CN101958771B - Eight antenna codebook design method by reusing LTE codebook - Google Patents

Abstract

The invention provides an eight antenna codebook design method by reusing an LTE codebook, which comprises the following steps of: based on a rotary DFT codebook, generating an eight antenna codebook of which the order is 1; recombining an LTE R8 four antenna HH codebook to generate an eight antenna LTE-A codebook of which the order is 8; and selecting subsets of column vectors from high-order code words according to a sequence that the order is arranged from high to low so as to generate low-order code words, and performing transmission power. The method not only keeps the backward compatibility of the LTE-A, but also naturally inherits various good properties of the LTE R8 codebook, including nesting, 8-PSK finite character table, a constant module and the like so as to effectively reduce the complexity of CQI calculation and code word selection on user equipment UE side and avoid unbalanced transmission power.

Description

Reuse the method for designing eight-antenna codebook of LTE code book

Technical field

The present invention relates to multiple-input and multiple-output (Multiple Input Multiple Output) field of wireless communications systems, particularly a kind of method for designing eight-antenna codebook based on the LTE-Advanced system.

Background technology

MIMO technology based on Limited Feedback all receives much concern in academia and industrial circle, not only becomes the basic part of many communication standards (such as 3GPP LTE), and is the key technology that satisfies the LTE-Advanced system requirements.List of references 1 " TR 36.814v1.0.0, Further Advancementsfor E-UTRA Physical Layer Aspects " points out that LTE-Advanced system descending peak rate should reach 1Gbps, and the availability of frequency spectrum is 30bps/Hz.Make transmission bandwidth be increased to 100MHz by carrier aggregation technology, and unite and use 4 layers of MIMO space multiplexing technique can reach the peak rate demand of 1Gbps.Yet the availability of frequency spectrum of 30bps/Hz requires the LTE-Advanced down emission system must expand to eight antennas, therefore is necessary for LTE-Advanced eight antenna systems redesign code book and corresponding feedback mechanism.

At present, the codebook design schemes of discussing in most of spheres of learning all is based on the independent same distribution Rayleigh channel, is exactly a kind of effective tool that designs the high-performance code book such as Grassmanian line/subspace packing (GLP/GSP).Yet the mimo channel in the real system and Rayleigh channel have huge difference, and for example, actual mimo channel may exist serious spatial coherence and sighting distance composition.In addition, because dual-polarized antenna configuration can effectively reduce antenna distance, the reduction system is to the demand of physical space, thereby important application is arranged in practice.Therefore, list of references 2 " ClerckxB; YongXing Z; Sungjin K.Practical Codebook Design for Limited FeedbackSpatial Multiplexing.ICC; 2008 " is pointed out, in true wireless communication system, a basic demand of code book design is to adapt to non-correlation channel, correlated channels and dual polarization channel.

The more important thing is, the code book of the different orders of GLP/GSP algorithm independent optimization, each in the code word all from

( Represent a kind of plural number) in select.This mode not only takies a large amount of memory spaces, and can cause a large amount of complex operations when codeword selection, thereby has improved computation complexity, and this is more obvious after using rank adaptation (rank adaptation) mechanism.In addition, the power imbalances (power amplifier imbalance) between transmitting antenna is avoided in the real system requirement as far as possible, namely require power-balance between transmitting antenna, yet the GLP/GSP algorithm can not the guaranteed output balance.

The 3GPP LTE R8 standard that proposes in the list of references 3 " TS 36.211V8.6.0; Evolved Universal Terrestrial RadioAccess (E-UTRA): Physical Channels and Modulation (Release 8) " has adopted four antenna codebooks based on Householder (HH) conversion, owing to possess the good characteristics such as nested (nesting) and limited character list (finite alphabet), should effectively reduce based on four antenna codebooks of HH conversion the design complexities of UE side hardware device, the permanent mould that this code book possesses (constant modulus) characteristic has also guaranteed the power-balance between antenna simultaneously.But be based on four antenna codebook mentalities of designing of HH conversion and be not suitable for the eight-antenna codebook design of LTE-Advanced system, this is because be difficult to guarantee constant modulus property (seeing also list of references 4 " R1-090388; " Precoding options for 8-Tx antennas inLTE-A DL "; Marvell ") after the octuple vector process HH conversion, can't avoid power imbalances.Therefore need new mode to produce the LTE-A eight-antenna codebook.

