CN1870610A - Channel estimating method of array antenna - Google Patents

Abstract

This invention provides an estimation method for array antenna channels, which first of all estimates channels of receiver signals, carries out channel estimation post process to the original channel response of part array elements in the array antenna to get the post process channel responses of said elements, the un-zero values of which are tapped and the values at the pig-tail of the original channel response of other array elements are maintained as the post process channel response of other elements.

Description

A kind of channel estimation methods of array antenna

Technical field

The present invention relates to channel estimation methods, especially a kind of channel estimation methods of array antenna.

Background technology

Because the complexity and the time variation of channel in the wireless mobile communications, in the coherent reception scheme, need estimate channel and measures at receiving terminal, and then the channel response that utilization obtains carries out coherent detection to signal.Except the application in input, channel estimating also plays important basic effect in correlation subsystem such as physical layer measurement, smart antenna, quick control and RRM.Array antenna is one group of antenna system of being made up of emission or receiving element (array element).

Be example with the channel estimating in time division multiplexing-S-CDMA (TD-SCDMA) system below, introduce the channel estimation methods of array antenna in the existing mobile communication system.

Fig. 1 is the burst structure of TD-SCDMA business time-slot, and the intermediate code (midamble) at burst middle part also can be described as channel estimating code as carrying out channel estimating, and the data block on both sides is used for transmit traffic data.For the same time slot of same sub-district, determine a basic intermediate code as basic code, different users adopts the different cyclic shift version conduct channel estimating code separately of this basic code, constitutes intermediate code sign indicating number collection, is called for short the sign indicating number collection.

In the existing TD-SCDMA system, (detailed content is referring to document B.Steiner to adopt Generalized S teiner estimator to carry out the channel estimating of array antenna, and P W Baier, " Low Cost Channel Estimation inthe Uplink Receiver of CDMA Mobile Radio Systems; " FREQUENZE, 47 (1993) 11-12), the estimated result that obtains is called original channel response, the i.e. total channel response vector in sub-district: h "=G ^-1e _MidWherein, e _MidCorresponding to the part of training sequence, G represents the circular matrix be made up of the basic code of this sub-district in the expression received signal.Compare with the ideal communication channel response, comprise adjacent area interference and receiving terminal The noise in the original channel response, therefore, after obtaining the original channel response, to further suppress or reduce the influence that described adjacent area interference and noise produce, this process is called the channel estimating reprocessing, and the channel response that obtains is known as post process channel response.

Present employed channel estimation method is normally made channel estimating at the multi-user's intermediate code in the sign indicating number collection of same basic code, i.e. solid size collection (sub-district) channel estimation methods.This method at first obtains the original channel response of all array elements of array antenna by Generalized S teiner estimator; And then in the channel estimating last handling process, calculate the average power of each tap, and this average power and the thresholding of being scheduled to are compared, array response kept greater than the tap of presetting thresholding.That is:

${\underset{\‾}{h^{\′}}}_j=\left\{\begin{array}{cc}{\underset{\‾}{h^{\′\′}}}_j& {\left|\right|{\underset{\‾}{h^{\′\′}}}_j\left|\right|}^2\≥\mathrm{\Γ}\\ 0& \mathrm{else}\end{array}\right.$

j＝1ΛP；

Wherein, P represents the tap number of original channel response, and Γ represents the reprocessing thresholding, H " _jJ tap of expression original channel response, H ' _jJ tap of expression post process channel response.

Many yards collection (sub-district) channel estimation methods of a kind of TD-SCDMA system is disclosed in the Chinese patent application number the 03100670.1st.This method at first obtains the original channel response of all array elements of array antenna by Generalized S teiner estimator.And then in the channel estimating last handling process: reduce adjacent area interference, promptly utilize the method for iteration, recover and offset the adjacent area interference of each tap; And, reducing the receiving terminal noise, this method is with top described single cell channel estimation method.

