CN1527513A - Information processing method and device using time domain pilot sequence in OFDM system - Google Patents

Abstract

The present invention proposes information processing method and device using time domain pilot sequence in OFDM system. The time domain pilot sequence is filled in the initial part of protecting interval of OFDM sign, and rest part of the protecting interval is filled with the circular prefix of OFDM sign, with FFT block being following the circular prefix. Or, the time domain pilot sequence is filled into the whole protecting interval of each OFDM sign, and FFT block follows the protecting interval. The time domain pilot sequence has self-correlation or periodical self-correlation characteristic, equal amplitude or nearly equal amplitude spectrum characteristic, and length of second power. For sake of system design and according to the features of TP sequence, the present invention proposes some transceiving system, time deviation estimation, carrier deviation estimation and channel estimation method and device based on TP sequence characteristic and OFDM sign structure characteristic.

Description

Use the information processing method and the device of time domain pilot sequence in the ofdm system

Technical field

The present invention relates to the field of information transmission in OFDM (hereinafter to be referred as the OFDM) system, be particularly related in ofdm system the information processing method of introducing time domain pilot sequence (Time domainPilot sequence) (hereinafter to be referred as TP) and based on the R-T unit of this method, and in ofdm system, use time migration estimation, the carrier shift of time domain pilot sequence to estimate and the method and apparatus of channel estimating.

Background technology

OFDM is a kind of sound communication technology of carrying out the effective information transmission in channel.This technology utilizes a plurality of subcarriers (sub-carrier frequency) parallel, the transmission low-rate data to realize the communication of high data rate.Its technical essential is that the Channel Transmission bandwidth is divided into the plurality of sub frequency band, uses the subcarrier transmitting data information of mutually orthogonal on each sub-band concurrently, utilizes the orthogonality of its each subcarrier at receiving terminal, isolates the data message of parallel transmission.

The OFDM technology successfully has been applied in many communication systems, for example, digital broadcasting (DAB) and Digital Television (DVB) the employing OFDM technology formulated by european telecommunications standards institute ETSI are the wireless transmission standards of air interface, and WLAN standard IEEE802.11 and wireless metropolitan area network standard IEEE802.16 have also adopted the OFDM technology in addition.

Effective use of OFDM technology needs the synchronous and carrier synchronization of receiving-transmitting sides energy strict time.In addition, for efficient recovery transmission information is arranged,, need the OFDM receiver to carry out channel estimating for dispersive channel.On the other hand, one of design object of wireless transmitting system is to utilize valuable frequency spectrum resource as far as possible, promptly needs to improve data transmission efficiency on certain transmission reliability basis.For reaching above-mentioned target, need ofdm system effectively utilizing on frequency spectrum resource and the jamproof basis, carry out real-time time migration, carrier shift detection and channel estimating, and be convenient to the signal processing that receiving-transmitting sides is correlated with.

Existing OFDM technology adopts fast discrete inverse Fourier transform (hereinafter to be referred as IFFT) and fast discrete Fourier transform (hereinafter to be referred as FFT) to carry out the modulation and demodulation of multicarrier base band at transmitting terminal and receiving terminal respectively more.In addition; in the ofdm system evolution process, once adopted blank time slot to reduce at interval (or elimination) transmission and intersymbol interference (ISI) of causing in dispersive channel, but adopted this method as protection; signal is through behind the dispersive channel, and each carrier wave is quadrature no longer.At this problem, current ofdm system commonly used has adopted Cyclic Prefix rather than blank time slot as protection at interval, utilizes this redundant information structure of Cyclic Prefix can reduce (or elimination) ISI and inter-carrier interference (ICI).Protection size at interval depends on the characteristic of channel and system requirements.

Ofdm communication system is very responsive for synchronous error, and system be if step-out will be destroyed the orthogonality between each subcarrier, and then causes the performance of ofdm communication system to reduce greatly.Thereby effective use of OFDM technology, need receiving-transmitting sides strict time (regularly to recover) synchronously and carrier synchronization.Wherein, time synchronized means the starting point that estimates each OFDM symbol at receiving terminal from received signal, and carrier synchronization means in receiving terminal calibration carrier shift.In addition, for efficient recovery transmission information is arranged,, need the OFDM receiver to carry out channel estimating for frequency selectivity and time selectivity channel.

Based on the Cyclic Prefix in OFDM System sign form, there are multiple OFDM time and carrier synchronization method based on existing.

One class method commonly used is to utilize to insert that pilot tone (pilot) or targeting sequencing (preamble) are convenient to that timing that receiver carries out OFDM recovers and to the calibration of carrier shift.In the ofdm communication system of current majority, all provide corresponding insertion pilot configuration as WLAN standard IEEE802.11 and wireless metropolitan area network standard IEEE802.16.Can be convenient to receiver based on the method for inserting pilot tone or targeting sequencing and carry out time and carrier synchronization, also can be used for carrying out channel estimating.But these class methods have additionally been added additional information owing to insert the introducing of pilot tone, will reduce the efficiency of transmission of ofdm system.

Another kind of method commonly used is to utilize the Cyclic Prefix of OFDM symbol to carry out timing recovery and carrier synchronization." the ML method of estimation of time and carrier shift in the ofdm system " (the ML estimation of time and frequencyoffset in OFDM systems that delivers as people such as Jan-Jaap van de Beek, IEEE Trans.On Signal Proceeding, vol.45, No.7, July 1997, pp.1800-1805).Need not additionally to introduce additional information, utilize this distinctive cycle characteristics of existing OFDM symbol, and carry out the method for synchronous that pilot tone is inserted in the last relatively class utilization of synchronous estimation approach, can improve the efficiency of transmission of ofdm system greatly, but these class methods are difficult to finish precise time in dispersive channel synchronous.

Summary of the invention

At the problems referred to above that prior art exists, the present invention proposes a kind of time domain pilot sequence (Time domain Pilot sequence, information processing method TP) and in ofdm system, introduced based on the R-T unit of this method.Time domain pilot sequence (following represent with the TP sequence) can be counted as a kind of transformat of bursty data, and the TP sequence of selection has with amplitude zero auto-correlation (CAZAC) characteristic.From being convenient to system design view, and at the characteristics of the TP sequence of selecting, time migration estimation, the carrier shift that the present invention proposes the characteristics of the OFDM symbolic construction that characteristic and the present invention based on the TP sequence propose estimated and the method and apparatus of channel estimating.

