CN100589340C - Bell idles transmitting diversity channel receiving demodulation method - Google Patents

Abstract

A method for receiving-demodulating idle code emission subset includes obtaining channel impulse response of subset antenna by carrying out channel estimation after data and train sequence is separated, carrying out convolution of channel impulse response on antenna separately with each own spread spectrum code to form transmission matrix, demodulating received data and unitedly solving out emission data of base station.

Description

Bell idles transmitting diversity channel receiving demodulation method

Technical field:

The present invention relates to the bell idles transmitting diversity channel receiving demodulation in the mobile communication system, relate in particular to a kind of code division multiple access (CDMA) system transmission diversity technology beacon channel signal receiving demodulation that is used for.

Background technology:

Be extensive use of the influence that diversity technique reduces multipath fading in wireless mobile communications, diversity technique can be divided into time diversity, frequency diversity and space diversity three classes.Compare with frequency diversity with time diversity, space diversity reception to communicate improves the reliability of transmission under the situation that does not increase transmitting power or sacrifice communication bandwidth, very attractive, becomes current research focus.

Space diversity is to utilize the antenna of separated by spaces to obtain transmitting and receiving of separate fading signal, improve system signal noise ratio, improve data rate, increase wireless system capacity and coverage rate, if adopt many antennas at transmitting terminal then be called transmit diversity, if adopt many antennas at receiving terminal then become receive diversity.In present cell mobile communication systems, the uplink direction base station is used many reception antennas to merge to received signal or is selected at receiving terminal, be implemented in the influence that has reduced channel fading when suppressing interchannel interference, do the quality and the excursion that can improve up link like this.But for down link, on less portable travelling carriage, be subjected to size restrictions to be not easy to install antenna more than two, so travelling carriage is difficult to use receive diversity.A kind of practicable method adopts transmit diversity exactly.Compare with receive diversity, not only have similar diversity gain, and can also realize that for the base station same signal makes a plurality of travelling carriages obtain the advantage of transmitting gains with the transmit diversity of exponent number.Like this, when improving systematic function, can also reduce the travelling carriage cost and keep relative simple.

When UTRAN (universal mobile telecommunications system land radio access web) side adopt bell idles transmitting diversity (SpaceCode Transmit Diversity, during SCTD) mode, the UE demodulate reception data.The application of SCTD is by high-rise appointment, if SCTD activates in sub-district, then SCTD is applied to any beacon channel.

As depicted in figs. 1 and 2, in method for emitting diversity code, the emission data of diversity antenna are the same, and each symbol is gone out by two antenna transmission through different spreading code spread spectrums again.

The SCTD radiation pattern: the transmit diversity of beacon channel is adopting under the bell idles transmitting diversity pattern, and data sequence is through c ₁₆ ^(k=1)And c ₁₆ ^(k=2)Spread spectrum and scrambling.Through c ₁₆ ^{{ k=1}}The just emission on antenna 1 of sequence behind the spread spectrum is through c ₁₆ ^{{ k=2}}The just emission on antenna 2 of sequence behind the spread spectrum, the transmitting power on every antenna equates.2 antennas are selected the different midamble shift of same basic Midamle sign indicating number (training sequence) for use, and antenna 1 is selected Midamle 1 for use, and antenna 2 is selected Midamle 2 for use.c ₁₆ ^(k=1)Subscript represents that spreading factor is 16 k spreading code, subscript k=1.

The SCTD down transmission diversity, chnnel coding, rate-matched, interweave consistent down with bit-sign map and non-diversity mode.For bell idles transmitting diversity, each symbol is gone out by two antenna transmission through different spreading code spread spectrums.Under diversity mode, the configuration spreading code is c ₁₆ ^(k=1)Beacon channel by c ₁₆ ^(k=1)And c ₁₆ ^(k=3)Spread spectrum, and through scrambling; And the configuration spreading code is c ₁₆ ^(k=2)Beacon channel by c ₁₆ ^(k=2)And c ₁₆ ^(k=4)Spread spectrum, and through scrambling.Then through c ₁₆ ^(k=3)And c ₁₆ ^(k=4)Sequence behind the spread spectrum is launched through diversity antenna.The transmitting power of every antenna equates.

