CN101394256B - Pre-coding method and codebook constructing method based on codebook mode - Google Patents

Abstract

The invention discloses a codebook construction method, which is applied to a multiple input and multiple output (MIMO) system with 4 transmitting antennae, a plurality of codebook matrices are calculated according to Theta being equal to P<m>E<k>MDFTP<n>, wherein the values of m, k and n are positive integers; E, MDFT and P are as shown in the right. Based on a pre-coding method in the codebook manner, a codebook is configured on a sending terminal and a receiving terminal after the codebook construction is finished, and then executed as follows: a channel matrix is decomposed by the receiving terminal after the channel matrix is obtained according to channel estimation; the corresponding codebook matrix is chosen from the codebook by the receiving terminal according to the number N of transmitting antennae which is required to be used in the sending terminal; the serial number of the codebook matrix feeds back to the sending terminal; the data stream is processed predicting coding by the front N of predicting coding matrix after a pre-coding matrix is obtained from the codebook configured on the sending terminal by the sending terminal according to the serial number of the received codebook matrix. By adopting the method, the feedback overhead of the codebook is 6 bits; at the same time, by using a combination of the different powers of a plurality of cyclic shift matrices, a four-dimensional space is covered in most excellent quality and most uniformity.

Description

A kind of method for precoding and code book construction method based on codebook mode

Technical field

The present invention relates to a kind of multiple-input and multiple-output (MIMO) mobile radio system, relate in particular to a kind of method for precoding and code book construction method based on codebook mode.

Background technology

(Multiple Input and Multiple Output, MIMO) system becomes in LTE (third generation mobile long evolving system) research the extremely technology paid close attention to of people owing to effectively improving channel capacity to multiple-input and multiple-output.Use precoding technique to carry out multiplexing between multiple data stream and the antenna and can more effectively utilize the existing channel resource, can improve power system capacity through power division, and can reduce the interference between the data flow, improve the overall performance of system data flow.Therefore precoding technique also becomes new research focus.

To introduce the basic theories method and the implementation of precoding in this part; The basic thought of this method is that receiving terminal obtains channel matrix through channel estimating, and this channel matrix is carried out obtaining transmitting terminal and employed pre-coding matrix V of receiving terminal and U after the singular value decomposition (SVD).Use i column vector of V matrix to send data flow as its weights when transmitting antenna; And i the column vector that reception antenna uses the U matrix (i=1 during as its weights; 2 ... s) during receiving data stream, this data flow just and only in i spatial sub-channel, transmit.Transmitting terminal can access the situation of the concrete element value of V matrix, is called desirable method for precoding, promptly based on the method for precoding of non-codebook mode.Based on drawing of codebook mode is owing to need the plain value of V entry of a matrix be fed back to transmitting terminal; But feedback space is not enough to transmit the information of all elements in the V matrix; So need simplify feedback information through making up code book, the code book through feedback and V approximate matrix carries out precoding.

In the prior art, realize for system based on the pre-coding scheme of codebook mode, as depicted in figs. 1 and 2.Receiving terminal is through the SVD decomposition computation; In precoding weights code book, search out an immediate code book, the sequence number of this code book is fed back to transmitting terminal, after the information via that transmitting terminal produces information source is encoded, interweaved, modulates; Code book sequence number in conjunction with receiving reconstructs code book; After information carried out weighting, after OFDMA (OFDM) modulation, send to receiving terminal; After receiving terminal is received, it is carried out restoring this information after OFDMA demodulation, detection, demodulation, deinterleaving, the channel decoding.

Summary of the invention

The technical problem that the present invention will solve has provided a kind of method for precoding and code book construction method based on codebook mode, to solve the precoding problem of 4 system of transmit antennas.

