CN1917490A - Method of reducing peak even ratio of orthoganal frequency division complexing signals - Google Patents

Abstract

The method comprises: a) according to the preset sequence, saving multi weighted sequences; b) the data vector in OFDM (orthogonal frequency division multiplexing) signals is divided into multi subvectors; c) selecting one weighted sequence from said multi weighted sequences in order to make peak value of the signals formed by the combination of the weighted sequence and said multi subvectors to be least; d) according to the location of the weighted sequence selected in multi weighted sequences, shifting the pilot frequency in OFDM signals.

Description

Reduce the method for the peak-to-average force ratio of orthogonal frequency-division multiplex singal

Technical field

The present invention relates to the method for peak-to-average force ratio (PAPR) of a kind of reduction OFDM (OFDM) signal and the method for corresponding restore data, it is in efficient that can raising information sends when reducing peak-to-average ratio.

Background technology

OFDM is a kind of data transfer mode efficiently, and its basic thought is in frequency domain given channel to be divided into many orthogonal sub-channels, uses a subcarrier to modulate on each subchannel, and each subcarrier parallel transmission.Like this, although total channel be non-flat forms, have frequency selectivity, but each subchannel is a relatively flat, what carry out on each subchannel is narrow band transmission, and signal bandwidth is less than the respective bandwidth of channel, so the just interference between the erasure signal waveform greatly.

OFDM with respect to the difference of general multi-carrier transmission is, its allows subcarrier spectrum to overlap, as long as can satisfy between subcarrier mutually orthogonally, just can isolate data-signal from the subcarrier of aliasing.Because OFDM allows the subcarrier spectrum aliasing, its spectrum efficiency improves greatly, thereby is a kind of modulation system efficiently.

OFDM is adapted at transmitting high speed data in the wireless mobile channel of multipath transmisstion and Doppler frequency shift.It can effectively resist multipath effect, eliminates intersymbol interference, the decline of contrary frequency selectivity, and channel utilization height.The OFDM technology is successively adopted by systems such as European digital audio broadcast (DAB), European digital video broadcasting (DVB), HIPERLAN and IEEE802.11 WLAN (wireless local area network).

In ofdm system, need the ratio of peak power with the average power of the signal after reduction is modulated, be called for short peak-to-average force ratio (PAPR).Document 1 (Xiaodong Li, L J Cimini, " Effectsof clipping and filtering on the performance of OFDM ", IEEEcommunications Letters, 1998.2 (5): the method with amplitude limit 131～133.) reduces peak-to-average force ratio.Yet amplitude limit will cause disturbing and out-of-band noise in the serious band, thereby reduce the performance of system.

Document 2 (Stefan H Muller, Johanners B Huber; " A comparisonof peak power reduction schemes for OFDM. "; GlobalTelecommunications Conference.1997.1; IEEE, pp.3～8.) in use and select the method for mapping (SLM) to reduce peak-to-average force ratio.The random phase sequence of vectors P that the basic thought of the method for document 2 is different with M, length is N _u(u=1 ..., M) carry out dot product with input X, then the sequence after the dot product is carried out the IFFT computing, obtain M time-domain signal, in the signal of this M time domain, select the signal of PAPR minimum to be used for transmission.Simultaneously, with used random phase sequence P _mSend to the recipient as supplementary (side information) and be used for demodulation.

Document 3 (Heung-Gyoon Ryu, " A new PAPR reduction scheme:SPW (subblock phase weighting) ", IEEE Transactions on ConsumerElectronics, 2002,48 (1): 81～89), provided the method (PTS) of part transfer sequence.This method is based on the principle identical with SLM, but its converting vector has different structures.The data vector that the method for PTS at first will be come in is divided into the subvector X of K non-overlapping copies ₁..., X _K, the number of each subvector nonzero value is N/K.Each subvector X _j(j=1 ..., all subcarriers K) multiply by identical phase factor P respectively _j, as shown in Figure 9.If the possibility that has the M kind to select then selects the subcarrier of PAPR minimum to be used for transmission, and is same, (the P of its optimum ₁..., P _K) pass to transmit leg as supplementary.

Therefore, existing method need send supplementary (sideinformation) to the recipient, and this has reduced the efficient that transmits on the one hand, need to receive reliably supplementary on the other hand, otherwise mistake appears in the demodulation meeting.

Summary of the invention

In view of the above problems, the present invention has been proposed, so that in the peak-to-average force ratio that reduces ofdm signal, improve information transfer efficiency.