A kind of code book based on Complex Hadamard Transformation (CHT) is proposed in list of references 5 " R1-091246; " Codebook Design for 8-Tx Transmission inLTE-A "; Samsung ", this code book has been inherited the excellent characteristic of most of LTE R8 four antenna codebooks, but can not be used for eight-antenna codebook.In list of references 6 " R1-091281; " DL MIMOcodebook "; Huawei ", utilize the DFT code book of rotation to improve the performance of CHT code book when low-rank, but because this code book is not followed nested and 8-PSK character list characteristic, cause the UE computation complexity higher.

In sum, in view of a large amount of different channel circumstances, the factors such as codebook selecting and CQI computation complexity and power imbalances are so that existing code book design can't satisfy the demand of LTE-Advanced system.

Summary of the invention

The objective of the invention is to overcome existing code book and can't satisfy the defective of the demand of LTE-A system, thereby a kind of code book method for designing that can satisfy the LTE-A system is provided.

To achieve these goals, the invention provides a kind of method for designing eight-antenna codebook of the LTE of reusing code book, the method comprises:

Step 1), based on the DFT code book of rotation, generate order and be 1 eight-antenna codebook;

Step 2), reconfigure the four antenna HH code books of LTE R8, generate order and be 8 eight antenna LTEs-Advanced code book;

The order of step 3), arranging from high to low according to order, take step 2) order that obtains as 8 eight antenna LTEs-the Advanced code book is the basis, from the code word of high order, select the subset of column vector, generate the code word of low-rank, and carry out transmitting power normalization, thereby generate the code book of order r from 7 to 2;

Step 4), combination step 1)-step 3) resulting result, generate eight antenna LTEs-Advanced code book.

In the technique scheme, described step 1) comprising:

Step 1-1), definition 8 * 8DFT code book DFT ₈

${\mathrm{DFT}}_8=\left[\begin{array}{cccccccc}1& 1& 1& 1& 1& 1& 1& 1\\ 1& \frac{1+j}{\sqrt{2}}& j& \frac{-1+j}{\sqrt{2}}& -1& \frac{-1-j}{\sqrt{2}}& -j& \frac{1-j}{\sqrt{2}}\\ 1& j& -1& -j& 1& j& -1& -j\\ 1& \frac{-1+j}{\sqrt{2}}& -j& \frac{1+j}{\sqrt{2}}& -1& \frac{1-j}{\sqrt{2}}& j& \frac{-1-j}{\sqrt{2}}\\ 1& -1& 1& -1& 1& -1& 1& -1\\ 1& \frac{-1-j}{\sqrt{2}}& j& \frac{1-j}{\sqrt{2}}& -1& \frac{1+j}{\sqrt{2}}& -j& \frac{-1+j}{\sqrt{2}}\\ 1& -j& -1& j& 1& -j& -1& j\\ 1& \frac{+1-j}{\sqrt{2}}& -j& \frac{-1-j}{\sqrt{2}}& -1& \frac{-1+j}{\sqrt{2}}& j& \frac{1+j}{\sqrt{2}}\end{array}\right]$

Step 1-2), the definition size is 8 * 8 rotation diagonalizable matrix D ₁Be unit matrix, definition D ₂For

Wherein diag represents diagonalizable matrix;

Step 1-3), by aforesaid 8 * 8DFT code book DFT ₈, rotation diagonalizable matrix D ₁And described matrix D ₂The generation order is 1 eight-antenna codebook CB ⁽¹⁾, wherein:

${\mathrm{CB}}^{\left(1\right)}=\{\frac{1}{\sqrt{8}}{D}_1\×{\mathrm{DFT}}_8,\frac{1}{\sqrt{8}}{D}_2\×{\mathrm{DFT}}_8\}.$

In the technique scheme, described step 2) comprising:

Step 2-1), definition spin matrix U at the tenth of the twelve Earthly Branches _Rot, the computing formula of this matrix is as follows:

