CN101997805A - Pilot symbol processing method and device - Google Patents

Abstract

The invention discloses a pilot symbol processing method and device. The method comprises the following steps: adding a compensation part into the effective pilot symbol to obtain a transmission pilot symbol, wherein the compensation part is used for counteracting the interference of the information symbol on the effective pilot symbol at the pilot frequency point of the effective pilot symbol; and mapping the transmission pilot symbol onto the pilot subcarrier, and carrying out windowing on the transmission pilot symbol which is mapped onto the pilot subcarrier by using a double-window function,which is identical to the information symbol, to obtain the transmission pilot symbol after windowing. The embodiment of the invention can be used for obtaining an accurate pilot value at the receiving end.

Description

The processing method of frequency pilot sign and device

Technical field

The present invention relates to wireless communication technology, particularly a kind of processing method of frequency pilot sign and device.

Background technology

(Orthogonal Frequency Division Multiplexing, OFDM) technology has very consequence at wireless communication field to OFDM, has availability of frequency spectrum height, subcarrier permutation characteristics closely.These characteristics is an advantage, also can cause some negative influences simultaneously, and for example, These characteristics makes ofdm system be subject to the influence of frequency deviation, frequency dispersion.In real system, the deviation of receiver and transmitter crystal oscillator frequency and the error of Frequency Synchronization make frequency deviation to avoid; Under quick time-varying channel, can there be serious Doppler spread in channel again.The performance of the badly damaged ofdm system of unavoidable frequency deviation and dispersion phenomenon meeting in the above-mentioned real system.For frequency deviation and the dispersion phenomenon that resists system, a kind of double window OFDM method has been proposed in the prior art, even subcarriers adopts different window function sequences to modulate respectively with symbol on the odd subcarriers in this method.In traditional ofdm system (not adopting double window OFDM method), frequency pilot sign and information symbol adopt same modulation system, be that frequency pilot sign utilizes IFFT to be modulated on the pilot sub-carrier, information symbol adopts IFFT to be modulated on the information subcarrier, because frequency pilot sign is modulated on the different subcarriers with information symbol, and not through the windowing operation, thereby can the holding frequency orthogonality between frequency pilot sign and the information symbol, receiving terminal can separate frequency pilot sign and information symbol by the FFT computing, and frequency pilot sign afterwards can be used for computings such as channel estimating.

The inventor finds prior art in realizing process of the present invention there are the following problems at least: frequency deviation and frequency dispersion problem in order to overcome ofdm system, can adopt double window OFDM method, and need to consider the handling problem of frequency pilot sign in the double window ofdm system this moment.If the processing method of frequency pilot sign in traditional ofdm system is indiscriminately imitated in the double window ofdm system, owing to passed through the windowing operation in the double window ofdm system, can cause frequency pilot sign and the information symbol can not the holding frequency orthogonality, cause the interference that on the pilot tone frequency at frequency pilot sign place, has information symbol, influence the accuracy of frequency pilot sign.

Summary of the invention

The embodiment of the invention has proposed a kind of processing method and device of frequency pilot sign, solves and directly the processing method of frequency pilot sign in traditional ofdm system is indiscriminately imitated the inaccurate problem of frequency pilot sign on the pilot tone frequency that causes in the double window ofdm system.

The embodiment of the invention provides a kind of processing method of frequency pilot sign, comprising:

Add compensated part and obtain transmitted pilot symbol in effective frequency pilot sign, described compensated part is used for offsetting the interference of information symbol to described effective frequency pilot sign on the pilot tone frequency at described effective frequency pilot sign place;

Described transmitted pilot symbol is mapped on the pilot sub-carrier, and the employing double window function identical, the described transmitted pilot symbol that is mapped on the pilot sub-carrier is carried out windowing process, obtain the transmitted pilot symbol after the windowing with described information symbol.