In one aspect of the invention, proposed a kind of method that reduces the peak-to-average force ratio of orthogonal frequency-division multiplex singal, comprised step: a) by the predetermined a plurality of weighting sequences of sequential storage; B) data vector in the orthogonal frequency-division multiplex singal is divided into a plurality of subvectors; C) from described a plurality of weighting sequences, select a weighting sequence, make peak value minimum by the signal that linear combination constituted of this weighting sequence and described a plurality of subvectors; D) according to the position of this weighting sequence in a plurality of weighting sequences of pressing predetermined sequential storage, the pilot tone in the orthogonal frequency-division multiplex singal is shifted.

In another aspect of this invention, proposed a kind of from the orthogonal frequency-division multiplex singal that receives the method for restore data, comprise step: a) estimate channel vector according to the orthogonal frequency-division multiplex singal and the pilot signal that receive; B) the cyclic shift characteristic of utilizing Fourier transform is determined the position in first footpath from estimated channel vector; C) from the corresponding weighting sequence in position according to selection a plurality of weighting sequences of predefined procedure storage and described first footpath; D) described orthogonal frequency-division multiplex singal successively divided by corresponding weight coefficient in corresponding channel coefficients and the described weighting sequence in the channel vector.

In one embodiment of the invention, the present invention utilizes the constant power characteristic of optimum pilot frequency sequence, uses the block pilot tone of OFDM, with the part of pilot frequency sequence as the PTS weighting sequence.At receiving terminal, utilize the characteristic of FFT, determine by the position in identification channel first footpath which part pilot frequency sequence is as the PTS weighting sequence.

Utilize above-mentioned method, compare, do not need to send supplementary (side information), improved the information transmitting efficiency, avoided because of supplementary makes a mistake the error code that causes with traditional PTS method.

Description of drawings

Fig. 1 is the schematic diagram of the data block of an OFDM Frame and OFDM.

Fig. 2 is the schematic diagram of block pilot tone.

Fig. 3 is a schematic diagram of determining PTS at receiving terminal.

Fig. 4 shows the location drawing of expectation channel.

Fig. 5 is the flow chart according to the operation of the transmitting terminal execution of first embodiment of the invention.

Fig. 6 is according to the flow chart of first embodiment of the invention in the operation of receiving terminal execution.

Fig. 7 is according to the flow chart of second embodiment of the invention in the operation of transmitting terminal execution.

Fig. 8 is according to the flow chart of second embodiment of the invention in the operation of receiving terminal execution.

Fig. 9 is the existing schematic diagram that reduces PAPR by part transfer sequence (PTS).

Embodiment

The contrast accompanying drawing describes embodiments of the invention in detail below.

[model definition and channel estimating]

The definition shape as

Matrix (n * n) is a circular matrix.Be that each row of circular matrix are obtained by the first row cyclic shift.

Like this, matrix A can be expressed as:

A＝Cir(a ₁?a ₂…a _n) (2)

In formula (2), first of expression A matrix is classified (a as ₁, a ₂..., a _N), then according to shown in (1), structure circular matrix A.

For pilot tone X, make s=IFFT (X), then s is the time-domain representation of pilot tone X or the pilot tone that is called time domain.Make that r is the signal (after removing CP) that time domain receives, then the Model in Time Domain of SISO-OFDM is:

r＝Sh+w (3)

In formula (3),

S＝cir(s ₁?s ₂…s _n) (4)

And w is the time domain noise.

h＝[h ₁?h ₂…h _N] ^T＝[h ₁…h _L?0…0] ^T (5)

In formula (3), received signal r equals to add noise w behind s and the channel matrix h circular convolution.

Fig. 1 has provided the graphical diagram of OFDM.If the length of cyclic prefix CP is greater than the maximum multipath time delay length of channel.Like this, at receiving terminal, removing and protecting the signal that obtains at interval is y (n), handles through FFT then, and time-domain signal y (n) is converted to frequency-region signal Y (k):

Y(k)＝FFT(y(n))，k＝0，1，…，N-1 (6)

In following formula, counting of FFT is N.

Like this, the frequency domain of ofdm system reception model is:

Y＝XH+W (7)

In formula (7), X is N * N diagonal matrix, and its diagonal entry is the frequency pilot sign of frequency domain, and H is the channel response of frequency domain, and it is N * 1 vector, and W is the frequency domain noise vector of N * 1.