According to a first aspect of the invention; a kind of information processing method that uses the time domain pilot sequence in ofdm system is provided; adopt one or more time domain pilot sequences to be filled to the protection interval of each OFDM symbol, the time domain pilot sequence has auto-correlation or cycle autocorrelation performance.And the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude.

Herein, the time domain pilot sequence is filled to the protection interval stem of the symbol of each OFDM, and protection remainder is at interval filled with the Cyclic Prefix of OFDM symbol, and Cyclic Prefix is a fft block afterwards.Perhaps, the time domain pilot sequence is filled to the whole protecting interval of the symbol of each OFDM, is fft block after the protection at interval.

And the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude.Can select the time domain pilot sequence length is the time domain pilot sequence of 2 powers, and for example, selecting the time domain pilot sequence length is having with the Frank-Zadoff sequence of amplitude zero autocorrelation performance or Chu sequence as the time domain pilot sequence of 2 powers.And, at the different time domain pilot sequence length, select corresponding time domain pilot sequence, when the time domain pilot sequence length is 16,64 and, select the Frank-Zadoff sequence at 256 o'clock, when sequence length is 8,32,128 and, select the Chu sequence at 512 o'clock.

According to a second aspect of the invention, provide emission system and the receiving system of in ofdm system, using the time domain pilot sequence.

The emission system of time domain pilot sequence of using in ofdm system of the present invention comprises:

IFFT modular converter (31) carries out the FFT conversion to data or modulation data information (30);

Parallel/serial modular converter (32), the signal that IFFT modular converter (31) is exported carries out parallel/serial conversion and becomes time-domain signal;

Sequence selection and Cyclic Prefix are selected controll block (35), select at first described time-domain signal to be added Cyclic Prefix on request and obtain first signal under the control of controll block (35) in sequence selection and Cyclic Prefix; And then add one or more time domain pilot sequences 34 and obtain secondary signal;

Blender (36), form the OFDM symbol according to described first signal that is input to blender and described secondary signal, wherein one or more time domain pilot sequences are filled to the protection interval stem of the symbol of each OFDM, protection remainder is at interval filled with the Cyclic Prefix of OFDM symbol, and the length sum of time domain pilot sequence and Cyclic Prefix equals protection at interval;

D/A converter module (37) is carried out digital-to-analogue conversion to formed OFDM mark signal;

Transmitting antenna (38) is launched the output signal of digital-to-analogue conversion (37).

In addition; in the receiving system of in ofdm system, using the time domain pilot sequence of the present invention; one or more time domain pilot sequences are filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude.Described receiving system comprises:

Analog-to-digital conversion module (41), (40) carry out analog-to-digital conversion to received signal;

Sequence selection and Cyclic Prefix are selected controll block (42);

Parameter estimator (43), select at sequence selection and Cyclic Prefix under the control of controll block (42), parameter estimator (43) at a part of signal deadline of analog-to-digital conversion module (41) output synchronously, the signal processing of carrier synchronization and channel estimating and output synchronously and channel information (48);

Eliminating the time domain pilot sequence influences module 44, selects under the control of controll block (42) signal removal that analog-to-digital conversion module (41) is exported causes the time domain pilot sequence of filling that data are handled owing to multipath channel interference in sequence selection and Cyclic Prefix;

Remove cyclic prefix module (45), select under the control of controll block (42), influence the processing that data that module (44) exports are eliminated Cyclic Prefix eliminating the time domain pilot sequence in sequence selection and Cyclic Prefix;

FFT processing module (46) is used for that the signal of removing cyclic prefix module (45) output is carried out FFT and handles to obtain the data message (47) after the FFT demodulation.

According to a third aspect of the invention we; provide a kind of in ofdm system, use the time domain pilot sequence estimated time deviant method; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, and described estimated time, the method for deviant comprised the steps:

In the sample sequence zone of selecting, the related operation of the OFDM sample sequence of slip TP sequence and execution and selection, in slip related operation process, write down coefficient module value that each slip related operation obtains greater than the location point of setting thresholding, first location point is the original position of the OFDM code element of received signal (70);

According to described original position deviant computing time (θ).

In addition; also provide a kind of in ofdm system, use the time domain pilot sequence estimated time deviant device; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, it is characterized in that described device comprises:

Autocorrelation Detection device (74), autocorrelation performance according to the time domain pilot sequence, in the sample sequence zone of selecting, the related operation of the OFDM sample sequence of slip TP sequence and execution and selection, in slip related operation process, write down coefficient module value that each slip related operation obtains greater than the location point of setting thresholding, first location point is the original position of the OFDM code element of received signal (70);

The time migration calculator is according to described original position deviant computing time (θ).

In addition, described estimated time deviant method and apparatus in the time domain pilot sequence can be for having same magnitude or near the spectral characteristic of same magnitude.

According to a forth aspect of the invention; a kind of method of using the estimation carrier shift value of time domain pilot sequence in ofdm system is provided; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, it is characterized in that described method comprises the steps:

Use Autocorrelation Detection device (74) determines received signal according to the autocorrelation performance of time domain pilot sequence the starting point of OFDM symbol to obtain time offset value, use θ _AutoThe start point information of the OFDM symbol of expression received signal;

Carry out shifting processing to received signal with shift register (71);

With conjugate operation device (72) signal of the output of shift register (71) is carried out conjugate operation;

With multiplier (73) output signal of conjugate operation device (72) is carried out multiplication mutually with received signal;

Start point information θ according to the OFDM symbol of Autocorrelation Detection device (74) output _Auto, accumulator (75) carries out accumulation calculating to the output signal of multiplier, the output parameter of accumulator γ (θ _Auto) expression;

Use the output parameter γ (θ of carrier shift estimator (76) by accumulator _Auto) estimate that by following formula carrier shift value ε is:

$\widetilde{\mathrm{\ϵ}}=-\frac{1}{2\mathrm{\π}}\frac{N}{N+L}\∠\mathrm{\γ}\left({\mathrm{\θ}}_{\mathrm{auto}}\right)$

Wherein ∠ is expressed as phase angle, and N is the sub-carrier signal number, and L is the number of decline multipath in the frequency-selective channel.