The embodiment of the invention provides a kind of processing unit of frequency pilot sign, comprising:

Module is added in compensation, is used for adding compensated part at effective frequency pilot sign and obtains transmitted pilot symbol, and described compensated part is used for offsetting the interference of information symbol to described effective frequency pilot sign on the pilot tone frequency at described effective frequency pilot sign place;

Pilot tone mapping windowing module, be used for described transmitted pilot symbol is mapped to pilot sub-carrier, and the employing double window function identical with described information symbol, the described transmitted pilot symbol that is mapped on the pilot sub-carrier is carried out windowing process, obtain the transmitted pilot symbol after the windowing.

As shown from the above technical solution, the embodiment of the invention is by effectively adding compensated part in the frequency pilot sign, and this compensated part can be offset information symbol in the interference to this effective frequency pilot sign on the pilot tone frequency, the frequency pilot sign that can not existed information symbol to disturb after cancelling out each other on this pilot tone frequency obtains frequency pilot sign accurately.

Description of drawings

Fig. 1 is the structural representation of the double window ofdm system of embodiment of the invention employing;

Fig. 2 is the time domain waveform figure of one group of double window function in the double window OFDM method of embodiment of the invention employing;

Fig. 3 is the method flow schematic diagram of first embodiment of the invention;

Fig. 4 is the method flow schematic diagram of second embodiment of the invention;

Fig. 5 is the schematic diagram that pilot sub-carrier distributes in the second embodiment of the invention;

Fig. 6 is the method flow schematic diagram of third embodiment of the invention;

The method that Fig. 7 adopts for the embodiment of the invention is at the graph of relation that does not have signal to noise ratio and the error rate under the offset frequency situation;

The graph of relation of the method that Fig. 8 adopts for the embodiment of the invention signal to noise ratio and error rate under different offset frequency situation;

Fig. 9 is the apparatus structure schematic diagram of fifth embodiment of the invention;

Figure 10 is the apparatus structure schematic diagram of sixth embodiment of the invention.

Embodiment

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

In order to understand the present invention better, at first introduce double window OFDM method.

Fig. 1 is the structural representation of the double window ofdm system of embodiment of the invention employing.

The principle of double window OFDM method is as follows:

Suppose that the double window function that adopts is w ₁(n) and w ₂(n), wherein, n is a positive integer, and 0≤n≤N-1, and N is an even number, total number of expression system subcarrier.

At transmitting terminal, the symbol after at first will modulating adopts IFFT to be mapped on the subcarrier, afterwards, adopts w ₁(n) and w ₂(n) multiply each other with the time-domain signal of even subcarriers and odd subcarriers respectively and, obtain following baseband signal results added:

$x\left(n\right)=\underset{i=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i}\exp \left\{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i}{N}n\right\}{w}_1\left(n\right)+\underset{i=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i+1}\exp \left\{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i+1}{N}n\right\}{w}_2\left(n\right)$

Wherein, x (n) is a n sampled point of ofdm system baseband signal, s _mFor being mapped to m the symbol on the subcarrier.To use window function w ₁The signal definition of even subcarriers (n) is first group, will use window function w ₂The signal definition of odd subcarriers (n) is second group.

When not having channel fading not have the environment of noise yet, receiver use in turn two respectively with the window function of transmitter coupling carry out matched filtering to received signal.Because the window function that transmitter adopts is a real number, thereby the matching window function that receiver uses still is w ₁(n) and w ₂(n).

At receiving terminal, be through the signal after the windowing operation:

$y_r\left(n\right)=x\left(n\right)w_r\left(n\right)=\underset{i=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i}\exp \left\{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i}{N}n\right\}{w}_1\left(n\right)w_r\left(n\right)+\underset{i=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i+1}\exp \left\{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i+1}{N}n\right\}{w}_2\left(n\right)w_r\left(n\right)$

Wherein, y _r(n) output after the windowing of expression received signal, when r=1, w is used in expression ₁(n) coupling receives first group symbol, and r=2 then represents to use w ₂(n) coupling receives second group symbol.