According to document 4 (R.Negi and J.Cioffi, " Pilot tone selectionfor channel estimation in a mobile OFDM system; " IEEE Trans.Consum.Electron., vol.44, pp.1112-1128, Aug.1998), the LS of channel matrix (Least Square) estimates that (least mean-square estimate) is:

H _LS＝X ^-1Y (8)

$H_{\mathrm{LS}}\left(k\right)=\frac{Y\left(k\right)}{X\left(k\right)},k=\mathrm{0,1},...,N-1---\left(9\right)$

Therefore, when estimating channel, at first, utilize the signal frequency-domain that receives to represent and the frequency domain representation of pilot tone,, obtain the frequency domain response H of channel according to formula (9) _LSThen, by to H _LSCarry out contrary fast fourier transform, obtain the time-domain response of channel:

h _LS＝IFFT(H _LS) (10)

Next, in N channel estimation value, choose bigger exporting in the channel estimation value, other channel estimation value is put 0, obtain new time-domain response h as channel _LS, such as N=64, the h that obtains _LS=[1.2,0.8.0.5,0.001,0.002,0.0011 ..., 0.0012], the h after then choosing _LS=[1.2,0.8,0.5,0 ... ... ].Just, think that channel is 3 footpaths.

Certainly, can be with N channel estimation value and a threshold, think that the number greater than the pairing channel of channel estimation value of this threshold value is exactly the footpath number of channel.This threshold value can be a predetermined fixed, also can be to calculate in real time, for example is c times of root side's value of the noise average power estimated, and wherein c is a constant.

At last, obtain new H by fast fourier transform _LS=FFT (h _LS).Therefore, by above processing, removed the influence of partial noise.

[cyclic shift of FFT]

Make X=fft (x), x, X are respectively the vector that length is N.X represents the time-domain representation (supposing that s is the row vector) of sequence vector, and X is a frequency domain representation.Then

$X\left[m\right]=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}x\left[k\right]e^{-j2\mathrm{\πmk}/N}---\left(11a\right)$

$x\left[k\right]=\frac{1}{N}\underset{m=0}{\overset{N-1}{\mathrm{\Σ}}}X\left[m\right]e^{j2\mathrm{\πmk}/N}---\left(11b\right)$

Definition x[(k+n) _N] for the circulation to the right of x moves the n position, then and (11b) according to formula (11a), to x[(x+n) _N] carry out Fourier transform, obtaining its frequency-domain expression is e ^{J2 π mn/N}X[m].Promptly in time-domain cyclic shift, the result of frequency domain is phase shift.

In formula (3), ignore noise, can get s=[s ₁, s ₂..., s _N],

r＝hs (11c)

In the formula (11c),  represents circular convolution.

Make Y=fft (r), H=fft (h), X=fft (s).

Then

Y(m)＝X(m)*H(m)?0＜＝m＜＝N-1 (12)

That is, the convolution algorithm of time domain is corresponding to the phase multiplication of frequency domain, thereby:

$H\left(m\right)=\frac{Y\left(m\right)}{X\left(m\right)}0<=m<=N-1---\left(13\right)$

Can obtain the frequency domain value H (m) of channel from formula (13).

If send be s circulate to the right move n position, i.e. s[(k+n) _N].And the recipient thinks that send is s, then

Y(m)＝e ^j2πmn/NX(m)*H(m) (14)

That is to say, when channel estimating, be that s estimates according to what send, then

$\hat{H}\left(m\right)=\frac{Y\left(m\right)}{X\left(m\right)}=\frac{e^{j2\mathrm{\&pi;mn}/N}X\left(m\right)H\left(m\right)}{X\left(m\right)}=e^{j2\mathrm{\&pi;mn}/N}H\left(m\right)---\left(15\right)$

Will Transform to time domain, obtain:

$\hat{h}=h\left[{k+n)}_N\right]---\left(16\right)$

[first embodiment]

Fig. 2 shows the schematic diagram of pilot tone and data of the present invention.As the pilot tone that is used to estimate channel, data (M point) are followed in its back with certain OFDM symbol (N point).Think that in N+M some channel is constant (M＞=N).So doing is because in the environment of slow fading, and channel variation slower can be thought constant in long period of time.

Like this, can be with the data symbol of OFDM elongated (M point).And when estimating channel, the length of channel can estimate the time-domain response of this channel with less symbol (N point) in certain scope.

