CN101394216A - Pre-coding method and codebook constructing method based on code book mode - Google Patents

Abstract

A construction method of a code book is applicable to a multi-input multi-output system of 2 sending antenna. The method comprises the following steps: dividing a theta k and a phi k to i, j angle values which have same rank and are quantified; respectively substituting the quantified angle values to a V for figuring out a matrix, and the V is indicated in the right; after using the matrix to divide the root of the number N of a data stream which waits for sending, and taking out front N rows of the matrix to get a codebook. After configuring the code book on a sending terminal and a receiving terminal, a pre-coding method which is based the code book manner executes the following steps: the receiving terminal conducts the analysis of singular values on a channel matrix which is acquired through the estimation of a channel so as to get a pre-coding matrix V of the sending terminal; the receiving terminal finds out a code book matrix which is close to the V matrix on the code book which is configured on the receiving terminal, and sends the sequence number of the code book matrix to the sending terminal; the sending terminal obtains a pre-coding matrix from the code book which is configured on the sending terminal according to the received code book matrix sequence number, and uses the pre-coding matrix to conduct the pre-coding on the data stream. The invention has the advantages of enabling the 2 sending antenna to get better performance under the condition of costing a little.

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 by 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 by 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 the plain value of V entry of a matrix need 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 by making up code book, the code book by feedback and V approximate matrix carries out precoding.

In the prior art, realize for system, as depicted in figs. 1 and 2 based on the pre-coding scheme of codebook mode.Receiving terminal is by 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, is interweaved, modulates, reconstruct code book in conjunction with the code book sequence number that receives, after information is weighted, 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 invention provides a kind of method for precoding and code book construction method, with the precoding problem of the system that solves 2 transmitting antennas based on codebook mode.

The technical solution used in the present invention is:

The invention provides a kind of method for precoding, be applied in the multi-input multi-output system of 2 transmitting antennas, θ based on codebook mode _kAnd φ _kQuantize and basis $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Construct the code book of V matrix, and with this codebook configuration behind transmitting terminal and receiving terminal, carry out following steps:

The channel matrix that a, receiving terminal obtain channel estimating carries out obtaining after the singular value decomposition pre-coding matrix V of transmitting terminal;

B, receiving terminal find and the immediate codebook matrix of V matrix from configuration code book thereon, and the sequence number of this codebook matrix are sent 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, with pre-coding matrix data stream is carried out precoding.

Further, among the step b, find the step with the immediate codebook matrix of V matrix the code book of receiving terminal on being configured in receiving terminal, specifically comprise:

B1, basis $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Obtain θ _kAnd φ _k

B2, find out and θ respectively _kAnd φ _kThe angle value of immediate quantification

With

Find the code book on being configured in receiving terminal with

With Corresponding codebook matrix.

Further, the construction method of code book comprises:

M, with θ _kAnd φ _kBe divided into the angle value of the quantification of i, a j grade respectively;

N, the substitution respectively of the angle value after will quantizing $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Obtain matrix, and, take out the preceding N row of this matrix, obtain code book behind the evolution of this matrix divided by number of data streams N to be sent.

Further, φ _kWith the pi/2 is that magnitude is divided φ _kThe phase place starting point is any; θ _kValue after the quantification is: { π/4 π/4+ pi/2 π/4+ π π/4+3 pi/2 }.

Further, φ _kValue be: { 0 pi/2 π, 3 pi/2s }.

Further, when N=2, the number of codebook matrix is 16 in the code book; When N=1, the number of codebook matrix is 8 in the code book.

The present invention also provides a kind of construction method of code book, is applied to may further comprise the steps in the multi-input multi-output system of 2 transmitting antennas:

A, with θ _kAnd φ _kBe divided into the angle value of the quantification of i, a j grade respectively;

B, the substitution respectively of the angle value after will quantizing $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Obtain matrix, and, take out the preceding N row of this matrix, obtain code book behind the evolution of this matrix divided by number of data streams N to be sent.