After through the windowing operation, to signal y _r(n) do the FFT computing, extract symbol on corresponding even subcarriers or the odd subcarriers respectively, obtain transmitting on each subcarrier the valuation of symbol according to γ=1 or 2.

Under no offset frequency situation, for not containing, the intersymbol on assurance each subcarrier through extracting behind the FFT do not crosstalk, and the double window function should satisfy following orthogonality condition:

$\underset{i=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{w}_r^2\left(n\right)\exp \{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i}{N}n\}=0$ (guaranteeing the orthogonality between each subcarrier in the band demodulation group)

And

$\underset{i=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{w}_1\left(n\right)w_2\left(n\right)\exp \{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i+1}{N}n\}=0$ (guaranteeing the orthogonality between symbols to be demodulated and interference symbols)

Wherein, $i=0,...,\frac{N}{2}-1,$ r＝1，2。

The expression formula that satisfies the double window function of above-mentioned orthogonality condition can be as follows:

$w_1\left(n\right)=\sqrt{\frac{1}{N}+\mathrm{\&zeta;}\left(n\right)},$ $w_2\left(n\right)=\sqrt{\frac{1}{N}-\mathrm{\&zeta;}\left(n\right)}$

Wherein, $\mathrm{\&zeta;}\left(n\right)=\frac{1}{N}\underset{p=0}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{a}_{2p+1}\sin \left[\frac{2\mathrm{\&pi;}(2p+1)n}{N}\right]$

$a_{2p+1}(p=\mathrm{0,1},...,\frac{N}{2}-1)$ Be the window function parameter of reality, can obtain by the method for computer search.

Fig. 2 is the time domain waveform figure of one group of double window function in the double window OFDM method of embodiment of the invention employing.After adopting the aforementioned calculation method, can obtain one group of double window function as shown in Figure 2.

The above-mentioned channel that is based on does not have the decline and the hypothesis of noise, for the multidiameter fading channel of reality, only need add following treatment step and can make system equivalent for to propagate in the Gaussian channel environment in system.

At transmitting terminal; carry out after IFFT is mapped to subcarrier and double window and handles; add a Cyclic Prefix before each OFDM symbol, the purpose of adding prefix is that the intersymbol biography that the protection symbol is not caused by multipath is disturbed, and signal is modulated onto radio frequency and launches from antenna then.At receiving terminal, at first remove prefix and FFT computing, afterwards, the zero forcing equalization that carries out frequency domain in the orthogonality of receiving end signal, carries out processing such as demodulation to eliminate the influence of multipath channel decline then.

In double window OFDM method, because signal carried out windowing process in time domain, thereby its frequency spectrum is expanded, and this can cause can not the holding frequency orthogonality between each symbol.Therefore, after frequency pilot sign and information symbol adopted double window OFDM method to handle equally, after receiving terminal carried out the FFT computing, information symbol can cause interference to frequency pilot sign on frequency domain.

In order to recover frequency pilot sign accurately at receiving terminal, the embodiment of the invention at first compensates frequency pilot sign in advance in the time domain of transmitting terminal, so that after receiving terminal carries out frequency domain FFT conversion, can offset the interference of information symbol, obtains frequency pilot sign accurately.

Fig. 3 is the method flow schematic diagram of first embodiment of the invention, comprising:

Step 31: transmitter adds compensated part and obtains transmitted pilot symbol in effective frequency pilot sign, and described compensated part is used for offsetting the interference of information symbol to described effective frequency pilot sign on the pilot tone frequency at described effective frequency pilot sign place;

Step 32: transmitter is mapped to described transmitted pilot symbol on the pilot sub-carrier, and the employing double window function identical with described information symbol, the described transmitted pilot symbol that is mapped on the pilot sub-carrier is carried out windowing process, obtain the transmitted pilot symbol after the windowing.

