CN1722718A - A kind of frequency synchronization device of orthogonal frequency-division multiplex singal and method thereof - Google Patents

Abstract

The frequency synchronization device of orthogonal frequency-division multiplex singal of the present invention and method thereof, feature are on the basis of error signal being carried out the feature accumulation, obtain the correlation of pilot signal in the adjacent orthogonal frequency division multiplexing symbol by maximum value search; In frequency offset estimating, the method of utilizing weighting to merge will leak into that the energy of pilot signal fully utilizes on the adjacent sub-carrier, and obtain the essence estimation of main value phase place and the rough estimate that differs according to the positional information after phase information after the correlation merging and the merging of mould value tag respectively, handle the phase hit problem that overcomes on the π border by residual error, obtain the estimated value of frequency deviation.The frequency synchronization algorithm that the present invention proposes can rapid and reliablely reach Frequency Synchronization, does not need for Frequency Synchronization additionally increases expense, and can do compromise preferably at estimated performance with between lock in time.

Description

A kind of frequency synchronization device of orthogonal frequency-division multiplex singal and method thereof

Technical field:

The present invention relates to OFDM (OFDM) mobile communication technology field, particularly frequency synchronization device in the ofdm communication system and method thereof.

Background technology:

OFDM (OFDM) technology is generally believed it is indispensable technology in the 4th third-generation mobile communication system.But ofdm system is relatively more responsive to carrier wave frequency deviation, so carrier frequency synchronization is a key technology in the ofdm system.

United States Patent (USP) 5,732,113 disclose the method for a kind of OFDM timing and Frequency Synchronization, but this method need increase extra synchronizing symbol, and this can reduce message transmission rate.

" international electronics and The Institution of Electrical Engineers's consumer electronics journal " (IEEE Trans.On Consumer Electronics, Volume 47, Issue 3, pp.364-369, Aug.2001) deliver a kind of utilization in and done the method that the pilot signal of channel estimating (Pilot) is carried out Frequency Synchronization, but the residual frequency difference of this method is bigger, needs the smart Synchronous Processing of further frequency, and can not reach synchronous reliably when signal to noise ratio is low.

Technology contents:

The invention provides a kind of frequency synchronization device and method thereof of orthogonal FDM communication system, make system's rapid and reliable realization Frequency Synchronization under the prerequisite of high data transmission efficiency.

The frequency synchronization device of orthogonal frequency-division multiplex singal of the present invention, at the pilot plug-in unit of transmitting terminal with even equally spaced being inserted in the OFDM symbol of pilot signal;

It is characterized in that:

At receiving terminal, the frequency-region signal that receives by feature accumulation module, passes through frequency deviation estimating modules more at last earlier by characteristic extracting module;

In described characteristic extracting module, the output port of memory cell is connected to the cyclic shift correlation unit;

In described feature accumulation module, an input port of accumulative element is connected to the cyclic shift correlation unit in the characteristic extracting module, and another input port is connected to initialization unit; The input port of judgment variables generation unit is connected to accumulative element, and an output port of judgment variables generation unit is connected to decision unit, and another output port is connected to correlation merge cells and the mould value tag merge cells in the frequency deviation estimating modules; An output port of decision unit is connected to the signal memory cell in the characteristic extracting module, and another output port is connected to correlation merge cells and the mould value tag merge cells in the frequency deviation estimating modules;

In described frequency deviation estimating modules, the output port of correlation merge cells is connected to smart phase calculation unit; The output port of mould value tag merge cells is connected to thick phase calculation unit; An input port of residual error processing unit is connected to smart phase calculation unit, and another input port is connected to thick phase calculation unit, and the output port of residual error processing unit is connected to the phase frequency converting unit.

The frequency synchronization method of orthogonal frequency-division multiplex singal of the present invention adopts even equally spaced pilot signal interleaved plan at transmitting terminal, promptly all uniformly-spaced evenly distributes on time and frequency direction;

Be characterised in that its receiving terminal may further comprise the steps:

A carries out feature extraction to the received signal to be handled, promptly by the relevant error signal that obtains of computation cycles displacement;

B carries out feature accumulation to the error signal that obtains to be handled, and promptly error signal is weighted to merge accumulation, and the received signal to noise ratio after will accumulate is as judgment variables, when the value of judgment variables is higher than when presetting thresholding, enters step C, otherwise returns steps A;

C carries out correlation to the error signal after accumulating and merges, and goes out the smart estimated value of main value phase place according to the calculated signals after merging;

The error signal of D after to accumulation carried out the mould value tag and merged, and the rough estimate evaluation that goes out to differ according to the calculated signals after merging, and this is differed decomposes on the principal value interval;

Slightly differing after E decomposes according to smart phase place and main value obtains the smart estimated value that differs that frequency deviation accumulates out in the time interval at adjacent 2 OFDMSymbol that comprise Pilot, and converts the correspondent frequency value to, obtains the estimated value of frequency deviation.