Fig. 3 shows the flow chart of first embodiment of the invention in the operation of transmitting terminal execution.In first embodiment, the frequency domain representation that defines basic pilot tone is s ₁, s ₂, s ₃, s ₄, the time-domain representation of basic pilot tone is a ₁, a ₂, a ₃, a ₄All store predetermined weighting sequence at transmitting terminal and receiving terminal, for example M PTS weighting sequence P ₁=[p ₁₁, p ₂₁..., p _K1], P ₂=[p ₁₂, p ₂₂..., p _K2] ..., P _M=[p _1M, p _2M..., p _KM] (S310).

Then, the signal after the modulation is reduced the processing (S320) of PAPR.Tentation data vector X=[x ₀, x ₁..., X _N-1].Then data vector X is divided into the K group.Such as N=8, K=2, every group of 4 values.With x ₀To x ₃Form the first subvector X as one group ₁, X then ₁=[x ₀, x ₁, x ₂, x ₃, 0,0,0,0], with x ₄To x ₇Form the second subvector X as one group ₂, X then ₂=[0,0,0,0, x ₄, x ₅, x ₆, x ₇], then with of the combination of this K subvector by following formula:

${X_j}^{\&prime;}=\underset{i=1}{\overset{K}{\mathrm{\&Sigma;}}}{p}_{\mathrm{ij}}{X}_i---\left(17\right)$

, p _Ij(1＜=i＜=K, 1＜=j＜=M) are weight coefficients, and as supplementary (sideinformation), satisfy p _Ij=exp (j θ _Ij), and θ _Ij∈ [0,2 π].

Then, to X ' _jCarry out the IDFT conversion, obtain x _j'=IDFT (X _j').And according to formula (17), and utilize the linear characteristic of IDFT, obtain:

${x_j}^{\&prime;}=\mathrm{IDFT}\left({X_j}^{\&prime;}\right)=\underset{i=1}{\overset{K}{\mathrm{\&Sigma;}}}{p}_{\mathrm{ij}}\mathrm{IDFT}\left(X_i\right)---\left(18\right)$

By suitable selection weight coefficient p _Ij, make the x that calculates in the formula (18) _j' peak value reach minimum, the x of this moment _j' be exactly the time domain transmission signal of PAPR minimum, and best weight coefficient should satisfy:

$(p_{1j},...,p_{\mathrm{Kj}})=\underset{\left(p_{1j}{,...,P}_{\mathrm{Kj}}\right)}{\arg \min }\left(\underset{1\&le;n\&le;N}{\max }{\left|\underset{i=1}{\overset{K}{\mathrm{\&Sigma;}}}{p}_{\mathrm{ij}}\mathrm{IDFT}\left(X_i\right)\right|}^2\right)---\left(19\right)$

In (19), a total M PTS weighting sequence is available.

If selected the individual PTS weighting sequence of Q (Q is smaller or equal to M) from M PTS weighting sequence, then with pilot shift (Q-1) * B position, wherein B is more than or equal to 1 (S330).Then, to inserting processing through the pilot tone of displacement.

For example, if the PTS weighting sequence of selecting is second weighting sequence, then when time domain is carried out the insertion of pilot tone, send a ₃, a ₄, a ₁, a ₂, promptly the 3rd of the matrix A shown in the formula (1) the be listed as.

Fig. 4 shows the flow chart of first embodiment of the invention in the operation of receiving terminal execution.For restore data, at first carry out channel estimating according to equation (9), utilize equation (9) to estimate the frequency domain response H of channel _LS, carry out contrary fast fourier transform then, obtain the time-domain response h of channel _LS, and carry out threshold process, with the influence of filtering noise.Next, to carrying out fast fourier transform, obtain the frequency domain response (S410) after the Filtering Processing through the time-domain response of filtering.

Then, judge the position (S420) of the PTS weighting sequence that will select according to the position in first footpath of channel response.According to formula (15) and (16) as can be known, several of time domain pilot ring shift lefts, then estimated channel value ring shift left is several.Such as, for two footpath channels, if the pilot tone of time domain is basic pilot frequency sequence a ₁, a ₂, a ₃, a ₄And the pilot tone that sends is skew not, and the channel that then estimates is h ₁, h ₂, 0,0.That is, first of the expectation footpath is at first.If the pilot tone that time domain is used moves to left one, be a ₂, a ₃, a ₄, a ₁, then estimated channel is h ₂, 0,0, h ₁If the pilot tone that time domain is used has moved to left two, be a ₃, a ₄, a ₁, a ₂, then estimated channel be 0,0, h ₁, h ₂

Then, the estimated channel value is moved to right by turn, when obtaining Z ..., Z, 0, (full position zero, certain value back Fig. 6), just stops during ..0.In this example, move to right two and obtain h ₁, h ₂, 0,0.So determining to carry out peak-to-average force ratio by transmitting terminal, to reduce the PTS weighting sequence that is adopted be second PTS weighting sequence P ₂(S430).