Present embodiment is by effectively adding compensated part in the frequency pilot sign, and this compensated part can be offset information symbol in the interference to this effective frequency pilot sign on the pilot tone frequency, the frequency pilot sign that can not existed information symbol to disturb after cancelling out each other on this pilot tone frequency obtains frequency pilot sign accurately.

Suppose that ofdm system has N subcarrier, wherein, the number of pilot sub-carrier is M, and the sequence number of pilot sub-carrier is respectively l ₀..., l _M-1, frequency pilot sign is respectively p ₀..., p _M-1, make φ _P={ l ₀..., l _M-1, P _s={ p ₀..., p _M-1, M≤N, 0≤l ₀＜...＜l _M-1≤ N-1.Frequency pilot sign transmits on pilot sub-carrier, and information symbol transmits on the information subcarrier, and the information subcarrier is the subcarrier except pilot sub-carrier in the system.The double window function that system adopts is w ₁(n) and w ₂(n).

Fig. 4 is the method flow schematic diagram of second embodiment of the invention, comprising:

Step 41: transmitter distributes pilot sub-carrier.In order to guarantee uniform evaluation characteristic in the whole system bandwidth, this pilot sub-carrier can be evenly distributed in the sub carrier group of pilot sub-carrier and information subcarrier composition.

Fig. 5 is the schematic diagram that pilot sub-carrier distributes in the second embodiment of the invention, referring to Fig. 5, for example, pilot sub-carrier can be selected the pectination form, be that frequency pilot sign is spacedly distributed on frequency, Fig. 5 is the situation of two the information subcarriers in interval between the adjacent pilot frequencies subcarrier.

Step 42: transmitter is mapped to information symbol on the information subcarrier, and adopts the double window function of systemic presupposition to carry out windowing process, obtains the information symbol x (n) after the windowing.The information subcarrier is the subcarrier except pilot sub-carrier in the system.

Computing formula can for:

$x\left(n\right)=\underset{\underset{2i\&NotElement;{\mathrm{\&phi;}}_P}{i=0}}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i}\exp \left\{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i}{N}n\right\}{w}_1\left(n\right)+\underset{\underset{2i+1\&NotElement;{\mathrm{\&phi;}}_P}{i=0}}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i+1}\exp \left\{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{2i+1}{N}n\right\}{w}_2\left(n\right)$

Wherein, s _mFor being mapped to m the information symbol on the subcarrier, m=2i, 2i+1, $i=0,...,\frac{N}{2}-1.$

Step 43: transmitter calculates the frequency domain components I of information symbol on the pilot tone frequency after this windowing.

Computing formula can for:

I=[I _i] _{M * 1}, and $I_i=\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp \{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{l_i}{N}n\},$ I=0 ..., M-1, I _iBe the capable element of the i of I.

Because the windowing operation can make signal on each subcarrier at frequency domain quadrature no longer, therefore, information symbol can produce interference distributing on the pilot tone frequency (pilot sub-carrier) of frequency pilot sign, for example, (is l in the system at i pilot sub-carrier _iIndividual subcarrier) on, the interference that information symbol causes is the frequency domain components of information symbol on this pilot tone frequency, and computing formula is:

$I_i=\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp \{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100915866E0000021.png,H2009100915866E0000051.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{l_i}{N}n\}$

Above-mentioned information symbol is above-mentioned frequency domain components I, I=[I to the form that the interference table of frequency pilot sign is shown vector on each pilot sub-carrier ₀... I _M-1] ^T, [*] ^TExpression is carried out the transposition computing to vector [*].

Step 44: transmitter obtains the pilot tone transformation matrix according to the sequence number of double window function and effective pilot sub-carrier.

Computing formula is:

B=[B _{I, j}] _{M * M}, and

Wherein, B is this pilot tone transformation matrix, B _{I, j}Be the element of the capable j row of the i of B, represent that j frequency pilot sign modulation is afterwards at l _iThe frequency domain components that produces on the individual subcarrier, l _iBe the sequence number of effective pilot sub-carrier, the l under the promptly above-mentioned assumed condition ₀..., l _M-1

Be understandable that step 44 does not have the sequential restriction relation with step 42-43.

