CN101917355A - Channel estimation method and system - Google Patents

Abstract

The invention provides a channel estimation method and a channel estimation system to improve the accuracy of channel estimation. The method comprises the following steps of: calculating a channel response estimation value at a pilot signal position; performing iterative filtering on the channel response estimation value at the pilot signal position to obtain a final channel response estimation value at the pilot signal position; and estimating channel response estimation values of all subcarriers and symbols according to the final channel response estimation value at the pilot signal position. Through multiple iterations, the method and the system can reduce the influence of noise on the channel response estimation values so as to improve the accuracy of the channel estimation.

Description

A kind of channel estimation methods and system

Technical field

The present invention relates to the signal processing technology field, particularly relate to a kind of channel estimation methods and system.

Background technology

As LTE (LongTerm Evolution, the Long Term Evolution) technology in 3G epoch behind the wireless network, compare the advantage of having more with 3G, for example: improved traffic rate, spectrum efficiency, downward compatibility, also reduced time-delay simultaneously.To have adopted OFDM (Orthogonal Frequency Division Multiplexing) be orthogonal frequency division multiplexi to 3GPP (third generation partner program) descending, subchannel in the OFDM technology is mutually orthogonal, thereby reduced the interference of intercarrier and eliminated intersymbol interference, channel equalization is also relatively easy afterwards to make channel estimating.

Usually, channel estimation methods can be divided into blind estimating method and half-blindness method of estimation.Wherein, the half-blindness method of estimation is the auxiliary method of estimation of pilot tone, has advantages such as algorithm is simple, real-time.The distribution of pilot tone is divided into block pilot tone and thin shape pilot tone two classes, and the channel estimating of block pilot tone is applicable to slow fading channel; The channel estimating of dredging the shape pilot tone can satisfy brings disaster to the demand that becomes channel, and by the CFR (channel frequency response, channel frequency response) of estimating pilot frequency position, interpolation obtains the channel response of data division.

The auxiliary channel estimation methods of pilot tone is a kind of channel estimation methods that is most widely used among the OFDM, it inserts some in the data flow of transmitting terminal known signal is a pilot signal, the channel impulse response that signal that receives in the receiving terminal utilization and pilot signal estimate the pilot frequency locations place, and, obtain the estimated value of whole channel response by certain interpolation algorithm.

Existing OFDM channel estimation methods based on pilot tone can be divided into least mean-square error (LS) and two kinds of methods of linear minimum mean-squared error (LMMSE) substantially.Because the LMMSE method makes the mean square error minimum of channel estimating in AWGN (Additive White Gaussion Noise, additive white Gaussian noise) channel, therefore be widely used in the channel estimating of OFDM.The LMMSE channel estimating is according to MMSE (Minimum Mean Squared Error, least mean-square error) criterion the LS channel estimation results to be carried out Filtering Processing one time, can eliminate the influence of partial noise like this.But also there are a certain distance in LMMSE performance for estimating channel and ideal communication channel between estimating, the error rate of system is still waiting to improve.

Summary of the invention

Technical problem to be solved by this invention provides a kind of channel estimation methods and system, to improve the accuracy of channel estimating.

In order to address the above problem, the invention discloses a kind of channel estimation methods, comprising:

Calculate the channel response estimated value on the pilot positions;

Channel response estimated value on the described pilot positions is carried out iteration filtering, obtain the final channel response estimated value on the pilot positions;

Utilize the final channel response estimated value on the described pilot positions, estimate the channel response estimated value on all subcarriers and the symbol.

Preferably, the present invention calculates the channel response estimated value on the pilot positions in the following manner: according to predefined received signal value and the functional relation that sends signal value, bring the pilot signal value that sends into described functional relation, calculate the pilot signal value of reception; The pilot signal value of the described reception that calculates divided by the pilot signal value that sends, is obtained the channel response estimated value on the pilot positions.

Wherein, described iteration filtering is based on the LMMSE channel estimating, and iterative formula is as follows:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n;$

Wherein: H _nBe the channel response estimated value on the pilot positions, the n round numbers,

Be the cross-correlation matrix of all subcarriers,

Be the autocorrelation matrix of pilot signal virgin carrier wave, β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio, The representation unit matrix.

