CN101547067B - Method and device for tracking precoding matrix - Google Patents

Abstract

The invention discloses a method and a device for tracking a precoding matrix. The method comprises the following steps: using a matrix Euclidean distance as a measure to determine an adjacent precoding matrix group for each precoding matrix in a preset precoding codebook; and using the adjacent precoding matrix group corresponding to an optimized precoding matrix selected last time in the domainas a current alternative codebook space, and selecting an optimized precoding matrix for the time from the current alternative codebook space. The device for tracking the precoding matrix comprises acodebook determining module and a tracking module. The precoding tracking proposal of the invention can effectively improve the performance of a system while lower precoding feedback information content is maintained.

Description

A kind of pre-coding matrix tracking and device

Technical field

The present invention relates to multiple-input and multiple-output (MIMO) technology, relate in particular to the pre-coding matrix tracking in a kind of mimo system.

Background technology

Future mobile communications is had higher requirement to wireless communication system at aspects such as transmission rate, performance and system business capacity.Multiple-input and multiple-output (MIMO) system all adopts multi-antenna structure at transmitting terminal and receiving terminal, not only power system capacity and the availability of frequency spectrum can increase exponentially, thereby satisfy the requirement of high transfer rate and high system business capacity, but also can utilize space diversity to improve the performance of communication system fully.

Precoding refers to earlier signal to be sent be carried out preliminary treatment at transmitting terminal, and then sends signal after handling to receiving terminal.Precoding technique is a kind of key technology that improves the mimo system performance.

In pre-coding system, the Chang Yong precoding technique that is based on code book comparatively.Specifically, system according to such as maximum capacity, minimum error rates criterions such as (BER), pre-determines the code word that comprises in the code book according to the information such as the probability distribution of channel, variation when variance is isometric, and these code words can occur with the form of matrix; After determining code word, also preserve at transmitting terminal and receiving terminal.Receiving terminal is selected the optimization pre-coding matrix of this signal transmission according to factors such as channel estimation results, and in signals transmission, utilize this optimization pre-coding matrix that signal to be transmitted is carried out precoding by transmitting terminal, again the precoding result is sent to receiving terminal, so that receiving terminal receives and detect data.

Carry out if select to optimize the transmitting terminal that operates in of pre-coding matrix, then transfer pre-coding also needs selected optimization pre-coding matrix index is sent to receiving terminal, so that decoding as a result the time; Carry out if select to optimize the receiving terminal that operates in of pre-coding matrix, then the receiving terminal optimization pre-coding matrix index that needs to select sends to transmitting terminal, so that coding.The bit number that is often used in transfer pre-coding matrix index between transmitting terminal and the receiving terminal is called the precoding feedback information.When the pre-coding matrix number that comprises in the code book was D, the precoding feedback information needed (log ₂D) bit.

In order to reduce the precoding feedback information, a kind of method of selecting this suboptimization pre-coding matrix in frequency domain based on chordal distance in the code word around the optimization pre-coding matrix of last carrier wave bunch (cluster) has appearred at present.So-called carrier wave bunch refers to comprise the group of a plurality of subcarriers, be about to whole subcarriers and be divided into N carrier wave bunch, include some continuous subcarriers in each carrier wave bunch, for example: have 256 subcarriers, after being divided into 4 carrier waves bunch, can include 64 subcarriers in each carrier wave bunch.In signals transmission, utilize a carrier wave bunch to carry data to be transmitted at every turn.Because since second carrier wave bunch, in selecting the optimization pre-coding matrix process of current carrier wave bunch, utilized previous optimization pre-coding matrix, therefore to be also referred to as be the pre-coding matrix tracking to this method.

In this pre-coding matrix tracking, according to mimo system adopt empty the time processing mode generate precoding codebook in advance and according to performance requirements tracking amount E be set.According to chordal distance, namely a kind of cambered surface distance on the superspace is 2 of the definite vicinity of each pre-coding matrix in the code book then ^EIndividual pre-coding matrix.When pre-coding matrix is optimized in a bunch selection at first carrier wave, all pre-coding matrixes in the code book are carried out traversal search, select the optimization pre-coding matrix of first carrier wave bunch, the whole code words in this moment code book all are in the alternative code book space hunting zone maximum.Since second carrier wave bunch, will with 2 of last carrier wave bunch vicinity ^EIndividual pre-coding matrix is as current alternative code book space, and selects the optimization pre-coding matrix of current carrier wave bunch in this current alternative code book space.

From above-mentioned pre-coding matrix tracing process as can be seen, be that first carrier wave bunch is when selecting to optimize pre-coding matrix, all pre-coding matrixes in the precoding codebook are searched for, supposed to comprise altogether in the precoding codebook D pre-coding matrix, precoding this moment feedback information needs (log ₂D) bit; Since second carrier wave bunch, each precoding feedback information only needs E bit, and E is the tracking amount.And, in the practical application, 2 ^EPermanent in D.Like this, and all precoding codebook is carried out exhaustive search at every turn and compare, the precoding feedback information volume can access effective reduction in this method.

Consider from another angle, in existing pre-coding matrix tracking, be to estimate from precoding codebook, to determine with the contiguous part pre-coding matrix of the optimization pre-coding matrix of last carrier wave bunch as current alternative code book space with chordal distance, in order to since second carrier wave bunch, from current alternative code book space, find the optimization pre-coding matrix.We can say that chordal distance is estimated the decisive factor which pre-coding matrix in the alternative code book space is chosen as the optimization pre-coding matrix.Yet, though the starting point of this method is to wish that selected pre-coding matrix can be infinitely near theoretic optimization pre-coding matrix, by actual effect and not ideal enough.So, utilize such pre-coding matrix that information to be transmitted is encoded after, can not eliminate fading channel effectively to the influence of signals transmission, then can not more effectively reduce the error rate of signal transmission, thereby the mimo system performance is lower.