The principle of feature extraction described in the present invention is as follows:

The signal transformation that receives can be expressed as behind frequency domain:

$Y_i\left(k\right)=X_i\left(k\right)H_i\left(k\right)\frac{\sin \left(\mathrm{\π\ϵ}\right)}{N\sin (\mathrm{\π\ϵ}/N)}\·e^{\mathrm{j\π\ϵ}(N-1)/N}\·e^{j{\mathrm{\θ}}_i}+I_i\left(k\right)+W_i\left(k\right),(k=0,\·\·\·,N-1)----\left(1\right)$

Wherein, X _i(k) be among i the Symbol, the signal that transmitting terminal sends on k subcarrier; H _i(k) be among i the Symbol, the frequency response on k subcarrier; ε is the carrier wave frequency deviation that normalizes to subcarrier spacing; θ _iBe differing that carrier wave initial phase and frequency deviation ε cause on i Symbol.W _i(k) be white Gaussian noise; I _i(k) disturb between subcarrier.

If Pilot takies M subcarrier, be inserted in N the subcarrier by ratio R=M/N is equally spaced; Pilot is spaced apart d OFDM Symbol on time orientation.When there being frequency deviation ε=ε _Int+ ε _FraThe time, subcarrier spacing integer frequency offset ε _IntCan produce the cyclic shift of subcarrier, fractional part of frequency offset ε _FraCan cause the Power leakage of subcarrier.Because Pilot is even at interval being inserted on the subcarrier of R, and have only Pilot to be correlated with between adjacent 2 OFDM Symbol that comprise Pilot, so can search for Pilot energy distributions position after displacement and the leakage by formula (2).

$C_i\left(j\right)=\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}{Y}_i^{*}(\mathrm{mR}+j)\·Y_{i+d}(\mathrm{mR}+j),j\∈[0,R)----\left(2\right)$

Wherein, Y _i, Y _I+dBe adjacent 2 the OFDM Symbol that comprise Pilot.

By formula (1) as can be known, C _i(j) phase place of correlation of Pilot component is differing that frequency deviation ε accumulates out in a Symbol.When | ε _Fra| during ≈ 0, sub-carrier power is leaked very little, so C _i(j) has only a peak value; When | ε _Fra| during ≈ 0.5, Pilot Power leakage is greatly arranged to an adjacent subcarrier, so C _i(j) two adjacent peak values can appear, so the mould value tag of this peak value has also been indicated frequency deviation information.So can be according to G _i(j) mould value tag and C _i(j) phase information is estimated carrier wave frequency deviation.

The principle of the accumulation of feature described in the present invention is as follows:

Feature accumulation module adopts the estimated value of the reception SNR after the accumulation

As judgment variables, when reception SNR was low, number of times improved estimated performance by increasing accumulation; When reception SNR is higher, under the prerequisite that guarantees estimated accuracy, reduce the accumulation number of times as far as possible.The accumulation of error signal as shown in Equation (3), the accumulation of SNR as shown in Equation (4), the calculating of judgment variables is as shown in Equation (5).

$C\left(j\right)=\mathrm{\Σ}\left|C_i\left(j\right)\right|C_i\left(j\right)----\left(3\right)$

$\widehat{\mathrm{\γ}}\left(j\right)=\underset{i}{\mathrm{\Σ}}{\widehat{\mathrm{\γ}}}_i\left(j\right)----\left(4\right)$

$\widetilde{\mathrm{\γ}}=\widehat{\mathrm{\γ}}\left(K_m\right)+\widehat{\mathrm{\γ}}\left(K_s\right)----\left(5\right)$

Wherein,

Calculating as shown in Equation (6); K _m, K _sCalculating shown in formula (8)～(9).

