CN105282081A - Carrier frequency offset estimation method and device - Google Patents

Abstract

The invention discloses a carrier frequency offset estimation method and a carrier frequency offset estimation device, which relate to the technical field of communication. The carrier frequency offset estimation method comprises the steps of: respectively carrying out zero-insertion processing on frequency domain channel responses of all pilot subcarriers of a first OFDM symbol and all pilot subcarriers of a second OFDM symbol in a received downlink baseband receiving signal to obtain a first zero-insertion frequency domain channel response and a second zero-insertion frequency domain channel response; subjecting the first zero-insertion frequency domain channel response and the second zero-insertion frequency domain channel response to Fourier inverse transformation respectively to obtain a first time domain channel response and a second time domain channel response; and determining carrier frequency offset according to an obtained phase relation between peak values in the first time domain channel response and the second time domain channel response. The carrier frequency offset estimation method and the carrier frequency offset estimation device can converge signal energy at peak values of the time domain channel responses by transforming the frequency domain channel estimation of the pilot subcarriers into time domain, so as to improve the frequency offset estimation performance, and avoid the problem that the frequency offset estimation is limited to the same subcarrier position.

Description

A kind of method of Nonlinear Transformation in Frequency Offset Estimation and device

Technical field

The present invention relates to communication technical field, particularly the method for the Nonlinear Transformation in Frequency Offset Estimation of OFDM (OFDM:OrthogonalFrequencyDivisionMultiplexing) system and device.

Background technology

In the method that existing Nonlinear Transformation in Frequency Offset Estimation is common, comprise CP correlation method and conventional RS method.

Wherein, Cyclic Prefix (CP:CyclicPrefix) correlation method utilizes the cyclic prefix CP of OFDM symbol to carry out frequency deviation estimation, because CP is the same with the transmission data of OFDM symbol tail end, the transmission data of OFDM symbol tail end are multiplied by the conjugation of corresponding CP segment data, just can obtain the phase difference that carrier wave frequency deviation causes, and then estimate frequency deviation.But the problem that estimated accuracy is poor can be there is.

Routine reference signal (RS:ReferenceSignal) method utilizes the domain channel response in the same pilot sub-carrier of former and later two OFDM symbol to carry out frequency deviation estimation, directly two domain channel response conjugation are taken advantage of, and then the phase place determination frequency deviation of the result taken advantage of according to conjugation.But the pilot tone that this method limit two OFDM symbol must in identical sub-carrier positions, otherwise frequency offset estimation result can by multipath or time inclined having a strong impact on.Concrete, such as in Long Term Evolution (LTE:LongTermEvolution) system, a subframe of conventional cyclic prefix (NormalCP) frame structure comprises 14 OFDM symbol, symbol 0 is identical with the pilot subcarrier positions of symbol 7, symbol 4 and symbol 11, frequency deviation can be estimated by conventional RS method based on them, but estimation range is little, only has-/+1KHz; If can do frequency deviation based on symbol 4 and symbol 7 to estimate, then estimation range can reach-/+2.3KHz, but their pilot subcarrier positions offsets one from another, and conventional RS method is unavailable in this case.

Summary of the invention

The object of the present invention is to provide a kind of method and device of Nonlinear Transformation in Frequency Offset Estimation, the estimated accuracy that can solve the existence of existing carrier frequency bias estimation is poor, and the problem that applicable elements is limited.

According to an aspect of the present invention, provide a kind of method of Nonlinear Transformation in Frequency Offset Estimation, comprising:

Respectively zero insertion process is carried out to the domain channel response of all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol, obtains the first zero insertion domain channel response and the second zero insertion domain channel response;

Respectively inverse Fourier transform is carried out to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

According to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determine carrier wave frequency deviation.

Preferably, user terminal or the domain channel response of adjacent base station to all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol carry out zero insertion process respectively, obtain the first zero insertion domain channel response and the second zero insertion domain channel response;

Respectively inverse Fourier transform is carried out to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

According to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determine carrier wave frequency deviation.

