CN104836769A - Combined timing and frequency synchronization method based on conjugated structure preamble - Google Patents

Abstract

The invention provides a combined timing and frequency synchronization method based on a conjugated structure preamble. The method comprises following steps: 1. calculating a correlated signal r0(n, d) of a reception signal r(n) and a preamble signal c(n); 2. obtaining a difference correlation signal p(m, d) through calculation; 3. performing weighted accumulation on the difference correlation signal p(m, d) so as to obtain a weighted correlation function P(d); 4. normalizing the weighted correlation function P(d) by the use of the energy of the reception signal in a sliding window so as to obtain a normalized timing metric value M(d); 5. working out the maximum of the normalized timing metric value M(d) so as to obtain a timing offset estimated value epsilon-hat according to a formula shown in the description; 6. calculating a carrier wave frequency offset estimated value xi-hat of a decimal part; 7. compensating the reception signal by the use of the carrier wave frequency offset estimated value xi-hat of the decimal part so as to obtain the compensated reception signal r1(n, epsilon-hat); 8. calculating a carrier wave frequency offset estimated value q-hat of an integer part by the use of the reception signal compensated according to decimal frequency offset; and 9. working out the carrier wave frequency offset estimated value according to a formula that v-hat = q-hat + xi-hat. By employing the method, only one preamble signal having the conjugated structure is employed for combined signal timing and carrier wave frequency synchronization, and signal timing synchronization is not influenced by the frequency offset.

Description

A kind of associating leading based on conjugated structure timing and frequency synchronization method

Technical field

The invention belongs to digital wireless communication transmission technique field, particularly a kind of associating leading based on conjugated structure timing and frequency synchronization method.

Background technology

OFDM (Orthogonal Frequency Division Multiplexing, OFDM) effectively can resist the multipath effect of channel, has the higher availability of frequency spectrum, can provide the high speed data transfer under wireless fading channel.OFDM system is applied in fields such as digital video broadcasting (DVB) and land mobile communications of new generation and becomes international and industry standard.In satellite communication field, OFDM is applicable to the high speed data transfer under wideband satellite communication channel, and such as European satellite standard DVB-SH devises and adopts the mixing ground of OFDM or TDM technology and the communication system of satellite.

Suppose that highspeed serial data stream information rate is R _b, mark space is T _b=1/R _b.First serial data is at a high speed flowed through serial to parallel conversion and obtains the parallel sub data flow of relative low speeds by OFDM transmitting terminal.The information rate of the parallel sub-stream pairs obtained through serial to parallel conversion (S/P) is reduced to 1/N (the i.e. R of input serial data stream information speed _b/ N), mark space expands to original N doubly (i.e. NT _b).Then, by inverse Fourier transform (IFFT), parallel data stream is modulated on N number of mutually orthogonal subcarrier.Finally, the frequency domain intubating length after IFFT conversion is greater than the Cyclic Prefix (CP) of the maximum multipath time delay of channel, and carries out parallel serial conversion (P/S), obtains transmitting terminal baseband OFDM symbols, is expressed as

$x\left(n\right)=\frac{1}{\sqrt{N}}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right)e^{j2\mathrm{\πkn}/N},n=-N_g,...,N-1---\left(1\right)$

Wherein, X (k) is the data on a kth subcarrier, and N is the size of IFFT, N _gfor circulating prefix-length.

After experience multidiameter fading channel, there is the time delay and frequency deviation introduced by wireless channel in ofdm signal, receiving terminal baseband OFDM symbols is expressed as usually

$r\left(n\right)=y(n-\mathrm{\ϵ})e^{j(2\mathrm{\πvn}/N)}+w\left(n\right)=\underset{m=0}{\overset{L-1}{\mathrm{\Σ}}}h\left(m\right)x(n-\mathrm{\ϵ}-m)e^{j(2\mathrm{\πvn}/N)}+w\left(n\right)---\left(2\right)$

Wherein, ε is unknown symbol time offset, and v is normalized carrier frequency offset, and w (n) is complex value white Gaussian noise, and h (m) is channel impulse response, and L is channel memory length.

