CN101848183B - Channel estimation method and device in multiple input multiple output OFDM (Orthogonal Frequency Division Multiplexing) system - Google Patents

Abstract

The invention relates to channel estimation method and device in a multiple input multiple output OFDM (Orthogonal Frequency Division Multiplexing) system. The method comprises the following steps that the system codes the pilot subcarrier data of each transmitting antenna to generate time domain OFDM signals and then transmitting the time domain OFDM signals to a receiving antenna; the system extracts continuous pilot subcarrier block data on each receiving antenna to obtain pilot receiving data on each transmitting antenna; the system obtains time domain channel response values after obtaining the frequency response of all pilot subcarriers on each transmitting antenna by carrying out frequency domain LS (Least Square) channel estimation on the pilot receiving data on each transmitting antenna; the system carries out peak search, peak point diffusion coefficient calculation and offset iteration on the obtained time domain channel response values and carries out FFT (Fast Fourier Transform Algorithm) transformation processing on the outputted valid time domain multipath channel response values to obtain channel frequency response values of each subcarrier on each transmitting antenna to complete channel estimation. By applying the invention, the problem of path diffusion phenomenon when the time domain channel estimation is carried out is solved, and meanwhile, partial noise is restrained, and finally, the channel estimation precision is improved.

Description

Channel estimation methods and device in the multi-input multi-output-orthogonal frequency-division multiplexing system

Technical field

The present invention relates to wireless communication field, relate to especially channel estimation methods and device in a kind of multi-input multi-output-orthogonal frequency-division multiplexing system.

Background technology

For the MIMO-OFDM that has empty subcarrier (multi-input multi-output-orthogonal frequency-division multiplexing) system, present existing channel estimation methods mainly is the frequency domain interpolation method, it is linear interpolation, Gauss interpolation, Wiener filtering interpolation and transform domain interpolation, but existing domain of variation interpolation can only the establishment partial noise, but can't suppress because there is the time domain footpath diffusion effect that causes in empty subcarrier, thereby so that than high s/n ratio the time, " floor effect " appears in channel estimating, time domain directly spreads the mis-behave phenomenon of bringing, so that the accuracy error of channel estimating is large.

This shows that the technical scheme of a kind of new channel estimating of current needs solves the problems referred to above that the frequency domain interpolation method that adopts in the MIMO-OFDM system of the empty subcarrier of current existence exists.

Summary of the invention

Technical problem to be solved by this invention provides channel estimation methods and device in a kind of multi-input multi-output-orthogonal frequency-division multiplexing system, solved the problem of footpath diffusion phenomena when suppressing to carry out the time domain channel estimation, but the while is the establishment partial noise also, thereby has finally improved the precision of channel estimating.

In order to address the above problem, the invention provides channel estimation methods in a kind of multi-input multi-output-orthogonal frequency-division multiplexing system, comprising:

After the Walsh Walsh orthogonal code that system distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the orthogonal frequency division multiplex OFDM signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out inverse fast fourier transformed IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to reception antenna;

System carries out fast fourier transform FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna, the Walsh orthogonal code of the every transmitting antenna that is complementary with transmitting terminal multiplies each other and is cumulative, obtains the pilot reception data on the every transmitting antenna;

System is by carrying out frequency domain LS channel estimating to the pilot reception data on the every transmitting antenna, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, obtain the time domain channel response value according to the transform domain mode; Iteration is calculated and offset to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, and the effective time domain multipath channel response of output obtains the channel frequency response value of each data subcarrier on each transmitting antenna, finishes channel estimating.