Preferably, the step that the described domain channel response to all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol carries out zero insertion process respectively comprises:

All frequency domain pilot channels responses of the first OFDM symbol are placed on the preset pilot subcarrier positions of the first OFDM symbol respectively, and by the zero setting of all non-pilot subcarriers;

And, all frequency domain pilot channels responses of the second OFDM symbol are placed on the preset pilot subcarrier positions of the second OFDM symbol respectively, and by the zero setting of all non-pilot subcarriers.

Preferably, the peak phase relation in described the first time domain channel response according to obtaining and the second time domain channel response, determine that the step of carrier wave frequency deviation comprises:

According to described first time domain channel response and the second time domain channel response, determine that the peak phase between described first time domain channel response and the second time domain channel response is poor;

According to the first OFDM symbol and the second OFDM symbol preset time interval, determine the carrier wave frequency deviation corresponding to described peak phase difference.

Preferably, described according to described first time domain channel response and the second time domain channel response, determine that the step of the peak phase difference between described first time domain channel response and the second time domain channel response comprises:

According to described first time domain channel response and the second time domain channel response, determine the time domain channel response of the first time domain channel response and the second time domain channel response peak respectively;

According to the time domain channel response of described first time domain channel response and the second time domain channel response peak, determine that the peak phase between described first time domain channel response and the second time domain channel response is poor.

Preferably, the step that peak is chosen is comprised:

According to described first time domain channel response and the second time domain channel response, determine the maximum crest value corresponding to described first time domain channel response and the second time domain channel response respectively;

By the maximum crest value of more described first time domain channel response and the second time domain channel response, using the peak of all peaks of OFDM symbol large for maximum crest value as described first time domain channel response and the second time domain channel response.

Preferably, the peak phase relation in described the first time domain channel response according to obtaining and the second time domain channel response, determine that the step of carrier wave frequency deviation also comprises:

If there is extra phase difference in the first OFDM symbol and the second OFDM symbol, then according to described first OFDM symbol and the second OFDM symbol preset pilot frequency locations skew and time domain channel time delay determine that described extra phase is poor;

According to the peak phase relation in described extra phase difference and the first time domain channel response and the second time domain channel response, determine carrier wave frequency deviation.

According to a further aspect in the invention, provide a kind of device of Nonlinear Transformation in Frequency Offset Estimation, comprising:

Zero insertion module, for carrying out zero insertion process respectively to the domain channel response of all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol, obtain the first zero insertion domain channel response and the second zero insertion domain channel response;

Conversion module, for carrying out inverse Fourier transform respectively to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

Determination module, for according to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determines carrier wave frequency deviation.

Preferably, described zero insertion module comprises further:

First submodule, for being placed in the preset pilot subcarrier positions of the first OFDM symbol respectively by all frequency domain pilot channels responses of the first OFDM symbol, and by the zero setting of all non-pilot subcarriers;

Second submodule, for being placed in the preset pilot subcarrier positions of the second OFDM symbol respectively by all frequency domain pilot channels responses of the second OFDM symbol, and by the zero setting of all non-pilot subcarriers.

Preferably, described determination module comprises further:

Difference submodule, for according to described first time domain channel response and the second time domain channel response, determines that the peak phase between described first time domain channel response and the second time domain channel response is poor;

Frequency deviation submodule, for according to the first OFDM symbol and the second OFDM symbol preset time interval, determines the carrier wave frequency deviation corresponding to described peak phase difference.

Compared with prior art, beneficial effect of the present invention is: by the channel estimation in frequency domain of pilot sub-carrier is transformed to time domain, the peak value on time domain channel response can be made to converge signal energy, realize effective restraint speckle, improve frequency deviation estimated performance, it is more accurate that frequency deviation is estimated.Meanwhile, the problem that frequency deviation estimates to be confined to identical sub-carrier positions is avoided.