In the channel estimating last handling process of the channel estimation methods of above-mentioned list (many) sub-district, the process of calculating the average power of tap and carrying out the tap Interference Cancellation all is to utilize the response of all array elements in the array antenna to carry out, this process has very big amount of calculation in system, thereby has reduced the treatment effeciency of channel estimating.On the other hand, consider the actual treatment ability of system, complicated channel estimation process has limited the actual array number that can participate in channel estimating and Multiuser Detection, promptly have only in the array antenna part array element can participate in carrying out channel estimating and Multiuser Detection is handled, yet the minimizing that participates in the array number of processing will make the decreased performance of channel estimating and Multiuser Detection.

Summary of the invention

The problem to be solved in the present invention provides a kind of channel estimation methods of array antenna, and this method can improve the channel estimation process efficient of system.

For solving the problems of the technologies described above, the objective of the invention is to be achieved through the following technical solutions:

Receiver signal is carried out channel estimation process, obtain the original channel response of array antenna; The channel estimating reprocessing is carried out in original channel response to part array element in the array antenna, obtains the post process channel response of this part array element; For the non-vanishing tap of the post process channel response value of described part array element, the response of the original channel of all the other array elements is in the value of this tap, as the post process channel response of described all the other array elements in the reserved array antenna.

For the channel estimating of single sub-district, the channel estimating reprocessing described in the said method comprises: the original channel of part array element is estimated that response carries out decision process, satisfy the tap of the original channel response signal of certain condition with reservation, to reduce the receiving terminal noise.

A kind of implementation method of described decision process is: sets channel estimating performance parameter thresholding, judges whether the performance parameter in the tap is not less than described performance parameter thresholding in the original channel response, if then keep this tap, otherwise with this tap zero setting.

The another kind of implementation method of described decision process is: set the tap number thresholding, the power/amplitude ordering with the value in the tap in the original channel response keeps the relatively large tap of power/range value, and makes the tap number that is retained equal described tap number thresholding.

For the channel estimating of many sub-districts, in the above-mentioned channel estimating reprocessing, except reducing the receiving terminal noise, also comprise original channel is responded the processing that reduces adjacent area interference.Its implementation is: the tap by described original channel response recovers each sub-district original channel response, and then offsets the neighbor cell original channel response that is comprised in each tap from receiver signal.

In the method for the present invention, utilize Generalized S teiner estimator that the signal that receiver obtains is carried out channel estimation process, to obtain the original channel response.

Above technical scheme as can be seen, because in channel estimation methods provided by the present invention, utilize part array element to respond and carry out the channel estimating last handling process, obtain the post process channel response of part array element, and then determine the post process channel response of all the other array elements in the array antenna according to the post process channel response of described part array element, thereby the present invention has reduced the amount of calculation of channel estimation method, and the system that makes has the more antennas of more surplus resource support to carry out Multiuser Detection.Channel estimation methods provided by the invention is realized simple, be applicable to the channel estimating of single sub-district (sign indicating number collection) or many sub-districts, and, though this method can cause the loss of channel response precision, but compare with the performance boost that Multiuser Detection is brought, the lifting of Multiuser Detection performance is more remarkable.

Description of drawings

Fig. 1 is a TD-SCDMA business time-slot burst structure;

Fig. 2 is the embodiment of the present invention flow chart.

Embodiment

Core concept of the present invention is: receiver signal is carried out channel estimating, obtain the original channel response of array antenna; The channel estimating reprocessing is carried out in original channel response to part array element in the array antenna, obtains the post process channel response of this part array element; For the non-vanishing tap of the post process channel response value of described part array element, the response of the original channel of all the other array elements is in the value of this tap, as the post process channel response of described all the other array elements in the reserved array antenna.

According to above-mentioned core concept, with reference to Fig. 2, be example with the TD-SCDMA system, introduce of the present invention

Embodiment.

Step 21: array antenna received machine received signal.