The technical scheme that the present invention adopts is:

The invention provides a kind of method for precoding, be applied to the multi-input multi-output system of 4 transmitting antennas, earlier according to Θ=P based on codebook mode ^mE ^kM _DFTP ⁿGenerate a plurality of codebook matrix, wherein: m, k, n are positive integer,

$E=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& e^{j2\mathrm{\&pi;}\frac{1}{16}}& 0& 0\\ 0& 0& e^{j2\mathrm{\&pi;}\frac{2}{16}}& 0\\ 0& 0& 0& e^{j2\mathrm{\&pi;}\frac{3}{16}}\end{array}\right],$ $M_{\mathrm{DFT}}=\frac{1}{\sqrt{4}}\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& j& -1& -j\\ 1& -1& 1& -1\\ 1& -j& -1& j\end{array}\right],$ $P=\left[\begin{array}{cccc}0& 0& 0& 1\\ 1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\end{array}\right],$

Then with this codebook configuration at transmitting terminal and receiving terminal; Carry out following steps again:

A, receiving terminal decompose channel matrix after obtaining channel matrix according to channel estimating;

B, receiving terminal according to transmitting terminal the number N of the transmitting antenna that will use, from code book, select corresponding codebook matrix, and the sequence number of codebook matrix fed back to transmitting terminal;

C, transmitting terminal be according to the sequence number of the codebook matrix that receives, obtain pre-coding matrix the code book on being configured in transmitting terminal after, use the preceding N of pre-coding matrix be listed as data flowed and carry out precoding.

Further, the value of m, k, n travels through 1,2,3,4 respectively.

Further, according to Θ=P ^mE ^kM _DFTP ⁿThe codebook matrix number that generates is 64.

Further, among the step a, said receiving terminal is the pre-coding matrix of transmitting terminal and the pre-coding matrix of receiving terminal through singular value decomposition with channel matrix decomposition; Among the step b, receiving terminal selects the method for codebook matrix to comprise following two kinds:

First kind: receiving terminal is selected the immediate codebook matrix of pre-coding matrix with transmitting terminal from configuration code book above that;

Second kind: calculate with the pre-coding matrix of channel matrix and receiving terminal and to make signal to noise ratio reach peaked codebook matrix.

Further, when the number of the transmitting antenna that sends data flow is N, with the evolution of this codebook matrix divided by N.

The present invention also provides a kind of construction method of code book, is applied to the multi-input multi-output system of 4 transmitting antennas, according to Θ=P ^mE ^kM _DFTP ⁿCalculate a plurality of codebook matrix, wherein: the value of m, k, n is a positive integer,

$E=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& e^{j2\mathrm{\&pi;}\frac{1}{16}}& 0& 0\\ 0& 0& e^{j2\mathrm{\&pi;}\frac{2}{16}}& 0\\ 0& 0& 0& e^{j2\mathrm{\&pi;}\frac{3}{16}}\end{array}\right],$ $M_{\mathrm{DFT}}=\frac{1}{\sqrt{4}}\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& j& -1& -j\\ 1& -1& 1& -1\\ 1& -j& -1& j\end{array}\right],$ $P=\left[\begin{array}{cccc}0& 0& 0& 1\\ 1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\end{array}\right].$

Further, the value of m, k, n travels through 1,2,3,4 respectively.

Further, according to Θ=P ^mE ^kM _DFTP ⁿThe codebook matrix number that generates is 64.

Further, when the number of the transmitting antenna that sends data flow is N, with the evolution of this codebook matrix divided by N.

Adopt the present invention, the feedback overhead of code book is 6 bits, utilizes the inferior combination of different powers of several cycles shift matrix to accomplish optimum, covering the most uniformly for 4 dimension spaces simultaneously.

Description of drawings

Fig. 1 is based on the transmitter flow process block diagram of the pre-coding scheme of codebook mode in the prior art;

Fig. 2 is based on the receiver FB(flow block) of the pre-coding scheme of codebook mode in the prior art;

Fig. 3 is the flow chart of method for precoding in the embodiment of the invention.

Embodiment

To combine accompanying drawing and embodiment that technical scheme of the present invention is explained in more detail below.