Wherein, described iteration is filtered into the filtering of one or many iteration.

Wherein, to the LTE receiving terminal, on frequency domain, estimate a channel response estimated value on all subcarriers of symbol earlier; Then, on time domain, estimate the channel response estimated value on all symbols.

The present invention also provides a kind of channel estimation system, comprising:

The pilot tone estimation module is used to calculate the channel response estimated value on the pilot positions;

The iteration filtration module is used for the channel response estimated value on the described pilot positions is carried out iteration filtering, obtains the final channel response estimated value on the pilot positions;

The channel response estimation module is used to utilize the final channel response estimated value on the described pilot positions, estimates the channel response estimated value on all subcarriers and the symbol.

Preferably, described pilot tone estimation module comprises:

Receive the pilot signal calculating sub module, be used for bringing the pilot signal value that sends into described functional relation, calculate the pilot signal value of reception according to predefined received signal value and the functional relation that sends signal value;

Response estimator module is used for pilot signal value with the described reception that calculates divided by the pilot signal value that sends, and obtains the channel response estimated value on the pilot positions.

Wherein, described iteration filtering is based on the LMMSE channel estimating, and iterative formula is as follows:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n;$

Wherein: H _nBe the channel response estimated value on the pilot positions, the n round numbers, Be the cross-correlation matrix of all subcarriers,

Be the autocorrelation matrix of pilot signal virgin carrier wave, β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio,

The representation unit matrix.

Wherein, described iteration is filtered into the filtering of one or many iteration.

Preferably, described channel response estimation module comprises:

Domain channel response estimator module is used for the receiving terminal to LTE, on frequency domain, estimates a channel response estimated value on all subcarriers of symbol earlier;

Time domain channel response estimator module is used in time domain, estimates the channel response estimated value on all symbols.

Compared with prior art, the present invention has the following advantages:

At first, the present invention proposes a kind of channel estimation methods, this method is improved on the basis of existing LMMSE channel estimation methods, compare with existing LMMSE channel estimation methods, the present invention carries out iteration filtering based on the LMMSE channel estimation methods to the channel response estimated value on the pilot positions, reduce the influence of noise through iteration repeatedly, thereby improved the accuracy of ginseng channel estimating the channel response estimated value.Simultaneously, owing to only pilot signal is carried out iteration filtering, its matrix dimension can be very not big, can not cause very big computational complexity.And existing LMMSE channel estimation methods has only carried out Filtering Processing one time to the LS channel estimation results.

Secondly, in the iteration filtering of the present invention, the channel response estimated value H on the pilot positions _nBe to obtain, and be directly to utilize the pilot signal that receives to calculate, so the present invention has further reduced The noise unlike existing LMMSE method by function calculation.

Description of drawings

Fig. 1 is the described LTE system model of embodiment of the invention figure;

Fig. 2 is the channel estimation methods flow chart of the described a kind of LTE of being applicable to of embodiment of the invention system;

Fig. 3 is the structure chart of the described a kind of channel estimation system of the embodiment of the invention.

Embodiment

For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

The present invention proposes a kind of channel estimation methods, and this method is improved on the basis of existing LMMSE channel estimation methods, thereby improves the accuracy of channel estimating.

Because the present invention and existing LMMSE channel estimation methods are closely related, in order to describe improvement thinking of the present invention and concrete improving one's methods in detail, below introduce existing LMMSE channel estimation methods in detail earlier.

At first, pilot tone is meant cell special reference, the auxiliary channel estimation process of pilot tone is generally: receiving terminal at first extracts pilot signal in the signal that receives, utilize pilot signal to recover the channel information of pilot positions, utilize certain processing means (as interpolation, filtering etc.) to obtain channel information on all subcarriers and the symbol then.

In above-mentioned channel estimation process, the LMMSE method is mainly used in utilizes pilot signal to recover the channel information of pilot positions.The LMMSE method is to make the mean square error of channel estimating reach minimum, specific as follows in awgn channel:

If the mode of signal is as follows:

Y(k)＝X(k)H(k)+N(k) (1)

Wherein: the signal value of X (k) for sending, the signal value of Y (k) for receiving, H (k) is the frequency domain response function of channel function, N (k) is the frequency-domain expression of Gaussian noise.