Step 22: receiver utilizes Generalized S teiner estimator to carry out channel estimating to received signal, obtain the original channel response of array of cells antenna, described channel estimating comprises that single cell channel is estimated or multi-cell channel estimates that described Generalized S teiner estimator equation expression is:

$\begin{array}{cc}{\underset{\‾}{h^{\′\′}}}_n^{\left(k_a\right)}={\left({\underset{\‾}{G}}_n\right)}^{-1}{\underset{\‾}{e}}_{\mathrm{mid}}^{\left(k_a\right)}& k_a=1\mathrm{\Λ}{K}_a;n=1\mathrm{\Λ}\end{array}N$

Wherein, N represents the sub-district number, and when single cell channel was estimated, the N value was 1; K _aAntenna number in the expression receiving terminal array is if 8 antennas constitute aerial array, then K _aValue is 8; e _Mid ^(ka)Represent k _aIn the received signal of root antenna corresponding to the part of training sequence, G _nThe circular matrix that expression is made up of the basic code (midamble) of n sub-district, H " _n ^(ka)Expression is corresponding to the k of n sub-district _aThe original channel response of root antenna.

Step 23: in the original channel response of above-mentioned array antenna, the channel estimating reprocessing is carried out in the original channel response of part array element, obtained the post process channel response of this part array element H ' _{N, j} ^(ka)

In single cell channel was estimated, the channel estimating reprocessing only reduced the processing of receiving terminal noise, and its process is formulated as:

${\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a\right)}=\left\{\begin{array}{cc}{\underset{\‾}{h^{\′\′}}}_{n,j}^{\left(k_a\right)}& \frac{1}{L}\underset{k_a=1}{\overset{L}{\mathrm{\Σ}}}{\left|{\underset{\‾}{h^{\′\′}}}_{n,j}^{\left(k_a\right)}\right|}^2\≥{\mathrm{\Γ}}_n\\ 0& \mathrm{else}\end{array}\right.$

J=1 Λ P; k _a=1 Λ L (L＜K _a); N=1 Λ N wherein, P represents the tap number of original channel response; L represents to participate in the antenna number of channel estimating last handling process, and the L value is less than K _a, promptly participate in the antenna number of the antenna number of channel estimating reprocessing less than array; Γ _nThe reprocessing thresholding of representing n sub-district; H " _{N, j} ^(ka)The k that represents n sub-district _aJ tap in the original channel response of root antenna, when single cell channel was estimated, the n value was 1, H ' _{N, j} ^(ka)The k that represents n sub-district _aJ tap in the post process channel response of root antenna.

In the channel estimating of many sub-districts, the channel estimating last handling process comprises: reduce the processing of adjacent area interference, promptly pass through repeatedly iterative process, progressively eliminate the channel response of the adjacent sub-district that is comprised in each tap; Reduce the processing of receiving terminal noise, its process is identical with channel estimating post-processing approach in single cell channel estimation.Multi-cell channel estimation method can be referring to disclosed technical scheme in the patent document of Chinese patent application number 03100670.1.

Step 24: the channel estimating reprocessing result of L array element is generalized to the channel estimating reprocessing of M (L＜M≤8) array element, obtains the post process channel response of M array element.Formulate is:

${\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a^{\′}\right)}=\left\{\begin{array}{cc}{\underset{\‾}{h^{\′\′}}}_{n,j}^{\left(k_a^{\′}\right)}& {\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a\right)}\≠0\\ 0& {\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a\right)}=0\end{array}\right.$

j＝1ΛP；k _a′＝L+1ΛM(L＜M≤K _a)；

k _a＝1ΛL(L＜K _a)；n＝1ΛN

Wherein, P represents the tap number of original channel response; K _aAntenna number in the expression receiving terminal array; M represents to participate in the aerial array array number (L＜M≤K that follow-up Multiuser Detection is handled _a); k _aCorresponding to L array element, k _a' corresponding to the residue array element of not carrying out reprocessing in the M array element.Can be got by this formula: for the non-vanishing tap of the post process channel response value of L array element, the original channel response in the M array element that the follow-up Multiuser Detection of participation is handled in the reserved array antenna is in the value of this tap, as the post process channel response of M array element.