The mode of the structure code book that the present invention adopted is:

Θ＝P ^mE ^kM _DFTP ⁿ

Wherein: m, k, n=1,2,3,4,

$E=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& e^{j2\mathrm{\&pi;}\frac{1}{16}}& 0& 0\\ 0& 0& e^{j2\mathrm{\&pi;}\frac{2}{16}}& 0\\ 0& 0& 0& e^{j2\mathrm{\&pi;}\frac{3}{16}}\end{array}\right],$ $M_{\mathrm{DFT}}=\frac{1}{\sqrt{4}}\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& j& -1& -j\\ 1& -1& 1& -1\\ 1& -j& -1& j\end{array}\right],$ $P=\left[\begin{array}{cccc}0& 0& 0& 1\\ 1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\end{array}\right]$

The P matrix is the cyclic shift matrices of row, row, and it is to make matrix do cyclic shift to row that the effect of P matrix is taken advantage of on the right side, and the effect of premultiplication P matrix is to make matrix do cyclic shift to row; M _DFTMatrix is the basis matrix that the most often uses when making up code book, and its characteristic is can the optimum discretization of accomplishing the space, makes the epigranular of spatial distribution; The effect of E matrix is to change the phase intervals granularity; 4 powers of P, E matrix equal P, E matrix self, so the two all is that power is had circulative matrix.

The value of 3 exponent m, k, p all need travel through 1,2,3,4, therefore can produce 64 matrixes, promptly can produce 64 codebook matrix, and the feedback overhead of this codebook mode is 6bit.We with these 64 matrixes be designated as respectively Mat_0, Mat_1 ..., Mat_i ..., Mat_63.The code book tabulation under the situation of using 1 transmit antennas (Rank1), use 2 transmit antennas (Rank2), use 3 transmit antennas (Rank3), use 4 transmit antennas (Rank4) respectively is as shown in table 1.

The tabulation of table 14 transmitting antenna code books

Numeral in " [] " is being carried out the columns of precoding time institute weighting value in matrix, and the 1st row and the 2nd of getting matrix like [12] expression are listed as, and preceding 3 row of matrix are got in [123] expression, and other in like manner.Is power to be carried out normalization handle with matrix divided by the purpose of a divisor, makes when transmitting antenna adopts this codebook matrix to send data, can not increase transmitting power.This divisor should be the evolution of the number of antennas that is used for sending data flow in the transmitting antenna.As under the Rank2 mode; 63 this matrix M of number at_63 (:; [12])/ preceding two row of Mat_63 matrix are got in expression, 1/

effect be power to be carried out normalization handle.

Before carrying out precoding, need to generate codebook matrix according to the method for generating codebooks of above-mentioned 4 transmitting antennas, as shown in table 1, and with this codebook configuration at transmitting terminal and receiving terminal.

Carry out the method for precoding on this basis, as shown in Figure 3, may further comprise the steps:

The first step: receiving terminal obtains channel matrix H according to channel estimating, and the H matrix is carried out obtaining the pre-coding matrix V of transmitting terminal and the pre-coding matrix U of receiving terminal after SVD decomposes;

Second step: the number of antennas N that receiving terminal will use according to transmitting terminal, select only codebook matrix, and the sequence number of this codebook matrix fed back to transmitting terminal from above-mentioned code book.Select the method for optimum codebook matrix to have following two kinds:

First kind: selection is only codebook matrix with the immediate codebook matrix of V matrix;

Second kind: calculate with matrix H and U and to make signal to noise ratio reach peaked codebook matrix;

The 3rd step: transmitting terminal is found out required precoding codebook matrix according to the sequence number of the codebook matrix that receives from configuration code book tabulation above that, use the preceding N of this codebook matrix be listed as to the data flow that will launch carry out precoding.

This programme is applicable to the OFDMA system, equally also is applicable to the system of other scheme.