Summary of the invention

The invention provides a kind of pre-coding matrix tracking, can improve the mimo system performance.

In pre-coding matrix tracking of the present invention, comprising:

Set in advance tracking amount E, and 2 ^ELess than the pre-coding matrix number in the precoding codebook that sets in advance;

According to described tracking amount E, for each pre-coding matrix in the described precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix;

The contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence once selected before in this territory as current alternative code book space, and is selected this suboptimization pre-coding matrix in this current alternative code book space.

The present invention also provides a kind of pre-coding matrix tracking means, can improve the mimo system performance.

In pre-coding matrix tracking means of the present invention, comprising: codebook determining module and tracking module.Wherein, described codebook determining module is used for the matrix Euclidean distance for estimating, for each pre-coding matrix in the precoding codebook that sets in advance is determined contiguous pre-coding matrix group; Described tracking module is for the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of once selecting before codebook determining module reads this territory, as current alternative code book space, and in this current alternative code book space, select this suboptimization pre-coding matrix.

Pre-coding matrix tracking means of the present invention further comprises: module is set, is used for setting in advance precoding codebook and tracking amount E, and 2 ^ELess than the pre-coding matrix number in the described precoding codebook; Described tracking module reads tracking amount E and precoding codebook from described the setting the module, according to described tracking amount E, for each pre-coding matrix in the described precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix.

By such scheme as seen, the present invention is determining contiguous pre-coding matrix group time, estimate as criterion with the matrix Euclidean distance, select to optimize pre-coding matrix and be exactly and from alternative code book space, select the pre-coding matrix that " approaches " the most with the theoretical optimization pre-coding matrix.Can be by approach proof and checkings such as theoretical derivation and emulation, from probability meaning, the matrix Euclidean distance more can play leading role than chordal distance when choosing the pre-coding matrix that " approaches " the most with the theoretical optimization pre-coding matrix.Therefore, the optimization pre-coding matrix that chooses can more effectively improve signal transmission quality, and reduces the error rate of signal transmission effectively, thereby improves the mimo system performance.

Description of drawings

To make clearer above-mentioned and other feature and advantage of the present invention of those of ordinary skill in the art by describe exemplary embodiment of the present invention in detail with reference to accompanying drawing below, in the accompanying drawing:

Fig. 1 is the exemplary process diagram of pre-coding matrix tracking among the present invention;

Fig. 2 is the exemplary block diagram of pre-coding matrix tracking means among the present invention;

Fig. 3 is the flow chart of the embodiment of the invention 1 frequency domain pre-coding matrix tracking;

Fig. 4 is that the mimo system pre-coding matrix tracking performance based on the Space-Time Block Coding structure compares schematic diagram in the embodiment of the invention 1 frequency domain;

Fig. 5 is the structural representation of pre-coding matrix tracking means in the embodiment of the invention 1;

Fig. 6 is the flow chart of the embodiment of the invention 2 frequency domain pre-coding matrix trackings;

Fig. 7 be in the embodiment of the invention 2 in the time domain based on the mimo system pre-coding matrix tracking performance of Space-Time Block Coding structure schematic diagram relatively;

Fig. 8 is the structural representation of the pre-coding system of the application embodiment of the invention 1 and embodiment 2.

Embodiment

For making purpose of the present invention, technical scheme clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, the present invention is described in further detail.

The present invention is carrying out pre-coding matrix when following the tracks of operation, as estimating definite alternative code book space, and selects the optimization pre-coding matrix of current carrier wave bunch with the matrix Euclidean distance in determined alternative code book.

Fig. 1 shows the exemplary process diagram of pre-coding matrix tracking among the present invention.Referring to Fig. 1, in this pre-coding matrix tracking, carry out following step:

In step 101, for estimating, be the definite contiguous pre-coding matrix group of each pre-coding matrix in the precoding codebook that sets in advance with the matrix Euclidean distance;

In step 102, the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence once selected before in this territory as current alternative code book space, and is selected this suboptimization pre-coding matrix in this current alternative code book space.

From two above-mentioned steps as can be known, the present invention is determining contiguous pre-coding matrix group time, estimate as criterion with the matrix Euclidean distance, select to optimize pre-coding matrix and be exactly and from alternative code book space, select the pre-coding matrix that " approaches " the most with the theoretical optimization pre-coding matrix.Can be by approach proof and checkings such as theoretical derivation and emulation, from probability meaning, the matrix Euclidean distance more can play leading role than chordal distance when choosing the pre-coding matrix that " approaches " the most with the theoretical optimization pre-coding matrix.Therefore, the optimization pre-coding matrix that chooses can more effectively improve signal transmission quality, and reduces the error rate of signal transmission effectively, thereby improves the mimo system performance.

Fig. 2 is the exemplary block diagram of pre-coding matrix tracking means among the present invention.Referring to Fig. 2, this device comprises: codebook determining module and tracking module.Wherein, codebook determining module is used for the matrix Euclidean distance for estimating, for each pre-coding matrix in the precoding codebook that sets in advance is determined contiguous pre-coding matrix group; The contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of once selecting before tracking module reads in this territory from codebook determining module as current alternative code book space, and selects this suboptimization pre-coding matrix in this current alternative code book space.

Below will be by the pre-coding matrix tracking scheme among frequency domain and two detailed description of the Invention the present invention of time domain.

Embodiment 1

Present embodiment is at frequency domain, adopt according to mimo system empty the time after processing mode generates precoding codebook in advance and according to performance requirements tracking amount E is set, each pre-coding matrix in the precoding codebook one by one as current pre-coding matrix, is sought and 2 of the matrix Euclidean distance minimum of current pre-coding matrix ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of this current pre-coding matrix; And, since second carrier wave bunch, be the benchmark code word with the optimization pre-coding matrix of last carrier wave bunch, from the contiguous pre-coding matrix group of this benchmark code word, select the optimization pre-coding matrix of current carrier wave bunch.