In OFDM receiver, because Received signal strength exists time delay and frequency deviation, need to carry out Symbol Timing and carrier frequency synchronization.Typical is Schmidl algorithm based on leading Symbol Timing and carrier frequency synchronization method.This algorithm utilizes has the leading of two sections of same structures, and its timing metric exists platform and causes timing estimation poor-performing, thus affects Nonlinear Transformation in Frequency Offset Estimation performance.In order to improve Schmidl algorithm timing estimation accuracy and the scope of expansion Nonlinear Transformation in Frequency Offset Estimation, Ren algorithm adopts the pseudo random sequence leading symbol identical to two sections, front and back to be weighted.Suppose that pseudo random sequence is s _n, the leading symbol of weighting is expressed as x _n'=s _nx _n.Ren algorithm timing metric is expressed as

$M\left(d\right)=\frac{P\left(d\right)}{R\left(d\right)}=\frac{{|\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}{s}_n{s}_{n+N/2}{r}^{*}(d+n)\·r(d+n+N/2)|}^2}{{\left(\frac{1}{2}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{\left|r(d+n)\right|}^2\right)}^2}---\left(3\right)$

Choose d corresponding to the maximum of timing metric M (d) as timing metric estimator carrier wave frequency deviation v=α+2 β is divided into fractional part frequency deviation α and integer part frequency deviation β by Ren algorithm.Utilize phase calculation fractional part frequency deviation estimator, namely according to after compensating the fractional part frequency deviation of Received signal strength, by result and known preamble x _n' conjugate multiplication obtains data sequence according to calculating target function I (β), the β asking for the maximum of target function corresponding is integer part frequency deviation estimator.Target function I (β) is expressed as

$I\left(\mathrm{\β}\right)={|\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{r}^{\′}(n,\widehat{\mathrm{\ϵ}})\·e^{-j4\mathrm{\π\βn}/N}|}^2,\mathrm{\β}=-\frac{N}{4},...,\frac{N}{4}---\left(4\right)$

According to above-mentioned result of calculation, Nonlinear Transformation in Frequency Offset Estimation amount is expressed as frequency offset estimation range is ± N/2.Ren algorithm adopts pseudo random sequence to be weighted leading symbol, improves the performance of Symbol Timing and carrier frequency synchronization.But, the power spectrum that pseudo random sequence weighting process can worsen ofdm signal is carried out to leading symbol, produces more serious band external leakage, affect adjacent frequency band signal.Therefore, for the problem of conventional symbols timing in OFDM receiver under multidiameter fading channel with the poor-performing of carrier frequency synchronization algorithm.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, provide a kind of associating leading based on conjugated structure timing and frequency synchronization method, the leading symbol that the method only needs employing one to have conjugated structure carries out union of symbol timing and carrier frequency synchronization, wherein timing synchronization is not by the impact of frequency departure, frequency offset estimation range can reach ± N/2, under a multipath fading channel, the Symbol Timing of the method and carrier frequency synchronization performance are better than traditional algorithm.

Above-mentioned purpose of the present invention is realized by following scheme:

The associating timing leading based on conjugated structure and a frequency synchronization method, comprise the steps:

(1), in the sliding window that length is N, conjugate multiplication is carried out to Received signal strength r (n) and leading symbol c (n) of OFDM receiver, obtains coherent signal r ₀(n, d):

r ₀(n,d)＝r(n+d)c ^*(n)；

Wherein, n=0,1 ..., N-1; D=0,1 ..., M _s× N _s; N _s=N+N _g, N is the sample number of an OFDM symbol of setting, M _sfor OFDM symbol number in every frame data of setting, N _gfor the Cyclic Prefix number of OFDM symbol; And described leading symbol c (n), there is conjugated structure, that is:

[c(0) c(1) … c(N/2-1)]＝[c ^*(N/2) c ^*(N/2+1) … c ^*(N-1)]；

(2), according to the slip coherent signal r that step (1) obtains ₀(n, d) calculates differential correlation signal p (m, d):

$p(m,d)=\underset{k=m}{\overset{N-1}{\mathrm{\Σ}}}{r}_0(k,d)\·{r_0}^{*}(k-m,d);$

Wherein, m=1,2 ..., M ₀, M ₀for positive integer and M ₀≤ N-1;

(3), be weighted cumulative to the differential correlation signal p (m, d) that step (2) calculates, obtain weighting correlation function P (d);