$U_{\mathrm{rot}}=\frac{1}{\sqrt{2}}\×\left[\begin{array}{cccccccc}1& 0& 0& 0& -1& 0& 0& 0\\ 0& 1& 0& 0& 0& -1& 0& 0\\ 0& 0& 1& 0& 0& 0& -1& 0\\ 0& 0& 0& 1& 0& 0& 0& -1\\ 1& 0& 0& 0& 1& 0& 0& 0\\ 0& 1& 0& 0& 0& 1& 0& 0\\ 0& 0& 1& 0& 0& 0& 1& 0\\ 0& 0& 0& 1& 0& 0& 0& 1\end{array}\right]$

Step 2-2), be to select a code word 4 LTE R8 four antenna codebooks from order, be labeled as A _n, make A _n=W _n, n=1～16, wherein W _nRepresent that this order is n code word in 4 LTE R8 four antenna codebooks;

Step 2-3), from step 2-2) described in order be to select another code word 4 LTE R8 four antenna codebooks, be labeled as B _n, its computing formula is as follows:

B ₀＝W ₄ B ₁＝W ₅ B ₂＝W ₆ B ₃＝W ₇

B ₄＝W ₁ B ₅＝W ₀ B ₆＝W ₃ B ₇＝W ₂

B ₈＝W ₆ B ₉＝W ₇ B ₁₀＝W ₄ B ₁₁＝W ₅

B ₁₂＝W ₃ B ₁₃＝W ₂ B ₁₄＝W ₁ B ₁₅＝W ₀

Step 2-4), at the resulting code word A of abovementioned steps _n, code word B _nAnd the tenth of the twelve Earthly Branches spin matrix U _RotThe basis on, generate order and be n code word in 8 the LTE-Advanced eight-antenna codebook

This code word can be expressed as:

${\mathrm{CB}}_n^{\left(8\right)}=\frac{1}{\sqrt{2}}\×U_{\mathrm{rot}}\×\left[\begin{array}{cc}{A}_n& 0_{4\×4}\\ 0_{4\×4}& -B_n\end{array}\right]$

Step 2-5), be that 80 to 15 Number character carries out column permutation to order, form final order and be 8 code word;

Step 2-6), be in the of 0 from the n value, repeating step 2-4) and step 2-5), until the n value is 15, generate order and be all 16 code words in 8 the LTE-Advanced eight-antenna codebook, finally obtain order and be 8 LTE-Advanced eight-antenna codebook CB ⁽⁸⁾

In the technique scheme, described step 3) comprising:

Step 3-1), initialization r=7;

Step 3-2), from order be the code book CB of r+1 ^(r+1)Code word

Middle deletion one row are the code word of r as order with resulting result Column vector;

Step 3-3), according to formula "

N=0～15 " to step 3-2) code word that generates carries out the normalization of transmitting power, namely all code words multiply by a transmitting power normalization factor

Satisfy equation "

N=0～15 ", finally forming order is the code book CB of r ^(r)

Step 3-4), make r from subtracting 1, repeat above-mentioned steps 3-2) to step 3-4), thereby obtain the code book of order from 7 to 2.

The invention has the advantages that:

The present invention not only keeps the backwards compatibility of LTE-A, and a lot of good characteristics of LTE R8 code book have naturally been inherited, comprise the limited character list of nested, 8-PSK and permanent mould etc., UE side CQI calculates and the complexity of codeword selection thereby effectively reduce, and avoids transmitting power unbalance.

Description of drawings

Fig. 1 is method flow diagram of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is illustrated.

Consider good characteristics such as nested and limited character list that the four antenna HH code books of LTE R8 possess and based on the DFT code book of the rotation superperformance at low-rank, the present invention combines these two kinds of code books and generates the eight-antenna codebook that is applicable to the LTE-Advanced system.The generation method is as follows:

Step 1, based on the DFT code book of rotation, generate order and be 1 eight-antenna codebook CB ⁽¹⁾

Step 2, reconfigure the four antenna HH code books of LTE R8, generate order and be 8 eight antenna LTEs-Advanced code book CB ⁽⁸⁾

Eight antenna LTEs as 8 of step 3, the order of arranging from high to low according to order, the order that obtains take step 2-Advanced code book CB ⁽⁸⁾Be the basis, from the code word of high order, select the subset of column vector, generate the code word of low-rank, and carry out transmitting power normalization, thereby generate the code book CB of order r from 7 to 2 ^(r)