The channel estimating expression formula that is obtained least squares error (LS) by formula (1) is:

H _LS＝X ^-1Y

Wherein, H _LSBeing the channel response estimated value on the pilot positions, is directly the pilot signal value Y that receives to be obtained divided by the pilot signal value X that sends.

The channel estimating expression formula of linear minimum mean-squared error (LMMSE) is:

$H_{\mathrm{lmmse}}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+{\mathrm{\σ}}_N{\left({\mathrm{XX}}^H\right)}^{-1})}^{-1}{\hat{H}}_{\mathrm{LS}}---\left(2\right)$

Wherein: Be the cross-correlation matrix of all subcarriers, Be the autocorrelation matrix of pilot signal virgin carrier wave, σ ² _NBe the Gaussian noise mean square deviation,

Be H _LSConjugation, " 1 " representing matrix in the upper right corner is inverted, the transposition of " H " representing matrix in the upper right corner.

The operand of LMMSE method is big more a lot of than LS, and calculate H all needs to calculate at every turn

This amount of calculation is just very big, and also comprises in the matrix inversion in the formula

Expression channel power delay spectrum is a statistic, fixes in for a long time.If transmission symbol is mapped to same planisphere (planisphere is meant modulation system, for example the planisphere of QPSK, 16QAM etc.), (XX so ^H) ^-1Can represent with its expectation:

${\mathrm{\σ}}_N^2{\left({\mathrm{XX}}^H\right)}^{-1}=E\left\{{\mathrm{\σ}}_N^2{\left({\mathrm{XX}}^H\right)}^{-1}\right\}=I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}}$

Therefore, H _LmmseCan further be reduced to:

$H_{\mathrm{lmmse}}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{\hat{H}}_{\mathrm{LS}}---\left(3\right)$

Wherein: β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio,

The representation unit matrix.If QPSK (quarternary phase-shift keying (QPSK) modulation), then β=1; If 16QAM (quadrature amplitude modulation), then β=17/9.

In digital communicating field, often digital signal is represented on complex plane that to represent the relation between signal and the signal intuitively, this diagram is exactly a planisphere.

Can see that from formula (3) existing LMMSE channel estimating is according to the MMSE criterion LS channel estimation results to be carried out Filtering Processing one time, can eliminate the influence of partial noise like this.

On the basis of the above, the present invention proposes the channel estimation methods of a kind of LMMSE iteration filtering, and it is as follows that it improves thinking:

The calculating of channel response estimated value H on the pilot positions is divided into following two steps:

Step 1, if the pilot signal that X (k) sends for transmitting terminal, so at receiving terminal, the channel response estimated value on the pilot positions is:

${\hat{H}}_n\left(k\right)=\frac{Y\left(k\right)}{X\left(k\right)}=\frac{X\left(k\right)H\left(k\right)}{X\left(k\right)}+\frac{N\left(k\right)}{X\left(k\right)}---\left(4\right)$

Wherein: the pilot signal value of X (k) for sending, the pilot signal value of Y (k) for receiving, H (k) is the frequency domain response function of channel function, N (k) is the frequency-domain expression of Gaussian noise.

Step 2 is to the channel response estimated value on the pilot positions

Carry out iteration filtering based on the LMMsE algorithm, to reduce the influence of noise, just to the channel impulse response valuation:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n---\left(5\right)$

Wherein:

Be the cross-correlation matrix of all subcarriers,

Be the autocorrelation matrix of pilot signal virgin carrier wave, H _nFor

Conjugation, the n round numbers, " 1 " representing matrix in the upper right corner is inverted.β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio,

The representation unit matrix.If QPSK (quarternary phase-shift keying (QPSK) modulation), then β=1; If 16QAM (quadrature amplitude modulation), then β=17/9.

Repeating step two just can reduce the error rate through iteration repeatedly, thereby improves the performance of system.Because the channel response estimated value at pilot signal place is through repeatedly LMMSE iteration filtering, the meeting that influences of noise and interference is further eliminated, thereby has improved the accuracy of ginseng channel estimating.Simultaneously, owing to only pilot signal is carried out iteration filtering, its matrix dimension can be very not big, can not cause very big computational complexity.