Further, said method also can comprise, after the Walsh orthogonal code that described system distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the ofdm signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out the IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to reception antenna, specifically is divided into following steps:

The Walsh orthogonal code that the continuous pilot block of sub-carriers data on the transmitting antenna and corresponding each transmitting antenna distribute is encoded by described system, data on the data subcarrier in non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece are finished by constellation mapping by the bit stream on independent each transmitting antenna, and the data subcarrier after the pilot sub-carrier piece behind the coding and constellation mapping are finished forms the ofdm signal of frequency domain;

After described system carries out the IFFT conversion to the ofdm signal of every the above frequency domain of transmitting antenna, carry out after parallel-serial conversion adds Cyclic Prefix simultaneously, generate the ofdm signal of time domain, be transferred to reception antenna by wireless multiple-input, multiple-output mimo channel.

Further, said method also can comprise, described system carries out the FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extracts the continuous pilot block of sub-carriers data on the every reception antenna, specifically refers to:

After Cyclic Prefix and string and conversion are removed to the time domain OFDM signal that receives on the every reception antenna by described system, by the FFT conversion process, generate the ofdm signal of frequency domain on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna.

Further, said method also can comprise, described system is by carrying out frequency domain LS channel estimating to the pilot reception data on the every transmitting antenna, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, obtain the time domain channel response value according to the transform domain mode, specifically refer to:

Described system is by carrying out frequency domain LS channel estimating to the pilot reception data on the every transmitting antenna, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, insert several zero, and then carry out again the IFFT conversion, obtain the time domain channel response value, wherein, inserting zero number is to be counted and the insertion interval of pilot sub-carrier is determined by pilot sub-carrier number, FFT.

Further, said method also can comprise, iteration is calculated and offset in described system to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, the effective time domain multipath channel response of output, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, finish channel estimating, specifically be divided into following steps:

The time domain channel response value of described system to obtaining, by carrying out after peak value searching determines peak value and correspondence position thereof, calculate the diffusion coefficient of this position sampling point on all time domain sampling points, and it is offset from the initial time domain channel response value that obtains, carry out again the peak value searching iteration of a new round, until dropping to, this peak value that searches out sets below the thresholding, stop iteration, effective time domain multipath channel response to output is carried out the FFT conversion process, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, finish channel estimating.

The present invention also provides channel estimating apparatus in a kind of multi-input multi-output-orthogonal frequency-division multiplexing system, comprises the antenna coding module, and antenna decoder module and footpath diffusion suppress module, wherein,

Described antenna coding module, after being used for the Walsh Walsh orthogonal code that pilot sub-carrier data and the respective transmit antenna of each transmitting antenna are distributed encoded, with the orthogonal frequency division multiplex OFDM signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out inverse fast fourier transformed IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to described antenna decoder module;

Described antenna decoder module, be used for time domain OFDM signal on the every reception antenna that receives is carried out fast fourier transform FFT conversion process, extract the continuous pilot block of sub-carriers data on the every reception antenna, the Walsh orthogonal code of the every transmitting antenna that is complementary with transmitting terminal multiplies each other and is cumulative, obtain the pilot reception data on the every transmitting antenna, and send to described footpath diffusion inhibition module;

The diffusion of described footpath suppresses module, is used for by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, obtain the time domain channel response value according to the transform domain mode; Iteration is calculated and offset to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, and the effective time domain multipath channel response of output obtains the channel frequency response value of each data subcarrier on each transmitting antenna, finishes channel estimating.

Further, said apparatus also can comprise, after the Walsh orthogonal code that described antenna coding module distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the ofdm signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out the IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, generate the ofdm signal of time domain, specifically refer to:

Described antenna coding module is encoded the Walsh orthogonal code that the continuous pilot block of sub-carriers data on the transmitting antenna and corresponding each transmitting antenna distribute, data on the data subcarrier in non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece are finished by constellation mapping by the bit stream on independent each transmitting antenna, and the data subcarrier after the pilot sub-carrier piece behind the coding and constellation mapping are finished forms the ofdm signal of frequency domain; After the ofdm signal of every the above frequency domain of transmitting antenna carried out the IFFT conversion, carry out after parallel-serial conversion adds Cyclic Prefix simultaneously, generate the ofdm signal of time domain.