Step 25: the post process channel response of output M array element.And then the single user who utilizes the post process channel response of this M array element to carry out up single sub-district or many sub-districts detects or Multiuser Detection; Or, utilize the post process channel response of this M array element to carry out descending transmission user's wave beam forming.

Above-mentioned is preferred embodiment of the present invention, and step 23 is carried out in the channel estimating reprocessing of part array element, comprises the processing that reduces the receiving terminal noise, and this processing is mainly adjudicated original channel response values of tap.The method of this decision process can be by setting channel estimating performance parameter thresholding, and then judge whether the performance parameter in the tap is not less than described performance parameter thresholding in the original channel response, and keep tap greater than described performance parameter thresholding, its specific implementation method comprises:

The method of signal-noise ratio threshold: set signal-noise ratio threshold, with signal to noise ratio in the original estimation result greater than thresholding Γ _nTap on value keep, and with remaining tap zero setting;

The method of power or amplitude thresholding: setting power or amplitude thresholding, the thresholding of described power/amplitude can be the mean value of each array element power in this tap, with power in the original estimation result or amplitude greater than thresholding Γ _nTap on value keep, and with remaining tap zero setting.

In addition to the above methods, the described method that original channel response values of tap is carried out decision process also can be: set the tap number thresholding, power/amplitude ordering with the value in the tap in the original channel response, keep the relatively large tap of power/range value, and make the tap number that is retained equal described tap number thresholding.

Following mask body is with two sub-districts, and the received signal of the array that 8 antennas in every sub-district constitute is that example illustrates channel estimation methods of the present invention.

Be located in the multi-cell signals that junction, two sub-districts receiver receives, the signal response that belongs to two sub-districts is the strongest, and the circular matrix that the basic code of these two sub-districts is formed is respectively G ₁, G ₂, the channel response vector is respectively h ₁And h ₂, this moment, receiver signal was:

$e_{\mathrm{mid}}=\underset{n=1}{\overset{2}{\mathrm{\Σ}}}{G}_n{h}_n+n_0$

N in the following formula ₀Other all noises beyond the multi-cell signals are removed in expression.For any one G _n(n=1,2), the total signal of receiver can be expressed as again:

e _mid＝G _nh _n+n _n

n _nWith n ₀Between the pass be:

n ₁＝G ₂h ₂+n ₀＝I ₂+n ₀

n ₂=G ₁h ₁+ n ₀=I ₁+ n ₀Wherein, I _nThe interference that expression is caused by the channel response of n sub-district.And then with reference to Chinese patent application number the 03100670.1st, present embodiment is specially:

Step 1: receiver obtains response signal, owing to can't separate single sub-district received signal and many sub-districts received signal, thereby the received signal e that is input as each total sub-district of each channel estimator _Mid, n=e _Mid, n=1,2.

Step 2: utilize single cell channel estimation method, carry out the channel estimating of single subdistrict respectively, obtain each sub-district original channel response at different sub-districts:

$h_n^{\′\′}=G_n^{-1}{e}_{\mathrm{mid},n},n=\mathrm{1,2}$

After obtaining the original channel response of each all array element of sub-district, at a certain sub-district, only earlier part array element in the aerial array of sub-district is carried out iterative process progressively eliminating the adjacent cell channel response that is comprised in this each tap of array element channel response, its embodiment such as step 3 are to step 6:

Step 3: finite time decision process.Response is handled to original channel, adopts the method by signal to noise ratio, and the setting signal-noise ratio threshold is ε＞0, utilizes the noise power σ that measures _n ², obtain the channel estimating h after the finite time decision process _n', if the norm squared value of original estimation result, then keeps the original channel response h of single sub-district estimator more than or equal to the product of signal-noise ratio threshold and noise power _n", and as the estimated value h after the finite time decision process _n', otherwise zero setting.

