CN101277290A - Method and apparatus for synchronization of orthogonal frequency division multiplexing system frequency - Google Patents

Abstract

The invention relates to a frequency synchronization method and device for an orthogonal frequency division multiplexing system, wherein a transmission end combines training symbols with a circular prefix and a plurality of data symbols added with the circular prefix and inserted with pilot frequency codes into an orthogonal frequency division multiplexing signal frame, and ends the orthogonal frequency division multiplexing signal; a receiving end performs associated operations to the circular prefix in the training symbols of the received orthogonal frequency division multiplexing signal and to the partial training symbols corresponding to the circular prefix in order to acquire fraction multiple frequency deviation; the circular prefixes of each orthogonal frequency division multiplexing symbols in the received orthogonal frequency division multiplexing signal are removed, and sliding difference associated operation is performed to the training symbols in the received orthogonal frequency division multiplexing signal and to the original training symbols to acquire the integer multiple frequency deviation; the pilot frequency codes of at least two continuous data symbols in the received orthogonal frequency division multiplexing signal are performed by the associated operations to acquire residual frequency deviation.

Description

A kind of frequency synchronization method of ofdm system and device

Technical field

The present invention relates to the broadband wireless access field, particularly the Frequency Synchronization technology of OFDM (OFDM) system is a kind of frequency synchronization method and device of ofdm system concretely.

Background technology

OFDM (OFDM) system was widely used more than 20 year as a kind of modulation and multiple access technique, and it is a kind of transmission technology of well-known spectral efficient, can resist the serious channel degradation that runs in the mobile channel.The OFDM technology is divided into a plurality of modes than the bit stream of low rate that are modulated on the different sub carrier by the bit stream with an independent two-forty, has realized eliminating in highly dispersed wireless channel most of because the intersymbol interference that high-speed transfer is brought with a kind of relatively low cost.

But, when realizing ofdm system, there are several distinct issues to need special consideration, one of them very crucial problem is the stationary problem of ofdm system receiving terminal.Because the characteristic of OFDM, system must satisfy time synchronized and Frequency Synchronization simultaneously.As everyone knows, ofdm system is for very responsive by the inconsistent carrier frequency shift that causes between transmitter crystal oscillator and the receiver crystal oscillator, the size of this frequency shift (FS) has several subcarrier spacings, is divided into integer frequency offset (integral multiple of subcarrier spacing) and mark frequency multiplication (less than half subcarrier spacing) partially usually.The skew of carrier frequency has destroyed the orthogonality between the carrier wave, thereby the performance of system descends significantly.The purpose of Frequency Synchronization is that the frequency deviation between transmitter crystal oscillator and the receiver crystal oscillator is reduced within the scope of ofdm system permission.

The method of Frequency Synchronization is divided into generally that integer frequency offset is estimated and the mark frequency multiplication estimates that partially two parts handle respectively, the integer frequency offset of prior art is estimated all to require training sequence to have certain symmetry, also requires simultaneously just can carry out the estimation of integer frequency offset after mark frequency multiplication offset compensation.The technical literature of relevant Frequency Synchronization has many pieces in the prior art, and is existing special with United States Patent (USP) 6,959, and 050, United States Patent (USP) 6,993,094 and following document:

Shrenik?Patel，Leonard?J.Cimini，Jr.and?Bruce?McNair，“Comparison?of?Frequency?OffsetEstimation?Techniques?for?Burst?OFDM”，IEEE?55th?VTC?Spring，Vol.2，6-9?May?2002，pp.772-776、

Michael?Speth，Stefan?A.Fechtel，“Optimum?Receiver?Design?for?Wireless?Broad-bandsystems?using?OFDM-Part?I”，IEEE?Trans.On?Comm.，Vo.47，No.11，Nov.1999、

Michael?Speth，Stefan?A.Fechtel，“Optimum?Receiver?Design?for?Wireless?Broad-bandsystems?using?OFDM-Part?II”，IEEE?Trans.On?Comm.，Vo.49，No.4，Apr.2001、

Thierry?Pollet，Paul?Spruyt?and?Marc?Moeneclaey，“The?BER?performance?of?OFDMsystems?using?Non-Synchronized?Sampling”，IEEE?Globe?Telecommunications?Conference，Vol.1，28Nov.-2Dec.pp.253-257，1994、

Hanli Zhou, Bruce McNair, " An integrated OFDM receiver for high speed mobile datacommunication ", disclosed content is herein incorporated, with as prior art document of the present invention.