In addition; a kind of device that uses the estimation carrier shift value of time domain pilot sequence in ofdm system also is provided; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, it is characterized in that described device comprises:

Autocorrelation Detection device (74), the starting point of OFDM symbol of determining received signal (70) according to the autocorrelation performance of time domain pilot sequence is used θ to obtain time offset value _AutoThe start point information of the OFDM symbol of expression received signal;

Shift register (71) carries out shifting processing to received signal;

Conjugate operation device (72) carries out conjugate operation to the signal of the output of shift register (71);

Multiplier (73) carries out multiplication mutually with the output signal of conjugate operation device (72) with received signal;

Accumulator (75) is according to the start point information θ of the OFDM symbol of Autocorrelation Detection device (74) output _AutoOutput signal to multiplier is carried out accumulation calculating, the output parameter of accumulator γ (θ _Auto) expression;

Carrier shift estimator (76) is with the output parameter γ (θ of accumulator _Auto) estimate that by following formula carrier shift value ε is:

$\widetilde{\mathrm{\ϵ}}=-\frac{1}{2\mathrm{\π}}\frac{N}{N+L}\∠\mathrm{\γ}\left({\mathrm{\θ}}_{\mathrm{auto}}\right)$

Wherein ∠ is expressed as phase angle, and N is the sub-carrier signal number, and L is the number of decline multipath in the frequency-selective channel.

In addition, the time domain pilot sequence of the method and apparatus of described estimation carrier shift value has same magnitude or near the spectral characteristic of same magnitude.

According to a fifth aspect of the invention; a kind of channel estimation methods that uses the time domain pilot sequence in ofdm system is provided; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, it is characterized in that described method comprises the steps:

Set a threshold value, [0, N _P+ τ _L-1] in the sample value zone, the slip related operation of slip TP sequence and execution and received signal; After the threshold value of mould value greater than setting of the relevant coefficient that obtains that slides, the relevant coefficient value that obtains of record slip divided by real number α, can obtain the gain h of estimated channel path l with this coefficient value _l(t), the gain h of channel path l _l(t) with respect to h ₀(t) position is the time delay τ of the normalized different path l of elapsed time of estimation _l, N wherein _PBe the total length of TP piece, τ _LIt is the maximum time time-delay of channel.

According to a sixth aspect of the invention; a kind of interference elimination method that uses the time domain pilot sequence in ofdm system is provided; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, and described method comprises that elimination disturbs the method for I from the ISI of last OFDM symbol and comprise the method for the interference of the copy of eliminating L the TP sequence that multi-path influence forms at receiver.Elimination disturbs the method for I to comprise the steps: from the ISI of last OFDM symbol

Received signal is outputed to elimination protection interval module; Eliminating the protection interval module will be at N _p+ N _gThe preceding N of each the OFDM symbol signal that receives in the protection length at interval of the OFDM symbol signal of forming by TP sequence and Cyclic Prefix of individual sampled point correspondence _p+ N _gIndividual sampled point is removed.

Eliminating multi-path influence comprises the steps: in the method for the interference of the copy of L TP sequence of receiver formation

Estimate relevant channel parameter: the gain of channel path l $\{{\tilde{h}}_l\left(t\right),l=\mathrm{0,1},...,L\}$ Time delay with normalized different path l of elapsed time $\{{\widetilde{\mathrm{\τ}}}_l,l=\mathrm{0,1},...,L\};$

The gain of the channel path l that utilization estimates $\{{\tilde{h}}_l\left(t\right),l=\mathrm{0,1},...,L\}$ Time delay with normalized different path l of elapsed time $\{{\widetilde{\mathrm{\τ}}}_l,l=\mathrm{0,1},...,L\},$ Be calculated as follows the copy of multi-path influence in L TP sequence of receiver formation:

Wherein, R ₁..., R _LThe copy of L the TP sequence that is expressed as multi-path influence and forms at receiver.

The information processing method that in ofdm system, uses the time domain pilot sequence that the present invention proposes and have following beneficial effect based on the correlation method and the device of this method:

1.TP the introducing of sequence will only take the protection interval of OFDM, with respect to utilizing the method for inserting pilot tone or targeting sequencing, be convenient to reduce system loading, improve system transmissions efficient;

2.TP system design is convenient in the selection and the introducing of sequence, the system of being convenient to carries out Fast Channel estimation and automated power control (AGC);

3. utilize the cycle characteristics of the OFDM symbolic construction of the autocorrelation performance of TP sequence and proposition, be convenient to that the OFDM receiver carries out the time and carrier synchronization detects, wherein the carrier shift scope is: $(-\frac{N}{2(N+L)},\frac{N}{2(N+L)}).$ Adopt the standard variance parameter as the algorithm performance evaluating, emulation shows: under awgn channel, the synchronized algorithm that adopts the present invention to propose, time migration standard variance are zero, carrier shift standard variance＜10 ^-5Under the 2-path multipath channel, when signal to noise ratio snr＞12, time migration standard variance＜10 ^-1, carrier shift standard variance＜10 ^-4This result is suitable in most cases the synchronous requirement to carrier wave and time;

4. adopt the method for filling TP sequence and Cyclic Prefix to be convenient to the OFDM receiver and carry out channel estimating, utilize (cycle) autocorrelation performance of TP sequence, being convenient to the OFDM receiver estimates relevant channel parameter, when the TP block length greater than the channel maximum multipath time delay, be more convenient for adopting the channel estimation method of multiple maturation;

5. the certain interference of bringing for the processing of reception data-signal to the introducing of TP sequence is reduced or eliminated.

Description of drawings

Fig. 1 traditional based on the Cyclic Prefix in OFDM System symbolic construction;

Fig. 2 A, the OFDM symbolic construction that 2B and 2C the present invention propose;

The emission system that Fig. 3 the present invention proposes based on the time domain pilot sequence;

The receiving system that Fig. 4 the present invention proposes based on the time domain pilot sequence;

That disturbs in Fig. 5 OFDM reception information influences schematic diagram;

The OFDM loop cycle graph of a relation that Fig. 6 is an example with the shown OFDM symbolic construction-1 of Fig. 2 A;

Carrier wave and time synchronizing device that the recurrence relation based on the correlation properties of time domain pilot sequence and OFDM symbol that Fig. 7 the present invention proposes is carried out.