(4), utilize the energy of Received signal strength in sliding window to be normalized weighting correlation function P (d) that step (3) calculates, obtain normalization timing metric value M (d);

(5), maximum is asked for normalization timing metric M (d); Difference is correlated with timing slip estimator equal the value of d corresponding to described maximum, namely

(6) fractional part Nonlinear Transformation in Frequency Offset Estimation amount, is calculated

$\widehat{\mathrm{\ξ}}=\frac{1}{\mathrm{\π}}\mathrm{angle}(\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}{r}_0(n,\widehat{\mathrm{\ϵ}})\·r_0^{*}(n+\frac{N}{2},\widehat{\mathrm{\ϵ}}));$

Wherein, phase bit arithmetic is got in angle () representative;

(7) the Nonlinear Transformation in Frequency Offset Estimation amount of the fractional part, utilizing step (6) to calculate compensate computing to received signal, obtain the Received signal strength after decimal frequency bias compensation

$r_1(n,\widehat{\mathrm{\ϵ}})=r_0(n,\widehat{\mathrm{\ϵ}})\·\exp (-j2\mathrm{\πn}\widehat{\mathrm{\ξ}}/N);$

(8) Received signal strength after, utilizing decimal frequency bias to compensate ask for target function Γ (q), then maximum is asked for described target function Γ (q), and using the frequency deviation estimator of parameter q corresponding for described maximum as integer part specific implementation process is as follows:

(8a), calculating target function Γ (q):

$\mathrm{\Γ}\left(q\right)={|\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{r}_1(n,\widehat{\mathrm{\ϵ}})\·e^{-j2\mathrm{\πqn}/N}|}^2,q=-\frac{N}{2},-\frac{N}{2}+1,...,\frac{N}{2};$

(8b), then maximum is asked for described target function Γ (q), and using the frequency deviation of parameter q corresponding for described maximum as integer part namely

(9), by the Nonlinear Transformation in Frequency Offset Estimation amount of fractional part with the frequency deviation estimator of integer part summation, obtains Nonlinear Transformation in Frequency Offset Estimation amount namely

The above-mentioned associating timing leading based on conjugated structure and frequency synchronization method, in step (3), the computing formula of weighting correlation function P (d) is as follows:

$P\left(d\right)=\underset{m=1}{\overset{M_0}{\mathrm{\Σ}}}\frac{(N-m)\·{\left|p(m,d)\right|}^2}{M_{0}N-M_0(1+M_0)/2}.$

The above-mentioned associating timing leading based on conjugated structure and frequency synchronization method, in step (3), the computing formula of weighting correlation function P (d) is as follows:

$P\left(d\right)=\underset{m=1}{\overset{M_0}{\mathrm{\Σ}}}\frac{1}{M_0}\·{\left|p(m,d)\right|}^2.$

The above-mentioned associating timing leading based on conjugated structure and frequency synchronization method, in step (4), the computing formula of normalization timing metric value M (d) is:

$M\left(d\right)=\frac{P\left(d\right)}{{\left(R\left(d\right)\right)}^2},R\left(d\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{\left|r(n+d)\right|}^2.$

The present invention compared with prior art, has the following advantages:

1), the present invention only needs a simple conjugated structure leading, do not need to carry out scrambler process to leading symbol, avoids the power spectrum characteristic worsening ofdm signal;

2), the present invention have employed the intermediate variable of timing estimation in frequency deviation is estimated, this combined synchronization method simplifies frequency offset estimation procedure.

3), the present invention's difference dependency structure of adopting time domain parameter adjustable, there is the timing metric of pulse type, solve the timing metric fuzzy problem of traditional timing algorithm;

4), the present invention under the multidiameter fading channel of low signal-to-noise ratio, the MSE Performance Ratio traditional algorithm of timing estimation improves and reaches 8dB.