In present prior art, do not see receiving demodulation method as yet to bell idles transmitting diversity.

Summary of the invention:

The technical problem to be solved in the present invention is, (the SpaceCode Transmit Diversity of bell idles transmitting diversity in a kind of cdma system is proposed, SCTD) reception data demodulation method, this method can make at beacon channel and adopt under the situation of transmit diversity techniques, the UE end still can use simple algorithm to finish demodulating data, be easy to software and hardware and realize, reduce intersymbol interference and multiple access simultaneously and disturb, and can improve link performance.

Technical scheme of the present invention is: at first, data with after training sequence separates, are carried out channel estimating, and the channel impulse response that obtains diversity antenna is (under the situation of two antennas, be meant the impulse response of first, second antenna transmission signal, i.e. fading characteristic); Then, the channel impulse response of antenna is carried out convolution with separately spreading code respectively, make up transmission matrix; At last, to receiving data demodulates, unite the emission data that solve the base station.

Particularly, can be described as:

1) training sequence that receives is expressed as

e＝Gh+n

Wherein, the G matrix is the ring shift right matrix that is made of a basic Midamble sign indicating number, and h is user's a channel impulse response, and n is a white Gaussian noise;

2) finish the maximal possibility estimation of channel impulse response h

$\hat{h}=G^{-1}e;$

3) be that length intercepts in order with W

Channel estimation value obtains the channel impulse response of diversity antenna respectively

With

4) earlier with diversity antenna spread spectrum scrambler and channel impulse response separately

With

Generate block diagonal matrix A, the piece V that constitutes A is made up of the vector that spread spectrum scrambler multiplexed sequence and channel impulse response convolution form: first row are to use the convolution vector of the impulse response of first Midamble sign indicating number skew correspondence on the spread spectrum scrambler multiplexed sequence of the 1st spreading code and first antenna, secondary series is to use the convolution vector of the corresponding impulse response of first Midamble sign indicating number skew on the spread spectrum scrambler multiplexed sequence of the 3rd spreading code and second antenna, the 3rd row are to use on the spread spectrum scrambler multiplexed sequence of the 2nd spreading code and first antenna convolution vector of the corresponding impulse response of second Midamble sign indicating number skew, and the 4th row are to use on the spread spectrum scrambler multiplexed sequence of the 4th spreading code and second antenna convolution vector of the corresponding impulse response of second Midamble sign indicating number skew; Described spread spectrum scrambler multiplexed sequence is meant, a scrambler is in the cycle, the sequence that spreading code and scrambler dot product constitute;

5) then, the transmission matrix diversity that will receive the transmit diversity user merges, and is about to the impulse response column corresponding element addition on the corresponding different antennae of identical Midamble sign indicating number skew institute among the V, generation

By

Reconstruct new diversity transmission matrix

6) to receiving data demodulates, unite the emission data that solve the base station by following formula:

$\hat{d}={({\tilde{A}}^H\·\tilde{A})}^{-1}{\tilde{A}}^{H}e$

Perhaps $\hat{d}={({\tilde{A}}^H{R_n}^{-1}\tilde{A}+{R_d}^{-1})}^{-1}{\tilde{A}}^H{R_n}^{-1}e$

Wherein, R _nBe the spatial noise correlation matrix, R _dBe to send the data correlation matrix, H represents matrix is asked conjugate transpose.

Adopt the reception data demodulation method of bell idles transmitting diversity of the present invention, the UE end still can use simple algorithm to finish demodulating data, being easy to software and hardware realizes, when the influence of adopting transmit diversity techniques to reduce multipath fading brings gain, also reduce intersymbol interference and multiple access and disturb, and can improve link performance.

Description of drawings:

Fig. 1 is a SCTD transmit diversity structure chart;

Fig. 2 is the SCTD transmit diversity structure chart of LCR TDD (low spreading rate time division duplex) system P-CCPCH (Primary Common Control Physical Channel);

Fig. 3 is a flow chart of the present invention.

Embodiment:

Fig. 3 is a flow chart of the present invention, and its main contents are partly introduced at summary of the invention.In conjunction with the characteristics of transmit diversity, the process to receiving demodulation is described in detail below.

At first, data with after training sequence separates, are carried out channel estimating.