Summary of the invention

The objective of the invention is to, a kind of frequency synchronization method and device of ofdm system are provided, in order to overcome the system performance degradation that the frequency step-out is brought, provide a Frequency Synchronization scheme that overcomes owing to the inconsistent frequency shift (FS) that causes between transmitter crystal oscillator and the receiver crystal oscillator.Technical scheme of the present invention is:

A kind of OFDM frequency synchronization method, transmitting terminal has the training symbol of Cyclic Prefix and a plurality of data symbol mutual group that has increased Cyclic Prefix and the inserted pilot code frequency-division multiplex singal frame that is orthogonal with one, and sends this orthogonal frequency-division multiplex singal; Receiving terminal carries out related operation with the Cyclic Prefix that part of training symbol corresponding with this Cyclic Prefix of the training symbol of the orthogonal frequency-division multiplex singal that receives, and to obtain the mark frequency multiplication inclined to one side; The Cyclic Prefix of each OFDM symbol in the orthogonal frequency-division multiplex singal that remove to receive, and the training symbol of the orthogonal frequency-division multiplex singal that receives and the original training symbol difference related operation that slides obtained integer frequency offset; The pilot code of at least two continuous data symbols of the orthogonal frequency-division multiplex singal that receives is carried out related operation obtain residual frequency deviation.

Described training symbol is the modulation sequence with good cross correlation and autocorrelation; And when having increased the common framing of data symbol of Cyclic Prefix, described training symbol is at the start-up portion of this frame with a training symbol.

The described orthogonal frequency-division multiplex singal that is loaded with pilot code is meant: described pilot code is inserted on the subcarrier of described data symbol.

The inclined to one side related operation of mark frequency multiplication comprises: the frequency deviation value of the estimation of normalization

Wherein:

${\widehat{\mathrm{\δ}}}_f=\arg (\frac{1}{G\×N_{\mathrm{fft}}}\underset{n=0}{\overset{G\×N_{\mathrm{fft}}-1}{\mathrm{\Σ}}}x(n+N_{\mathrm{fft}})\·x{\left(n\right)}^{*})/2\mathrm{\π}$

N wherein _FftBe meant the size of FFT;

G is meant the ratio of circulating prefix-length and useful symbol lengths;

X (n) is meant n sampling point of training symbol;

Arg (x) is meant the angle of calculated complex variable x.

The orthogonal frequency-division multiplex singal of having removed Cyclic Prefix is carried out fast fourier transform.

The related operation of integer frequency offset comprises: the estimated value of integer frequency offset

Wherein:

${\widehat{\mathrm{\δ}}}_{f_I}=\mathrm{\Δf}*\underset{m}{\arg \max }|\underset{l=0}{\overset{P-2}{\mathrm{\Σ}}}X\left(l\right)X^{*}(l+1)Y(m,l)Y^{*}(m,(l+1))|$

Wherein, X (l) is meant the original training symbol of transmitting terminal framing;

(m l) is meant the training symbol that the skew of m sampling point is arranged of reception to Y;

M=0, ± 1, ± 2, L, ± f _I. f _IBe meant the estimation range of the integer frequency offset of normalization;

L=0...P-2. P represents the length of training symbol;

Δ f is meant subcarrier spacing.

The related operation of residual frequency deviation comprises: the frequency deviation value of the estimation of normalization

Wherein:

${\widehat{\mathrm{\δ}}}_{\mathrm{fr}}=\arg \left(\frac{1}{N_p}\underset{k=0}{\overset{N_p-1}{\mathrm{\Σ}}}{p}_l^{*}\left(k\right)p_m\left(k\right)\right)/2\mathrm{\π}$

Wherein, N _pIt is the number that is used for the pilot code of frequency-tracking in described each data symbol;

p _l(k) and p _m(k) be meant pilot code on k the subcarrier of m data symbol and the 1st data symbol respectively.