Accompanying drawing explanation

Fig. 1 is the Method And Principle figure of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides;

Fig. 2 is the structure drawing of device of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides;

Fig. 3 is the LTE downlink reference signal RS mapping graph of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides;

Fig. 4 is LTE4, the 7 symbol time domain channel response extra phase difference figure of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides;

Fig. 5 is the overall flow figure of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides.

Embodiment

Below in conjunction with accompanying drawing to a preferred embodiment of the present invention will be described in detail, should be appreciated that following illustrated preferred embodiment is only for instruction and explanation of the present invention, is not intended to limit the present invention.

Fig. 1 is the Method And Principle figure of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides, and as shown in Figure 1, concrete steps are as follows:

Step S1: carry out zero insertion process respectively to the domain channel response of all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol, obtains the first zero insertion domain channel response and the second zero insertion domain channel response.

In step sl, user terminal or the domain channel response of adjacent base station to all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol carry out zero insertion process respectively, obtain the first zero insertion domain channel response and the second zero insertion domain channel response;

Respectively inverse Fourier transform is carried out to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

According to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determine carrier wave frequency deviation.

Further, all frequency domain pilot channels responses of the first OFDM symbol are placed on the preset pilot subcarrier positions of the first OFDM symbol respectively, and by the zero setting of all non-pilot subcarriers;

And, all frequency domain pilot channels responses of the second OFDM symbol are placed on the preset pilot subcarrier positions of the first OFDM symbol respectively, and by the zero setting of all non-pilot subcarriers.

Step S2: respectively inverse Fourier transform is carried out to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response.

Step S3: according to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determine carrier wave frequency deviation.

In step s3, according to described first time domain channel response and the second time domain channel response, determine that the peak phase between described first time domain channel response and the second time domain channel response is poor;

According to the first OFDM symbol and the second OFDM symbol preset time interval, determine the carrier wave frequency deviation corresponding to described peak phase difference.

Further, described according to described first time domain channel response and the second time domain channel response, determine that the step of the peak phase difference between described first time domain channel response and the second time domain channel response comprises:

According to described first time domain channel response and the second time domain channel response, determine the time domain channel response of the first time domain channel response and the second time domain channel response peak respectively;

According to the time domain channel response of described first time domain channel response and the second time domain channel response peak, determine that the peak phase between described first time domain channel response and the second time domain channel response is poor.

Further, the step that peak is chosen is comprised:

According to described first time domain channel response and the second time domain channel response, determine the maximum crest value corresponding to described first time domain channel response and the second time domain channel response respectively;

By the maximum crest value of more described first time domain channel response and the second time domain channel response, using the peak of all peaks of OFDM symbol large for maximum crest value as described first time domain channel response and the second time domain channel response.

Further, the peak phase relation in described the first time domain channel response according to obtaining and the second time domain channel response, determine that the step of carrier wave frequency deviation also comprises:

If there is extra phase difference in the first OFDM symbol and the second OFDM symbol, then according to described first OFDM symbol and the second OFDM symbol preset pilot frequency locations skew and time domain channel time delay determine that described extra phase is poor;

According to the peak phase relation in described extra phase difference and the first time domain channel response and the second time domain channel response, determine carrier wave frequency deviation.

Fig. 2 is the structure drawing of device of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides, and as shown in Figure 2, comprising: zero insertion module, conversion module and determination module.

Described zero insertion module is used for carrying out zero insertion process respectively to the domain channel response of all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol, obtains the first zero insertion domain channel response and the second zero insertion domain channel response.Wherein, the first submodule of described zero insertion module is placed in the preset pilot subcarrier positions of the first OFDM symbol respectively for being responded by all frequency domain pilot channels of the first OFDM symbol, and by the zero setting of all non-pilot subcarriers.Second submodule of described zero insertion module is placed in the preset pilot subcarrier positions of the first OFDM symbol respectively for being responded by all frequency domain pilot channels of the second OFDM symbol, and by the zero setting of all non-pilot subcarriers.

Described conversion module is used for carrying out inverse Fourier transform respectively to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response.