In addition, the displacement of carrying out at transmitting terminal and receiving terminal not necessarily only is shifted one at every turn, also can seek for displacement by B (B＞1).When B＞1, and (because The noise the multipath of false channel occurred or do not estimated certain multipath) when wrong appear in channel estimating, can differentiate displacement more accurately, thereby determine the PTS weighting sequence.

The current PTS weighting sequence that obtained is such as P ₂=[p ₁₂, p ₂₂]=[1 ,-1].Received signal has obtained y=[y after removing Cyclic Prefix ₁, y ₂..., y _N].Y is carried out the IFFT conversion obtains,

Y=IFFT (y) (20) also supposes that the channel value of frequency domain is H=[h ₁, h ₂..., h _N], then

Z _i＝Y _i/h _i/p ₁₂(i＝0，1，2，3)

Z _i＝Y _i/h _i/p ₂₂(i＝4，5，6，7)

That is, the received signal of frequency domain is removed (Y after the influence of channel _i/ h _i), obtain the signal (noisy) of the actual transmission of frequency domain, but the signal of the actual transmission of frequency domain is real symbol that sends and the PTS weighting sequence result of (linear combination) that multiplies each other, so will be divided by corresponding weight coefficient the recipient.Then to Z _iCarry out the estimation that demodulation has just obtained sending data symbol.

Present embodiment has defined a basic pilot frequency sequence, and several possibilities of the weighting sequence of the good PTS of predefined, respectively in transmitting terminal and receiving terminal storage.After having determined the position of PTS weighting sequence in the process that is reducing PAPR,, be the cyclic shift of basic pilot frequency sequence at the real pilot frequency sequence that sends of time domain according to its position.At receiving terminal, utilize the characteristic of FFT, determine that by the position in identification channel first footpath which PTS weighting sequence carries out data as receiving terminal and recovers required PTS weighting sequence, compare with traditional PTS method, do not need to send supplementary (side information), improve efficient, avoided because of supplementary makes a mistake the error code that causes.

[second embodiment]

Fig. 7 shows the flow chart of second embodiment of the invention in the operation of transmitting terminal execution.The difference of the method for second embodiment and first embodiment is that a part with pilot tone is as the PTS weighting sequence.

As mentioned above, in channel estimation process, if make the LS estimation performance of channel best, then the s-matrix in the formula (3) must be an orthogonal matrix, and promptly the time domain pilot tone is a shift-orthogonal.And concerning the block pilot tone that satisfies above condition, requiring pilot tone is constant power.The power of supposing the pilot tone symbol is 1, and then pilot tone can be e ^{J θ}(θ is 0 to 2 π arbitrary value) so just can satisfy above-mentioned requirements.Therefore, can be with the part of the frequency domain representation of pilot frequency sequence as the PTS weighting sequence.

If N=4 is divided into the K=2 piece with pilot tone, defining basic pilot tone is s ₁, s ₂, s ₃, s ₄The time domain pilot of basic pilot tone is a ₁, a ₂, a ₃, a ₄With s ₁, s ₂As first PTS weighting sequence, with s ₃, s ₄As second PTS weighting sequence (S710).

In data symbol, select sending of PAPR minimum according to the method identical then, thereby determine to make the PTS weighting sequence of PAPR minimum with first embodiment.

Suppose that the PTS weighting sequence of selection is second PTS weighting sequence s ₃, s ₄, then the original position of first PTS weighting sequence is 3 (S720).When time domain is carried out the insertion of pilot tone, send a ₃, a ₄, a ₁, a ₂, promptly the 3rd of the matrix A shown in the formula (1) the be listed as.Therefore, can come pilot tone be shifted (S730) according to the position of the PTS sequence of selecting.

Fig. 8 shows the flow chart of second embodiment of the invention in the operation of receiving terminal execution.As shown in Figure 8, at first carry out channel estimating according to equation (9), the pilot tone in equation (9) is basic pilot frequency sequence, promptly in equation (9), and X (1)=s ₁, X (2)=s ₂, X (3)=s ₃, X (4)=s ₄(S810).