The present invention also provides a kind of OFDM frequency synchronization device, and this device comprises: transmitter and receiver; Described transmitter is used for having the training symbol of Cyclic Prefix and a plurality of data symbol mutual group that has increased Cyclic Prefix and the inserted pilot code frequency-division multiplex singal frame that is orthogonal with one, and sends this orthogonal frequency-division multiplex singal; Described receiver receives this orthogonal frequency-division multiplex singal; Described receiver comprises: the inclined to one side estimation unit of mark frequency multiplication, the Cyclic Prefix that part of training symbol corresponding with this Cyclic Prefix that is used for the training symbol of the orthogonal frequency-division multiplex singal that will receive carry out related operation to obtain the mark frequency multiplication inclined to one side; Cyclic prefix removal unit is used for removing the Cyclic Prefix of each OFDM symbol of the orthogonal frequency-division multiplex singal of reception; The integer frequency offset estimation unit is used for the training symbol of the orthogonal frequency-division multiplex singal that will receive and the original training symbol difference related operation that slides and obtains integer frequency offset; The residual frequency deviation estimation unit, the pilot code that is used at least two continuous data symbols of the orthogonal frequency-division multiplex singal that will receive is carried out related operation and is obtained residual frequency deviation; Frequency Synchronization scheme among the present invention comprises two processes: the synchronous and thin Frequency Synchronization of coarse frequency.Coarse frequency is meant catching of frequency synchronously, and is inclined to one side in order to eliminate integer frequency offset and mark frequency multiplication.Thin Frequency Synchronization is meant the tracking of frequency, in order to eliminate the phase error of being brought by frequency errors and the sampling frequency deviation of remnants.Specifically can be divided into three parts: the estimation that the mark frequency multiplication is inclined to one side, the estimation of integer frequency offset and the tracking of residual frequency deviation.The present invention has avoided restriction of the prior art, and the scheme of a new Frequency Synchronization is provided.

Description of drawings

Fig. 1 be the specific embodiment of the invention ofdm system structured flowchart;

Fig. 2 is the structured flowchart of the receiver of the specific embodiment of the invention;

Fig. 3 is a frame structure schematic diagram of the present invention;

Fig. 4 is the structured flowchart of the inclined to one side estimation unit of mark frequency multiplication of the specific embodiment of the invention;

Fig. 5 is the structured flowchart of the integer frequency offset estimation unit of the specific embodiment of the invention;

Fig. 6 is the schematic diagram of the frequency-tracking of the specific embodiment of the invention.

Embodiment

Below in conjunction with description of drawings the specific embodiment of the present invention.The invention provides a kind of ofdm communication system owing to the estimation of the inconsistent frequency shift (FS) that causes between transmitter crystal oscillator and the receiver crystal oscillator and the method and the device of compensation.The signal of this ofdm communication system has the frame structure of being made up of a training symbol and a plurality of OFDM data symbol, and described OFDM data symbol has inserted pilot code on some subcarrier.

Typical ofdm system schematic diagram shown in Figure 1 is a preferred embodiment of the present invention.In OFDM transmitter 100, data source 101 produces a string constellation point symbol, and the output of data source unit 101 is carried out data map in data map and pilot code insertion unit 102, and carries out the distribution of subcarrier and the insertion of pilot code.Contrary 103 pairs of input signals of fast Fourier transformer carry out contrary fast fourier transform (IFFT) and generate the OFDM symbol, for fear of the intersymbol interference (ISI) that brings owing to multipath fading, increasing cyclic prefix module 104 increases the Cyclic Prefix of regular length to the start-up portion of each OFDM symbol, usually, utilize the last part of OFDM symbol to produce Cyclic Prefix, the length of Cyclic Prefix generally depends on the feature of the channel that this ofdm signal is sent out.

In order to generate frame structure as shown in Figure 3, in framing module 105, generated complete OFDM frame, this signal is admitted to analog-digital converter 106 and carries out D/A switch then, and is admitted to transmitter front ends 107.After this, this ofdm signal is launched and is experienced wireless channel 110 through antenna.