Described determination module is used for, according to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determining carrier wave frequency deviation.Wherein, the difference submodule of described determination module is used for according to described first time domain channel response and the second time domain channel response, determines that the peak phase between described first time domain channel response and the second time domain channel response is poor.The frequency deviation submodule of described determination module is used for, according to the first OFDM symbol and the second OFDM symbol preset time interval, determining the carrier wave frequency deviation corresponding to described peak phase difference.

Fig. 3 is the LTE downlink reference signal RS mapping graph of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides, as shown in Figure 3, user terminal or adjacent base station receive from after the downgoing baseband Received signal strength of base station, by the response of the frequency domain pilot channels of downgoing baseband Received signal strength according to preset resource mapping method (namely, the mapping mode of LTE downlink reference signal RS) be placed on sub-carrier positions originally, the zero setting of non-pilot subcarrier, builds the domain channel response of zero insertion with this.

Suppose that in downgoing baseband Received signal strength, former and later two OFDM symbol are designated as Sym1, Sym2 respectively, the time interval is Δ t, each symbol has N number of sub-carrier positions, the pilot frequency locations set of Sym1 is P1, the pilot frequency locations of Sym2 relative to the pilot frequency locations skew υ (if toward the skew of little direction, getting negative value) of Sym1, and sets subcarrier spacing between pilot tone as Δ K.For obtaining domain channel response H1 (k) and the H2 (k) of the pilot frequency locations of two OFDM symbol respectively, first discrete Fourier transform (DFT:DiscreteFourierTransform) is done to Sym1, Sym2,

$X1\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}[\mathrm{Sym}1\left(n\right)*\exp \left(\frac{-j2\mathrm{\πkn}}{N}\right)]$

$X2\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}[\mathrm{Sym}2\left(n\right)*\exp \left(\frac{-j2\mathrm{\πkn}}{N}\right)]$

Then least square (LS:Least-Square) is adopted to estimate domain channel response value,

$H1\left(k\right)=\left\{\begin{array}{c}\frac{X1\left(k\right)}{\mathrm{Pilot}1\left(k\right)},k\∈P1\\ 0,\mathrm{otherwise}\end{array}\right.$

$H2\left(k\right)=\left\{\begin{array}{c}\frac{X2\left(k\right)}{\mathrm{Pilot}2\left(k\right)},(k-\mathrm{\υ})\∈P1\\ 0,\mathrm{otherwise}\end{array}\right.$

Wherein, k span [0, N-1]; Pilot1 (k), Pilot2 (k) are defined as the pilot symbol transmitted of Sym1 and Sym2 respectively, and when k belongs to pilot subcarrier positions, they are respectively asked for corresponding frequency domain pilot channels response.

Inverse discrete Fourier transform (IDFT:InverseDiscreteFourierTransform) is done to H1 (k), H2 (k) and obtains time domain channel response:

$h1\left(n\right)=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[H1\left(k\right)*\exp \left(\frac{j2\mathrm{\πkn}}{N}\right)]$

$h2\left(n\right)=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[H2\left(k\right)*\exp \left(\frac{j2\mathrm{\πkn}}{N}\right)]$

Wherein, the span of n is [0, N-1].

Then, from time domain channel response h1 (n), h2 (n), peak is obtained.Because subcarrier spacing is Δ K, so have the peak value that Δ K part repeats in time domain channel response h1 (n), h2 (n).

Finally, Fig. 4 is LTE4, the 7 symbol time domain channel response extra phase difference figure of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides, as shown in Figure 4, according to the phase difference between time domain channel response h1 (n), h2 (n) peak value with frequency deviation relation, fully utilize one or more peak estimation frequency deviation, basic formula is as follows:

Wherein,

In fact, when there is no frequency deviation, between the peak value of time domain channel response, still may there is phase difference, supposing that time domain channel time delay is m ₀, time domain channel response h (n)=δ (n _i-m ₀), then

$H\left(k\right)=\mathrm{DFT}\left(h\left(n\right)\right)=\exp (-j\frac{2\mathrm{\π}}{N}{\mathrm{km}}_0)$