Further, said apparatus also can comprise, described antenna decoder module carries out the FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extracts the continuous pilot block of sub-carriers data on the every reception antenna, specifically refers to:

After described antenna decoder module is removed Cyclic Prefix and string and conversion to the time domain OFDM signal that receives on the every reception antenna, by the FFT conversion process, generate the ofdm signal of frequency domain on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna.

Further, said apparatus also can comprise, the diffusion of described footpath suppresses module by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, obtain the time domain channel response value according to the transform domain mode, specifically refer to:

The diffusion of described footpath suppresses module by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, insert several zero, and then carry out again the IFFT conversion, obtain the time domain channel response value, wherein, inserting zero number is to be counted and the insertion interval of pilot sub-carrier is determined by pilot sub-carrier number, FFT.

Further, said apparatus also can comprise, the diffusion of described footpath suppresses module iteration is calculated and offset to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, the effective time domain multipath channel response of output, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, specifically refer to:

The diffusion of described footpath suppresses the time domain channel response value of module to obtaining, by carrying out after peak value searching determines peak value and correspondence position thereof, calculate the diffusion coefficient of this position sampling point on all time domain sampling points, and it is offset from the initial time domain channel response value that obtains, carry out again the peak value searching iteration of a new round, until dropping to, this peak value that searches out sets below the thresholding, stop iteration, effective time domain multipath channel response to output is carried out the FFT conversion process, obtains the channel frequency response value of each data subcarrier on each transmitting antenna.

Compared with prior art, use the present invention, the footpath diffusion effect that the MIMO-OFDM system that has empty subcarrier occurs when the channel estimating has been carried out certain inhibition, weakened to a great extent " floor effect ", also suppressed simultaneously partial noise, effectively improved the precision of channel estimating, and its complexity is lower, realizes relatively simple.

Description of drawings

Fig. 1 is the flow chart of channel estimation methods in the multi-input multi-output-orthogonal frequency-division multiplexing system of the present invention;

Fig. 2 is the schematic diagram of channel estimating in the input multi-output-orthogonal frequency-division multiplexing system in the example;

Fig. 3 is structural representation in the antenna coding module in the example;

Fig. 4 is structural representation in the antenna decoder module in the example;

Fig. 5 is that the diffusion of example central diameter suppresses structural representation in the module.

Embodiment

The invention will be further described below in conjunction with the drawings and specific embodiments.

Implementation condition of the present invention is for the MIMO-OFDM system that has empty subcarrier.(wherein, mimo channel condition: piece decline (namely the same sub-carrier upper frequency channel response in a plurality of OFDM symbols is constant)+white noise).Enforcement of the present invention can realize by memory and a plurality of calculator (such as multiplier, adder etc.).

The below is with N _T* N _RThe MIMO-OFDM system be example, (wherein, N _TBe transmitting antenna, N _RBe reception antenna) channel estimation methods in the multi-input multi-output-orthogonal frequency-division multiplexing system of the present invention, may further comprise the steps:

Step 110, system are encoded Walsh (Walsh) orthogonal code that the continuous pilot block of sub-carriers data on the transmitting antenna and corresponding each transmitting antenna distribute, data on the data subcarrier in non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece are finished by constellation mapping by the bit stream on independent each transmitting antenna, and the data subcarrier after the pilot sub-carrier piece behind the coding and constellation mapping are finished forms the ofdm signal of frequency domain;

System is with N _T(wherein, pilot block length is N to continuous pilot block of sub-carriers on the root transmitting antenna _C, the data on each pilot sub-carrier are entirely for " 1 ") and (code length also is N for the Walsh orthogonal code of distributing with corresponding each transmitting antenna _C) multiply each other (namely encoding), finished by constellation mapping by the bit stream on independent each transmitting antenna for the data on the data subcarrier in the non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece.