Embodiment

1. the OFDM sign form that proposes of the present invention

Fig. 1 has described traditional OFDM sign form based on Cyclic Prefix (following represent with CP).In traditional OFDM sign form shown in Figure 1, FFT (or DFT) piece 12 is positioned at after the Cyclic Prefix 11, and Cyclic Prefix is used to eliminate the intersymbol interference (ISI) from previous OFDM symbol as the protection interval of OFDM symbol.

Fig. 2 A has described the OFDM sign form that utilizes time domain pilot sequence (following represent with TP) of redundant information structure that the present invention proposes.In Fig. 2 A, the TP piece is made of a TP sequence, and TP piece 21 is placed on each OFDM symbol foremost, and immediately following after the TP piece being CP piece 22, TP piece 21 and CP piece 22 have been replaced protection shown in Figure 1 at interval 11 jointly.In Fig. 2 B, the TP piece is made of two or more back-to-back TP sequences.In Fig. 2 C, the piece 21 that one or more TP sequences are formed has been replaced protection interval 11 shown in Figure 1 alone, and the OFDM sign form that utilizes the TP piece shown in Fig. 2 C can be counted as the special case of Fig. 2 A.The selection of TP block size should be less than or equal to the protection interval of system.

The characteristics of Fig. 2 A and Fig. 2 B structure are that one or more TP sequences are placed at each OFDM symbol foremost, can follow the CP piece afterwards, are fft block after the CP piece.Select this structure mainly to be because: because the influence of multidiameter delay, generally the ISI that is more vulnerable to foremost from previous OFDM symbol of each OFDM symbol disturbs.And when the strong sequence of TP sequence selection auto-correlation, utilize autocorrelation performance, be easy to from this interference, extract useful information.The CP piece is the Cyclic Prefix from the OFDM symbol, and its producing method is identical with the producing method of traditional OFDM Cyclic Prefix.The effect of CP piece is: when the TP block length less than the protection gap length, the CP piece can be used for polishing protection gap length; Be used to eliminate from the TP piece of front with from the interference of last OFDM symbol; Inaccurate when synchronously, when received signal synchronous error scope is adjusted to this CP piece zone, utilize the cycle characteristics of CP, and, be convenient to the OFDM receiving system and recover primary signal by processing such as FFT and equilibriums.For the situation of Fig. 2 A, the length of TP piece may can utilize the autocorrelation performance of TP sequence to finish the parameter of extracting relative synchronous and channel less than the channel maximum multipath time delay.For the situation shown in Fig. 2 B, two or more back-to-back TP sequences can be convenient to utilize the cycle autocorrelation performance of TP sequence, estimate synchronously and other processing.For the situation shown in Fig. 2 C, the length of TP piece is greater than the channel maximum multipath time delay, and this condition is convenient to system and is adopted multiple channel estimation method commonly used.

2. the time domain pilot sequence chooses

Choosing of the length of time domain pilot sequence (TP) and type should be convenient to system design as far as possible.The FFT module based on 2 has mainly been adopted in the multi-carrier modulation of the transceiver of current ofdm system and demodulation part, and a lot of channel estimation methods is based on, and FFT designs, therefore in the present invention, the length P of TP sequence is chosen for power 2 times, so that based on the channel estimation method of 2 FFT.The system of should being convenient to that chooses of TP sequence carries out channel estimating fast in addition, is convenient to automated power control (AGC).Therefore the TP sequence need have good auto-correlation or cycle autocorrelation performance, and has same magnitude or near the spectral characteristic of same magnitude.Promptly ideally, this sequence is with amplitude zero auto-correlation (Constant AmplitudeZero Auto-Correlation, CAZAC) sequence.Also promptly for non-zero offset, this sequence shows as autocorrelation performance null cycle, and null cycle, the auto-correlation expression was seen formula (1) (2).

Suppose the long complex sequences S=(S of P that is ₁, S ₂..., S _P, S _t(1≤t≤P) is the sequence sample value.K+1 serial sequence S has cyclophysis, K 〉=1, promptly $S_{i+k^{*}P}=S_i,i=\mathrm{1,2},...,P;k=\mathrm{0,1},...,K.$ Any continuous drawing 2P-1 sequence sample value from K+1 serial sequence S, autocorrelation performance null cycle that complex sequences has shows as:

α is a real number.(1)

Periodic auto-correlation function ρ is expressed as:

$\mathrm{\ρ}(s;m)\underset{=}{\mathrm{\Δ}}\frac{1}{P}\underset{j=1}{\overset{P}{\mathrm{\Σ}}}{s}_j{s}_{j+m}^{*},m=\mathrm{0,1},...,P-1-------\left(2\right)$

In the formula (2), * represents conjugation.

When TP sequence selection length P is the CAZAC sequence of 2 powers, can adopt Frank-Zadoff sequence or Chu sequence." polyphase code of good cycle autocorrelation performance " (Polyphase Codes with GoodPeriodic Correlation Properities that the method for generation Chu sequence is delivered referring to D.C.Chu, IEEE Tran.Info.Theory, July1972, pp.531-532), " frameshit mutually of good cycle autocorrelation performance " (Phase ShiftCodes with Good Periodic Correlation Properities that the method for generation Frank-Zadoff sequence is delivered referring to R.L.Frank and S.A.Zadoff, IRE Trans.Info.Theory, Oct.1962, pp.381-382).