The present invention is applicable in the numerous employing OFDM The Application of Technology system, as the LTE system, will will be that example describes with the LTE system below.

Because the LTE physical layer has adopted the OFDM technology,, need to estimate and follow the tracks of the characteristic of fading channel usually for modulation and demodulation that ofdm signal at a high speed is concerned with.

With reference to Fig. 1, be the described LTE system model of embodiment of the invention figure.

At transmitting terminal, the downlink physical signal at first carries out chnnel coding at the transmitting terminal encoder, and the bit stream process scrambling modulation of transmitting terminal encoder output, layer mapping, precoding, physical resource unit mapping are after send on each antenna after the OFDM modulation.

At receiving terminal, adopt the processing procedure opposite with transmitting terminal, that is: the signal of reception process OFDM demodulation, channel estimating, input, layer are separated mapping, descrambling is exported after separating the mediation channel decoding.

In the LTE system, on time domain and frequency domain two-dimensional space, designed the distribution of pilot signal, so that the channel information that obtains respectively on time domain and the frequency domain is used for the signal correction demodulation.

With reference to Fig. 2, be the channel estimation methods flow chart of the described a kind of LTE of being applicable to of embodiment of the invention system.

As can be seen from Figure 1, after receiving terminal carries out the OFDM demodulation to the received signal, carry out channel estimating again, concrete steps are as follows:

Step 201 is extracted pilot signal the received signal after demodulation;

Step 202 is calculated the channel response estimated value on the pilot positions;

This step has multiple computational methods, and wherein the simplest as existing LS method, this method directly obtain channel response estimated value on the pilot positions with the pilot signal value that receives divided by the pilot signal value that sends.The LS method is directly used the pilot signal of reception, owing to have noise in the signal that receives, therefore can influence the accuracy of result of calculation.

And existing LMMSE method, with reference to formula (3), though be on the basis of LS method result of calculation, to have carried out a filtering again, owing to used the result of calculation of LS method, so the evaluated error that also exists noise to bring inevitably.

Based on above-mentioned analysis, present embodiment is made improvement to this:

At first,, bring the pilot signal value that sends into described functional relation, calculate the pilot signal value of reception according to predefined received signal value and the functional relation that sends signal value;

Then, the pilot signal value of the described reception that calculates divided by the pilot signal value that sends, is obtained the channel response estimated value on the pilot positions.

The mode of supposing signal is as follows:

Y(k)＝X(k)H(k)+N(k) (1)

Be received signal value and functional relation definition as (1) formula of sending signal value, then the computing formula of the pilot signal value of Jie Shouing is as follows:

${\hat{H}}_n\left(k\right)=\frac{Y\left(k\right)}{X\left(k\right)}=\frac{X\left(k\right)H\left(k\right)}{X\left(k\right)}+\frac{N\left(k\right)}{X\left(k\right)}---\left(4\right)$

By formula (4) as can be known, present embodiment does not directly use the pilot signal that receives, but calculates by formula, therefore can eliminate the influence of noise to result of calculation greatly.

Step 203 is carried out iteration filtering to the channel response estimated value on the described pilot positions, obtains the final channel response estimated value on the pilot positions;

The iterative formula that present embodiment adopts is as follows:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n---\left(5\right)$

According to the difference of application demand, described iteration filtering can be carried out once, also can carry out repeatedly.Whenever carry out iteration one time, promptly carried out once filter and made an uproar.

Present embodiment carries out an iteration and gets final product, like this can simplified system, and can reach reasonable denoising effect.A described iteration is meant: the value of n is from 0 to 2, wherein H ₀Calculate H by formula (4) ₁Calculated by formula (5), also do not carry out iteration this moment, iteration refers to promptly that once recurring formula (5) calculates H ₂In iterative process,

Calculate and once get final product.

Step 204 is utilized the final channel response estimated value on the described pilot positions, estimates the channel response estimated value on all subcarriers and the symbol.

For example, by linear interpolation, estimate the channel response estimated value on all subcarriers and the symbol.