Step 45: transmitter is compensated part according to this pilot tone transformation matrix B and this frequency domain components I, afterwards, obtains transmitted pilot symbol from effective frequency pilot sign.

Computing formula is:

P＝P _s+C＝P _s-B ^-1I

Wherein, P is a transmitted pilot symbol, P _sBe effective frequency pilot sign, promptly above-mentioned P _s={ p ₀..., p _M-1.

Afterwards, at receiving terminal, carry out the FFT computing after, the frequency domain components that transmitted pilot symbol produces on the pilot tone frequency is: P _f=B * P=B * (P _s-B ^-1I)=B * P _s-I.Because information symbol can cause interference on the pilot tone frequency, therefore, the frequency domain components that obtains on the pilot tone frequency should be both sums, i.e. P _f+ I=B * P _s-I+I=B * P _sAnd B * P _sThe effective frequency domain components on the pilot tone frequency of frequency pilot sign just, i.e. pilot tone value of symbol accurately.That is to say,, on the pilot tone frequency, offset the interference of information symbol, obtained frequency pilot sign value accurately through after the above-mentioned processing.Afterwards, the frequency pilot sign value can be used for purposes such as channel estimating accurately.

Step 46: transmitter is mapped to this transmitted pilot symbol on the pilot sub-carrier, and the employing double window function identical with information symbol carry out windowing process, obtains the transmitted pilot symbol after the windowing.

Because frequency pilot sign and information symbol have adopted double window OFDM method, can avoid the frequency deviation and the frequency dispersion problem of traditional ofdm system.

Step 47: information symbol and transmitted pilot symbol windowing after of transmitter after with windowing carries out overlap-add procedure, the signal after obtaining superposeing.

For fear of the multipath fading influence, can also comprise afterwards:

Step 48: after adding Cyclic Prefix in the signal of transmitter after stack, obtain base band transmit, afterwards, base band transmit is sent to receiver.

Present embodiment is by effectively adding compensated part in the frequency pilot sign, and this compensated part can be offset information symbol in the interference to this effective frequency pilot sign on the pilot tone frequency, the frequency pilot sign that can not existed information symbol to disturb after cancelling out each other on this pilot tone frequency obtains frequency pilot sign accurately; Present embodiment can overcome the frequency deviation and the frequency dispersion problem of traditional ofdm system by frequency pilot sign and information symbol are adopted double window OFDM processing method.

On the basis of the foregoing description, can carry out channel estimating in the following way:

Fig. 6 is the method flow schematic diagram of third embodiment of the invention, comprising:

Step 61: the baseband transmission information that the receiver receiver/transmitter sends, remove Cyclic Prefix wherein, afterwards, adopt the FFT computing to obtain frequency-region signal.This baseband transmission information is that the 4th by way of example obtains.

Step 62: receiver extracts the signal value on the pilot tone frequency, obtains receiving pilot value, and the effective pilot value when launching divided by the transmitter on the pilot tone frequency of correspondence, obtains the channel response value on this pilot tone frequency.

Step 63: receiver transforms to time domain with the channel response value on all pilot tone frequencies, obtains the time-domain response value of channel.

Present embodiment can obtain frequency pilot sign value accurately at receiving terminal by receiving the base band transmit after handling, and afterwards, can carry out channel estimating accurately.

In order to test the effect of the embodiment of the invention, can carry out emulation in the following way:

Emulation platform: MATLAB

Simulation parameter is as shown in table 1:

Table 1

Total number of sub-carriers N	?64
		Subcarrier spacing	?10kHz
Pilot sub-carrier at interval	3 information subcarriers of adjacent pilot frequencies subcarrier spacing
		Modulation system	?QPSK
Equalizer	Zero forcing equalization
		Pilot symbol energies/information symbol energy	1: 1 or 2: 1

Simulated channel: GPP TS45.005 TU6, the parameter of this signal model is as shown in table 2.