Fig. 3 is the flow chart of present embodiment frequency domain pre-coding matrix tracking.Referring to Fig. 3, this method comprises:

In step 301, according to mimo system adopt empty the time processing mode precoding codebook is set, and according to performance requirements tracking amount E is set.

In this step, according to mimo system adopt empty the time processing mode, for example Space-Time Block Coding, spatial reuse etc. generate the Grassmann precoding codebook, and each pre-coding matrix in this precoding codebook all have the call number of self.For example, total D pre-coding matrix in the precoding codebook, then the call number scope of these pre-coding matrixes can be 0～(D-1).

Simultaneously, also according to the performance requirement of mimo system, suitable tracking amount E is set in this step, wherein 2 ^E＜D.The quantity of the pre-coding matrix that the magnitude relationship of the tracking amount E here comprises among the contiguous pre-coding matrix group in the subsequent step, tracking amount E is more big, pre-coding matrix among the pre-coding matrix group is more many, certainly the optimization pre-coding matrix of therefrom selecting is more near the theoretical optimization pre-coding matrix, and the probability that systematic function improves is also more big; But the bit number that bigger tracking amount E can make the precoding feedback information need is more, and the resource that takies is also more.Therefore, can between performance requirements and precoding feedback information, trade off, determine the size of tracking amount E.

In step 302, according to tracking amount E, for each pre-coding matrix in the precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix.

There is following expression in optimization pre-coding matrix for i carrier wave bunch:

$F_i=\arg \underset{F\∈F}{\min }|{\left|\right|H_i{F}_{\mathrm{opt}}\left|\right|}_F-{\left|\right|H_{i}F\left|\right|}_F|$ Formula 1

Wherein, F _iBe the optimization pre-coding matrix of current carrier wave bunch, F _OptBe the theoretical optimization pre-coding matrix of current carrier wave bunch, F is the pre-coding matrix in the alternative code book space, H _iBe the channel state information matrix of current carrier wave bunch correspondence, min represents to get minimum value, ‖ ‖ _FThe F-norm is got in expression.

Suppose to have determined F _i, can be obtained by the correlation theory of matrix norm:

|‖H _iF _opt‖ _F-‖H _iF _i‖ _F|≤‖H _iF _opt-H _iF _i‖ _F＝‖H _i-1F _i-1-H _iF _i+H _iF _opt-H _i-1F _i-1‖ _F

≤‖H _i-1F _i-1-H _iF _i‖ _F+‖H _iF _opt-H _i-1F _i-1‖ _F

And

$|{|H_{i-1}{F}_{i-1}-H_i{F}_i||}_F$

$={\left|\right|H_{i-1}{F}_{i-1}{F}_{i-1}^H{F}_{i-1}-H_i{F}_i{F}_i^H{F}_i\left|\right|}_F$

$={\left|\right|H_{i-1}{F}_{i-1}{F}_{i-1}^H{F}_{i-1}-H_{i-1}{F}_i{F}_i^H{F}_{i-1}+H_{i-1}{F}_i{F}_i^H{F}_{i-1}-H_i{F}_i{F}_i^H{F}_i\left|\right|}_F$

$={\left|\right|H_{i-1}(F_{i-1}{F}_{i-1}^H-F_i{F}_i^H)F_{i-1}+(H_{i-1}-H_i)F_i+H_{i-1}{F}_i{F}_i^H(F_{i-1}-F_i)\left|\right|}_F$

$\≤{\left|\right|H_{i-1}\left|\right|}_F\·{\left|\right|F_{i-1}{F}_{i-1}^H-F_i{F}_i^H\left|\right|}_F\·{\left|\right|F_{i-1}\left|\right|}_F+{\left|\right|H_{i-1}-H_i\left|\right|}_F\·{\left|\right|F_i\left|\right|}_F+{\left|\right|H_{i-1}\left|\right|}_F\·{\left|\right|F_i{F}_i^H\left|\right|}_F\·{\left|\right|F_{i-1}-F_i\left|\right|}_F$

$=\sqrt{M}({\left|\right|H_{i-1}\left|\right|}_F\·({\left|\right|F}_{i-1}{F}_{i-1}^H-F_i{F}_i^H{\left|\right|}_F+{\left|\right|F_{i-1}-F_i\left|\right|}_F)+{\left|\right|H_{i-1}-H_i\left|\right|}_F)$

F wherein _I-1Be the optimization pre-coding matrix of last carrier wave bunch, H _I-1Be the channel state information matrix of last carrier wave bunch correspondence, [] ^HThe conversion of expression conjugate transpose, M is the way for the treatment of pre-code data stream.

Again because chordal distance d _ChordWith matrix Euclidean distance d _MEBetween the pass be:

$d_{\mathrm{chord}}=\frac{1}{\sqrt{2}}{\left|\right|F_{i-1}{F}_{i-1}^H-F_i{F}_i^H\left|\right|}_F\≤\sqrt{2M}\·{\left|\right|F_{i-1}-F_i\left|\right|}_F=\sqrt{2M}\·d_{\mathrm{ME}}$ Formula 2

So, can obtain:

${\left|\right|H_{i-1}{F}_{i-1}-H_i{F}_i\left|\right|}_F$

$\≤\sqrt{M}({\left|\right|H_{i-1}\left|\right|}_F\·({\left|\right|F_{i-1}{F}_{i-1}^H-F_i{F}_i^H\left|\right|}_F+{\left|\right|F_{i-1}-F_i\left|\right|}_F)+{\left|\right|H_{i-1}-H_i\left|\right|}_F)$

$=\sqrt{M}({\left|\right|H_{i-1}\left|\right|}_F\·(\sqrt{2}\·d_{\mathrm{chord}}+d_{\mathrm{ME}})+{\left|\right|H_{i-1}-H_i\left|\right|}_F)$