Accompanying drawing explanation

Fig. 1 is the theory diagram of the timing estimation method based on be correlated with average and windowing of the present invention;

Fig. 2 is the time domain waveform schematic diagram of normalization timing metric value M (d) that the present invention calculates;

Fig. 3 is the MSE performance comparison result emulating the timing estimation amount obtained in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing and instantiation, the present invention is described in further detail:

Under the multidiameter fading channel of low signal-to-noise ratio, in order to solve tradition timing and the problem of frequency synchronization algorithm poor-performing, the invention provides a kind of associating based on conjugated structure leading symbol timing and frequency synchronization method, in the method, ofdm system only adopts one to have the leading of simple conjugated structure, timing estimation amount is obtained by and weighted sum relevant to leading difference of carrying out Parameter adjustable in receiving terminal, and calculate fractional part frequency deviation and integer part frequency deviation respectively according to timing estimation amount, the two obtains total frequency deviation estimator after being added, for compensating the frequency deviation of Received signal strength in Frequency Synchronization.Wherein, timing synchronization is not by the impact of frequency departure, and frequency offset estimation range can reach ± N/2.Under a multipath fading channel, the Symbol Timing of the method and carrier frequency synchronization performance are better than traditional algorithm.

Method And Principle block diagram as shown in Figure 1, the associating leading based on conjugated structure timing of the present invention and frequency synchronization method, comprise the steps:

(1), in the sliding window that length is N, conjugate multiplication is carried out to Received signal strength r (n) and leading symbol c (n) of OFDM receiver, obtains coherent signal r ₀(n, d):

r ₀(n,d)＝r(n+d)c ^*(n)；

Wherein, n=0,1 ..., N-1; D=0,1 ..., M _s× N _s; N _s=N+N _g, N is the sample number of each OFDM symbol, M _sfor OFDM symbol number in every frame data, N _gfor the Cyclic Prefix number of OFDM symbol; And described leading symbol c (n), there is conjugated structure, that is:

[c(0) c(1) … c(N/2-1)]＝[c ^*(N/2) c ^*(N/2+1) … c ^*(N-1)]；

In above slip correlation computations, when sliding window position is equal with the original position of the leading symbol in Received signal strength, the conjugate multiplication of Received signal strength and known pilot can obtain the data sequence with the two sections of same structures in front and back, and this data sequence can be used for carrier frequency synchronization.

(2), according to the slip coherent signal r that step (1) obtains ₀(n, d) calculates differential correlation signal p (m, d):

$p(m,d)=\underset{k=m}{\overset{N-1}{\mathrm{\Σ}}}{r}_0(k,d)\·{r_0}^{*}(k-m,d);$

Wherein, m=1,2 ..., M ₀, M ₀for positive integer and M ₀≤ N-1;

(3), owing to calculating differential correlation signal p (m in step (2), d) time, carry out difference to the Received signal strength of different difference interval m to be correlated with, calculate p (m, d) cumulative item number is N-m, namely then cumulative item number is different for difference interval m difference, and that is the difference related data that obtains of different difference interval m is different for the impact of timing metric.Dimension needs to be weighted to add up to differential correlation signal p (m, d) to obtain weighting correlation function P (d).Concrete weighted accumulation formula is as follows:

$P\left(d\right)=\underset{m=1}{\overset{M_0}{\mathrm{\Σ}}}\frac{(N-m)\·{\left|p(m,d)\right|}^2}{M_{0}N-M_0(1+M_0)/2};$

Wherein, M is worked as ₀when value is less, the FFT size N=64 of such as ofdm system, 128,256,512,1024,2048,4096 time, then choose M ₀≤ 10,9,8,6,4,3,2, then M ₀the sum term number difference of individual difference correlated results p (m, d) is less, in order to simplify computational process, average weighted mode can be adopted to calculate weighting correlation function P (d), namely

(4), utilize the energy of Received signal strength in sliding window to be normalized weighting correlation function P (d) that step (3) calculates, obtain normalization timing metric value M (d):

$M\left(d\right)=\frac{P\left(d\right)}{{\left(R\left(d\right)\right)}^2},R\left(d\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{\left|r(n+d)\right|}^2;$

(5), maximum is asked for normalization timing metric M (d); As shown in Figure 2.Choose d corresponding to the maximum of M (d) as timing slip estimator namely

(6) fractional part Nonlinear Transformation in Frequency Offset Estimation amount, is calculated

$\widehat{\mathrm{\ξ}}=\frac{1}{\mathrm{\π}}\mathrm{angle}(\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}{r}_0(n,\widehat{\mathrm{\ϵ}})\·r_0^{*}(n+\frac{N}{2},\widehat{\mathrm{\ϵ}}));$

Wherein, phase bit arithmetic is got in angle () representative;