Table 2

Postpone (μ s)	0.0	0.2	0.6	1.6	2.4	5.0
							Energy (dB)	-3.0	0.0	-2.0	-6.0	-8.0	-10.0

Offset the compensated part that information symbol disturbs owing to added in the pilot tone, thereby this part signal takies part energy.For guaranteeing fairness relatively, in the emulation total pilot energy is limited, and with the energy of frequency pilot sign and the ratio P of information symbol energy _Pilot/ P _SymbolAs a reference.

The method that Fig. 7 adopts for the embodiment of the invention is at the graph of relation that does not have signal to noise ratio (snr) and the error rate (BER) under the offset frequency situation.Referring to Fig. 7, the method that the embodiment of the invention adopts and the situation of the known ideal communication channel parameter of receiver compare.Pilot design and channel estimation methods that the simulation result shows embodiment of the invention adopts can provide channel parameter estimation value more accurately, and bit error rate performance and ideal communication channel parameter Estimation difference are little.

The graph of relation of the method that Fig. 8 adopts for the embodiment of the invention signal to noise ratio and error rate under different offset frequency situation.Referring to Fig. 8, method and traditional OFDM method that the embodiment of the invention adopts compare.Do not having under the situation of frequency deviation, both performances are basic identical.Along with the increase of frequency deviation, the performance of traditional OFDM descends rapidly; And the decreased performance of double window ofdm system is slow, shows the performance of frequency offset resistant preferably, and ε represents different offset frequency situation.

Fig. 9 is the apparatus structure schematic diagram of fifth embodiment of the invention, comprises that module 91 is added in compensation, pilot tone is shone upon windowing module 92.Compensation is added module 91 and is used for obtaining transmitted pilot symbol in effective frequency pilot sign interpolation compensated part, and described compensated part is used for offsetting the interference of information symbol to described effective frequency pilot sign on the pilot tone frequency at described effective frequency pilot sign place; Pilot tone mapping windowing module 92 is added module 91 with compensation and is connected, be used for described transmitted pilot symbol is mapped to pilot sub-carrier, and the employing double window function identical with described information symbol, the described transmitted pilot symbol that is mapped on the pilot sub-carrier is carried out windowing process, obtain the transmitted pilot symbol after the windowing.

Present embodiment is by effectively adding compensated part in the frequency pilot sign, and this compensated part can be offset information symbol in the interference to this effective frequency pilot sign on the pilot tone frequency, the frequency pilot sign that can not existed information symbol to disturb after cancelling out each other on this pilot tone frequency obtains frequency pilot sign accurately.

Figure 10 is the apparatus structure schematic diagram of sixth embodiment of the invention, comprises that module 101 is added in compensation, pilot tone is shone upon windowing module 102, information mapping windowing module 103, computing module 104, compensation acquisition module 105, matrix acquisition module 106, distribution module 107, laminating module 108 and prefix and added module 109.Module 101, pilot tone mapping windowing module 102 are added in compensation can be as described in the 5th embodiment.

Information mapping windowing module 103 is used for information symbol is mapped to the information subcarrier, and adopts described double window function, and the described information symbol that is mapped on the information subcarrier is carried out windowing process, obtains the information symbol after the windowing; Computing module 104 is connected with described information mapping windowing module 103, is used to calculate the frequency domain components of information symbol on described pilot tone frequency after the described windowing; Compensation acquisition module 105 adds module 101 with described computing module 104 and described compensation and is connected, and is used for obtaining described compensated part according to the pilot tone transformation matrix and the described frequency domain components that obtain in advance.Matrix acquisition module 106 is connected with described compensation acquisition module 105, is used for the sequence number according to described double window function and described effective pilot sub-carrier, obtains described pilot tone transformation matrix.Distribution module 107 is connected with described pilot tone mapping windowing module 102, is used to distribute described pilot sub-carrier, and described pilot sub-carrier is evenly distributed in the sub carrier group of pilot sub-carrier and information subcarrier composition.Laminating module 108 is connected with described information mapping windowing module 103 and described pilot tone mapping windowing module 102, is used for the transmitted pilot symbol after information symbol after the described windowing and the described windowing is carried out overlap-add procedure the signal after obtaining superposeing; Prefix is added module 109 and is connected with described laminating module 108, is used for obtaining base band transmit after the signal after the stack adds Cyclic Prefix.The device of present embodiment can be transmitter.