$\≤\sqrt{M}({\left|\right|H_{i-1}\left|\right|}_F\·(2\sqrt{M}\·d_{\mathrm{ME}}+d_{\mathrm{ME}})+{\left|\right|H_{i-1}-H_i\left|\right|}_F)$

$=\sqrt{M}((2\sqrt{M}+1)\·d_{\mathrm{ME}}\·{\left|\right|H_{i-1}\left|\right|}_F+{\left|\right|H_{i-1}-H_i\left|\right|}_F)$

Then

${\left|\right|\left|H_i{F}_{\mathrm{opt}}\right||}_F-{\left|\right|H_i{F}_i\left|\right|}_F|$

$\≤\sqrt{M}((2\sqrt{M}+1)\·d_{\mathrm{ME}}\·{\left|\right|H_{i-1}\left|\right|}_F+{\left|\right|H_{i-1}-H_i\left|\right|}_F)+{\left|\right|H_i{F}_{\mathrm{opt}}-H_{i-1}{F}_{i-1}\left|\right|}_F$ Formula 3

F _OptBe the theoretical optimization pre-coding matrix of current carrier wave bunch, this matrix is by the channel state information matrix H of current carrier wave bunch _iSingular value decomposition after the preceding M row of right unitary matrix form.Because the optimization pre-coding matrix of wishing to select to the full extent near the theoretical optimization pre-coding matrix, is namely sought and is made | ‖ H _iF _Opt‖ _F-‖ H _iF _i‖ _F| that minimum pre-coding matrix, and from formula 3 as can be seen, matrix Euclidean distance d _MEMinimizing target function | ‖ H _iF _Opt‖ _F-‖ H _iF _i‖ _F| the aspect is than chordal distance d _ChordPlay more tangible leading role, therefore adopt the matrix Euclidean distance to make up contiguous pre-coding matrix group as estimating in the present embodiment, angle from statistics, can be than adopting chordal distance to obtain more optimization pre-coding matrix near the theoretical optimization pre-coding matrix, thus better system performance obtained.

Be that each pre-coding matrix in the precoding codebook is determined contiguous pre-coding matrix group time in this step, at first with any one pre-coding matrix in this code book as current pre-coding matrix, calculate the matrix Euclidean distance between all the other pre-coding matrixes and current pre-coding matrix, afterwards, will with 2 of the matrix Euclidean distance minimum of current pre-coding matrix ^EIndividual pre-coding matrix does not comprise current pre-coding matrix itself as the contiguous pre-coding matrix group of current pre-coding matrix among the contiguous pre-coding matrix group here; Then, if there is the pre-coding matrix of not determining contiguous pre-coding matrix group in the precoding codebook, then turn to one of them pre-coding matrix, repeat aforementioned definite contiguous pre-coding matrix group's operation, the whole pre-coding matrixes in handling precoding codebook.Certainly, because current pre-coding matrix and the matrix Euclidean distance of self are zero, so here also current pre-coding matrix can be included among its contiguous pre-coding matrix group, pre-coding matrix in this case just comprises: (2 of the matrix Euclidean distance minimum of current pre-coding matrix and all the other and current pre-coding matrix ^E-1) individual pre-coding matrix.

For instance, suppose to comprise 8 pre-coding matrixes in the precoding codebook altogether that namely precoding codebook is: [F ₀, F ₁, F ₂, F ₃, F ₄, F ₅, F ₆, F ₇], if this moment, tracking amount E was 1, so if do not comprise current pre-coding matrix itself, be after whole pre-coding matrixes find the contiguous pre-coding matrix group of correspondence according to the matrix Euclidean distance then, can obtain the code book after the following expansion:

$\left[\begin{array}{cccccccc}{F}_0& F_1& F_2& F_3& F_4& F_5& F_6& F_7\\ F_2& F_5& F_0& F_4& F_3& F_1& F_7& F_6\\ F_6& F_4& F_5& F_7& F_1& F_0& F_2& F_3\end{array}\right]$

The contiguous pre-coding matrix group of the corresponding pre-coding matrix of back two line displays in the code book after the expansion.

Above-mentioned step 301 and step 302 are the off-line operation of carrying out in advance, begin to be real-time processing section from following step 303.

In step 303, first carrier wave bunch as current carrier wave bunch, is selected the optimization pre-coding matrix of current carrier wave bunch in the precoding codebook that sets in advance.

At first determine first pilot tone frequency of first carrier wave bunch in this step, on this pilot tone frequency, according to adopt empty the time processing mode the whole pre-coding matrixes in the precoding codebook that sets in advance are carried out exhaustive search, find the optimization pre-coding matrix of this pilot tone frequency.For example, for the mimo system of spatial multiplexing mode, determine optimization pre-coding matrix F on first pilot tone frequency of first carrier wave bunch by linear codec here ₁, namely $F_1=\arg \underset{F_n\∈F}{\max }{\mathrm{\λ}}_{\min }\left\{H_1{F}_n\right\},$ H wherein ₁Be the channel state information matrix of first carrier wave bunch, F _nBe n pre-coding matrix in the precoding codebook that sets in advance, λ _Min{ H ₁F _nExpression H ₁F _nMinimum singular value.And for example, for the mimo system of Space-Time Block Coding mode, $F_1=\arg \underset{F_n\∈F}{\max }{\left|\right|H_1{F}_n\left|\right|}_F.$

Because present embodiment is when carrying out sub-clustering to carrier wave, each pilot tone frequency in the same carrier wave bunch had correlation as one of standard, therefore, behind the optimization pre-coding matrix of having determined on first pilot tone frequency, just can share to each the pilot tone frequency in first carrier wave bunch optimizing pre-coding matrix.Like this, the optimization pre-coding matrix on first pilot tone frequency can be looked at as the optimization pre-coding matrix of first carrier wave bunch.

In step 304, with next carrier wave bunch as current carrier wave bunch.