The training sequence that receives can be expressed as

e＝Gh+n

Wherein, the G matrix is the ring shift right matrix that is made of a basic Midamble sign indicating number, and h is user's a channel impulse response, and n is a white Gaussian noise.

Finish the maximal possibility estimation of channel impulse response h with following formula

Promptly

$\hat{h}{\left(G^{*T}G\right)}^{-1}{G}^{*T}e$

Because the G matrix is the ring shift right matrix, has

$\hat{h}=G^{-1}e$

Therefore, utilize the cyclic shift characteristic of matrix, above-mentioned channel estimating can adopt the FFT/IFFT fast method to realize, thereby has improved arithmetic speed significantly.

As shown in the formula:

$\hat{h}=\mathrm{ifft}(\mathrm{fft}\left(e\right)/\mathrm{fft}\left(m\right))$

For diversity antenna, the channel estimating of antenna 1 and antenna 2 is respectively $\hat{h}=G^{-1}e$ Be the estimated value of channel impulse response, utilize the FFT/IFFT fast method to realize, like this, obtain the channel impulse response of two antennas respectively.

Right with noise gate

Carrying out channel post-processing, is that window is long again with W, intercepts the channel estimation value of W length in order, obtains the channel impulse response of diversity antenna

With

Then, it is carried out convolution with separately spreading code respectively, includes the matrix of joint-detection in:

User data arrives receiver by after the spectrum-spreading and scrambling by air traffic channel, and received signal e can be expressed as:

e＝Ad+n

D is the column vector that all symbols of base station are formed, diversity antenna separately the spread spectrum scrambler and the channel impulse response of reprocessing

Generation system transmission matrix A.

A is the piece diagonal matrix, and the piece V that constitutes A is made up of the vector that spread spectrum scrambler multiplexed sequence and channel impulse response convolution form, and according to the radiation pattern of Fig. 2 as can be known, first is listed as v ₁Be to use the convolution vector of the corresponding impulse response of first Midamble sign indicating number skew on the spread spectrum scrambler multiplexed sequence of the 1st spreading code and first antenna, secondary series v ₂Be to use the convolution vector of the corresponding impulse response of first Midamble sign indicating number skew on the spread spectrum scrambler multiplexed sequence of the 3rd spreading code and second antenna, the 3rd row v ₃Be to use on the spread spectrum scrambler multiplexed sequence of the 2nd spreading code and first antenna convolution vector of the corresponding impulse response of second Midamble sign indicating number skew, the 4th row v ₄Be to use on the spread spectrum scrambler multiplexed sequence of the 4th spreading code and second antenna convolution vector of the corresponding impulse response of second Midamble sign indicating number skew.Similarly can be expressed as matrix form

$v_1=c{s}_{16}^{(k=1)}\&CircleTimes;h_{\mathrm{ka}\mathrm{1,1}},$ ${\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="C2006100601480009H1.png"\; state="\{\{state\}\}">v</figure-callout>}}_2=c{s}_{16}^{(k=3)}\&CircleTimes;h_{\mathrm{ka}2,1},$

$v_3=c{s}_{16}^{(k=2)}\&CircleTimes;h_{\mathrm{ka}1,2},$ $v_4=c{s}_{16}^{(k=4)}\&CircleTimes;h_{\mathrm{ka}\mathrm{2,2}}$

Cs ₁₆ ^(k=1)Be the vector that the spread spectrum scrambler multiplexed sequence of the 1st spreading code using of P-PCCPCH1 is formed, cs ₁₆ ^(k=2)Be the vector that P-PCCPCH2 uses the spread spectrum scrambler multiplexed sequence of the 1st spreading code to form, cs ₁₆ ^(k=3)Be the vector that P-PCCPCH1 uses the spread spectrum scrambler multiplexed sequence of the 2nd spreading code to form, cs ₁₆ ^(k=4)It is the vector that P-PCCPCH2 uses the spread spectrum scrambler multiplexed sequence of the 2nd spreading code to form.Spread spectrum scrambler multiplexed sequence is exactly, and a scrambler is in the cycle, the sequence that spreading code and scrambler dot product constitute.