$h1\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{k\∈P1}H\left(k\right)*\exp \left(j\frac{2\mathrm{\π}}{N}\mathrm{kn}\right)=\frac{1}{N}{\mathrm{\Σ}}_{k\∈P1}\exp \left(j\frac{2\mathrm{\π}}{N}k(n-m_0)\right)$

$h2\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{k\∈P1}H(k+\mathrm{\υ})*\exp \left(j\frac{2\mathrm{\π}}{N}(k+\mathrm{\υ})n\right)=\exp \left(j\frac{2\mathrm{\π}}{N}\mathrm{\υ}(n-m_0)\right)*h1\left(n\right)$

Visible at n ≠ m ₀to there is an extra peak phase poor in position (namely occurring the position of peak value in repeated segments) like this, just need when determining frequency deviation to do corresponding compensation.Therefore, the actual phase difference caused by frequency deviation obtained needs the extra phase difference eliminated inside the peak phase difference between time domain channel response just can obtain the phase difference finally determined for frequency deviation.

Fig. 5 is the overall flow figure of the Nonlinear Transformation in Frequency Offset Estimation that the embodiment of the present invention provides, and as shown in Figure 5, this embodiment is only the preferred embodiments of the present invention, is not limited to the present invention.For a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

With LTE bandwidth for 10M, conventional CP is example, corresponding Sym1 and the Sym2 of symbol 4,7 (15.36MHz sample rate), and concrete methods of realizing is as follows:

(1) domain channel response of zero insertion is built.Frequency domain pilot channels response is placed on sub-carrier positions originally, the zero setting of non-pilot subcarrier.

(2) N gets 1024, determines frequency domain pilot channels estimated value H1 (k) and the H2 (k) of symbol 4,7.Suppose that the time interval of former and later two baseband OFDM symbols 4,7 is Δ t, each symbol has N number of sub-carrier positions, the pilot frequency locations set of symbol 4 is P1, the pilot frequency locations of symbol 7 relative to the pilot frequency locations skew v (if toward the skew of little direction, getting negative value) of symbol 4, and sets subcarrier spacing between pilot tone as Δ K.For obtaining domain channel response H1 and the H2 of symbol 4,7 respectively, first DFT conversion being done to symbol 4,7, also can do fast Fourier transform (FFT:FastFourierTransform).Wherein, FFT and DFT effect is identical, just has higher efficiency.

$X1\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}[\mathrm{Sym}1\left(n\right)*\exp \left(\frac{-j2\mathrm{\πkn}}{N}\right)]$

$X2\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}[\mathrm{Sym}2\left(n\right)*\exp \left(\frac{-j2\mathrm{\πkn}}{N}\right)]$

Then, adopt LS to estimate domain channel response value, obtain:

$H1\left(k\right)=\left\{\begin{array}{c}\frac{X1\left(k\right)}{\mathrm{Pilot}1\left(k\right)},k\∈P1\\ 0,\mathrm{otherwise}\end{array}\right.$

$H2\left(k\right)=\left\{\begin{array}{c}\frac{X2\left(k\right)}{\mathrm{Pilot}2\left(k\right)},(k-\mathrm{\υ})\∈P1\\ 0,\mathrm{otherwise}\end{array}\right.$

Wherein, the span of k is [0, N-1]; Pilot1 (k), Pilot2 (k) are defined as the pilot symbol transmitted of symbol 4 and 7 respectively, and when k belongs to pilot subcarrier positions, they are respectively asked for corresponding frequency domain pilot channels response.

(3) IDFT conversion is done to the domain channel response of symbol 4,7 and obtain time domain channel response, also can make inverse fast Fourier transform (IFFT:InverseFastFourierTransform).Wherein, IFFT and IDFT effect is identical, just has higher efficiency.

IDFT conversion is done to H1 (k), H2 (k) and obtains time domain channel response:

$h1\left(n\right)=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[H1\left(k\right)*\exp \left(\frac{j2\mathrm{\πkn}}{N}\right)]$

$h2\left(n\right)=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[H2\left(k\right)*\exp \left(\frac{j2\mathrm{\πkn}}{N}\right)]$

Wherein, the span of n is [0, N-1].