Step 120, system carry out N to the ofdm signal of every the above frequency domain of transmitting antenna _FFTAfter the IFFT conversion of point, carry out parallel-serial conversion (P/S) and add simultaneously the rear ofdm signal that generates time domain of Cyclic Prefix (CP), be transferred to reception antenna by Technique of Wireless MIMO Channel;

System is to carrying out N on the every transmitting antenna _FFTIFFT (inverse fast fourier transformed) conversion of point again through parallel-serial conversion (P/S) and become the ofdm signal of time domain after adding Cyclic Prefix (CP), is transferred to receiving terminal by wireless fading channel at last.

Step 130, system pass through N after the time domain OFDM signal that receives on the every reception antenna is removed Cyclic Prefix and string and conversion (S/P) _FFTFFT (fast fourier transform) conversion process of point generates the ofdm signal of frequency domain on the every reception antenna, extracts the continuous pilot block of sub-carriers data on the every reception antenna;

Cyclic Prefix (CP), string and conversion (S/P) are at first removed to the receive data on the every reception antenna by system, pass through N again _FFTThe FFT conversion process of point is extracted the continuous pilot block of sub-carriers data on the every reception antenna at last.

The Walsh orthogonal code of the every transmitting antenna that step 140, system will be complementary with transmitting terminal, and the pilot sub-carrier blocks of data on the every reception antenna after extracting multiplies each other and cumulative, obtains the pilot reception data on the every transmitting antenna;

The Walsh orthogonal code of the every transmitting antenna that system will be complementary with transmitting terminal, pilot sub-carrier blocks of data on the last every reception antenna that extracts in itself and the step 130 multiplied each other and cumulative, thereby obtain the pilot reception data on the every transmitting antenna, namely removed simultaneously the interference that other transmitting antenna brings.

Step 150, system be by carrying out frequency domain LS channel estimating to the pilot reception data on the every transmitting antenna, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, according to transform domain mode (namely insert several zero), and then carry out again M _FFTThe IFFT conversion of point obtains M _FFTPoint time domain channel response value;

System can at first obtain the frequency response of all pilot sub-carriers on the every transmitting antenna by frequency domain LS channel estimation methods, and inserting several, zero (number is by pilot sub-carrier number N _p, the FFT points N _FFTAnd the insertion interval delta N of pilot sub-carrier _fDetermine), and then carry out again M _FFTThe IFFT conversion of point.

Step 160, the M of system to obtaining _FFTPoint time domain channel response value is at first carried out peak value searching, determine peak value and correspondence position thereof, and then calculate the diffusion coefficient of this position sampling point on all time domain sampling points, and with it from the initial M that obtains _FFTOffset in the some time domain channel response value, carry out again the peak value searching iteration of a new round, set below the thresholding until this peak value that searches out drops to, stop iteration, export effective M _FFTPoint time domain multipath channel response all is set to 0 with all the other sampling points;

Step 170, the M of system to obtaining _FFTPoint time domain multipath channel response is carried out N _FFTPut the FFT conversion process, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, finish channel estimating.

The invention will be further described below in conjunction with instantiation.

Symbolic interpretation is as follows among Fig. 2:

N _t(n _t=1,2 ... N _T) n OFDM symbol block of frequency domain data vector being formed by pilot sub-carrier and data subcarrier on the root transmitting antenna;

N _t(n _t=1,2 ... N _T) formed by pilot sub-carrier and data subcarrier on the root transmitting antenna

N OFDM symbol time-domain data blocks vector;

H (n): the time domain impulse response of Technique of Wireless MIMO Channel is expressed as with its discrete tapped delay line model usually

N _r(n _r=1,2 ... N _R) time domain on the root reception antenna receives signal;

N _r(n _r=1,2 ... N _R) frequency domain that gets on behind the Cyclic Prefix (CP) of root reception antenna receives signal;

N _tThe root transmitting antenna is to n _rTime domain channel impulse response between the root reception antenna;

N _tThe root transmitting antenna is to n _rThe frequency domain response of channel between the root reception antenna;

A: the antenna coding module, finish the orthogonal coding of the upper pilot sub-carrier data of each transmitting antenna;

B: the antenna decoder module, namely finish the contrary of modules A and process, mainly formed by multiplier and accumulator;

C: footpath diffusion suppresses module, finishes that time domain directly spreads, the inhibition of noise.