Judge and select the position (S820) of PTS in pilot tone for use according to the position in first footpath of channel response then.Such as, two footpath channels.If the pilot tone of time domain is basic pilot frequency sequence a ₁, a ₂, a ₃, a ₄, the channel that then estimates is h ₁, h ₂, 0,0.Promptly first of the expectation footpath is at first.If the pilot tone that time domain is used is a ₂, a ₃, a ₄, a ₁(the moving to left of basic sequence) (according to formula (15), (16)), then estimated channel is h ₂, 0,0, h ₁Several of time domain pilot ring shift lefts, then estimated channel value ring shift left is several.Because the pilot tone of using is a ₃, a ₄, a ₁, a ₂, then estimated channel be 0,0, h ₁, h ₂Then the estimated channel value is moved to right by turn, when obtaining Z ..., Z, 0, (full position zero, certain value back Fig. 6), just stops during ..0.In this example, move to right two and obtain h ₁, h ₂, 0,0.So determining used time domain pilot is that basic time domain pilot moves to left two and obtains, the original position that draws the PTS weighting sequence is s ₃, obtain s then ₃, s ₄Recover required PTS weighting sequence for carrying out data.

Present embodiment is the frequency domain representation segmentation of pilot frequency sequence, as the PTS weighting sequence.After having determined the position of corresponding PTS weighting sequence in pilot frequency sequence in the process that is reducing PAPR,, be the cyclic shift of basic pilot frequency sequence at the real pilot frequency sequence that sends of time domain according to its position.At receiving terminal, utilize the characteristic of FFT, determine that by the position in identification channel first footpath which part pilot frequency sequence recovers required PTS weighting sequence as carrying out data.Second embodiment need be at transmitting terminal and the special PTS weighting sequence of receiving terminal storage except can obtaining the effect identical with first embodiment.

The above; only be the embodiment among the present invention, but protection scope of the present invention is not limited thereto, anyly is familiar with the people of this technology in the disclosed technical scope of the present invention; the conversion that can expect easily or replacement all should be encompassed in of the present invention comprising within the scope.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.

Claims (8)

1, a kind of method that reduces the peak-to-average force ratio of orthogonal frequency-division multiplex singal comprises step:

A) by the predetermined a plurality of weighting sequences of sequential storage;

B) data vector in the orthogonal frequency-division multiplex singal is divided into a plurality of subvectors;

C) from described a plurality of weighting sequences, select a weighting sequence, make peak value minimum by the signal that linear combination constituted of this weighting sequence and described a plurality of subvectors;

D) according to the position of this weighting sequence in a plurality of weighting sequences of pressing predetermined sequential storage, the pilot tone in the orthogonal frequency-division multiplex singal is shifted.

2, the method for claim 1 is characterized in that, described a plurality of subvector non-overlapping copies.

3, method as claimed in claim 1 or 2 is characterized in that, described step c) comprises:

C1) successively described a plurality of weighting sequences and described a plurality of subvector are multiplied each other, obtain a plurality of linear combinations;

C2) inverse Fourier transform is carried out in described a plurality of linear combinations, obtain a plurality of time-domain signals;

C3) time-domain signal of definite peak value minimum from described a plurality of time-domain signals;

C4) determine the position of employed weighting sequence in described a plurality of weighting sequences in the linear combination corresponding with this time-domain signal.

4, method as claimed in claim 1 or 2 is characterized in that, if this weighting sequence is Q in described a plurality of weighting sequence, then described step d) comprises:

D1) with pilot shift (Q-1) * B position, B wherein is the constant more than or equal to 1;

D2) when time domain is carried out pilot tone insertion processing, send pilot tone through shifting processing.

5, the method for claim 1 is characterized in that, described weighting sequence is the part of pilot tone.

6, a kind of from the orthogonal frequency-division multiplex singal that receives the method for restore data, comprise step:

A) estimate channel vector according to the orthogonal frequency-division multiplex singal and the pilot signal that receive;

B) the cyclic shift characteristic of utilizing Fourier transform is determined the position in first footpath from estimated channel vector;

C) from the corresponding weighting sequence in position according to selection a plurality of weighting sequences of predefined procedure storage and described first footpath;

D) the subvector of the data vector in the described orthogonal frequency-division multiplex singal successively divided by corresponding weight coefficient in corresponding channel coefficients and the described weighting sequence in the channel vector.

7, method as claimed in claim 6 is characterized in that, described step a) comprises:

Estimated channel vector is carried out inverse Fourier transform, to obtain the channel coefficients of time domain; And

Channel coefficients in the estimated channel vector is carried out threshold process, with filtering noise.

8, method as claimed in claim 6 is characterized in that, described weighting sequence is the part of pilot tone.

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