In one embodiment of the invention, aforesaid step 1 may further comprise the steps:

Step 1.1, one 8 * 8 irrotational DFT code book DFT of definition ₈As follows:

${\mathrm{DFT}}_8=\left[\begin{array}{cccccccc}1& 1& 1& 1& 1& 1& 1& 1\\ 1& \frac{1+j}{\sqrt{2}}& j& \frac{-1+j}{\sqrt{2}}& -1& \frac{-1-j}{\sqrt{2}}& -j& \frac{1-j}{\sqrt{2}}\\ 1& j& -1& -j& 1& j& -1& -j\\ 1& \frac{-1+j}{\sqrt{2}}& -j& \frac{1+j}{\sqrt{2}}& -1& \frac{1-j}{\sqrt{2}}& j& \frac{-1-j}{\sqrt{2}}\\ 1& -1& 1& -1& 1& -1& 1& -1\\ 1& \frac{-1-j}{\sqrt{2}}& j& \frac{1-j}{\sqrt{2}}& -1& \frac{1+j}{\sqrt{2}}& -j& \frac{-1+j}{\sqrt{2}}\\ 1& -j& -1& j& 1& -j& -1& j\\ 1& \frac{+1-j}{\sqrt{2}}& -j& \frac{-1-j}{\sqrt{2}}& -1& \frac{-1+j}{\sqrt{2}}& j& \frac{1+j}{\sqrt{2}}\end{array}\right]---\left(1\right)$

Step 1.2, definition size are 8 * 8 rotation diagonalizable matrix D ₁Be unit matrix, definition D ₂For

Wherein diag represents diagonalizable matrix.

Step 1.3, by aforesaid 8 * 8DFT code book DFT ₈, rotation diagonalizable matrix D ₁And described matrix D ₂The generation order is 1 eight-antenna codebook CB ⁽¹⁾, the expression mode of this code book describes in the concrete code word table 1 below in this code book shown in following formula (2).

${\mathrm{CB}}^{\left(1\right)}=\{\frac{1}{\sqrt{8}}{D}_1\×{\mathrm{DFT}}_8,\frac{1}{\sqrt{8}}{D}_2\×{\mathrm{DFT}}_8\}---\left(2\right)$

Table 1

In table 1,

In one embodiment, step 2 specifically may further comprise the steps:

Step 2.1, definition spin matrix U at the tenth of the twelve Earthly Branches _Rot, the expression formula of this matrix is as follows:

$U_{\mathrm{rot}}=\frac{1}{\sqrt{2}}\×\left[\begin{array}{cccccccc}1& 0& 0& 0& -1& 0& 0& 0\\ 0& 1& 0& 0& 0& -1& 0& 0\\ 0& 0& 1& 0& 0& 0& -1& 0\\ 0& 0& 0& 1& 0& 0& 0& -1\\ 1& 0& 0& 0& 1& 0& 0& 0\\ 0& 1& 0& 0& 0& 1& 0& 0\\ 0& 0& 1& 0& 0& 0& 1& 0\\ 0& 0& 0& 1& 0& 0& 0& 1\end{array}\right]---\left(3\right)$

Step 2.2, be to select a code word 4 LTE R8 four antenna codebooks from order, be labeled as A _n, make A _n=W _n, n=1～16, wherein W _nRepresent that this order is n code word in 4 LTE R8 four antenna codebooks.

Step 2.3, be to select another code word 4 the LTE R8 antenna codebook from the order described in the step 2.2, be labeled as B _n, the computing formula of this code word is as follows:

B ₀＝W ₄ B ₁＝W ₅ B ₂＝W ₆ B ₃＝W ₇

B ₄＝W ₁ B ₅＝W ₀ B ₆＝W ₃ B ₇＝W ₂ (4)

B ₈＝W ₆ B ₉＝W ₇ B ₁₀＝W ₄ B ₁₁＝W ₅

B ₁₂＝W ₃ B ₁₃＝W ₂ B ₁₄＝W ₁ B ₁₅＝W ₀

Step 2.4, at the resulting code word A of abovementioned steps _n, code word B _nAnd the tenth of the twelve Earthly Branches spin matrix U _RotThe basis on, generate order and be n code word in 8 the LTE-Advanced eight-antenna codebook