Present embodiment is by effectively adding compensated part in the frequency pilot sign, and this compensated part can be offset information symbol in the interference to this effective frequency pilot sign on the pilot tone frequency, the frequency pilot sign that can not existed information symbol to disturb after cancelling out each other on this pilot tone frequency obtains frequency pilot sign accurately; Present embodiment can overcome the frequency deviation and the frequency dispersion problem of traditional ofdm system by frequency pilot sign and information symbol are adopted double window OFDM processing method.

One of ordinary skill in the art will appreciate that: all or part of step that realizes said method embodiment can be finished by the relevant hardware of program command, aforesaid program can be stored in the computer read/write memory medium, this program is carried out the step that comprises said method embodiment when carrying out; And aforesaid storage medium comprises: various media that can be program code stored such as ROM, RAM, magnetic disc or CD.

It should be noted that at last: above embodiment is only in order to technical scheme of the present invention to be described but not limit it, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that: it still can make amendment or be equal to replacement technical scheme of the present invention, and these modifications or be equal to replacement and also can not make amended technical scheme break away from the spirit and scope of technical solution of the present invention.

Claims (13)

1. the processing method of a frequency pilot sign is characterized in that, comprising:

Add compensated part and obtain transmitted pilot symbol in effective frequency pilot sign, described compensated part is used for offsetting the interference of information symbol to described effective frequency pilot sign on the pilot tone frequency at described effective frequency pilot sign place;

Described transmitted pilot symbol is mapped on the pilot sub-carrier, and the employing double window function identical, the described transmitted pilot symbol that is mapped on the pilot sub-carrier is carried out windowing process, obtain the transmitted pilot symbol after the windowing with described information symbol.

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

Information symbol is mapped on the information subcarrier, and adopts described double window function, the described information symbol that is mapped on the information subcarrier is carried out windowing process, obtain the information symbol after the windowing;

Calculate the frequency domain components of information symbol on described pilot tone frequency after the described windowing;

Obtain described compensated part according to pilot tone transformation matrix that obtains in advance and described frequency domain components.

3. method according to claim 2 is characterized in that, also comprises: according to the sequence number of described double window function and described effective pilot sub-carrier, obtain described pilot tone transformation matrix.

4. method according to claim 1 is characterized in that, also comprises:

Distribute described pilot sub-carrier, described pilot sub-carrier is evenly distributed in the sub carrier group of pilot sub-carrier and information subcarrier composition.

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

Described information symbol is mapped on the information subcarrier, and adopts described double window function, the described information symbol that is mapped on the information subcarrier is carried out windowing process, the computing formula that obtains the information symbol after the windowing is:

$x\left(n\right)=\underset{\underset{2i\&NotElement;{\mathrm{\&phi;}}_P}{i=0}}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i}\exp \left\{j2\mathrm{\&pi;}\frac{2i}{N}n\right\}{w}_1\left(n\right)+\underset{\underset{2i+1\&NotElement;{\mathrm{\&phi;}}_P}{i=0}}{\overset{\frac{N}{2}-1}{\mathrm{\&Sigma;}}}{s}_{2i+1}\exp \left\{j2\mathrm{\&pi;}\frac{2i+1}{N}n\right\}{w}_2\left(n\right)$