Frank-Zadoff sequence or Chu sequence are complex sequences.Make the long P of being of TP sequence, 0≤n≤P, the I road of TP sequence and the following expression of Q road signal:

I[n]＝cos(θ[n])Q[n]＝sin(θ[n]) (3)

When producing the Chu sequence, θ [n]=θ _Chu[n],

${\mathrm{\θ}}_{\mathrm{Chu}}\left[n\right]=\frac{{\mathrm{\πn}}^2}{P}--------\left(4\right)$

When producing the Frank-Zadoff sequence, θ [n]=θ _Frank[n]

${\mathrm{\θ}}_{\mathrm{Frank}}[n=\mathrm{\ρ}+\mathrm{\τ}\sqrt{P}]=\frac{2\mathrm{\π\ρ\τ}}{\sqrt{P}}--------\left(5\right)$

Wherein $\mathrm{\ρ}=\mathrm{0,1},...\sqrt{P},\mathrm{\τ}=\mathrm{0,1},...\sqrt{P}.$

The square root that the Frank-Zadoff sequence is suitable for sequence length P is the situation of integer.The Chu sequence then is suitable for arbitrary sequence length.But because the Chu sequence is heterogeneous, when the Chu sequence wishes to be designed to the Format Series Lines of " constant envelope sawtooth waveforms phase place ", be 16,64 and 256 for sequence length P, this requirement will need system to carry out additional designs.Therefore when sequence length P be 16,64 and 256 o'clock, the Frank-Zadoff sequence is selected in suggestion, and when sequence length P be 8,32,128 and 512 o'clock, the Chu sequence is selected in suggestion.

The length of TP sequence and the selection of sequence are referring to table one.

Table one the present invention advises the type and the length of the TP sequence that adopts

Sequence length P

Sequence type

8

Chu

16

Frank-Zadoff

32

Chu

64

Frank-Zadoff

128

Chu

256

Frank-Zadoff

512

Chu

3. corresponding receive-transmit system

Based on the OFDM symbolic construction of the present invention's proposition and the using method of TP sequence, Figure 3 shows that its corresponding emission system.After data or modulation data information 30 are passed through IFFT modular converter 31 and parallel/serial modular converter 32, be converted to time-domain signal.Select under the control of controll block 35 in sequence selection and Cyclic Prefix, can add Cyclic Prefix 33 on request, add one or more TP sequences 34 afterwards, these two signals are by blender 36, form Fig. 2 A that the present invention proposes, the OFDM sign form of Fig. 2 B and Fig. 2 C.Wherein sequence length and sequence type can be referring to tables one, and the length sum of TP piece and Cyclic Prefix equals protection at interval.The protection gap length can be selected by requirement of system design.The OFDM mark signal that forms is sent to transmitting antenna 38 after by digital-to-analogue conversion 37.

Based on the OFDM symbolic construction of the present invention's proposition and the using method of TP sequence, Figure 4 shows that its corresponding receiving system.Received signal 40 is through behind the analog-to-digital conversion module 41, the one part signal is sent to parameter estimator 43, select under the control of controll block 42 in sequence selection and Cyclic Prefix, parameter estimator 43 can be based on the OFDM sign form of TP sequence and the present invention's proposition, finish such as time synchronized, processing such as carrier synchronization and channel estimating, the synchronous and channel information 48 of its output can be used for the information processing of follow-up each functional module.Being imported into elimination time domain pilot sequence through the signal behind the analog-to-digital conversion module 41 influences module 44, to remove the interference that causes the TP block message of filling that data are handled owing to reasons such as multipath channels.Be imported into removal cyclic prefix module 45 subsequently to eliminate Cyclic Prefix through the data after module 44 processing.Eliminating the TP sequence influences module 44 and removes the control that cyclic prefix module 45 will be subjected to sequence selection and Cyclic Prefix selection controll block 42.Signal after module 45 is handled will be imported into FFT processing module 46 to obtain the data message 47 after the FFT demodulation.

4. the signal of the OFDM symbol of the present invention's proposition is formed

The TP sequence that adopts is Frank-Zadoff sequence or Chu sequence, and its sequence producing method is as (3) (4) (5), and the sequence of recommending at different sequence lengths sees Table one.The characteristics of Frank-Zadoff sequence or Chu sequence are: have the CAZAC characteristic, promptly show as autocorrelation performance null cycle, and have same magnitude or near the frequency domain characteristic of same magnitude, null cycle, the mathematical description of autocorrelation performance was seen formula (1) (2).This specific character is convenient to system and is carried out channel estimating fast, is convenient to AGC.The length P of these two kinds of TP sequences is 2 powers, is convenient to some channel estimation method based on 2 FFT like this.

Make that N is sub-carrier signal x (n) number, TP piece x _TP(n) total length is N _p, x here _TP(n) may comprise one or more TP sequences.The CP block length is N _gThen the OFDM mark signal for Fig. 2 A and 2B formation is:

The OFDM mark signal that forms for Fig. 2 C is:

5. based on the channel estimation methods of time domain pilot sequence

OFDM mark signal x _g(n) will experience frequency-selective channel arrival receiving terminal after the transmitter emission, received signal can be expressed as:

y _g(n)=x _g(n)h(n)+w(n) (7)

 is expressed as convolution in the formula, and h (n) is a channel impulse response, and w (n) is an additive white Gaussian noise, and h (n) can be expressed as:

$h\left(n\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_l\left(t\right)\mathrm{\δ}(\mathrm{\τ}-{\mathrm{\τ}}_i)------\left(8\right)$

{ h in the formula _l(t), l=0,1 ..., the complex gain in the different paths that become when L} is, { τ ₁, l=0,1 ..., L} is the time delays through normalized different paths of sampling time, L is the number of decline multipath in the frequency-selective channel.

The maximum time time-delay of supposing channel is τ _L, if ideal synchronisation, the initial point position of supposing each OFDM received signal is 0, then the TP sequence will act on [0, N _P+ τ _L-1] sample value zone.The protection of supposing OFDM is spaced apart τ, and τ 〉=τ _L, because the TP sequence has good autocorrelation performance, that is, its periodic auto-correlation function is

α is a real number.

Then we can [0, N _P+ τ-1] in the sample value zone, analyze by the convolution of TP sequence and received signal, thereby estimate relevant channel parameter { h _l(t), l=0,1 ..., L} and { τ _l, l=0,1 ..., L} etc.

