant gained be described received signal sequence first in lead sign indicating number regularly, and export described coefficient correlation peak value and described in lead sign indicating number regularly; And

The frequency offset estimating step, based in described difference correlation step, obtain described in lead sign indicating number regularly and described coefficient correlation peak value carry out frequency offset estimating, it comprises:

Thick frequency offset estimating step is estimated the thick frequency deviation of described received signal sequence based on the described coefficient correlation peak value that obtains in described difference correlation step;

Smart frequency offset estimating step, according in described difference correlation step, obtain described in lead the smart frequency deviation that sign indicating number is regularly estimated described received signal sequence; And

The frequency offset processing step is carried out combined treatment to described thick frequency deviation of estimating to obtain and the described smart frequency deviation that estimation obtains in described smart frequency offset estimating step in described thick frequency offset estimating step, thus the frequency deviation after obtaining handling.

21. frequency deviation estimating method as claimed in claim 20, wherein, in described smart frequency offset estimating step, utilize lead in described sign indicating number regularly find in the described received signal sequence in lead two same code sections of coded signal, and estimate the smart frequency deviation of described received signal sequence by the phase difference that calculates described two same code sections.

22. frequency deviation estimating method as claimed in claim 20, wherein, described difference correlation step comprises:

The first difference step is carried out calculus of differences to described received signal sequence, thereby obtains the differential received signal sequence;

The second difference step is carried out calculus of differences to leading the coded signal sequence in described this locality, thereby obtains leading in difference this locality the coded signal sequence; And

The related operation step, slide relevant to leading the coded signal sequence in the described differential received signal sequence that in the described first difference step, obtains and the described difference this locality that in the described second difference step, obtains in the hope of coefficient correlation, and detect the peak value loca of the coefficient correlation tried to achieve, get this peak value loca then as leading sign indicating number in the described received signal sequence regularly.

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