In this step, at a certain sub-district, only part array element in the aerial array of sub-district is carried out the finite time judgement, formulate is:

${\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a\right)}=\left\{\begin{array}{cc}{\underset{\‾}{h^{\′\′}}}_{n,j}^{\left(k_a\right)}& \frac{1}{L}\underset{k_a=1}{\overset{L}{\mathrm{\Σ}}}{\left|{\underset{\‾}{h^{\′\′}}}_{n,j}^{\left(k_a\right)}\right|}^2\≥\mathrm{\ϵ}{\mathrm{\σ}}_n^2\\ 0& \mathrm{else}\end{array}\right.$

J=1 Λ P; k _a=1 Λ 4; N=1,2P represent the tap number of original channel response; In the present embodiment, in the array that 8 array elements constitute, choose wherein 4 array elements and carry out decision process, k _a=1 Λ 4, promptly first sub-district and second sub-district are chosen 4 array elements respectively and are participated in carrying out finite time decision process, k _aFor the array element that participates in decision process; H " _{N, j} ^(ka)The k that represents n sub-district (n=1,2) _aJ tap in the original channel response of root antenna, H ' _{N, j} ^(ka)The k that represents n sub-district _aJ tap of channel response after the decision process of root antenna.

Above-mentioned signal-noise ratio threshold can adopt dynamic value, and for example, for the first time signal-noise ratio threshold is ε=5 during iteration, and signal-noise ratio threshold is ε=3 during iteration for the second time.

Step 4: recover to disturb: the channel estimating of utilizing the part array element after the finite time decision process H ' _{N, j} ^(ka)Recover the interference components I that each yard collection signal response causes _n', formulate is:

$I_n^{\′\left(k_a\right)}=G_n{h}_n^{\′\left(k_a\right)}$

Step 5: Interference Cancellation: for the array element of step 3 decision process, from the response of its total original channel, deduct the interference components that the response of another cell signal of recovery causes, obtain sub-district basic code matrix G _nCleaner signal e _{Mid, n} ^(ka)Promptly, for 8 array elements that participate in step 3 decision process (first sub-district and second sub-district are chosen 4 array elements respectively and participated in decision process), from total received signal of 4 array elements of first sub-district, deduct the interference components I that described 4 array element signals response in second sub-district causes ₂' ^(ka)(k _a=1 Λ 4), obtain the received signal e of comparatively clean described 4 array elements in first sub-district _{Mid, 1} ^(ka), in like manner, obtain the comparatively clean received signal e in second sub-district _{Mid, 2} ^(ka)

$e_{\mathrm{mid},n}^{\left(k_a\right)}=e_{\mathrm{mid}}^{\left(k_a\right)}-\underset{i\≠n}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}}{I}_i^{\′\left(k_a\right)}=e_{\mathrm{mid}}^{\left(k_a\right)}-\underset{i\≠n}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}}{G}_i{h}_i^{\′\left(k_a\right)}$

Step 6: obtain e _{Mid, n} ^(ka)After, judge whether described iterative processing reaches the iterations that presets, if do not have, basis then $h_n^{\′\′\left(k_a\right)}=G_n^{-1}{e}_{\mathrm{mid},n}^{\left(k_a\right)}$ Obtain 4 participations described in two sub-districts and carry out the original channel estimation of the array element of iterative processing, and carry out step 3, otherwise carry out step 7.

Step 7: the channel estimating post process channel response that obtains each 4 array element of two sub-districts that participate in the finite time judgement.Promptly according to the e that is obtained _{Mid, n} ^(ka)Obtain the post process channel response of this part array element H ' _{N, j} ^(ka)

Step 8: in any one sub-district, for above-mentioned 4 array elements, in the non-vanishing tap of processing channel response, the response of the original channel of all the other 4 array elements (8 array element array) is at the value of this tap, the post process channel response of these 4 array elements as all the other in the reserved array antenna.Formulate is:

${\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a^{\′}\right)}=\left\{\begin{array}{cc}{\underset{\‾}{h^{\′\′}}}_{n,j}^{\left(k_a^{\′}\right)}& {\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a\right)}\≠0\\ 0& {\underset{\‾}{h^{\′}}}_{n,j}^{\left(k_a\right)}=0\end{array}\right.$

j＝1ΛP；k _a′＝5Λ8；k _a＝1Λ4；n＝1，2

The final post process channel response that obtains array in the sub-district.