The process of the signal stream of describing among Fig. 2 is:

(1) modules A is exported the pilot sub-carrier data on each transmitting antenna;

(2) generation of time domain transmitted signal on each transmitting antenna:

$x_{n_t}\left(n\right)=T_{\mathrm{CP}}{F}_{N_{\mathrm{FFT}}}^H{X}_{n_t}\left(n\right),(n_t=\mathrm{1,2},\·\·\·N_T)$

Wherein, T _CPFor Cyclic Prefix adds matrix,

Be normalized Fourier transform matrix.

(3) above-mentioned transmitted signal is through after the Technique of Wireless MIMO Channel, in the reception form of receiving terminal is:

$y_{n_r}\left(n\right)=\underset{n_t=1}{\overset{N_t}{\mathrm{\Σ}}}{h}_{n_r,n_t}^{\mathrm{cir}}\left(n\right)x_{n_t}\left(n\right)+{\mathrm{\η}}_{n_r}\left(n\right)$

Wherein, Be by

The circular matrix that produces, Be Gaussian noise.

(4) further the receive data on the above-mentioned every reception antenna being carried out the FFT change process can obtain its frequency domain and receive vector and be:

$Y_{n_r}\left(n\right)=F_{N_{\mathrm{FFT}}}{y}_{n_r}\left(n\right)$

$=\underset{n_t=1}{\overset{N_t}{\mathrm{\Σ}}}\mathrm{diag}\left\{X_{n_t}\left(n\right)\right\}{\tilde{F}}_{N_{\mathrm{FFT}}}{h}_{n_r,n_t}\left(n\right)+{\mathrm{\Ξ}}_{n_r}\left(n\right)$

(5) module B carries out the quadrature separation to pilot sub-carrier data on each antenna that extracts;

(6) module C is output as effective time domain multipath channel response, and passes through N _FFTPoint FFT conversion obtains the channel frequency response of each data subcarrier on final each transmitting antenna:

${\hat{H}}_{n_r,n_t}\left(k\right)=\mathrm{FFT}\left[{\hat{h}}_{n_r,n_t}\left(n\right)\right].$

Internal structure as shown in Figure 3 in the modules A.

Symbolic interpretation is as follows among Fig. 3:

N _t(n _t=1,2 ... N _T) the root transmitting antenna Walsh orthogonal code of distributing, and have Wherein, each transmitting antenna distributes different Walsh orthogonal codes to have following orthogonal property, namely

N _t(n _t=1,2 ... N _T) encoded on the root transmitting antenna after k _pThe time-domain data blocks of individual pilot sub-carrier, and have

The signal of describing among Fig. 3 flows through journey: Namely

Internal structure as shown in Figure 4 among the module B.

Symbolic interpretation is as follows among Fig. 4:

N _r(n _r=1,2 ... N _R) root receives the k that extracts in the signal _pThe continuous pilot piece vector at individual pilot sub-carrier place, and have

Perhaps

$Y_{n_r}\left(k_p\right)=[\underset{n_t^{\′}=1}{\overset{N_t}{\mathrm{\Σ}}}{H}_{n_r,n_t^{\′}}\left(k_p\right)C_{n_t^{\′}}\left(0\right)+{\mathrm{\Ξ}}_{n_r}\left(0\right),\·\·\·\underset{n_t^{\′}=1}{\overset{N_t}{\mathrm{\Σ}}}{H}_{n_r,n_t^{\′}}\left(k_p\right)C_{n_t^{\′}}(N_C-1)+{\mathrm{\Ξ}}_{n_r}(N_C-1)];$

N _t(n _t=1,2 ... N _T) the root transmitting antenna is to n _r(n _r=1,2 ... N _R) k between the root reception antenna _p(p=0,1 ... N _P-1) receive data at individual pilot sub-carrier place.