For example, suppose at receiving terminal, carrier wave, code element and sampling time etc. are accurate synchronously, [0, N _P+ τ _L-1] sample value zone is with received signal y _g(n) with TP sequence x _TP(n) carry out convolution algorithm,

Then $y_g\left(n\right)\⊗x_{\mathrm{TP}}\left(n\right)=\mathrm{\α}\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_l\left(t\right)\mathrm{\δ}(\mathrm{\τ}-{\mathrm{\τ}}_l)+x\text{'}\left(n\right)\⊗x_{\mathrm{TP}}\left(n\right)+x_{\mathrm{TP}}\left(n\right)\⊗w\left(n\right)-----(8-0)$ In the formula (8-0) x ' (n) be [0, N _P+ τ _L-1] sub-carrier signal that receives of sample value zone says that from the statistical significance x ' is a random distribution (n), x ' (n) with TP sequence x _TP(n) do not have strong correlation.Thereby:

$y_g\left(n\right)\⊗x_{\mathrm{TP}}\left(n\right)=\mathrm{\α}\underset{l=0}{\mathrm{\Σ}}{h}_l\left(t\right)\mathrm{\δ}(\mathrm{\τ}-{\mathrm{\τ}}_l)+w\text{'}\left(n\right)-----(8-1)$

W ' is an additive white Gaussian noise (n) in the formula (8-1).

(8-1) formula of utilization can be estimated to comprise channel parameters such as the path gain and the path delay of time, for example sets a threshold value, [0, N _P+ τ _L-1] in the sample value zone, the slip related operation of slip TP sequence and execution and received signal; After the threshold value of mould value greater than setting of the relevant coefficient that obtains that slides, the relevant coefficient value that obtains of record slip divided by real number α, can obtain the gain h of estimated channel path l with this coefficient value _l(t), h _l(t) with respect to h ₀(t) position is the time delay τ of the path l of estimation _l

6. the interference elimination method of time domain pilot sequence

Figure 5 shows that the schematic diagram of received signal.In each OFDM received signal territory, if the protection of OFDM interval τ 〉=τ _L, disturb the influence of piece 50 will be no more than protection τ at interval from the ISI of last OFDM symbol.51 and 52 expressions are because multidiameter delay influences, and the TP piece is in the action scope of this OFDM symbol, and 53 represent the data-signal territories.52 and 53 lap represents that the partial action territory of TP sequence will overlap with the partial data signal domain owing to the influence of time-delay in shown in Figure 5, and this will bring specific interference to the processing that receives data-signal.But because the action scope of TP sequence be confined to [0, N _P+ τ-1], if we can obtain the characteristic of channel, because the TP sequence is known, then be easy to eliminate the interference of time domain pilot sequence data portion again.

[0, N _P+ τ-1] in the zone, received signal Y can be expressed as:

Y＝ D+ I+{ R ₁+，...，+ R _L}+ W (9)

In the formula:

I disturbs from the ISI of last OFDM symbol.

W represents additive white Gaussian noise.D represents to receive data-signal and its time-delay part.

R ₁..., R _LBe expressed as because multi-path influence, and the copy of L the TP sequence that forms at receiver.

(6.1) ISI that eliminates from last OFDM symbol disturbs I

If the protection of OFDM is τ 〉=τ at interval _L, then carrying out and eliminate the protection partitioning method, the ISI that eliminates from last OFDM symbol disturbs I.Specifically, the ISI that eliminates from last OFDM symbol disturbs the method for I to comprise the steps:

Received signal is outputed to elimination protection interval module;

Eliminating the protection interval module will be at N _p+ N _gThe preceding N of each the OFDM symbol signal that receives in the protection length at interval of the OFDM symbol signal of forming by TP sequence and Cyclic Prefix of individual sampled point correspondence _p+ N _gIndividual sampled point is removed.Work as N _p+ N _gThe protection gap length of individual sampled point correspondence is removed the preceding N of each the OFDM symbol signal that receives during greater than channel impulse response _p+ N _gIndividual sampled point, the ISI that can eliminate from last OFDM symbol disturbs I.

(6.2) eliminate the interference of multi-path influence at the copy of L TP sequence of receiver formation

Gain { the h of the channel path l that utilization estimates _l(t), l=0,1 ..., the time delay { τ of L} and normalized different path l of elapsed time _l, l=0,1 ..., L} is calculated as follows the copy of multi-path influence in L TP sequence of receiver formation:

Wherein, R ₁..., R _LThe copy of L the TP sequence that is expressed as multi-path influence and forms at receiver.

Make R _PrFor eliminating the signal after the TP sequence influences, then R _PrBe expressed as:

R _pr＝ Y-{ R ₁+...+ R _L} (11)

7. the time of the OFDM symbolic construction that proposes based on the present invention and the method for carrier synchronization

The OFDM sign form of Fig. 2 A that proposes with the present invention is an example, has following relation, and first is the autocorrelation performance of TP sequence; Second is the circulation copy relationship 62 in the same OFDM symbol; The 3rd is the recurrence relation 61 of the TP piece in the different OFDM symbols.The feasible time of the OFDM symbolic construction that proposes based on the present invention and the method for carrier synchronization are utilized just as co-relation and are carried out timing slip and carrier shift is estimated.The feasible time of the OFDM symbolic construction that proposes based on the present invention and the method step of carrier synchronization are: utilize the autocorrelation performance deadline skew of TP sequence to estimate; The recurrence relation of the TP sequence of the different OFDM symbols that propose with the present invention and the replicated relation of each OFDM symbol cyclic prefix are finished carrier shift and are estimated.

(7.1) utilize the autocorrelation performance deadline of TP sequence synchronous.

In frequency-selective channel, transmitting arrives the experience multipath in receiving terminal.For ofdm system, time synchronized requires to estimate the original position of each OFDM code element.Because the TP sequence has good autocorrelation performance, can utilize sliding correlation method to finish search to OFDM code element original position.Promptly in the sample sequence zone of selecting, carry out related operation in the OFDM sample sequence of slip TP sequence and selection, in slip related operation process, write down coefficient module value that each slip related operation obtains greater than the location point of setting thresholding, first location point is the original position that requires the OFDM code element estimated.

(7.2) utilize the autocorrelation performance of TP sequence to finish carrier synchronization.