Further, φ _kWith the pi/2 is that magnitude is divided φ _kThe phase place starting point is any; θ _kValue after the quantification is: { π/4 π/4+ pi/2 π/4+ π π/4+3 pi/2 }.

Further, φ _kValue be: { 0 pi/2 π, 3 pi/2s }.

Further, when N=2, the number of codebook matrix is 16 in the code book; When N=1, the number of codebook matrix is 8 in the code book.

Adopt the present invention, can under the little situation of expense, make 2 system of transmit antennas obtain preferable performance.And this programme is not only applicable to the OFDMA system, equally is applicable to the system of other scheme yet.

Description of drawings

Fig. 1 is based on the transmitting antenna FB(flow block) of the pre-coding scheme of codebook mode in the prior art;

Fig. 2 is based on the reception antenna 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

Below in conjunction with drawings and Examples technical scheme of the present invention is described in detail.

Precoding based on codebook mode is on the basis of using non-codebook type precoding, selects immediate code book to carry out correspondence for the V matrix.

The method that code book makes up is as follows.

For the situation of 2 transmitting antennas, because the V matrix is a unitary matrice, 2 * 2 V matrix has self characteristics, according to its character can be with the V expression matrix:

$V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$

Wherein, φ _kBe used to characterize the phase value of V matrix, its phase place starting point is any.Can be that magnitude is divided it with the pi/2, need the feedback space resource of 2 bits.4 phase places of recommending are:

{0?π/2?π?3π/2}；

θ _kFor being used to characterize the angle that range value quantizes.In order further to reduce feedback overhead, so amplitude is not quantized, the amplitude of all elements is all equated, only utilize the phase of each element _kSo the structure code book is θ _kCan only get following 4 values:

{π/4?π/4+π/2?π/4+π?π/4+3π/2}。

The construction method of code book proposed by the invention may further comprise the steps:

To θ _kAnd φ _kAfter quantizing, the angle value of each quantification is brought into $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ In, obtain the matrix of each quantized value correspondence.According to the number N of data flow to be sent (for 2 system of transmit antennas, N=1 or 2), when N=1, first row that take out each matrix in these 16 matrixes are as code book, but because in these 16 matrixes, first row for each matrix, all exist other a matrix to equate with its first row, therefore, for Rank1 situation (being the situation of N=1), the number of the codebook matrix in this code book is 8, and is as shown in table 1; When N=2, with the evolution of 16 matrixes, obtain 16 codebook matrix of V matrix under the Rank2 situation divided by N, as shown in table 2, and it is configured to transmitting terminal and receiving terminal respectively.

The code book of V matrix under the table 1 Rank1 mode

The code book of V matrix under the table 2 Rank2 mode

Wherein, the order that the Rank1 mode refers to channel matrix is 1, only have 1 layer to use, and transmitting antenna only sends a data flow; And the Rank2 mode refers to the order of channel matrix is 2, has 2 layers to use, and transmitting antenna can send 2 data flow simultaneously.(the Rank1 mode is coefficient before the codebook matrix

The Rank2 mode is ) effect be to make transmitting power normalization, can not increase transmitting power because of using the code book weighting.

Code book adopts this code book to carry out the method for precoding after making up and finishing, and may further comprise the steps:

The first step: receiving terminal obtains channel matrix H according to channel estimating, and it 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: from configuration code book thereon, find and the immediate codebook matrix of V matrix, and the sequence number of this codebook matrix is fed back to transmitting terminal with this sequence number; The step of searching immediate codebook matrix specifically comprises:

(1) according to formula $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ , the V matrix is decomposed, obtain θ wherein _kAnd φ _k

(2) θ that finds out and try to achieve _kAnd φ _kThe angle value of immediate quantification obtains and the corresponding codebook matrix of the angle value of this quantification, and this codebook matrix is the codebook matrix the most approaching with the V matrix;

The 3rd step: transmitting terminal obtains corresponding pre-coding matrix according to the sequence number that receives from configuration code book thereon, use this matrix according to prior art data stream to be carried out precoding.