(4) frequency deviation is estimated according to the peak phase relation in symbol 4,7 time domain channel response.Peak is obtained from time domain channel response h1 (n), h2 (n), because the subcarrier spacing between pilot tone is Δ K, so have the peak value that Δ K part repeats in time domain channel response h1 (n), h2 (n).Poor according to the peak phase between time domain channel response h1 (n) and h2 (n) with frequency deviation relation, fully utilize one or more peak value, estimate frequency deviation.

Six peak values of symbol 4,7 time domain channel response h1 (n), h2 (n) are greatly about n _i=n ₀* 1024/6 (n ₀=0,1 ... 5) near 6 different positions.

The search of peak can only be determined according to time domain channel response h1 (n) or h2 (n), also all can search in both and then get preferably peak.Concrete grammar is as follows:

$\mathrm{peak}\_\mathrm{pos}=\arg \underset{n}{\max }\left|h\left(n\right)\right|,$

n∈(n _I-cplength，n _I+cplength)

Cplength represents the CP length of current sign.If find out six peak values in symbol 4,7 separately, compare the size of peak-peak, the time domain channel response of six peaks of the symbol that peak-peak is little obtains according to six peaks of the large symbol of peak-peak.

In fact, when there is no frequency deviation, between the peak value of time domain channel response, still may there is phase difference, supposing that time domain channel time delay is m ₀, time domain channel response h (n)=δ (n _i-m ₀), the time domain channel response of then symbol 4,7 is determined as follows:

$h1\left(n\right)=\frac{1}{N}{\mathrm{\Σ}}_{k\∈P1}\exp \left(j\frac{2\mathrm{\π}}{N}k(n-m_0)\right)$

$h2\left(n\right)=\exp (-j\frac{2\mathrm{\π}}{1024}3(n-m_0))*h1\left(n\right)$

In this case, peak value position is n=n _i+ m ₀=m ₀+ n ₀* 1024/6, the extra phase difference at peak value place is namely be 0 in the extra phase difference at the the 1st, 3,5 peak value place, the extra phase difference at the the 2nd, 4,6 peak value place is π.Therefore, the actual phase difference caused by frequency deviation obtained needs the extra phase difference eliminated inside the peak phase difference between time domain channel response just can obtain the phase difference finally determined for frequency deviation.

The time domain channel response of 6 peaks of define symbol 4,7 is respectively d4 (n ₀), d7 (n ₀), n ₀=0,1 ..., 5, and the time between the symbol 4,7 obtained divided by sample rate according to counting of being separated by of symbol 4,7 be separated by, determine that frequency deviation is as follows:

In sum, the present invention has following technique effect: by the channel estimation in frequency domain of pilot sub-carrier is transformed to time domain, the peak value on time domain channel response can be made to converge signal energy, realize effective restraint speckle, improve frequency deviation estimated performance.In addition, because domain channel response has just been placed on atom carrier position before IFFT conversion, frequency deviation is estimated more accurate, thus the problem partially affected when pilot tone is not subject in same carrier wave position also no longer exists.

Although above to invention has been detailed description, the present invention is not limited thereto, those skilled in the art of the present technique can carry out various amendment according to principle of the present invention.Therefore, all amendments done according to the principle of the invention, all should be understood to fall into protection scope of the present invention.

Claims (10)

1. a method for Nonlinear Transformation in Frequency Offset Estimation, is characterized in that,

Respectively zero insertion process is carried out to the domain channel response of all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol, obtains the first zero insertion domain channel response and the second zero insertion domain channel response;

Respectively inverse Fourier transform is carried out to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

According to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determine carrier wave frequency deviation.

2. method according to claim 1, is characterized in that,

User terminal or the domain channel response of adjacent base station to all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol carry out zero insertion process respectively, obtain the first zero insertion domain channel response and the second zero insertion domain channel response;

Respectively inverse Fourier transform is carried out to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

According to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determine carrier wave frequency deviation.