${\widehat{\mathrm{\γ}}}_i\left(j\right)=\frac{\left|C_i\left(j\right)\right|}{{\stackrel{\‾}{P}}_i\left(j\right)-\left|C_i\left(j\right)\right|}-\mathrm{\Δ\γ}----\left(6\right)$

Wherein, P _i(J) average power that receives of expression, it calculates as shown in Equation (7); Δ γ is a little side-play amount, is used for the SNR that estimates is proofreaied and correct, and can obtain by emulation.

${\stackrel{\‾}{P}}_i\left(j\right)=\frac{1}{2}\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}[{\left|Y_i(\mathrm{mR}+j)\right|}^2+{\left|Y_{i+d}(\mathrm{mR}+j)\right|}^2]----\left(7\right)$

$K_m=\arg \left(\underset{j}{\max }\right|C\left(j\right)\left|\right),K_{\mathrm{sp}}={\left((K_m+1)\right)}_R,K_{\mathrm{sn}}={\left((K_m-1)\right)}_R----\left(8\right)$

$K_s=\left\{\begin{array}{cc}{K}_{\mathrm{sp}},& \mathrm{if}\left|\widehat{\mathrm{\γ}}\left(K_{\mathrm{sp}}\right)\right|\≥\left|\widehat{\mathrm{\γ}}\left(K_{\mathrm{sn}}\right)\right|\\ K_{\mathrm{sn}},& \mathrm{else}\end{array}\right.----\left(9\right)$

Wherein, ((k)) _RK is to the computing of R delivery value in expression.When satisfying $\widetilde{\mathrm{\γ}}\≥{\mathrm{\γ}}_{\mathrm{th}}$ The time (γ _ThBe judging threshold), promptly change frequency offset estimation procedure over to from cumulative process.

The principle of frequency offset estimating described in the present invention is as follows:

Because the energy of Pilot mainly is diffused on the adjacent subcarrier, the energy of this part leakage comprises our needed frequency deviation information equally, the present invention utilizes method that weighting merges that the energy of this part leakage is fully utilized, and the method for merging is shown in formula (10)～(11); Formula (10) merges for correlation, and the phase place of combined signal C is smart phase value, as shown in Equation (12), this phase place is differing at principal value interval (π of accumulating out of frequency deviation as can be known, π] on main value, it has higher precision, but has 2 π fuzzy problems; Formula (11) merges for the mould value tag, value after the merging has been indicated the position of Pilot component on the subcarrier axle, can utilize this positional information to obtain the rough estimate of frequency deviation by formula (13), and then obtain the rough estimate that differs that accumulates out by frequency deviation according to this frequency deviation rough estimate, and decompose by main value and to obtain this and differ the main value of rough estimate evaluation on principal value interval and the multiple of 2 π, as shown in Equation (14), there are not 2 π fuzzy problems in this rough estimate that differs as can be seen, but precision is very low; Owing to have the phase hit problem on the π border, the present invention adopts to residual error and solves this problem near processing method, as shown in Equation (15), and by obtaining the essence that the differs estimation that frequency deviation accumulates out after the residual error processing, and then obtain the estimated value of frequency deviation, as shown in Equation (16).

$\stackrel{\‾}{C}=\frac{\left|C\left(K_m\right)\right|\·C\left(K_m\right)+\left|C\left(K_{\mathrm{sp}}\right)\right|\·C\left(K_{\mathrm{sp}}\right)+\left|C\left(K_{\mathrm{sn}}\right)\right|\·C\left(K_{\mathrm{sn}}\right)}{\left|C\left(K_m\right)\right|+\left|C\left(K_{\mathrm{sp}}\right)\right|+\left|C\left(K_{\mathrm{sn}}\right)\right|}----\left(10\right)$

${\stackrel{\‾}{K}}_0=\frac{\left|C\left(K_m\right)\right|\·K_m+\left|C\left(K_{\mathrm{sp}}\right)\right|\·(K_m+1)+\left|C\left(K_{\mathrm{sn}}\right)\right|\·(K_m-1)}{\left|C\left(K_m\right)\right|+\left|C\left(K_{\mathrm{sp}}\right)\right|+\left|C\left(K_{\mathrm{sn}}\right)\right|}----\left(11\right)$