In the present embodiment,, on frequency domain, estimate a channel response estimated value on all subcarriers of symbol earlier to the LTE receiving terminal; Then, on time domain, estimate the channel response estimated value on all symbols.

In sum, the present invention compares with existing LMMSE channel estimation methods, and following 2 differences are arranged:

The first, the present invention carries out iteration filtering based on the LMMSE channel estimation methods to the channel response estimated value on the pilot positions, reduces the influence of noise to the channel response estimated value through iteration repeatedly, thereby reduces the error rate; And existing LMMSE channel estimation methods has only carried out Filtering Processing one time to the LS channel estimation results.

The second, in the iteration filtering formula of the present invention (5), the channel response estimated value H on the pilot positions _nBe to obtain, and be directly to utilize the pilot signal that receives to calculate, so the present invention has further reduced The noise unlike existing LMMSE method by function calculation.

Based on the explanation of said method embodiment, the present invention also provides corresponding system embodiment.

With reference to Fig. 3, be the structure chart of the described a kind of channel estimation system of the embodiment of the invention.

Described channel estimation system can comprise:

Pilot tone estimation module 301 is used to calculate the channel response estimated value on the pilot positions;

Iteration filtration module 302 is used for the channel response estimated value on the described pilot positions is carried out iteration filtering, obtains the final channel response estimated value on the pilot positions;

Channel response estimation module 303 is used to utilize the final channel response estimated value on the described pilot positions, estimates the channel response estimated value on all subcarriers and the symbol.

Wherein, described iteration filtering is based on the LMMSE channel estimating, and iterative formula is as follows:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n---\left(5\right)$

Wherein: H _nBe the channel response estimated value on the pilot positions, the n round numbers,

Be the cross-correlation matrix of all subcarriers,

Be the autocorrelation matrix of pilot signal virgin carrier wave, β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio, The representation unit matrix.

Described iteration filtering can be the filtering of one or many iteration, and each iteration is promptly once filtered the processing of making an uproar.

Usually, described channel estimation system is arranged at signal receiving end, its processing procedure is: after receiving terminal receives signal and carries out the OFDM demodulation, pilot tone estimation module 301 at first estimates the channel response estimated value on the pilot positions, carry out iteration filtering by 302 pairs of described estimated values of iteration filtration module then, filtering noise is to the influence of estimated value, the channel response estimated value on the still pilot positions that obtains this moment; At last, channel response estimation module 303 is utilized the filtered pilot frequency locations estimated value of described iteration, finally estimates channel response estimated value on all subcarriers and the symbol by methods such as interpolation.

Preferably, in order further to reduce The noise, described pilot tone estimation module 301 further can comprise:

Receive pilot signal calculating sub module 3011, be used for bringing the pilot signal value that sends into described functional relation, calculate the pilot signal value of reception according to predefined received signal value and the functional relation that sends signal value;

Response estimator module 3012 is used for pilot signal value with the described reception that calculates divided by the pilot signal value that sends, and obtains the channel response estimated value on the pilot positions.

As from the foregoing, pilot tone estimation module 301 is not directly used the noisy pilot signal that receives, but draws by function calculation, therefore can reduce the influence of noise to estimated result.

Described channel estimation system is applicable to and adopts OFDM The Application of Technology system that in the LTE system, described channel response estimation module 303 further can comprise:

Domain channel response estimator module 3031 is used for the receiving terminal to LTE, on frequency domain, estimates a channel response estimated value on all subcarriers of symbol earlier;

Time domain channel response estimator module 3032 is used in time domain, estimates the channel response estimated value on all symbols.

In sum, channel estimation system of the present invention is compared with existing LMMSE channel estimation system, has the following advantages:

The first, the present invention carries out iteration filtering based on the LMMSE channel estimating to the channel response estimated value on the pilot positions, reduces the influence of noise to the channel response estimated value through iteration repeatedly, thereby has improved the accuracy of ginseng channel estimating.Simultaneously, owing to only pilot signal is carried out iteration filtering, its matrix dimension can be very not big, can not cause very big computational complexity.And existing LMMSE channel estimation system has only carried out Filtering Processing one time to the LS channel estimation results.