The signal of describing among Fig. 4 flows through journey:

Internal structure as shown in Figure 5 among the module C.

Symbolic interpretation is as follows among Fig. 5:

N _t(n _t=1,2 ... N _T) the root transmitting antenna is to n _r(n _r=1,2 ... N _R) time domain channel impulse response initial between the root reception antenna estimates;

n _Max ^(m): the peak point position after the m time iteration,

The diffusion coefficient of peak point position on all sampling points after the m time iteration;

After M iteration offset, n _t(n _t=1,2 ... N _T) the root transmitting antenna is to n _r(n _r=1,2 ... N _R) the time domain channel impulse response is estimated between the root reception antenna.

The signal of describing among Fig. 5 flows through journey:

(1) upgrade input signal,

(2) carry out peak value searching,

(3) Predict Diffusion Coefficient,

$g_{n_r,n_t}(n_{\max },n)=e^{\frac{-j2\mathrm{\π}{k}_0{n}_{\max }}{N_{\mathrm{FFT}}}}{e}^{\frac{-\mathrm{j\π}(N_p-1)(n_{\max }-n)}{M_{\mathrm{FFT}}}\frac{\sin \frac{\mathrm{\π}(n_{\max }-n)N_p}{M_{\mathrm{FFT}}}}{\sin \frac{\mathrm{\π}(n_{\max }-n)}{M_{\mathrm{FFT}}}}.}$

Channel estimating apparatus in a kind of multi-input multi-output-orthogonal frequency-division multiplexing system of the present invention comprises the antenna coding module, and antenna decoder module and footpath diffusion suppress module, wherein,

Described antenna coding module, after being used for the Walsh Walsh orthogonal code that pilot sub-carrier data and the respective transmit antenna of each transmitting antenna are distributed encoded, with the orthogonal frequency division multiplex OFDM signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out inverse fast fourier transformed IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to described antenna decoder module;

Described antenna decoder module, be used for time domain OFDM signal on the every reception antenna that receives is carried out fast fourier transform FFT conversion process, extract the continuous pilot block of sub-carriers data on the every reception antenna, the Walsh orthogonal code of the every transmitting antenna that is complementary with transmitting terminal multiplies each other and is cumulative, obtain the pilot reception data on the every transmitting antenna, and send to described footpath diffusion inhibition module;

The diffusion of described footpath suppresses module, is used for by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, obtain the time domain channel response value according to the transform domain mode; Iteration is calculated and offset to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, and the effective time domain multipath channel response of output obtains the channel frequency response value of each data subcarrier on each transmitting antenna, finishes channel estimating.

After the Walsh orthogonal code that described antenna coding module distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the ofdm signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out the IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, generate the ofdm signal of time domain, specifically refer to:

Described antenna coding module is encoded the Walsh orthogonal code that the continuous pilot block of sub-carriers data on the transmitting antenna and corresponding each transmitting antenna distribute, data on the data subcarrier in non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece are finished by constellation mapping by the bit stream on independent each transmitting antenna, and the data subcarrier after the pilot sub-carrier piece behind the coding and constellation mapping are finished forms the ofdm signal of frequency domain; After the ofdm signal of every the above frequency domain of transmitting antenna carried out the IFFT conversion, carry out after parallel-serial conversion adds Cyclic Prefix simultaneously, generate the ofdm signal of time domain.

Described antenna decoder module carries out the FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extracts the continuous pilot block of sub-carriers data on the every reception antenna, specifically refers to:

After described antenna decoder module is removed Cyclic Prefix and string and conversion to the time domain OFDM signal that receives on the every reception antenna, by the FFT conversion process, generate the ofdm signal of frequency domain on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna.