${\widehat{\mathrm{\θ}}}_{\mathrm{fine}}={\tan }^{-1}\left\{\frac{\mathrm{Im}\left(\stackrel{\‾}{C}\right)}{\mathrm{Re}\left(\stackrel{\‾}{C}\right)}\right\},{\widehat{\mathrm{\θ}}}_{\mathrm{fine}}\∈(-\mathrm{\π},\mathrm{\π}]----\left(12\right)$

${\widehat{\mathrm{\ϵ}}}_{\mathrm{coarse}}=\left\{\begin{array}{cc}{\left(({\stackrel{\‾}{K}}_0-K_0)\right)}_R,& \mathrm{if}{\left(({\stackrel{\‾}{K}}_0-K_0)\right)}_R\∈[0,\frac{R}{2}]\\ {\left(({\stackrel{\‾}{K}}_0-K_0)\right)}_R-R,& \mathrm{else}\end{array}\right.----\left(13\right)$

$\mathrm{\Δ}{\widehat{\mathrm{\θ}}}_{\mathrm{coarse}}=2\mathrm{\π}{\widehat{\mathrm{\ϵ}}}_{\mathrm{coarse}}(1+r_G)=2\mathrm{m\π}+{\widehat{\mathrm{\θ}}}_{\mathrm{coarse}},{\widehat{\mathrm{\θ}}}_{\mathrm{coarse}}\∈(-\mathrm{\π},\mathrm{\π}]----\left(14\right)$

$\mathrm{\Δ}{\widehat{\mathrm{\θ}}}_{\mathrm{fine}}=\left\{\begin{array}{cc}2\mathrm{m\π}+{\widehat{\mathrm{\θ}}}_{\mathrm{fine}}+2\mathrm{\π}\·\mathrm{sign}\left({\widehat{\mathrm{\θ}}}_{\mathrm{coarse}}\right),& \mathrm{if}|{\widehat{\mathrm{\θ}}}_{\mathrm{coarse}}-{\widehat{\mathrm{\θ}}}_{\mathrm{fine}}|\≥\mathrm{\π}\\ 2\mathrm{m\π}+{\widehat{\mathrm{\θ}}}_{\mathrm{fine}},& \mathrm{else}\end{array}\right.----\left(15\right)$

$\widehat{\mathrm{\ϵ}}=\frac{\mathrm{\Δ}{\widehat{\mathrm{\θ}}}_{\mathrm{fine}}}{2\mathrm{\π}(1+r_G)}----\left(16\right)$

Compared with prior art, the feature that the present invention is leaked according to the sub-carrier power that is caused by carrier wave frequency deviation in frequency offset estimating, made full use of the energy that leaks into Pilot on the adjacent sub-carrier, utilization is by the phase information and the mould value tag of the cyclic shift correlation function of the adjacent S ymbol of feature extraction acquisition, use technology such as residual error processing, finish frequency rough simultaneously synchronously with synchronously smart; Increased the feature cumulative process in addition, this can guarantee that enough SNR carry out reliably synchronously, can also do compromise preferably at estimated performance with between lock in time.So the present invention can rapid and reliablely reach Frequency Synchronization, and does not need additionally to increase expense for Frequency Synchronization.

Description of drawings:

Accompanying drawing 1 is that OFDM Frequency Synchronization of the present invention system realizes block diagram.

Accompanying drawing 2 be one embodiment of the present of invention SNR and integration time relation simulation curve.

Accompanying drawing 3 is the SNR and the simulation curve of estimating the mean square error relation of one embodiment of the present of invention.

Embodiment:

Below in conjunction with the description of drawings embodiments of the invention.

Embodiment 1:

The OFDM cell length that the present embodiment system uses is 2048, and channel adopts COST207 six footpath models, and maximum multipath time delay is 10us, and six footpaths are spacedly distributed in 0～10us, and the power spectral density in each footpath satisfies common Jake model.

In the present embodiment, adopt the Pilot interleaved plan of even pectination, i.e. the interval d=1 of Pilot on time orientation at transmitting terminal.Pilot length is 256, at interval 8 be inserted on the subcarrier.