Fig. 3 is the frame structure that is applicable to typical ofdm system of the present invention, described frame is made up of a plurality of OFDM symbols 302, each described symbol 302 is made up of the Cyclic Prefix 303 of useful information data 304 and regular length, usually, this Cyclic Prefix is the last part generation by its corresponding OFDM symbol.As shown in Figure 3, the start-up portion of each described frame has added a training symbol, and this training symbol is to have the good cross correlation and the training sequence of autocorrelation.

Among Fig. 1 119 is receivers.At first, front end 111 at receiver receives ofdm signal, then the ofdm signal that receives is carried out mould/number conversion in analog-digital converter 112, in separating frame module 113, this received signal is separated frame, before separating frame, must at first realize time synchronized, this step be in Unit 114, realize and synchronizing information fed back to separate frame module 113, take out training symbol the frame module 113 and be used for carrying out the inclined to one side estimation of mark frequency multiplication from described separating at the inclined to one side estimation unit 109 of mark frequency multiplication.The operation of in removing cyclic prefix unit 114, each OFDM symbol of described reception being removed Cyclic Prefix.Then signal is carried out fast fourier transform 115.Symbol after the conversion at first carries out the estimation of integer frequency offset at integer frequency offset estimation unit 108, simultaneously, the pilot code of at least two continuous described OFDM data symbols extracted carry out frequency-tracking 120, this frequency tracking method will carry out detailed explanation in Fig. 6.At last, will carry out OFDM symbol after the frequency correction sends into data and separates map unit 116 and revert to a string constellation point symbol and send into 117 outputs of data output unit.

As shown in Figure 2, Frequency Synchronization comprises frequency offset estimating and compensation.The data that receive from radio-frequency front-end 111 at first are admitted to analog/digital conversion unit 112 and carry out mould/number conversion, time synchronized unit 118 is used to realize symbol/frame synchronization, after having realized time synchronized, the inclined to one side estimation unit 201 of mark frequency multiplication utilizes the Cyclic Prefix of training symbol to realize the estimation that the mark frequency multiplication is inclined to one side, and the detail that the mark frequency multiplication is estimated is partially introduced in Fig. 4.After then described received signal being carried out fast fourier transform, integer frequency offset estimation unit 202 utilizes training symbol to realize the estimation of integer frequency offset, and the detail that integer frequency offset is estimated is introduced in Fig. 5.Then, the output of unit 201 and unit 202 is combined in merge cells 205 and frequency deviation is compensated, at last residual frequency deviation is followed the tracks of 203 to eliminate remaining frequency deviation.

Following mask body is introduced the inclined to one side estimation of mark frequency multiplication.Utilize the training symbol in the frame structure shown in Figure 3 to carry out the inclined to one side estimation of mark frequency multiplication in the present invention.As shown in Figure 4, at first training symbol extracting unit 401 extracts training symbol, and n sampling point supposing this training symbol is x (n). and unit 402 is delayers, and signal is by being delayed N after Unit 402 _FftIndividual sampling point, N herein _FftBe meant the size of fast Fourier transform (FFT), then with the Cyclic Prefix of this training sequence be delayed N _FftThis training sequence of individual sampling point carries out related operation in correlator 403, and calculates angle in asking angle module 404, and the angle value that obtains estimating is as follows:

${\widehat{\mathrm{\δ}}}_f=\arg (\frac{1}{G\×N_{\mathrm{fft}}}\underset{n=0}{\overset{G\×N_{\mathrm{fft}}-1}{\mathrm{\Σ}}}x(n+N_{\mathrm{fft}})\·x{\left(n\right)}^{*})/2\mathrm{\π}$

Wherein, δ _f=Δ f/f _s, Δ f is that real mark frequency multiplication is inclined to one side, f _sBe subcarrier spacing, G is the ratio of Cyclic Prefix and this useful OFDM symbol lengths.The mark frequency multiplication that just can estimate normalization based on above condition is inclined to one side.The estimation range of one's duty several times frequency deviation estimating method is ± f _s/ 2, the frequency shift (FS) that surpasses this scope is to be considered as integer frequency offset, estimates to obtain by integer frequency offset.