In step 305, with the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the last carrier wave of the current carrier wave bunch bunch alternative code book space as current carrier wave bunch, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current carrier wave bunch.

In this step, for the current carrier wave after first carrier wave in the frequency domain bunch bunch, with the optimization pre-coding matrix of the last carrier wave bunch datum mark as the optimization pre-coding matrix of seeking current carrier wave bunch.Owing in abovementioned steps 302, be that whole pre-coding matrixes in the precoding codebook have all been determined corresponding contiguous pre-coding matrix group according to the matrix Euclidean distance, therefore the contiguous pre-coding matrix group who reads this datum mark correspondence the code book after expanding here, and as the alternative code book space of current carrier wave bunch.

Then, on first pilot tone frequency of current carrier wave bunch, from each pre-encoding codeword in alternative code book space, select the pre-coding matrix that the theoretical optimization pre-coding matrix with current carrier wave bunch " approaches " the most, as the optimization pre-coding matrix of first pilot tone frequency of current carrier wave bunch, and share all the other pilot tone frequencies of giving current carrier wave bunch.Here select mode and the mode in the abovementioned steps 303 of optimization pre-coding matrix basic identical, just the range of choice in this step is alternative code book space, and the range of choice in the step 303 is the whole pre-coding matrixes in the precoding codebook.

In step 306, judge whether to handle all carrier waves bunch, if then finish the pre-coding matrix trace flow in the present embodiment; Otherwise, return execution in step 304.

So far, finish present embodiment and in frequency domain, carry out the operation that pre-coding matrix is followed the tracks of according to the matrix Euclidean distance.

In order to determine that present embodiment pre-coding matrix tracking to the influence of systematic function, has carried out emulation according to the parameter of table 1 to the mode that no precoding mode, pre existing encoder matrix tracking mode, present embodiment pre-coding matrix tracking mode and each subcarrier based on the Space-Time Block Coding structure all carry out the precoding codebook exhaustive search.

Table 1 frequency domain simulation parameter

Fig. 4 is according to the parameter in the table 1, and the mimo system pre-coding matrix tracking performance based on the Space-Time Block Coding structure in the frequency domain compares schematic diagram.Referring to Fig. 4, w/o prec represents not have the precoding mode, chordal represents that with chordal distance be the pre-coding matrix tracking mode of estimating, it is the pre-coding matrix tracking mode of estimating that ME represents in the present embodiment with the matrix Euclidean distance, and exhaustive represents all the pre-coding matrix that sets in advance to be carried out on each subcarrier the mode of exhaustive search.As can be seen from Figure 4, under the identical situation of signal to noise ratio (snr), the BER that no precoding mode obtains is the highest, be to be that the BER that obtains of the pre-coding matrix tracking mode estimated is placed in the middle with the matrix Euclidean distance in the pre-coding matrix tracking mode estimated and the present embodiment with chordal distance, it is minimum all the pre-coding matrix that sets in advance to be carried out the BER that the mode of exhaustive search obtains on each subcarrier.As SNR during less than 8dB, it is basic identical that the pre-coding matrix tracking mode of present embodiment and existing pre-coding matrix tracking mode obtain BER; But after SNR was greater than 8dB, the BER that the pre-coding matrix tracking mode of present embodiment obtains decreased than existing mode, and gap between the two enlarges gradually along with the increase of SNR.Equally, the mimo system based on the spatial reuse structure is carried out emulation, can determine that the pre-coding matrix tracking in the present embodiment can obtain to be higher than the performance of existing method in statistical significance.

In addition, under the fixed prerequisite of precoding codebook, though the mode of all pre-coding matrix that sets in advance being carried out exhaustive search on each subcarrier can obtain best performance, the precoding feedback information is up to (Zlog ₂, D) bit, D are pre-coding matrix number in the code book, Z is carrier wave bunch number.Huge like this precoding feedback information volume expense is difficult in real system realize that therefore this mode is ideal situation only, and does not have practicality.Pre-coding matrix tracking mode in the present embodiment is identical with the precoding feedback information of existing mode, all is (log ₂D+ (Z-1) E) bit, wherein E is the tracking amount, and 2 ^E＜D, under the situation of E and the suitable value of D, such precoding feedback information volume can be far smaller than the precoding feedback information volume of above-mentioned ideal situation; Thereby the precoding mode in the present embodiment can also reduce error rate of system effectively when keeping less precoding feedback information, improves systematic function.

Fig. 5 shows the structural representation of pre-coding matrix tracking means in the present embodiment, and this device has increased on the basis of Fig. 2 module is set.In the pre-coding matrix tracking means of present embodiment, the operation that module is used for execution in step 301 is set, namely according to mimo system adopt empty the time processing mode precoding codebook is set, and according to performance requirements tracking amount E is set, and 2 ^ELess than the pre-coding matrix number D in the precoding codebook.Codebook determining module is used for the operation of execution in step 302, namely reads tracking amount E and precoding codebook from module is set, according to the tracking amount E that reads, for each pre-coding matrix in the precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix.The precoding codebook that sets in advance is namely read in the operation of tracking module execution in step 303 to 306 from module is set, select the optimization pre-coding matrix of first carrier wave bunch from this precoding codebook; Since second carrier wave bunch, with the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the last carrier wave of the current carrier wave bunch bunch alternative code book space as current carrier wave bunch, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current carrier wave bunch.Further, tracking module also judges whether to handle all carrier waves bunch, if then finish the pre-coding matrix trace flow after selecting the optimization pre-coding matrix of current carrier wave bunch; Otherwise, carry out the operation turn to next carrier wave bunch.

Embodiment 2

Present embodiment is at time domain, because in a period of time, channel has stronger correlation, therefore interior channel state information matrix can adopt continuous pre-coding matrix to follow the tracks of processing during this period of time.In order to guarantee systematic function, reduce the error diffusion that error tracking may bring, then carry out the exhaustive search of first-time precoding code book at set intervals.This time period is the cycle in the present embodiment, and comprises a plurality of moment in one-period.In the practical application, in one-period, can utilize the optimization pre-coding matrix of previous moment to select the optimization pre-coding matrix of current time.