In the present embodiment, realize block diagram as shown in Figure 1 in the OFDM of receiving terminal Frequency Synchronization system.Wherein, feature extraction functions is finished in unit 102,103, extracts error signal according to input signal; Feature accumulation function is finished in unit 105,106,107,108, and error signal is carried out the feature accumulation; The frequency offset estimating function is finished in unit 112,113,114,115,116,117, carries out frequency offset estimating according to the error signal after the accumulation; 102 is signal memory cell, the baseband digital signal of receiving that transforms to frequency domain 101 is carried out buffer memory, when the signal of buffer memory reaches 2 OFDM Symbol, cyclic shift correlation unit 103 beginning by formula (2) calculates cyclic shift correlation function between adjacent two Symbol, and promptly error signal 104; 105 is initialization unit, in the initial moment accumulation register is carried out zero clearing, 103 error signals that calculate 104 be sent to accumulative element 106 by formula (3) carry out the accumulation of error signal, accumulative element 106 also by formula calculates reception SNR in (6), (7) in addition, and by formula (4) carry out the SNR accumulation; 107 is the judgment variables generation unit, and by formula (5), (8), (9) calculate judgment variables and deliver to decision unit 108 according to the signal after accumulating for it; Decision unit 108 compares decision value and the predetermined threshold of receiving, when being no more than thresholding, decision unit 108 produces accumulation triggering signal 109 and delivers to signal memory cell 102, signal memory cell 102 is sent next OFDM Symbol according to this triggering signal, cyclic shift correlation unit 103 calculates the error signal 104 that makes new advances according to this Symbol, 106 pairs of error signals that newly calculate 104 of accumulative element accumulate, calculate the reception SNR of this Symbol simultaneously, and carry out the SNR accumulation; Judgment variables generation unit 107 just enters frequency offset estimation procedure, and sends the error signal 110 after the accumulation according to the value of the signal update judgment variables after accumulating when this decision value surpasses the thresholding of decision unit 108; The maximum value position signal 111 that error signal 110 after the accumulation that correlation merge cells 112 is sent according to decision unit 108 and judgment variables generation unit 107 are sent by formula (10) carries out correlation and merges; The maximum value position signal 111 that error signal 110 after the accumulation that mould value tag merge cells 113 is sent according to decision unit 108 and judgment variables generation unit 107 are sent by formula (11) carries out the mould value tag and merges; The result that smart phase calculation unit 114 merges according to correlation by formula (12) essence of calculating the main value phase place estimates that this phase place has higher precision but has 2 π phase fuzzy problem; Thick phase calculation unit 115 according to the result of mould value tag merge cells by formula (13) calculate the rough estimate of frequency deviation, and then obtain slightly differing accordingly by formula (14), and this is slightly differed carry out main value and decompose, this precision that slightly differs is very low but do not have 2 π phase fuzzy problem; Slightly differing by formula after residual error processing unit 116 decomposes according to smart phase place and main value (15) obtains the essence that differs that frequency deviation accumulates out and estimates in an OFDM Symbol time; At last, phase frequency converting unit 117 by formula (16) essence differed convert corresponding frequency offset estimating value to.

Accompanying drawing 2,3 is respectively under the channel models of COST207 six footpath, carrier wave frequency deviation ε=1.5 o'clock, SNR and between integration time, the simulation curve that concerns between SNR and the estimation mean square error.In emulation, the threshold value of accumulation module is made as 5dB, i.e. 10log ₁₀(γ _Th)=5, wherein γ _ThPredetermined threshold for unit 111; Side-play amount is 0.025 in the formula (6), i.e. Δ γ=0.025; The maximum Doppler frequency offset of curve a in the accompanying drawing 2 is 700Hz, and the maximum Doppler frequency offset of curve b is 200Hz, and the maximum Doppler frequency offset of curve c is 50Hz; The maximum Doppler frequency offset of curve d in the accompanying drawing 3 is 700Hz, and the maximum Doppler frequency offset of curve e is 200Hz, and the maximum Doppler frequency offset of curve f is 50Hz.

Curvilinear characteristic is in the accompanying drawing 2:

1. along with the increase of SNR, reduce the integration time of curve a, b, c.

2. after SNR is higher than 5dB, quickly converge on 3 Symbol the integration time of curve a, b, c.

3. under identical SNR, be slightly larger than curve b the integration time of curve a, be slightly larger than curve c the integration time of curve b.

Curvilinear characteristic is in the accompanying drawing 3:

1. the estimation mean square error of curve d, e, f rises and falls very little with the variation of SNR.

2. be higher than curve e at identical SNR lower curve d, curve e is higher than curve f.