Introduce the estimation of integer frequency offset below.As shown in Figure 5, utilize the initial training symbol of every frame to carry out the estimation of integer frequency offset usually.At first, training symbol abstraction module 501 extracts training symbol from received signal, this training symbol contains the frequency deviation that remains to be estimated, 502 pairs of above-mentioned training symbols that extract of sliding window control unit slide with certain interval and extract and export one group of sequence that original position is different, slide and be generally a subcarrier at interval, the scope of sliding window generally depends on required integer frequency offset scope, and the original position of extraction is unfixing, generally can be set to required integer frequency offset scope point.The sequence of respectively organizing of sliding after extracting is carried out the difference related operation respectively in order to eliminate the influence of multipath fading in differential correlator 503, the computing in the differential correlator 503 can be represented with following formula:

R _Y(m，l)＝Y(m，l)Y ^*(m，(l+1))

Wherein, (m l) is the sequence with m sampling point skew that extracts to Y;

L=0...P-2. P is meant the length of training symbol;

Original training symbol generator 504 produces the training sequence of original transmission, and its output is admitted in another differential correlator 505 carries out the difference related operation, and this computing can be represented with following formula:

T _X(l)＝X(l)X ^*(l+1)

Wherein, X (l) is original training sequence.

Afterwards, the output of differential correlator 503 and differential correlator 503 all is admitted to correlator 506 and carries out related operation and produce a series of data C _m, these data can be expressed as follows:

$C_m=\underset{l=0}{\overset{P-2}{\mathrm{\Σ}}}{T}_X\left(l\right)R_Y(m,l)$

Wherein, m=0, ± 1, ± 2, L, ± f _I, f _IBe meant the integral times bias frequency range of estimation;

Selector 507 is selected C _mIn maximum as estimated value and utilize following formula to carry out integer frequency offset

Calculating:

${\widehat{\mathrm{\δ}}}_{f_I}=\mathrm{\Δf}*S,$ Wherein $S=\underset{m}{\arg \max }\left|C_m\right|,$ Δ f is meant subcarrier spacing.

The purpose of frequency-tracking is further to have eliminated remaining frequency deviation after having carried out branch several times and integer frequency offset compensation, pilot code is most suitable in the OFDM symbol is used for realizing frequency offset tracking because tracer request real-time continuous ground is carried out, and in the OFDM data symbol, have only pilot code to satisfy this requirement.Specifically introduce the method for frequency-tracking below in conjunction with Fig. 6.

As shown in Figure 6, at first, pilot code extracting unit 601 extracts the pilot code in the OFDM data symbol, and the foundation of extraction is to realize according to the position of presetting in the pilot tone pattern table 602, and the pilot code that extracts has postponed m*N through behind the time delay device 603 _FftIndividual sampling point, wherein, m be one more than or equal to 1 integer.With current pilot code and time delay m*N _FftPilot code behind the individual sampling point is carried out N in correlator 604 _pThe related operation of individual sampling point, and be converted into concrete angle value by angle calculation module 605.In compensate of frequency deviation module 606, utilize this angle value that estimates to carry out frequency compensation.

Suppose that the pilot code on k subcarrier of m OFDM symbol and the 1st OFDM symbol is respectively p _l(k) and p _m(k), the residual frequency deviation that estimates so

Can be expressed as follows:

${\widehat{\mathrm{\δ}}}_{\mathrm{fr}}=\arg \left(\frac{1}{N_p}\underset{k=0}{\overset{N_p-1}{\mathrm{\Σ}}}{p}_l^{*}\left(k\right)p_m\left(k\right)\right)/2\mathrm{\π}$

Wherein, N _pIt is the number of total points that can be used for the pilot sub-carrier of frequency offset tracking in each OFDM symbol.

Frequency Synchronization scheme among the present invention comprises two processes: the synchronous and thin Frequency Synchronization of coarse frequency.Coarse frequency is meant catching of frequency synchronously, and is inclined to one side in order to eliminate integer frequency offset and mark frequency multiplication.Thin Frequency Synchronization is meant the tracking of frequency, in order to eliminate the phase error of being brought by frequency errors and the sampling frequency deviation of remnants.Specifically can be divided into three parts: the estimation that the mark frequency multiplication is inclined to one side, the estimation of integer frequency offset and the tracking of residual frequency deviation.The present invention has avoided restriction of the prior art, and the scheme of a new Frequency Synchronization is provided.