Present embodiment adopt according to mimo system empty the time after processing mode generates precoding codebook in advance and according to performance requirements tracking amount E is set, each pre-coding matrix in the precoding codebook one by one as current pre-coding matrix, is sought and 2 of the matrix Euclidean distance minimum of current pre-coding matrix ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of this current pre-coding matrix; And, from second moment in each cycle, be the benchmark code word with the optimization pre-coding matrix of previous moment, from the contiguous pre-coding matrix group of benchmark code word, select the optimization pre-coding matrix of current time.

Fig. 6 is the flow chart of present embodiment frequency domain pre-coding matrix tracking.Referring to Fig. 6, this method comprises:

In step 601, according to mimo system adopt empty the time processing mode precoding codebook is set, and according to performance requirements tracking amount E is set.

The operation that precoding codebook and tracking amount E are set in this step is all identical with the operation of step 301 among the embodiment 1.

In step 602, according to tracking amount E, for each pre-coding matrix in the precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix.

According to the theoretical proof process in embodiment 1 step 302, can know by inference equally, the inequality of similar formula 3 in the time domain, just the channel state information matrix in this inequality of present embodiment and pre-coding matrix are all at previous moment and current time.So, can access such conclusion equally: in time domain, matrix Euclidean distance d _MEMinimizing target function | ‖ H _iF _Opt‖ _F-‖ H _iF _i‖ _F| the aspect is than chordal distance d _ChordPlay more tangible leading role.Therefore present embodiment can adopt the matrix Euclidean distance to make up contiguous pre-coding matrix group as estimating in time domain, angle from statistics, can be than adopting chordal distance to obtain more optimization pre-coding matrix near the theoretical optimization pre-coding matrix, thus better system performance obtained.

Operation and the step 302 among the embodiment 1 of determining contiguous pre-coding matrix group in this step are identical.

Similar to embodiment 1, above-mentioned step 601 and step 602 are the off-line operation of carrying out in advance, begin to be real-time processing section from following step 603.

In step 603, judge whether to arrive the cycle that sets in advance, if then execution in step 604; Otherwise, execution in step 605.

In step 604, in the cycle first constantly as current time, selected the optimization pre-coding matrix of current time in the precoding codebook that sets in advance.

In this step, according to adopt empty the time processing mode the whole pre-coding matrixes in the precoding codebook that sets in advance are carried out exhaustive search, find the optimization pre-coding matrix in this moment.For example, for the mimo system of spatial multiplexing mode, the optimization pre-coding matrix F on first pilot tone frequency of first carrier wave bunch ₁Be by $F_1=\arg \underset{F_n\∈F}{\max }{\mathrm{\λ}}_{\min }\left\{H_1{F}_n\right\}$ Determine, wherein H ₁Be first channel state information matrix constantly, F _nBe n pre-coding matrix in the precoding codebook that sets in advance, λ _Min{ H ₁F _nExpression H ₁F _nMinimum singular value.And for example, for the mimo system of Space-Time Block Coding mode, $F_1=\arg \underset{F_n\∈F}{\max }{\left|\right|H_1{F}_n\left|\right|}_F.$

In step 605, with next constantly as current time.

In step 606, with the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the previous moment of the current time alternative code book space as current time, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current time, and return execution in step 603.

In this step, for first the current time after constantly in the cycle, with the optimization pre-coding matrix of previous moment in the time domain datum mark as the optimization pre-coding matrix of seeking current time.Therefore the contiguous pre-coding matrix group who reads this datum mark correspondence in the code book after from abovementioned steps 602, expanding here, and as the alternative code book space of current time.

Then, on first pilot tone frequency of current time, from each pre-encoding codeword in alternative code book space, select the pre-coding matrix the most approaching with the theoretical optimization pre-coding matrix of current time, as the optimization pre-coding matrix of current time.Here select mode and the mode in the abovementioned steps 604 of optimization pre-coding matrix basic identical, just the range of choice in this step is alternative code book space, and the range of choice in the step 604 is the whole pre-coding matrixes in the precoding codebook.

So far, finish present embodiment and in time domain, carry out the operation that pre-coding matrix is followed the tracks of according to the matrix Euclidean distance.

Here according to the parameter of table 2 mode that no precoding mode, pre existing encoder matrix tracking mode, present embodiment pre-coding matrix tracking mode and each subcarrier based on the Space-Time Block Coding structure all carry out the precoding codebook exhaustive search has been carried out emulation.

Number of transmit antennas	4	The reception antenna number	1
				Modulation system	QPSK	Codebook size (bit)	8
Channel model	20-order AR	Coefficient R [1]	0.9
				Tracking amount (bit)	1	Cycle (s)	8T (8 moment)

Table 2 time-domain-simulation parameter

Fig. 7 is according to the parameter in the table 2, and the mimo system pre-coding matrix tracking performance based on the Space-Time Block Coding structure in the time domain compares schematic diagram.Referring to Fig. 7, w/o prec represents not have the precoding mode, chordal represents that with chordal distance be the pre-coding matrix tracking mode of estimating, it is the pre-coding matrix tracking mode of estimating that ME represents in the present embodiment with the matrix Euclidean distance, and exhaustive represents that each all carries out the mode of exhaustive search constantly to the pre-coding matrix that sets in advance.As can be seen from Figure 7, under the identical situation of SNR, the BER that no precoding mode obtains is the highest, be to be that the BER that obtains of the pre-coding matrix tracking mode estimated is placed in the middle with the matrix Euclidean distance in the pre-coding matrix tracking mode estimated and the present embodiment with chordal distance, it is minimum that each constantly all carries out the BER that the mode of exhaustive search obtains to the pre-coding matrix that sets in advance, but last a kind of mode is because its huge precoding information feedback quantity and do not have practicality.With regard to the present embodiment and pre existing encoder matrix tracking mode of ideal situation, as SNR during less than 8dB, it is basic identical that the pre-coding matrix tracking mode of present embodiment and existing pre-coding matrix tracking mode obtain BER with regard to the precoding information feedback quantity; But after SNR was greater than 6dB, the BER that the pre-coding matrix tracking mode of present embodiment obtains decreased than existing mode, and gap between the two enlarges gradually along with the increase of SNR.