More than by the implementation of specific embodiment explanation the present invention in 2 cell channels are estimated, those skilled in the art can be applied to the method for the foregoing description in the channel estimating of single sub-district or many sub-districts equally; Simultaneously, in carrying out channel estimating, can realize the present invention in conjunction with other this areas technological means commonly used in each step equally, as: in interference-cancellation process, adopt complete Interference Cancellation or partial interference cancellation, or in the step 3 of the foregoing description, use additive method or parameter to realize the finite time judgement.

More than the channel estimation methods of a kind of array antenna provided by the present invention is described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (10)

1, a kind of channel estimation methods of array antenna is characterized in that:

1) receiver signal is carried out channel estimating, obtain the original channel response of array antenna;

2) the channel estimating reprocessing is carried out in the original channel response of part array element in the array antenna, obtained the post process channel response of this part array element;

3) for the non-vanishing tap of the post process channel response value of described part array element, the response of the original channel of all the other array elements is in the value of this tap, as the post process channel response of described all the other array elements in the reserved array antenna.

2, the channel estimation methods of array antenna as claimed in claim 1 is characterized in that step 2) described in carry out the channel estimating reprocessing and comprise:

Decision process is carried out in original channel estimation response to part array element, satisfies the tap of the original channel response signal of certain condition with reservation.

3, the channel estimation methods of array antenna as claimed in claim 2 is characterized in that, described decision process is carried out in such a way:

Set channel estimating performance parameter thresholding, judge whether the performance parameter in the tap is not less than described performance parameter thresholding in the original channel response, if then keep this tap, otherwise with this tap zero setting.

4, the channel estimation methods of array antenna as claimed in claim 2 is characterized in that, described decision process is carried out in such a way:

Set the tap number thresholding, the power/amplitude ordering with the value in the tap in the original channel response keeps the relatively large tap of power/range value, and makes the tap number that is retained equal described tap number thresholding.

5, the channel estimation methods of array antenna as claimed in claim 2 is characterized in that step 2) described in carry out the channel estimating reprocessing and also comprise:

Response reduces the processing of adjacent area interference to original channel.

6, the channel estimation methods of array antenna as claimed in claim 5 is characterized in that, the processing of the adjacent area interference of described reduction is specially:

Tap by described original channel response recovers each sub-district original channel response, and then offsets the neighbor cell original channel response that is comprised in each tap from receiver signal.

7, the channel estimation methods of array antenna as claimed in claim 1 is characterized in that:

Utilize Generalized S teiner estimator that the signal that receiver obtains is carried out channel estimating in the step 1).

8, a kind of channel estimation methods of array antenna, every array of cells is made up of 8 array elements, it is characterized in that:

1) receiver signal is carried out channel estimating, obtain the original channel response of 8 array element arrays;

2) the channel estimating reprocessing is carried out in the original channel response of choosing 4 array elements in the described array, obtains the post process channel response of this 4 array element;

3), keep the value of the original channel response of all the other 4 array elements in this array, as the post process channel response of described all the other 4 array elements in this tap in the non-vanishing tap of the post process channel response value of described 4 array elements.

9, the channel estimation methods of array antenna as claimed in claim 8 is characterized in that step 2) described in carry out the channel estimating reprocessing and comprise:

The original channel of 4 array elements chosen is estimated that response carries out decision process, satisfy the tap of the original channel response signal of certain condition with reservation.

10, the channel estimation methods of array antenna as claimed in claim 9 is characterized in that step 2) in also comprise:

The original channel response of 4 selected array elements is reduced the processing of adjacent area interference.