Certainly; The present invention also can have other various embodiments; Under the situation that does not deviate from spirit of the present invention and essence thereof; Those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims (9)

1. method for precoding based on codebook mode is applied to the multi-input multi-output system of 4 transmitting antennas, it is characterized in that, earlier according to Θ=P ^mE ^kM _DFTP ⁿGenerate a plurality of codebook matrix, wherein: m, k, n are positive integer,

$E=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& e^{j2\mathrm{\&pi;}\frac{1}{16}}& 0& 0\\ 0& 0& e^{j2\mathrm{\&pi;}\frac{2}{16}}& 0\\ 0& 0& 0& e^{j2\mathrm{\&pi;}\frac{3}{16}}\end{array}\right],$ $M_{\mathrm{DFT}}=\frac{1}{\sqrt{4}}\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& j& -1& -j\\ 1& -1& 1& -1\\ 1& -j& -1& j\end{array}\right],$ $P=\left[\begin{array}{cccc}0& 0& 0& 1\\ 1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\end{array}\right],$

Then with this codebook configuration at transmitting terminal and receiving terminal; Carry out following steps again:

A, receiving terminal decompose said channel matrix after obtaining channel matrix according to channel estimating;

B, said receiving terminal according to said transmitting terminal the number N of the transmitting antenna that will use, from said code book, select corresponding codebook matrix, and the sequence number of said codebook matrix fed back to said transmitting terminal;

C, said transmitting terminal be according to the sequence number of the said codebook matrix that receives, obtain pre-coding matrix the code book on being configured in said transmitting terminal after, use the preceding N of said pre-coding matrix be listed as data flowed and carry out precoding.

2. the method for claim 1 is characterized in that, the value of m, k, n travels through 1,2,3,4 respectively.

3. the method for claim 1 is characterized in that, according to Θ=P ^mE ^kM _DFTP ⁿThe codebook matrix number that generates is 64.

4. the method for claim 1 is characterized in that, among the step a, said receiving terminal is the pre-coding matrix of said transmitting terminal and the pre-coding matrix of said receiving terminal through singular value decomposition with said channel matrix decomposition; Among the step b, said receiving terminal selects the method for codebook matrix to comprise following two kinds:

First kind: said receiving terminal is selected the immediate codebook matrix of pre-coding matrix with said transmitting terminal from configuration code book above that;

Second kind: calculate with the pre-coding matrix of said channel matrix and said receiving terminal and to make signal to noise ratio reach peaked codebook matrix.

5. the method for claim 1 is characterized in that, when the number of the transmitting antenna that sends data flow is N, with the evolution of this codebook matrix divided by N.

6. the collocation method of a code book is applied to the multi-input multi-output system of 4 transmitting antennas, it is characterized in that, according to Θ=P ^mE ^kM _DFTP ⁿCalculate a plurality of codebook matrix, wherein: the value of m, k, n is a positive integer,

$E=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& e^{j2\mathrm{\&pi;}\frac{1}{16}}& 0& 0\\ 0& 0& e^{j2\mathrm{\&pi;}\frac{2}{16}}& 0\\ 0& 0& 0& e^{j2\mathrm{\&pi;}\frac{3}{16}}\end{array}\right],$ $M_{\mathrm{DFT}}=\frac{1}{\sqrt{4}}\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& j& -1& -j\\ 1& -1& 1& -1\\ 1& -j& -1& j\end{array}\right],$ $P=\left[\begin{array}{cccc}0& 0& 0& 1\\ 1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\end{array}\right];$

Then with this codebook configuration at transmitting terminal and receiving terminal.

7. method as claimed in claim 6 is characterized in that the value of m, k, n travels through 1,2,3,4 respectively.

8. method as claimed in claim 6 is characterized in that, according to Θ=P ^mE ^kM _DFTP ⁿThe codebook matrix number that generates is 64.

9. method as claimed in claim 6 is characterized in that, when the number of the transmitting antenna that sends data flow is N, with the evolution of this codebook matrix divided by N.

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