The second, in the iteration filtering of the present invention, the channel response estimated value H on the pilot positions _nBe to obtain, and be directly to utilize the pilot signal that receives to calculate, so the present invention has further reduced The noise unlike existing LMMSE system by function calculation.

Each embodiment in this specification all adopts the mode of going forward one by one to describe, and what each embodiment stressed all is and the difference of other embodiment that identical similar part is mutually referring to getting final product between each embodiment.For system embodiment, because it is similar substantially to method embodiment, so description is fairly simple, relevant part gets final product referring to the part explanation of method embodiment.

More than to a kind of channel estimation methods provided by the present invention and system, be described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (10)

1. a channel estimation methods is characterized in that, comprising:

Calculate the channel response estimated value on the pilot positions;

Channel response estimated value on the described pilot positions is carried out iteration filtering, obtain the final channel response estimated value on the pilot positions;

Utilize the final channel response estimated value on the described pilot positions, estimate the channel response estimated value on all subcarriers and the symbol.

2. method according to claim 1 is characterized in that, calculates the channel response estimated value on the pilot positions in the following manner:

According to predefined received signal value and the functional relation that sends signal value, bring the pilot signal value that sends into described functional relation, calculate the pilot signal value of reception;

The pilot signal value of the described reception that calculates divided by the pilot signal value that sends, is obtained the channel response estimated value on the pilot positions.

3. method according to claim 1 is characterized in that:

Described iteration filtering is based on the LMMSE channel estimating, and iterative formula is as follows:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n;$

Wherein: H _nBe the channel response estimated value on the pilot positions, the n round numbers,

Be the cross-correlation matrix of all subcarriers,

Be the autocorrelation matrix of pilot signal virgin carrier wave, β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio,

The representation unit matrix.

4. according to claim 1 or 3 described methods, it is characterized in that:

Described iteration is filtered into the filtering of one or many iteration.

5. method according to claim 1 and 2 is characterized in that:

To the LTE receiving terminal, on frequency domain, estimate a channel response estimated value on all subcarriers of symbol earlier; Then, on time domain, estimate the channel response estimated value on all symbols.

6. a channel estimation system is characterized in that, comprising:

The pilot tone estimation module is used to calculate the channel response estimated value on the pilot positions;

The iteration filtration module is used for the channel response estimated value on the described pilot positions is carried out iteration filtering, obtains the final channel response estimated value on the pilot positions;

The channel response estimation module is used to utilize the final channel response estimated value on the described pilot positions, estimates the channel response estimated value on all subcarriers and the symbol.

7. system according to claim 6 is characterized in that, described pilot tone estimation module comprises:

Receive the pilot signal calculating sub module, be used for bringing the pilot signal value that sends into described functional relation, calculate the pilot signal value of reception according to predefined received signal value and the functional relation that sends signal value;

Response estimator module is used for pilot signal value with the described reception that calculates divided by the pilot signal value that sends, and obtains the channel response estimated value on the pilot positions.

8. system according to claim 6 is characterized in that:

Described iteration filtering is based on the LMMSE channel estimating, and iterative formula is as follows:

$H_{n+1}=R_{{\mathrm{HH}}_p}{(R_{H_P{H}_P}+I_{N_P}\frac{\mathrm{\β}}{\mathrm{SNR}})}^{-1}{H}_n;$

Wherein: H _nBe the channel response estimated value on the pilot positions, the n round numbers,

Be the cross-correlation matrix of all subcarriers,

Be the autocorrelation matrix of pilot signal virgin carrier wave, β=E{|Z _k| ²E{1/|Z _k| ², Z (k) is the point on the planisphere, SNR represents signal to noise ratio,

The representation unit matrix.

9. according to claim 6 or 8 described systems, it is characterized in that:

Described iteration is filtered into the filtering of one or many iteration.

10. according to claim 6 or 7 described systems, it is characterized in that described channel response estimation module comprises:

Domain channel response estimator module is used for the receiving terminal to LTE, on frequency domain, estimates a channel response estimated value on all subcarriers of symbol earlier;

Time domain channel response estimator module is used in time domain, estimates the channel response estimated value on all symbols.

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