Wherein, x (n) is the information symbol after the described windowing, and N is total number of information subcarrier and pilot sub-carrier, w ₁(n) and w ₂(n) be described double window function, s _mFor being mapped to m the information symbol on the subcarrier, m=2i, 2i+1, φ _PSet for the pilot sub-carrier composition;

The computing formula of the frequency domain components of the information symbol after the described windowing of described calculating on described pilot tone frequency is:

I=[I _i] _{M * 1}, and $I_i=\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp \{-j2\mathrm{\&pi;}\frac{l_i}{N}n\},$ i＝0，...，M-1

Wherein, I is described frequency domain components, I _iBe the capable element of the i of I, M is the number of pilot sub-carrier, l _iSequence number for pilot sub-carrier;

The computing formula that pilot tone transformation matrix that described basis obtains in advance and described frequency domain components obtain described compensated part is:

C＝-B ^-1I

Wherein, C is described compensated part, and B is described pilot tone transformation matrix, B ^-1Inverse matrix for described pilot tone transformation matrix.

6. method according to claim 3 is characterized in that, described sequence number according to described double window function and described effective pilot sub-carrier obtains described pilot tone The calculation of transformation matrix formula and is:

B=[B _{I, j}] _{M * M}, and

Wherein, B is described pilot tone transformation matrix, B _IjBe the element of the capable j row of the i of B, N is total number of information subcarrier and pilot sub-carrier, w ₁(n) and w ₂(n) be described double window function, l _iBe the sequence number of effective pilot sub-carrier, M is the number of pilot sub-carrier.

7. method according to claim 2 is characterized in that, also comprises:

Transmitted pilot symbol after information symbol after the described windowing and the described windowing is carried out overlap-add procedure, the signal after obtaining superposeing;

After adding Cyclic Prefix in the signal after stack, obtain base band transmit.

8. the processing unit of a frequency pilot sign is characterized in that, comprising:

Module is added in compensation, is used for adding compensated part at effective frequency pilot sign and obtains transmitted pilot symbol, and described compensated part is used for offsetting the interference of information symbol to described effective frequency pilot sign on the pilot tone frequency at described effective frequency pilot sign place;

Pilot tone mapping windowing module, be used for described transmitted pilot symbol is mapped to pilot sub-carrier, and the employing double window function identical with described information symbol, the described transmitted pilot symbol that is mapped on the pilot sub-carrier is carried out windowing process, obtain the transmitted pilot symbol after the windowing.

9. device according to claim 8 is characterized in that, also comprises:

Information mapping windowing module is used for information symbol is mapped to the information subcarrier, and adopts described double window function, and the described information symbol that is mapped on the information subcarrier is carried out windowing process, obtains the information symbol after the windowing;

Computing module is connected with described information mapping windowing module, is used to calculate the frequency domain components of information symbol on described pilot tone frequency after the described windowing;

The compensation acquisition module is connected with described computing module and described interpolation module, is used for obtaining described compensated part according to the pilot tone transformation matrix and the described frequency domain components that obtain in advance.

10. device according to claim 9 is characterized in that, also comprises:

The matrix acquisition module is connected with described compensation acquisition module, is used for the sequence number according to described double window function and described effective pilot sub-carrier, obtains described pilot tone transformation matrix.

11. device according to claim 8 is characterized in that, also comprises:

Distribution module is connected with described pilot tone mapping windowing module, is used to distribute described pilot sub-carrier, and described pilot sub-carrier is evenly distributed in the sub carrier group of pilot sub-carrier and information subcarrier composition.

12. device according to claim 9 is characterized in that, also comprises:

Laminating module is connected with described information mapping windowing module and described pilot tone mapping windowing module, is used for the transmitted pilot symbol after information symbol after the described windowing and the described windowing is carried out overlap-add procedure the signal after obtaining superposeing;

Prefix is added module, is connected with described laminating module, is used for obtaining base band transmit after the signal after the stack adds Cyclic Prefix.

13. arbitrary according to Claim 8-12 described device is characterized in that described device is a transmitter.

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