3. the mean square error scope of curve d is 10 ^-4～10 ^-3

Work as ε _FraDuring ≈ 0.5, sub-carrier power is leaked the most serious, and this moment, the decay of Pilot sub-carrier positions self-energy was the strongest, and the interference of other data bit simultaneously is also maximum.By the characteristics of accompanying drawing 2,3, along with the increase of SNR can reduce integration time, generally only need the accumulation of 2～3 Symbol can reach predetermined performance, under the situation of very severe, also only need the accumulation of 4～6 Symbol just can reach pre-determined characteristics; And after accumulation, estimated performance rises and falls very little with the variation of SNR; When Doppler frequency deviation increases, increase owing to disturb between subcarrier, estimated performance can reduce, but notices simultaneously, and when maximum Doppler frequency offset was 700Hz, estimated mean-square was 10 ^-4～10 ^-5, still have preferable performance.

The present invention obtains the correlation of Pilot among the adjacent S ymbol by maximum value search on the basis of error signal being carried out the feature accumulation; In frequency offset estimating, the feature that the sub-carrier power that causes according to frequency deviation is leaked, the method of utilizing weighting to merge will leak into that the energy of Pilot fully utilizes on the adjacent sub-carrier, and the phase information after merging according to correlation respectively and the mould value tag positional information after merging obtain having phase ambiguity but the higher main value phase place of precision smart estimate and do not have phase ambiguity but precision very low differ rough estimate, handle the phase hit problem that overcomes on the π border by residual error, finish frequency rough simultaneously synchronously with synchronously smart, obtain the estimated value of frequency deviation; The frequency synchronization algorithm that the present invention proposes can rapid and reliablely reach Frequency Synchronization, does not need for Frequency Synchronization additionally increases expense, and can do compromise preferably at estimated performance with between lock in time.

Claims (2)

1, a kind of frequency synchronization device of orthogonal frequency-division multiplex singal, at the transmitting terminal pilot plug-in unit with even equally spaced being inserted in the OFDM symbol of pilot signal;

It is characterized in that,

At receiving terminal, the frequency-region signal that receives by feature accumulation module, passes through frequency deviation estimating modules more at last earlier by characteristic extracting module;

In described characteristic extracting module, the output port of memory cell is connected to the cyclic shift correlation unit;

In described feature accumulation module, an input port of accumulative element is connected to the cyclic shift correlation unit in the characteristic extracting module, and another input port is connected to initialization unit; The input port of judgment variables generation unit is connected to accumulative element, and an output port of judgment variables generation unit is connected to decision unit, and another output port is connected to correlation merge cells and the mould value tag merge cells in the frequency deviation estimating modules; An output port of decision unit is connected to the signal memory cell in the characteristic extracting module, and another output port is connected to correlation merge cells and the mould value tag merge cells in the frequency deviation estimating modules;

In described frequency deviation estimating modules, the output port of correlation merge cells is connected to smart phase calculation unit; The output port of mould value tag merge cells is connected to thick phase calculation unit; An input port of residual error processing unit is connected to smart phase calculation unit, and another input port is connected to thick phase calculation unit, and the output port of residual error processing unit is connected to the phase frequency converting unit.

2, a kind of frequency synchronization method of orthogonal frequency-division multiplex singal adopts even equally spaced pilot tone interleaved plan at transmitting terminal, promptly all uniformly-spaced evenly distributes on time and frequency direction;

It is characterized in that receiving terminal may further comprise the steps,

A carries out feature extraction to the received signal to be handled, promptly by the relevant error signal that obtains of computation cycles displacement;

B carries out feature accumulation to the error signal that obtains to be handled, and promptly error signal is weighted to merge accumulation, and the received signal to noise ratio after will accumulate is as judgment variables, when the value of judgment variables is higher than when presetting thresholding, enters step C, otherwise returns steps A;

C carries out correlation to the error signal after accumulating and merges, and goes out the smart estimated value of main value phase place according to the calculated signals after merging;

The error signal of D after to accumulation carried out the mould value tag and merged, and the rough estimate evaluation that goes out to differ according to the calculated signals after merging, and this is differed decomposes on the principal value interval;

Slightly differing after E decomposes according to smart phase place and main value obtains the smart estimated value that differs that accumulates out in the time interval at adjacent 2 OFDM symbols that comprise pilot tone, and converts the correspondent frequency value to, obtains the estimated value of frequency deviation.

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