The diffusion of described footpath suppresses module by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, obtain the time domain channel response value according to the transform domain mode, specifically refer to:

The diffusion of described footpath suppresses module by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, insert several zero, and then carry out again the IFFT conversion, obtain the time domain channel response value, wherein, inserting zero number is to be counted and the insertion interval of pilot sub-carrier is determined by pilot sub-carrier number, FFT.

The diffusion of described footpath suppresses module iteration is calculated and offset to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, the effective time domain multipath channel response of output, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, specifically refer to:

The diffusion of described footpath suppresses the time domain channel response value of module to obtaining, by carrying out after peak value searching determines peak value and correspondence position thereof, calculate the diffusion coefficient of this position sampling point on all time domain sampling points, and it is offset from the initial time domain channel response value that obtains, carry out again the peak value searching iteration of a new round, until dropping to, this peak value that searches out sets below the thresholding, stop iteration, effective time domain multipath channel response to output is carried out the FFT conversion process, obtains the channel frequency response value of each data subcarrier on each transmitting antenna.

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

Claims (6)

1. channel estimation methods in the multi-input multi-output-orthogonal frequency-division multiplexing system is characterized in that, comprising:

After the Walsh Walsh orthogonal code that system distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the orthogonal frequency division multiplex OFDM signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out inverse fast fourier transformed IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to reception antenna;

System carries out fast fourier transform FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna, the Walsh orthogonal code of the every transmitting antenna that is complementary with transmitting terminal multiplies each other and is cumulative, obtains the pilot reception data on the every transmitting antenna;

System is by carrying out frequency domain LS channel estimating to the pilot reception data on the every transmitting antenna, obtain the frequency response of all pilot sub-carriers on the every transmitting antenna after, obtain the time domain channel response value according to the transform domain mode; Wherein said system is by carrying out frequency domain LS channel estimating to the pilot reception data on the every transmitting antenna, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, insert several zero, and then carry out again the IFFT conversion, obtain the time domain channel response value, wherein, inserting zero number is to be counted and the insertion interval of pilot sub-carrier is determined by pilot sub-carrier number, FFT;

Iteration is calculated and offset in system to the time domain channel response value that obtains by peak value searching, peak point diffusion coefficient, the effective time domain multipath channel response of output, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, finish channel estimating; The time domain channel response value of wherein said system to obtaining, by carrying out after peak value searching determines peak value and correspondence position thereof, calculate the diffusion coefficient of this position sampling point on all time domain sampling points, and it is offset from the initial time domain channel response value that obtains, carry out again the peak value searching iteration of a new round, until dropping to, this peak value that searches out sets below the thresholding, stop iteration, effective time domain multipath channel response to output is carried out the FFT conversion process, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, finish channel estimating.

2. channel estimation methods as claimed in claim 1 is characterized in that,

After the Walsh orthogonal code that described system distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the ofdm signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out the IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to reception antenna, specifically is divided into following steps:

The Walsh orthogonal code that the continuous pilot block of sub-carriers data on the transmitting antenna and corresponding each transmitting antenna distribute is encoded by described system, data on the data subcarrier in non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece are finished by constellation mapping by the bit stream on independent each transmitting antenna, and the data subcarrier after the pilot sub-carrier piece behind the coding and constellation mapping are finished forms the ofdm signal of frequency domain;

After described system carries out the IFFT conversion to the ofdm signal of every the above frequency domain of transmitting antenna, carry out after parallel-serial conversion adds Cyclic Prefix simultaneously, generate the ofdm signal of time domain, be transferred to reception antenna by wireless multiple-input, multiple-output mimo channel.

3. channel estimation methods as claimed in claim 1 or 2 is characterized in that,

Described system carries out the FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extracts the continuous pilot block of sub-carriers data on the every reception antenna, specifically refers to:

After Cyclic Prefix and string and conversion are removed to the time domain OFDM signal that receives on the every reception antenna by described system, by the FFT conversion process, generate the ofdm signal of frequency domain on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna.