Above embodiment only is used to illustrate the present invention, but not is used to limit the present invention.

Claims (14)

1. OFDM frequency synchronization method, transmitting terminal has the training symbol of Cyclic Prefix and a plurality of data symbol mutual group that has increased Cyclic Prefix and the inserted pilot code frequency-division multiplex singal frame that is orthogonal with one, and sends this orthogonal frequency-division multiplex singal; It is characterized in that:

Receiving terminal carries out related operation with the Cyclic Prefix that part of training symbol corresponding with this Cyclic Prefix of the training symbol of the orthogonal frequency-division multiplex singal that receives, and to obtain the mark frequency multiplication inclined to one side;

The Cyclic Prefix of each OFDM symbol in the orthogonal frequency-division multiplex singal that remove to receive, and the training symbol of the orthogonal frequency-division multiplex singal that receives and the original training symbol difference related operation that slides obtained integer frequency offset;

The pilot code of at least two continuous data symbols of the orthogonal frequency-division multiplex singal that receives is carried out related operation obtain residual frequency deviation.

2. method according to claim 1 is characterized in that, described training symbol is the modulation sequence with good cross correlation and autocorrelation; And,

When having increased the common framing of data symbol of Cyclic Prefix, described training symbol is at the start-up portion of this frame with a training symbol.

3. method according to claim 1 is characterized in that, the described orthogonal frequency-division multiplex singal that is loaded with pilot code is meant: described pilot code is inserted on the subcarrier of described data symbol.

4. method according to claim 1 is characterized in that, the inclined to one side related operation of mark frequency multiplication comprises: the frequency deviation value of the estimation of normalization

Wherein:

${\widehat{\mathrm{\δ}}}_f=\arg (\frac{1}{G\×N_{\mathrm{fft}}}\underset{n=0}{\overset{G\×N_{\mathrm{fft}}-1}{\mathrm{\Σ}}}x(n+N_{\mathrm{fft}})\·x{\left(n\right)}^{*})/2\mathrm{\π}$

N wherein _FftBe meant the size of FFT;

G is meant the ratio of circulating prefix-length and useful symbol lengths;

X (n) is meant n sampling point of training symbol;

Arg (x) is meant the angle of calculated complex variable x.

5. method according to claim 1 is characterized in that, the orthogonal frequency-division multiplex singal of having removed Cyclic Prefix is carried out fast fourier transform.

6. method according to claim 1 is characterized in that, the related operation of integer frequency offset comprises: the estimated value of integer frequency offset

Wherein:

${\widehat{\mathrm{\δ}}}_{f_l}=\mathrm{\Δf}*\underset{m}{\arg \max }\left|\underset{l=0}{\overset{P-2}{\mathrm{\Σ}}}X\left(l\right)X^{*}(l+1)Y(m,l)Y^{*}(m,(l+1))\right|$

Wherein, X (l) is meant the original training symbol of transmitting terminal framing;

(m l) is meant the training symbol that the skew of m sampling point is arranged of reception to Y;

M=0, ± 1, ± 2, L, ± f _l.f _lBe meant the estimation range of the integer frequency offset of normalization;

L=0...P-2.P represents the length of training symbol;

Δ f is meant subcarrier spacing.

7. method according to claim 1 is characterized in that, the related operation of residual frequency deviation comprises: the frequency deviation value of the estimation of normalization

Wherein:

${\widehat{\mathrm{\δ}}}_{\mathrm{fr}}=\arg \left(\frac{1}{N_p}\underset{k=0}{\overset{N_p-1}{\mathrm{\Σ}}}{p_l}^{*}\left(k\right)p_m\left(k\right)\right)/2\mathrm{\π}$

Wherein, N _pIt is the number that is used for the pilot code of frequency-tracking in described each data symbol;

p _l(k) andp _m(k) be meant pilot code on k the subcarrier of m data symbol and the 1st data symbol respectively.