The transmission matrix diversity that receives the transmit diversity user merges, and the row of the impulse response of identical Midamble sign indicating number skew correspondence carry out addition in the matrix, reconstruct new diversity transmission matrix It also is the piece diagonal matrix.

At last, carry out joint-detection, can unite and solve multiple signals.

Use matrix

To the user data demodulation, can use whitened matched filter algorithm (WMF), ZF linear block balance device algorithm (ZF), lms algorithm multiple joint detection algorithms such as (MMSE).Here be that example is carried out data estimation with the lms algorithm, have

$\hat{d}={({\tilde{A}}^H{R_n}^{-1}\tilde{A}+{R_d}^{-1})}^{-1}{\tilde{A}}^H{R_n}^{-1}e$

Thereby obtain each user's demodulating data.In the following formula, R _nBe the spatial noise correlation matrix, R _dBe to send the data correlation matrix, H represents matrix is asked conjugate transpose.

The present invention is applicable to that all are applied to all cdma systems, particularly TDD-CDMA system and SCDMA system of institute.Any have a signal processing, and the engineer of knowledge background such as communication can design corresponding transmit diversity according to the present invention and receive the joint-detection device, and it all should be included in thought of the present invention and the scope.

Claims (2)

1, a kind of bell idles transmitting diversity channel receiving demodulation method at first, with after training sequence separates, carries out channel estimating to data, obtains the channel impulse response of diversity antenna; Then, the channel impulse response of each antenna is carried out convolution with separately spreading code respectively, make up transmission matrix; At last,, unite the emission data that solve the base station to receiving data demodulates,

The described channel impulse response that obtains diversity antenna is meant the fading characteristic that obtains first and second transmission signals,

The described concrete grammar that obtains the channel impulse response of diversity antenna is:

1) training sequence that receives is expressed as

e＝Gh+n

Wherein, the G matrix is the ring shift right matrix that is made of a basic Midamble sign indicating number, and h is user's a channel impulse response, and n is a white Gaussian noise;

2) finish the maximal possibility estimation of channel impulse response h

$\hat{h}=G^{-1}e;$

3) be that length intercepts in order with W

Channel estimation value obtains the channel impulse response of diversity antenna respectively

With

The method of described structure transmission matrix is:

Earlier with diversity antenna spread spectrum scrambler and channel impulse response separately

With

Generate block diagonal matrix A, the piece V that constitutes A is made up of the vector that spread spectrum scrambler multiplexed sequence and channel impulse response convolution form: first row are to use the convolution vector of the impulse response of first Midamble sign indicating number skew correspondence on the spread spectrum scrambler multiplexed sequence of the 1st spreading code and first antenna, secondary series is to use the convolution vector of the corresponding impulse response of first Midamble sign indicating number skew on the spread spectrum scrambler multiplexed sequence of the 3rd spreading code and second antenna, the 3rd row are to use on the spread spectrum scrambler multiplexed sequence of the 2nd spreading code and first antenna convolution vector of the corresponding impulse response of second Midamble sign indicating number skew, and the 4th row are to use on the spread spectrum scrambler multiplexed sequence of the 4th spreading code and second antenna convolution vector of the corresponding impulse response of second Midamble sign indicating number skew; Described spread spectrum scrambler multiplexed sequence is meant, a scrambler is in the cycle, the sequence that spreading code and scrambler dot product constitute;

Then, the transmission matrix diversity that will receive the transmit diversity user merges, and is about to the impulse response column corresponding element addition on the corresponding different antennae of identical Midamble sign indicating number skew institute among the V, generation

By

Reconstruct new diversity transmission matrix

2, the described bell idles transmitting diversity channel receiving demodulation method of claim 1 is characterized in that, to receiving data demodulates, unites the emission data that solve the base station by following formula:

$\hat{d}={({\tilde{A}}^H\&CenterDot;\tilde{A})}^{-1}{\tilde{A}}^{H}e$

Perhaps $\hat{d}={({\tilde{A}}^H{R_n}^{-1}\tilde{A}+{R_d}^{-1})}^{-1}{\tilde{A}}^H{R_n}^{-1}e,$

Wherein, R _nBe the spatial noise correlation matrix, R _dBe to send the data correlation matrix, H represents matrix is asked conjugate transpose.

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