Therefore, the precoding mode in the present embodiment can reduce error rate of system effectively when keeping less precoding feedback information, thereby improves systematic function.

Present embodiment can adopt the structure of the pre-coding matrix tracking means shown in Fig. 4, and this device has also increased on the basis of Fig. 2 module is set.In the pre-coding matrix tracking means of present embodiment, the operation that module is used for execution in step 601 is set, namely according to mimo system adopt empty the time processing mode precoding codebook is set, and according to performance requirements tracking amount E is set.Codebook determining module is used for the operation of execution in step 602, namely reads tracking amount E and precoding codebook from module is set, according to the tracking amount E that reads, for each pre-coding matrix in the precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix.Tracking module reads the precoding codebook that sets in advance from module is set, select first optimization pre-coding matrix constantly in this cycle from this precoding codebook; Since second moment, with the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the previous moment of the current time alternative code book space as current time, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current time.Further, tracking module first in the cycle that will set in advance constantly as current time before, also judge whether to arrive the described cycle, if first in the cycle that will set in advance of then carrying out is constantly as the operation of current time; Otherwise, turn to next constantly.

More than be applied to the embodiment of frequency domain or time domain separately for the pre-coding matrix tracking scheme among the present invention.In actual applications, can also carry out the frequency domain pre-coding matrix tracking scheme of above-described embodiment 1 and the time domain pre-coding matrix tracking scheme of embodiment 2 simultaneously, and above-mentioned two processes are separate.

Fig. 8 shows the structural representation of the pre-coding system of using above-described embodiment 1 and embodiment 2.Referring to Fig. 8, this system comprises: transmitting end equipment and receiving device.Transmitting end equipment wherein comprises that at least one width of cloth transmitting antenna, Space Time Coding device, precoder, invert fast fourier transformation (IFFT)/Cyclic Prefix (CP) unit and pre-coding matrix search the unit; Receiving device comprises at least one secondary reception antenna, goes Cyclic Prefix/fast Fourier transform unit, symbol decoupling zero and decoding device, channel estimator and pre-coding matrix tracking means.

Before the transmission signal at first by off-line operation according to mimo system adopt empty the time processing mode generate the Grassmann precoding codebook, and have this consistent code book of content at the pre-coding matrix tracking means that the pre-coding matrix of sending ending equipment is searched unit and receiving device.Pre-coding matrix tracking means in the receiving device with the matrix Euclidean distance for estimating, and according to the tracking amount that sets in advance and the channel state information matrix of channel estimator, for all pre-coding matrixes in the precoding codebook are determined corresponding contiguous pre-coding matrix group.When having primary signal waiting for transmission, for first carrier wave in the frequency domain bunch or time domain in the cycle first constantly, the pre-coding matrix tracking means during according to sky processing mode in all pre-coding matrixes of precoding codebook, select this optimization pre-coding matrix, and the pre-coding matrix that its index is transferred to sending ending equipment is searched the unit; Pre-coding matrix is searched the unit and find this optimization pre-coding matrix from the Grassmann precoding codebook, and submits to precoder.Behind the Space Time Coding and merging processing of primary signal through the Space Time Coding device, this suboptimization pre-coding matrix that the precoder utilization is searched the unit from pre-coding matrix carries out precoding processing to the received signal, precoding processing result carries out the IFFT conversion and increases Cyclic Prefix in the IFFT/CP unit, then be assigned to again on each transmitting antenna, be transferred to reception antenna.Reception antenna with the signal that receives after past Cyclic Prefix and FFT conversion, arrive in symbol decoupling zero and decoding device and the channel estimator, symbol decoupling zero and decoding device at first are separated into the signal that receives the estimated signal of corresponding primary signal constellation point, then utilize this suboptimization pre-coding matrix come from the pre-coding matrix tracking means to decode, restore first carrier wave bunch or first primary signal constantly of cycle.

Since second moment in second carrier wave or cycle, the pre-coding matrix tracking means with the contiguous pre-coding matrix group of previous optimization pre-coding matrix correspondence in this territory as current alternative code book space, the current channel condition information matrix that utilizes channel estimator to provide is selected this optimization pre-coding matrix from this space.And then repeat the above-mentioned operation of submitting to transmitting end equipment and sending and receiving end processing signals, the rest may be inferred, to the last last of carrier wave bunch or cycle constantly till.

The mimo system of certain above-mentioned Fig. 8 also can be carried out the pre-coding matrix tracing process in frequency domain and the time domain simultaneously.

To sum up, pre-coding matrix tracking scheme among the present invention utilizes channel relevancy, since second moment in second carrier wave bunch or cycle, be to estimate to dwindle alternative code book space and increase the probability that optimum pre-coding matrix is positioned at this alternative code book space from the statistical significance with the matrix Euclidean distance.Therefore, this scheme can be selected the pre-coding matrix of more optimizing based on the pre-coding matrix tracking scheme of chordal distance than existing when effectively reducing the precoding feedback information volume, thereby obtains the lower error rate, improves the mimo system performance effectively.

The above only is preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of making, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (14)

1. a pre-coding matrix tracking is characterized in that, this method comprises:

Set in advance tracking amount E, and 2 ^ELess than the pre-coding matrix number in the precoding codebook that sets in advance;

According to described tracking amount E, for each pre-coding matrix in the described precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix;

The contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence once selected before in this territory as current alternative code book space, and is selected this suboptimization pre-coding matrix in this current alternative code book space.