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 (10)

1, a kind of method for precoding based on codebook mode is applied to it is characterized in that, to θ in the multi-input multi-output system of 2 transmitting antennas _kAnd φ _kQuantize and basis $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left(j{\mathrm{\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Construct the code book of V matrix, this codebook configuration behind transmitting terminal and receiving terminal, carried out following steps:

The channel matrix that a, described receiving terminal obtain channel estimating carries out obtaining after the singular value decomposition pre-coding matrix V of described transmitting terminal;

B, described receiving terminal find and the immediate codebook matrix of described V matrix from configuration code book thereon, and the sequence number of this codebook matrix are sent to described transmitting terminal;

C, described transmitting terminal be according to the sequence number of the described codebook matrix that receives, obtain pre-coding matrix the code book on being configured in described transmitting terminal after, with described pre-coding matrix data stream is carried out precoding.

2, the method for claim 1 is characterized in that, among the step b, finds the step with the immediate codebook matrix of described V matrix the code book of described receiving terminal on being configured in described receiving terminal, specifically comprises:

B1, basis $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left(j{\mathrm{\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Obtain θ _kAnd φ _k

B2, find out and described θ respectively _kAnd φ _kThe angle value of immediate quantification

With

Find the code book on being configured in described receiving terminal with described

With

Corresponding codebook matrix.

3, the method for claim 1 is characterized in that, the construction method of described code book comprises:

M, with θ _kAnd φ _kBe divided into the angle value of the quantification of i, a j grade respectively;

N, the substitution respectively of the angle value after will quantizing $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left(j{\mathrm{\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Obtain matrix, and, take out the preceding N row of this matrix, obtain code book behind the evolution of this matrix divided by number of data streams N to be sent.

4, as claim 1 or 3 described methods, it is characterized in that described φ _kWith the pi/2 is that magnitude is divided, described φ _kThe phase place starting point is any; Described θ _kValue after the quantification is: { π/4 π/4+ pi/2 π/4+ π π/4+3 pi/2 }.

5, method as claimed in claim 4 is characterized in that, described φ _kValue be: { 0 pi/2 π, 3 pi/2s }.

6, method as claimed in claim 4 is characterized in that, when N=2, the number of codebook matrix is 16 in the code book; When N=1, the number of codebook matrix is 8 in the code book.

7, a kind of construction method of code book is applied to it is characterized in that in the multi-input multi-output system of 2 transmitting antennas, may further comprise the steps:

A, with θ _kAnd φ _kBe divided into the angle value of the quantification of i, a j grade respectively;

B, the substitution respectively of the angle value after will quantizing $V=\left[\begin{array}{cc}\cos \left({\mathrm{\θ}}_k\right)& -\sin \left({\mathrm{\θ}}_k\right)\\ \sin \left({\mathrm{\θ}}_k\right)\exp \left(j{\mathrm{\φ}}_k\right)& \cos \left({\mathrm{\θ}}_k\right)\exp \left({\mathrm{j\φ}}_k\right)\end{array}\right]$ Obtain matrix, and, take out the preceding N row of this matrix, obtain code book behind the evolution of this matrix divided by number of data streams N to be sent.

8, method as claimed in claim 7 is characterized in that, described φ _kWith the pi/2 is that magnitude is divided, described φ _kThe phase place starting point is any; Described θ _kValue after the quantification is: { π/4 π/4+ pi/2 π/4+ π π/4+3 pi/2 }.

9, method as claimed in claim 7 is characterized in that, described φ _kValue be: { 0 pi/2 π, 3 pi/2s }.

10, method as claimed in claim 8 is characterized in that, when N=2, the number of codebook matrix is 16 in the code book; When N=1, the number of codebook matrix is 8 in the code book.

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