This code word can be expressed as:

${\mathrm{CB}}_n^{\left(8\right)}=\frac{1}{\sqrt{2}}\×U_{\mathrm{rot}}\×\left[\begin{array}{cc}{A}_n& 0_{4\×4}\\ 0_{4\×4}& -B_n\end{array}\right]---\left(5\right)$

Step 2.5, be that 80 to 15 Number character carries out column permutation to order in the resulting code book of previous step, the orders of original eight row are replaced according to table 2 by 1,2,3,4,5,6,7,8, form final order and be 8 code word.

Table 2

Step 2.6: be in the of 0 from the n value, repeating step 2.4 and step 2.5 until the n value is 15, generate order and are all 16 code words in 8 the LTE-Advanced eight-antenna codebook, finally obtain order and be 8 LTE-Advanced eight-antenna codebook CB ⁽⁸⁾

In one embodiment, step 3 specifically may further comprise the steps:

Step 3.1, initialization r=7.

Step 3.2, be the code book CB of r+1 from order ^(r+1)Code word Middle deletion one row are the code word of r as order with resulting result

Column vector.Wherein, in the deletion code word

In when row, delete which row and can realize by reference table 2.

Step 3.3, according to formula (6) code word that step 3.2 generates is carried out the normalization of transmitting power, be all code words and multiply by a transmitting power normalization factor

Thereby satisfy equation (7), finally forming order is the code book CB of r ^(r)

${\mathrm{CB}}_n^{\left(r\right)}=\sqrt{\frac{r+1}{r}}\×{\mathrm{CB}}_n^{\left(r\right)}$ n＝0～15 (6)

${\mathrm{CB}}_n^{\left(r\right)H}\×{\mathrm{CB}}_n^{\left(r\right)}=\frac{1}{r}{I}_{r\×r}\mathrm{or\; tr}({\mathrm{CB}}_n^{r\left(H\right)}\×{\mathrm{CB}}_n^{\left(r\right)})=1$ n＝0～15 (7)

Wherein I is unit matrix, the conjugate transpose of H representing matrix.

Step 3.4, make r from subtracting 1, repeat above-mentioned steps 3.2 to step 3.4, thereby know the code book of all orders (from 7 to 2).

The present invention is by reusing LTE R8 four antenna codebooks, the backwards compatibility that not only keeps LTE-A, and a lot of good characteristics of LTE R8 code book have naturally been inherited, comprise the limited character list of nested, 8-PSK and permanent mould etc., UE side CQI calculates and the complexity of codeword selection thereby effectively reduce, and avoids transmitting power unbalance.In addition, the simulation result of the resulting eight-antenna codebook of the inventive method shown that the code book of the present invention's design can both effectively reduce Block Error Rate in non-correlation channel, correlated channels and dual polarization channel scene, be a kind of efficient codebook design schemes.

It should be noted last that above embodiment is only unrestricted in order to technical scheme of the present invention to be described.Although with reference to embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is made amendment or is equal to replacement, do not break away from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (1)

1. method for designing eight-antenna codebook of reusing the LTE code book, the method comprises:

Step 1), based on the DFT code book of rotation, generate order and be 1 eight-antenna codebook, described step 1) comprises:

Step 1-1), definition 8 * 8DFT code book DFT ₈

Step 1-2), the definition size is 8 * 8 rotation diagonalizable matrix D ₁Be unit matrix, definition D ₂For $D_2=\mathrm{diag}\left(\left[\begin{array}{cccccccc}0& (1+j)/\sqrt{2}& j& (-1+j)/\sqrt{2}& 0& (1+j)/\sqrt{2}& j& (-1+j)/\sqrt{2}\end{array}\right]\right),$ Wherein diag represents diagonalizable matrix;

Step 1-3), by aforesaid 8 * 8DFT code book DFT ₈, rotation diagonalizable matrix D ₁And described matrix D ₂The generation order is 1 eight-antenna codebook CB ⁽¹⁾, wherein:

${\mathrm{CB}}^{\left(1\right)}=\{\frac{1}{\sqrt{8}}{D}_1\×{\mathrm{DFT}}_8,\frac{1}{\sqrt{8}}{D}_2\×{\mathrm{DFT}}_8\};$