8. OFDM frequency synchronization device, this device comprises: transmitter and receiver; Described transmitter is used for having the training symbol of Cyclic Prefix and a plurality of data symbol mutual group that has increased Cyclic Prefix and the inserted pilot code frequency-division multiplex singal frame that is orthogonal with one, and sends this orthogonal frequency-division multiplex singal; Described receiver receives this orthogonal frequency-division multiplex singal; It is characterized in that: described receiver comprises:

The inclined to one side estimation unit of mark frequency multiplication, the Cyclic Prefix that part of training symbol corresponding with this Cyclic Prefix that is used for the training symbol of the orthogonal frequency-division multiplex singal that will receive carry out related operation, and to obtain the mark frequency multiplication inclined to one side;

Cyclic prefix removal unit is used for removing the Cyclic Prefix of each OFDM symbol of the orthogonal frequency-division multiplex singal of reception;

The integer frequency offset estimation unit is used for the training symbol of the orthogonal frequency-division multiplex singal that will receive and the original training symbol difference related operation that slides and obtains integer frequency offset;

The residual frequency deviation estimation unit, the pilot code that is used at least two continuous data symbols of the orthogonal frequency-division multiplex singal that will receive is carried out related operation and is obtained residual frequency deviation;

9. device according to claim 8 is characterized in that, described training symbol is the modulation sequence with good cross correlation and autocorrelation; And,

When having increased the common framing of data symbol of Cyclic Prefix, described training symbol is at the start-up portion of this frame with a training symbol.

10. device according to claim 8 is characterized in that, described transmitter comprises: pilot code is inserted the unit, is used for pilot code is inserted into the subcarrier of described data symbol.

11. device according to claim 8 is characterized in that, the inclined to one side estimation unit of described mark frequency multiplication comprises: the frequency deviation value of the estimation of normalization

Wherein:

${\widehat{\mathrm{\δ}}}_f=\arg (\frac{1}{G\×N_{\mathrm{fft}}}\underset{n=0}{\overset{G\×N_{\mathrm{fft}}-1}{\mathrm{\Σ}}}x(n+N_{\mathrm{fft}})\·x{\left(n\right)}^{*})/2\mathrm{\π}$

N wherein _FftBe meant the size of FFT;

G is meant the ratio of circulating prefix-length and useful symbol lengths;

X (n) is meant n sampling point of training symbol;

Arg (x) is meant the angle of calculated complex variable x.

12. device according to claim 8 is characterized in that, described receiver also comprises: fast Fourier transform unit, the orthogonal frequency-division multiplex singal that is used for after cyclic prefix removal unit is handled carries out fast fourier transform.

13. device according to claim 8 is characterized in that, described integer frequency offset estimation unit comprises: the estimated value of integer frequency offset Wherein:

${\widehat{\mathrm{\δ}}}_{f_l}=\mathrm{\Δf}*\underset{m}{\arg \max }\left|\underset{l=0}{\overset{P-2}{\mathrm{\Σ}}}X\left(l\right)X^{*}(l+1)Y(m,l)Y^{*}(m,(l+1))\right|$

Wherein, X (l) is meant the original training symbol of transmitting terminal framing;

(m l) is meant the training symbol that the skew of m sampling point is arranged of reception to Y;

M=0, ± 1, ± 2, L, ± f _l.f _lBe meant the estimation range of the integer frequency offset of normalization;

L=0...P-2.P represents the length of training symbol;

Δ f is meant subcarrier spacing.

14. device according to claim 8 is characterized in that, described residual frequency deviation estimation unit comprises: the frequency deviation value of the estimation of normalization Wherein:

${\widehat{\mathrm{\δ}}}_{\mathrm{fr}}=\arg \left(\frac{1}{N_p}\underset{k=0}{\overset{N_p-1}{\mathrm{\Σ}}}{p_l}^{*}\left(k\right)p_m\left(k\right)\right)/2\mathrm{\π}$

Wherein, N _pIt is the number that is used for the pilot code of frequency-tracking in described each data symbol;

p _l(k) and p _m(k) be meant pilot code on k the subcarrier of m data symbol and the 1st data symbol respectively.

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