Below we will mainly introduce the recurrence relation of utilizing the TP piece and carry out the method that carrier synchronization detects.Under situations such as the clock of channel variation and transceiver is not synchronous, can take place regularly and carrier shift.Suppose that timing slip is θ, carrier shift is ε, baseband receiving signals y _g(k) can be expressed as:

y _g(k)＝r(k-θ)e ^j2πεk/N+w(k) (12)

Make that N is the sub-carrier signal number, L=N _p+ N _g, set Γ ≡ θ ..., θ+N _P+ 1}.Suppose that observed value is 2 (N+L)+N _pIndividual continuous received signal this means that having comprised at least one complete length in these observed values is N+L+N _pThe OFDM symbolic information.Suppose that we utilize the autocorrelation performance of TP sequence to determine the starting point θ of OFDM symbol _AutoIn the middle of two adjacent OFDM symbols, the y of TP piece _g(k) there are following correlation properties: k ∈ Γ,

Wherein ${\mathrm{\σ}}_s^2=E\left\{\right|x{\left(k\right)}^2\left|\right\},{\mathrm{\σ}}_n^2=E\left\{\right|w{\left(k\right)}^2\left|\right\}$

Utilize relational expression (13), definition: y in the adjacent OFDM symbol _g(k) expression γ (m) is

$\mathrm{\γ}\left(m\right)=\underset{k=m}{\mathrm{\Σ}}{y}_g\left(k\right)y_g(k+L+N)------\left(14\right)$

The carrier shift estimated statement is shown expression formula (15).

$\widetilde{\mathrm{\ϵ}}=-\frac{1}{2\mathrm{\π}}\frac{N}{N+L}\∠\mathrm{\γ}\left({\mathrm{\θ}}_{\mathrm{auto}}\right)---------\left(15\right)$

Wherein ∠ is expressed as phase angle.

The design of the method for synchronous that proposes based on the present invention as shown in Figure 7.Received signal 70 is determined the starting point 77 of OFDM symbol by Autocorrelation Detection device 74.Received signal 70 is by shift register 71 simultaneously, and the signal after the displacement is finished conjugate operation 72.The output signal of conjugate operation 72 and received signal 70 enter accumulator 75 after multiplying each other through multiplier 73, module 71,72, and 73 and 75 have realized relational expression (14) jointly.The output parameter of accumulator is by carrier shift estimator 76, the carrier shift value 78 that can obtain estimating.

Adopt this method to carry out carrier shift, its carrier shift calibration range is

$(-\frac{N}{2(N+L)},\frac{N}{2(N+L)}).$

Claims (15)

1. information processing method that in ofdm system, uses the time domain pilot sequence; adopt one or more time domain pilot sequences to be filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude.

2. in accordance with the method for claim 1, it is characterized in that the time domain pilot sequence is filled to the protection interval stem of each OFDM symbol, protection remainder is at interval filled with the Cyclic Prefix of OFDM symbol, and Cyclic Prefix is a fft block afterwards.

3. in accordance with the method for claim 1, it is characterized in that the time domain pilot sequence is filled to the whole protecting interval of each OFDM symbol, is fft block after the protection at interval.

4. according to claim 2 or 3 described methods, it is characterized in that selecting the time domain pilot sequence length is the time domain pilot sequence of 2 powers.

5. according to claim 2 or 3 described methods, it is characterized in that selecting the time domain pilot sequence length is having with the Frank-Zadoff sequence of amplitude zero autocorrelation performance or Chu sequence as the time domain pilot sequence of 2 powers.

6. according to claim 2 or 3 described methods, it is characterized in that, at the different time domain pilot sequence length, select corresponding time domain pilot sequence, when the time domain pilot sequence length is 16,64 and 256 o'clock, select the Frank-Zadoff sequence, when sequence length is 8,32,128 and 512 o'clock, select the Chu sequence.

7. emission system of using the time domain pilot sequence in ofdm system is characterized in that described emission system comprises:

IFFT modular converter (31) carries out the IFFT conversion to data or modulation data information (30);

Parallel/serial modular converter (32), the signal that IFFT modular converter (31) is exported carries out parallel/serial conversion and becomes time-domain signal;

Sequence selection and Cyclic Prefix are selected controll block (35), select at first described time-domain signal to be added Cyclic Prefix on request and obtain first signal under the control of controll block (35) in sequence selection and Cyclic Prefix; And then add one or more time domain pilot sequences 34 and obtain secondary signal;

Blender (36), form the OFDM symbol according to described first signal that is input to blender and described secondary signal, wherein one or more time domain pilot sequences are filled to the protection interval stem of each OFDM symbol, protection remainder is at interval filled with the Cyclic Prefix of OFDM symbol, and the length sum of time domain pilot sequence and Cyclic Prefix equals protection at interval;

D/A converter module (37) is carried out digital-to-analogue conversion to formed OFDM mark signal;

Transmitting antenna (38) is launched the output signal of digital-to-analogue conversion (37).

8. receiving system of in ofdm system, using the time domain pilot sequence; one or more time domain pilot sequences are filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude, it is characterized in that described receiving system comprises:

Analog-to-digital conversion module (41), (40) carry out analog-to-digital conversion to received signal;

Sequence selection and Cyclic Prefix are selected controll block (42);

Parameter estimator (43), select under the control of controll block (42) in sequence selection and Cyclic Prefix, parameter estimator (43) is synchronous at a part of signal deadline of analog-to-digital conversion module (41) output, the synchronous and channel information (48) of the signal processing of carrier synchronization and channel estimating and output;

Eliminating the time domain pilot sequence influences module (44), selects under the control of controll block (42) signal removal that analog-to-digital conversion module (41) is exported causes the time domain pilot sequence of filling that data are handled owing to multipath channel interference in sequence selection and Cyclic Prefix;

Remove cyclic prefix module (45), select under the control of controll block (42), influence the processing that data that module (44) exports are eliminated Cyclic Prefix eliminating the time domain pilot sequence in sequence selection and Cyclic Prefix;

FFT processing module (46) is used for that the signal of removing cyclic prefix module (45) output is carried out FFT and handles to obtain the data message (47) after the FFT demodulation.