2. the method for claim 1 is characterized in that, described is that each pre-coding matrix in the described precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix as the contiguous pre-coding matrix group of corresponding pre-coding matrix is:

Any one pre-coding matrix in the described precoding codebook as current pre-coding matrix, is calculated the matrix Euclidean distance between all the other pre-coding matrixes and current pre-coding matrix;

Will with 2 of the matrix Euclidean distance minimum of current pre-coding matrix ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of current pre-coding matrix;

If there is the pre-coding matrix of not determining contiguous pre-coding matrix group in the described precoding codebook, then turn to one of them pre-coding matrix, repeat described definite contiguous pre-coding matrix group's operation, the whole pre-coding matrixes in handling precoding codebook.

3. method as claimed in claim 2 is characterized in that, comprises described current pre-coding matrix itself among the contiguous pre-coding matrix group of described current pre-coding matrix, perhaps, described current pre-coding matrix is got rid of outside described contiguous pre-coding matrix group.

4. as any described method in the claim 1 to 3, it is characterized in that described this territory is frequency domain;

Described contiguous pre-coding matrix group with the optimization pre-coding matrix correspondence once selected before in this territory is as before the current alternative code book space, further comprise: B10. with first carrier wave bunch as current carrier wave bunch, according to adopt empty the time processing mode in described precoding codebook, select the optimization pre-coding matrix of current carrier wave bunch, and turn to next carrier wave bunch.

5. method as claimed in claim 4, it is characterized in that, described contiguous pre-coding matrix group with the optimization pre-coding matrix correspondence once selected before in this territory is as current alternative code book space, and selects this suboptimization pre-coding matrix be in this current alternative code book space:

B11. for the current carrier wave after first carrier wave bunch bunch, with the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the last carrier wave of the current carrier wave bunch bunch alternative code book space as current carrier wave bunch, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current carrier wave bunch.

6. method as claimed in claim 5 is characterized in that, selects described in the step B11 further to comprise after the optimization pre-coding matrix of current carrier wave bunch:

Judge whether to handle all carrier waves bunch, if then finish the pre-coding matrix trace flow; Otherwise, turn to the operation of next carrier wave bunch described in the execution in step B10.

7. as any described method in the claim 1 to 3, it is characterized in that described this territory is time domain;

Described contiguous pre-coding matrix group with the optimization pre-coding matrix correspondence once selected before in this territory is as before the current alternative code book space, further comprise: B20. with in the cycle that sets in advance first constantly as current time, in the precoding codebook that sets in advance, select the optimization pre-coding matrix of current time, and turn to next constantly.

8. method as claimed in claim 7, it is characterized in that, described contiguous pre-coding matrix group with the optimization pre-coding matrix correspondence once selected before in this territory is as current alternative code book space, and selects this suboptimization pre-coding matrix be in this current alternative code book space:

B21. for the current time after first moment in the described cycle, with the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the previous moment of the current time alternative code book space as current time, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current time.

9. method as claimed in claim 7 is characterized in that, described in the step B20 with in the cycle that sets in advance first constantly as before the current time, further comprise:

Judge whether to arrive the described cycle, if then carry out described with the operation of the moment first in the cycle that sets in advance as current time; Otherwise, turn to next operation constantly described in the execution in step B20.

10. a pre-coding matrix tracking means is characterized in that, this device comprises: codebook determining module and tracking module, wherein,

Described codebook determining module is used for the matrix Euclidean distance for estimating, for each pre-coding matrix in the precoding codebook that sets in advance is determined contiguous pre-coding matrix group;

Described tracking module is for the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of once selecting before codebook determining module reads this territory, as current alternative code book space, and in this current alternative code book space, select this suboptimization pre-coding matrix;

Described pre-coding matrix tracking means further comprises: module is set, is used for setting in advance precoding codebook and tracking amount E, and 2 ^ELess than the pre-coding matrix number in the described precoding codebook;

Described tracking module reads tracking amount E and precoding codebook from described the setting the module, according to described tracking amount E, for each pre-coding matrix in the described precoding codebook is determined and 2 of its matrix Euclidean distance minimum ^EIndividual pre-coding matrix is as the contiguous pre-coding matrix group of corresponding pre-coding matrix.

11. device as claimed in claim 10, it is characterized in that, described tracking module further reads described precoding codebook from module is set, with first carrier wave bunch as current carrier wave bunch, according to adopt empty the time processing mode in described precoding codebook, select the optimization pre-coding matrix of current carrier wave bunch, and turn to next carrier wave bunch; And for the current carrier wave after first carrier wave bunch bunch, tracking module is the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the last carrier wave of the current carrier wave bunch bunch alternative code book space as current carrier wave bunch, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current carrier wave bunch.

12. device as claimed in claim 11 is characterized in that, described tracking module further judges whether to handle all carrier waves bunch, if then finish the pre-coding matrix trace flow after selecting the optimization pre-coding matrix of current carrier wave bunch; Otherwise, carry out the described operation that turns to next carrier wave bunch.

13. device as claimed in claim 10, it is characterized in that, described tracking module further reads described precoding codebook from module is set, with in the cycle that sets in advance first constantly as current time, in described precoding codebook, select the optimization pre-coding matrix of current time, and turn to next constantly; And for the current time after first moment in the described cycle, tracking module is the contiguous pre-coding matrix group of the optimization pre-coding matrix correspondence of the previous moment of the current time alternative code book space as current time, and according to adopt empty the time processing mode in this alternative code book space, select the optimization pre-coding matrix of current time.

14. device as claimed in claim 13, it is characterized in that, described tracking module first in the cycle that will set in advance constantly as current time before, further judge whether to arrive the described cycle, if then carry out described with the operation of the moment first in the cycle that sets in advance as current time; Otherwise, carry out described next operation constantly that turns to.

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