4. channel estimating apparatus in the multi-input multi-output-orthogonal frequency-division multiplexing system is characterized in that,

Comprise the antenna coding module, antenna decoder module and footpath diffusion suppress module, wherein,

Described antenna coding module, after being used for the Walsh Walsh orthogonal code that pilot sub-carrier data and the respective transmit antenna of each transmitting antenna are distributed encoded, with the orthogonal frequency division multiplex OFDM signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out inverse fast fourier transformed IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, the ofdm signal that generates time domain is transferred to described antenna decoder module;

Described antenna decoder module, be used for time domain OFDM signal on the every reception antenna that receives is carried out fast fourier transform FFT conversion process, extract the continuous pilot block of sub-carriers data on the every reception antenna, the Walsh orthogonal code of the every transmitting antenna that is complementary with transmitting terminal multiplies each other and is cumulative, obtain the pilot reception data on the every transmitting antenna, and send to described footpath diffusion inhibition module;

The diffusion of described footpath suppresses module, be used for by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, obtain the time domain channel response value according to the transform domain mode, the diffusion of wherein said footpath suppresses module by the pilot reception data on the every transmitting antenna are carried out frequency domain LS channel estimating, after obtaining the frequency response of all pilot sub-carriers on the every transmitting antenna, insert several zero, and then carry out again the IFFT conversion, obtain the time domain channel response value, wherein, inserting zero number is by the pilot sub-carrier number, FFT counts and the insertion interval of pilot sub-carrier is determined; The time domain channel response value that obtains is passed through peak value searching, the peak point diffusion coefficient calculates and offsets iteration, the effective time domain multipath channel response of output, obtain the channel frequency response value of each data subcarrier on each transmitting antenna, finish channel estimating, the diffusion of wherein said footpath suppresses the time domain channel response value of module to obtaining, by carrying out after peak value searching determines peak value and correspondence position thereof, calculate the diffusion coefficient of this position sampling point on all time domain sampling points, and it is offset from the initial time domain channel response value that obtains, carry out again the peak value searching iteration of a new round, until dropping to, this peak value that searches out sets below the thresholding, stop iteration, effective time domain multipath channel response to output is carried out the FFT conversion process, obtains the channel frequency response value of each data subcarrier on each transmitting antenna.

5. channel estimating apparatus as claimed in claim 4 is characterized in that,

After the Walsh orthogonal code that described antenna coding module distributes pilot sub-carrier data and the respective transmit antenna of each transmitting antenna is encoded, with the ofdm signal of the pilot sub-carrier piece behind the coding and data subcarrier composition frequency domain; After carrying out the IFFT conversion by the ofdm signal to every the above frequency domain of transmitting antenna, generate the ofdm signal of time domain, specifically refer to:

Described antenna coding module is encoded the Walsh orthogonal code that the continuous pilot block of sub-carriers data on the transmitting antenna and corresponding each transmitting antenna distribute, data on the data subcarrier in non-pilot sub-carrier in the continuous pilot piece and the non-pilot data piece are finished by constellation mapping by the bit stream on independent each transmitting antenna, and the data subcarrier after the pilot sub-carrier piece behind the coding and constellation mapping are finished forms the ofdm signal of frequency domain; After the ofdm signal of every the above frequency domain of transmitting antenna carried out the IFFT conversion, carry out after parallel-serial conversion adds Cyclic Prefix simultaneously, generate the ofdm signal of time domain.

6. such as claim 4 or 5 described channel estimating apparatus, it is characterized in that,

Described antenna decoder module carries out the FFT conversion process to the time domain OFDM signal that receives on the every reception antenna, extracts the continuous pilot block of sub-carriers data on the every reception antenna, specifically refers to:

After described antenna decoder module is removed Cyclic Prefix and string and conversion to the time domain OFDM signal that receives on the every reception antenna, by the FFT conversion process, generate the ofdm signal of frequency domain on the every reception antenna, extract the continuous pilot block of sub-carriers data on the every reception antenna.

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