One kind in ofdm system, use the time domain pilot sequence estimated time deviant method; described one or more time domain pilot sequence is filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude, it is characterized in that the method for described estimated time of deviant comprises the steps:

In the sample sequence zone of selecting, the related operation of the OFDM sample sequence of slip TP sequence and execution and selection, in slip related operation process, write down coefficient module value that each slip related operation obtains greater than the location point of setting thresholding, first location point is the original position of the OFDM code element of received signal (70);

Obtain time offset value (θ) according to described original position.

One kind in ofdm system, use the time domain pilot sequence estimated time deviant device; described one or more time domain pilot sequence is filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude, it is characterized in that described device comprises:

Autocorrelation Detection device (74), autocorrelation performance according to the time domain pilot sequence, in the sample sequence zone of selecting, the related operation of the OFDM sample sequence of slip TP sequence and execution and selection, in slip related operation process, write down coefficient module value that each slip related operation obtains greater than the location point of setting thresholding, first location point is the original position of the OFDM code element of received signal (70);

The time migration calculator is according to described original position deviant computing time (θ).

11. method of in ofdm system, using the estimation carrier shift value of time domain pilot sequence; described one or more time domain pilot sequence is filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude, it is characterized in that described method comprises the steps:

Use Autocorrelation Detection device (74) determines received signal according to the autocorrelation performance of time domain pilot sequence the starting point of OFDM symbol to obtain time offset value, represent the start point information of the OFDM symbol of received signal with θ auto;

Carry out shifting processing to received signal with shift register (71);

With conjugate operation device (72) signal of the output of shift register (71) is carried out conjugate operation;

With multiplier (73) output signal of conjugate operation device (72) is carried out multiplication mutually with received signal;

Start point information θ according to the OFDM symbol of Autocorrelation Detection device (74) output _Auto, accumulator (75) carries out accumulation calculating to the output signal of multiplier, the output parameter of accumulator γ (θ _Auto) expression;

Use the output parameter γ (θ of carrier shift estimator (76) by accumulator _Auto) estimate that by following formula carrier shift value ε is:

$\widetilde{\mathrm{\ϵ}}=-\frac{1}{2\mathrm{\π}}\frac{N}{N+L}\∠\mathrm{\γ}\left({\mathrm{\θ}}_{\mathrm{auto}}\right)$

Wherein ∠ is expressed as phase angle, and N is the sub-carrier signal number, and L is the number of decline multipath in the frequency-selective channel.

12. device that in ofdm system, uses the estimation carrier shift value of time domain pilot sequence; described one or more time domain pilot sequence is filled to the protection interval of the symbol of each OFDM; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; and the time domain pilot sequence has same magnitude or near the spectral characteristic of same magnitude, it is characterized in that described device comprises:

Autocorrelation Detection device (74), the starting point of OFDM symbol of determining received signal (70) according to the autocorrelation performance of time domain pilot sequence is used θ to obtain time offset value _AutoThe start point information of the OFDM symbol of expression received signal;

Shift register (71) carries out shifting processing to received signal;

Conjugate operation device (72) carries out conjugate operation to the signal of the output of shift register (71);

Multiplier (73) carries out multiplication mutually with the output signal of conjugate operation device (72) with received signal;

Accumulator (75) is according to the start point information θ of the OFDM symbol of Autocorrelation Detection device (74) output _AutoOutput signal to multiplier is carried out accumulation calculating, the output parameter of accumulator γ (θ _Auto) expression;

Carrier shift estimator (76) is with the output parameter γ (θ of accumulator _Auto) estimate that by following formula carrier shift value ε is:

$\widetilde{\mathrm{\ϵ}}=-\frac{1}{2\mathrm{\π}}\frac{N}{N+L}\∠\mathrm{\γ}\left({\mathrm{\θ}}_{\mathrm{auto}}\right)$

Wherein ∠ is expressed as phase angle, and N is the sub-carrier signal number, and L is the number of decline multipath in the frequency-selective channel.

13. channel estimation methods that in ofdm system, uses the time domain pilot sequence; described one or more time domain pilot sequence is filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance, it is characterized in that described method comprises the steps:

Set a threshold value, [0, N _P+ τ _L-1] in the sample value zone, the slip related operation of slip TP sequence and execution and received signal; After the threshold value of mould value greater than setting of the relevant coefficient that obtains that slides, the relevant coefficient value that obtains of record slip divided by real number α, can obtain the gain h of estimated channel path l with this coefficient value _l(t), the gain h of channel path l _l(t) with respect to h ₀(t) position is the time delay τ of the normalized different path l of elapsed time of estimation _l, N wherein _PBe the total length of TP piece, τ _LIt is the maximum time time-delay of channel.

14. interference elimination method that in ofdm system, uses the time domain pilot sequence; described one or more time domain pilot sequence is filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; it is characterized in that described method comprises protection at interval the method for elimination from the ISI interference I of last OFDM symbol, the ISI that eliminates from last OFDM symbol disturbs the protection method at interval of I to comprise the steps:

Received signal is outputed to elimination protection interval module; Eliminating the protection interval module will be at N _p ^-+ N _gThe preceding N of each the OFDM symbol signal that receives in the protection length at interval of the OFDM symbol signal of forming by TP sequence and Cyclic Prefix of individual sampled point correspondence _p+ N _gIndividual sampled point is removed.

15. interference elimination method that in ofdm system, uses the time domain pilot sequence; described one or more time domain pilot sequence is filled to the protection interval of each OFDM symbol; the time domain pilot sequence has auto-correlation or cycle autocorrelation performance; it is characterized in that described method comprises the method for elimination multi-path influence in the interference of the copy of L TP sequence of receiver formation, the method for described elimination multi-path influence comprises the steps:

Estimate relevant channel parameter: the gain { h of channel path l _l(t), l=0,1 ..., the time delay { τ of L} and normalized different path l of elapsed time _l, l=0,1 ..., L},

Gain { the h of the channel path l that utilization estimates _l(t), l=0,1 ..., the time delay { τ of L} and normalized different path l of elapsed time _l, l=0,1 ..., L} is calculated as follows the copy of multi-path influence in L TP sequence of receiver formation:

Wherein, R _l..., R _LThe copy of L the TP sequence that is expressed as multi-path influence and forms at receiver.

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