Step 2), reconfigure the four antenna HH code books of LTE R8, generate order and be 8 eight antenna LTEs-Advanced code book, described step 2) comprising:

Step 2-1), definition spin matrix U at the tenth of the twelve Earthly Branches _Rot, the computing formula of this matrix is as follows:

$U_{\mathrm{rot}}=\frac{1}{\sqrt{2}}\×\left[\begin{array}{cccccccc}1& 0& 0& 0& -1& 0& 0& 0\\ 0& 1& 0& 0& 0& -1& 0& 0\\ 0& 0& 1& 0& 0& 0& -1& 0\\ 0& 0& 0& 1& 0& 0& 0& -1\\ 1& 0& 0& 0& 1& 0& 0& 0\\ 0& 1& 0& 0& 0& 1& 0& 0\\ 0& 0& 1& 0& 0& 0& 1& 0\\ 0& 0& 0& 1& 0& 0& 0& 1\end{array}\right]$

Step 2-2), be to select a code word 4 LTE R8 four antenna codebooks from order, be labeled as A _n, make A _n=W _n, n=0～15, wherein W _nRepresent that this order is n code word in 4 LTE R8 four antenna codebooks;

Step 2-3), from step 2-2) described in order be to select another code word 4 LTE R8 four antenna codebooks, be labeled as B _n, its computing formula is as follows:

B ₀=W ₄ B ₁=W ₅ B ₂=W ₆ B ₃=W ₇

B ₄=W ₁ B ₅=W ₀ B ₆=W ₃ B ₇=W ₂

B ₈=W ₆ B ₉=W ₇ B ₁₀=W ₄ B ₁₁=W ₅

B ₁₂=W ₃ B ₁₃=W ₂ B ₁₄=W ₁ B ₁₅=W ₀

Step 2-4), at the resulting code word A of abovementioned steps _n, code word B _nAnd the tenth of the twelve Earthly Branches spin matrix U _RotThe basis on, generate order and be n code word in 8 the LTE-Advanced eight-antenna codebook

This code word can be expressed as:

${\mathrm{CB}}_n^{\left(8\right)}=\frac{1}{\sqrt{2}}\×U_{\mathrm{rot}}\×\left[\begin{array}{cc}{A}_n& 0_{4\×4}\\ 0_{4\×4}& -B_n\end{array}\right]$

Step 2-5), be that 80 to 15 Number character carries out column permutation to order, form final order and be 8 code word;

Step 2-6), be in the of 0 from the n value, repeating step 2-4) and step 2-5), until the n value is 15, generate order and be all 16 code words in 8 the LTE-Advanced eight-antenna codebook, finally obtain order and be 8 LTE-Advanced eight-antenna codebook CB ⁽⁸⁾

Step 3), the order of arranging from high to low according to order, take step 2) order that obtains as 8 eight antenna LTEs-the Advanced code book is the basis, from the code word of high order, select the subset of column vector, generate the code word of low-rank, and carry out transmitting power normalization, thereby generate the code book of order r from 7 to 2, described step 3) comprises:

Step 3-1), initialization r=7;

Step 3-2), from order be the code book CB of r+1 ^(r+1)Code word

Middle deletion one row are the code word of r as order with resulting result Column vector;

Step 3-3), according to formula To step 3-2) code word that generates carries out the normalization of transmitting power, and namely all code words multiply by a transmitting power normalization factor

Satisfy equation " ${\mathrm{CB}}_n^{\left(r\right)H}\×{\mathrm{CB}}_n^{\left(r\right)}=\frac{1}{r}{I}_{r\×r}$ Or $\mathrm{tr}({\mathrm{CB}}_{\left(n\right)}^{\left(r\right)H}\×{\mathrm{CB}}_n^{\left(r\right)})=1,n=0~15$ ”，

Final formation order is the code book CB of r ^(r)

Step 3-4), make r from subtracting 1, repeat above-mentioned steps 3-2) to step 3-4), thereby obtain the code book of order from 7 to 2;

Step 4), combination step 1)-the resulting result of step 3), generate eight antenna LTEs-Advanced code book.

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