3. method according to claim 1, it is characterized in that, the step that the described domain channel response to all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol carries out zero insertion process respectively comprises:

All frequency domain pilot channels responses of the first OFDM symbol are placed on the preset pilot subcarrier positions of the first OFDM symbol respectively, and by the zero setting of all non-pilot subcarriers;

And, all frequency domain pilot channels responses of the second OFDM symbol are placed on the preset pilot subcarrier positions of the second OFDM symbol respectively, and by the zero setting of all non-pilot subcarriers.

4. method according to claim 1, is characterized in that, the peak phase relation in described the first time domain channel response according to obtaining and the second time domain channel response, determines that the step of carrier wave frequency deviation comprises:

According to described first time domain channel response and the second time domain channel response, determine that the peak phase between described first time domain channel response and the second time domain channel response is poor;

According to the first OFDM symbol and the second OFDM symbol preset time interval, determine the carrier wave frequency deviation corresponding to described peak phase difference.

5. method according to claim 4, is characterized in that, described according to described first time domain channel response and the second time domain channel response, determines that the step of the peak phase difference between described first time domain channel response and the second time domain channel response comprises:

According to described first time domain channel response and the second time domain channel response, determine the time domain channel response of the first time domain channel response and the second time domain channel response peak respectively;

According to the time domain channel response of described first time domain channel response and the second time domain channel response peak, determine that the peak phase between described first time domain channel response and the second time domain channel response is poor.

6. method according to claim 5, is characterized in that, comprises the step that peak is chosen:

According to described first time domain channel response and the second time domain channel response, determine the maximum crest value corresponding to described first time domain channel response and the second time domain channel response respectively;

By the maximum crest value of more described first time domain channel response and the second time domain channel response, using the peak of all peaks of OFDM symbol large for maximum crest value as described first time domain channel response and the second time domain channel response.

7. method according to claim 1, is characterized in that, the peak phase relation in described the first time domain channel response according to obtaining and the second time domain channel response, determines that the step of carrier wave frequency deviation also comprises:

If there is extra phase difference in the first OFDM symbol and the second OFDM symbol, then according to described first OFDM symbol and the second OFDM symbol preset pilot frequency locations skew and time domain channel time delay determine that described extra phase is poor;

According to the peak phase relation in described extra phase difference and the first time domain channel response and the second time domain channel response, determine carrier wave frequency deviation.

8. a device for Nonlinear Transformation in Frequency Offset Estimation, is characterized in that,

Zero insertion module, for carrying out zero insertion process respectively to the domain channel response of all pilot sub-carriers of the first OFDM symbol in the downgoing baseband Received signal strength received and all pilot sub-carriers of the second OFDM symbol, obtain the first zero insertion domain channel response and the second zero insertion domain channel response;

Conversion module, for carrying out inverse Fourier transform respectively to described first zero insertion domain channel response and the second zero insertion domain channel response, obtains the first time domain channel response and the second time domain channel response;

Determination module, for according to the peak phase relation in the first time domain channel response obtained and the second time domain channel response, determines carrier wave frequency deviation.

9. device according to claim 8, is characterized in that, described zero insertion module comprises further:

First submodule, for being placed in the preset pilot subcarrier positions of the first OFDM symbol respectively by all frequency domain pilot channels responses of the first OFDM symbol, and by the zero setting of all non-pilot subcarriers;

Second submodule, for being placed in the preset pilot subcarrier positions of the second OFDM symbol respectively by all frequency domain pilot channels responses of the second OFDM symbol, and by the zero setting of all non-pilot subcarriers.

10. device according to claim 8, is characterized in that, described determination module comprises further:

Difference submodule, for according to described first time domain channel response and the second time domain channel response, determines that the peak phase between described first time domain channel response and the second time domain channel response is poor;

Frequency deviation submodule, for according to the first OFDM symbol and the second OFDM symbol preset time interval, determines the carrier wave frequency deviation corresponding to described peak phase difference.