$r_0(n+\frac{N}{2},\widehat{\mathrm{\ϵ}})=r(n+\frac{N}{2},\widehat{\mathrm{\ϵ}})c^{*}(n+\frac{N}{2});$

(7) the Nonlinear Transformation in Frequency Offset Estimation amount of the fractional part, utilizing step (6) to calculate compensate computing to received signal, obtain the Received signal strength after decimal frequency bias compensation

$r_1(n,\widehat{\mathrm{\ϵ}})=r_0(n,\widehat{\mathrm{\ϵ}})\·\exp (-j2\mathrm{\πn}\widehat{\mathrm{\ξ}}/N);$

(8) Received signal strength after, utilizing decimal frequency bias to compensate ask for target function Γ (q), then maximum is asked for described target function Γ (q), and using the frequency deviation estimator of parameter q corresponding for described maximum as integer part specific implementation process is as follows:

(8a), calculating target function Γ (q):

$\mathrm{\Γ}\left(q\right)={|\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{r}_1(n,\widehat{\mathrm{\ϵ}})\·e^{-j2\mathrm{\πqn}/N}|}^2,q=-\frac{N}{2},-\frac{N}{2}+1,...,\frac{N}{2};$

(8b), then maximum is asked for described target function Γ (q), and using the frequency deviation of parameter q corresponding for described maximum as integer part namely

(9), by the Nonlinear Transformation in Frequency Offset Estimation amount of fractional part with the frequency deviation estimator of integer part summation, obtains Nonlinear Transformation in Frequency Offset Estimation amount namely

The present invention is utilized to calculate Nonlinear Transformation in Frequency Offset Estimation amount r (n) carries out compensate of frequency deviation to received signal, and according to timing slip estimator determine the window's position that OFDM receiving terminal FFT converts, namely complete associating timing and the Frequency Synchronization of OFDM Received signal strength.

Embodiment:

In the present embodiment, simulation analysis is carried out to the associating leading based on conjugated structure timing of the present invention and frequency synchronization method.Simulated conditions arranges as follows: ofdm system adopts block leading symbol, and system subcarrier number is N=256, and circulating prefix-length is N _g=32, signal bandwidth is 3MHz, and subcarrier spacing is 15kHz.Simulated channel adopts the rayleigh fading channel in 11 footpaths, and every footpath time delay component is [00.4630.9261.3891.8522.3152.7783.2413.7044.1674.4630] μ s, and channel has index power delay profile, namely for path gain A _ihave: wherein i represents i-th multipath.

Under above-mentioned simulated conditions, in ofdm system, adopt the inventive method, Ren algorithm and Schmidl algorithm to carry out timing synchronization respectively, emulate 10000 times and the MSE performance of adding up timing estimation amount as shown in Figure 3.When signal to noise ratio is greater than 5dB (SNR>5dB), the timing estimation performance of the inventive method and Ren algorithm is all better than Schmidl algorithm.When signal to noise ratio (SNR<10dB) is less, the MSE performance of the inventive method is better than Ren algorithm, can find out, as adjustable parameter M ₀=3, when 7, the MSE performance of timing estimation amount can improve 5dB and 8dB respectively.When signal to noise ratio (SNR>10dB) is larger, the MSE performance of two kinds of algorithms is similar.It should be noted that the inventive method under low signal-to-noise ratio along with adjustable parameter M ₀increase, the MSE performance of timing estimation amount is obviously improved.Work as M ₀during >7, the MSE performance of timing estimation amount tends to be steady, but the computation complexity of the method continues to increase.Therefore, in Practical OFDM Systems, adjustable parameter M ₀selection need between algorithm performance and implementation complexity compromise.

The above; be only the present invention's embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

The content be not described in detail in specification of the present invention belongs to the known technology of professional and technical personnel in the field.

Claims (4)

1. based on conjugated structure leading associating timing and a frequency synchronization method, it is characterized in that comprising the steps:

(1), in the sliding window that length is N, conjugate multiplication is carried out to Received signal strength r (n) and leading symbol c (n) of OFDM receiver, obtains coherent signal r ₀(n, d):

r ₀(n,d)＝r(n+d)c ^*(n)；

Wherein, n=0,1 ..., N-1; D=0,1 ..., M _s× N _s; N _s=N+N _g, N is the sample number of an OFDM symbol of setting, M _sfor OFDM symbol number in every frame data of setting, N _gfor the Cyclic Prefix number of OFDM symbol; And described leading symbol c (n), there is conjugated structure, that is:

[c(0) c(1) … c(N/2-1)]＝[c ^*(N/2) c ^*(N/2+1) … c ^*(N-1)]；

(2), according to the slip coherent signal r that step (1) obtains ₀(n, d) calculates differential correlation signal p (m, d):

$p(m,d)=\underset{k=m}{\overset{N-1}{\mathrm{\&Sigma;}}}{r}_0(k,d)\&CenterDot;{r_0}^{*}(k-m,d);$

Wherein, m=1,2 ..., M ₀, M ₀for positive integer and M ₀≤ N-1;

(3), be weighted cumulative to the differential correlation signal p (m, d) that step (2) calculates, obtain weighting correlation function P (d);

(4), utilize the energy of Received signal strength in sliding window to be normalized weighting correlation function P (d) that step (3) calculates, obtain normalization timing metric value M (d);

(5), maximum is asked for normalization timing metric M (d); Difference is correlated with timing slip estimator equal the value of d corresponding to described maximum, namely

(6) fractional part Nonlinear Transformation in Frequency Offset Estimation amount, is calculated

$\widehat{\mathrm{\&xi;}}=\frac{1}{\mathrm{\&pi;}}\mathrm{angle}(\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}{r}_0(n,\widehat{\mathrm{\&epsiv;}})\&CenterDot;r_0^{*}(n+\frac{N}{2},\widehat{\mathrm{\&epsiv;}}));$

Wherein, phase bit arithmetic is got in angle () representative;

(7) the Nonlinear Transformation in Frequency Offset Estimation amount of the fractional part, utilizing step (6) to calculate compensate computing to received signal, obtain the Received signal strength after decimal frequency bias compensation

$r_1(n,\widehat{\mathrm{\&epsiv;}})=r_0(n,\widehat{\mathrm{\&epsiv;}})\&CenterDot;\exp (-j2\mathrm{\&pi;n}\widehat{\mathrm{\&xi;}}/N);$

(8) Received signal strength after, utilizing decimal frequency bias to compensate ask for target function Γ (q), then maximum is asked for described target function Γ (q), and using the frequency deviation estimator of parameter q corresponding for described maximum as integer part specific implementation process is as follows:

(8a), calculating target function Γ (q):

$\mathrm{\&Gamma;}\left(q\right)={|\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{r}_1(n,\widehat{\mathrm{\&epsiv;}})\&CenterDot;e^{-j2\mathrm{\&pi;qn}/N}|}^2,q=-\frac{N}{2},-\frac{N}{2}+1,...,\frac{N}{2};$

(8b), then maximum is asked for described target function Γ (q), and using the frequency deviation of parameter q corresponding for described maximum as integer part namely

(9), by the Nonlinear Transformation in Frequency Offset Estimation amount of fractional part with the frequency deviation estimator of integer part summation, obtains Nonlinear Transformation in Frequency Offset Estimation amount namely

2. a kind of associating leading based on conjugated structure timing according to claim 1 and frequency synchronization method, is characterized in that: in step (3), the computing formula of weighting correlation function P (d) is as follows:

$P\left(d\right)=\underset{m=1}{\overset{M_0}{\mathrm{\&Sigma;}}}\frac{(N-m)\&CenterDot;{\left|p(m,d)\right|}^2}{M_{0}N-M_0(1+M_0)/2}.$

3. a kind of associating leading based on conjugated structure timing according to claim 1 and frequency synchronization method, is characterized in that: in step (3), the computing formula of weighting correlation function P (d) is as follows:

$P\left(d\right)=\underset{m=1}{\overset{M_0}{\mathrm{\&Sigma;}}}\frac{1}{M_0}\&CenterDot;{\left|p(m,d)\right|}^2.$

4. a kind of associating leading based on conjugated structure timing according to claim 1 and frequency synchronization method, it is characterized in that: in step (4), the computing formula of normalization timing metric value M (d) is:

$M\left(d\right)=\frac{P\left(d\right)}{{\left(R\left(d\right)\right)}^2},R\left(d\right)=\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\left|r(n+d)\right|}^2.$