CN101873190B - Pre-coding method and device - Google Patents

Abstract

The invention discloses a pre-coding method and a pre-coding device. The pre-coding method comprises that: a transmitting end acquires channel information of a plurality of antennas to two users respectively, and acquires channel related matrixes according to the channel information; the transmitting end acquires generalized characteristic vectors of the channel related matrixes; the transmitting end determines transmitting pre-coding vectors of the two users according to the generalized characteristic vectors, acquires receiving vectors of the two users according to the transmitting pre-coding vectors, and acquires equivalent channel matrixes corresponding to the two users according to the receiving vectors and the channel information respectively; and the transmitting end acquires power scaling matrixes, feedback matrixes and feed-forward matrixes corresponding to the two users according to the equivalent channel matrixes respectively, and performing THP on the two users according to the receiving vectors, the power scaling matrixes, the feedback matrixes and the feed-forward matrixes. According to the technical scheme, the number of the antennas collocated by the two users cannot be limited.

Description

Precoding method and device

Technical Field

The invention relates to the technical field of network communication, in particular to a THP (Total harmonic distortion) technology in a Multi-Input-Multi-Output (MIMO) system.

Background

In a multiple input multiple output Broadcast Channel (MIMO Broadcast Channel), Dirty Paper Coding (DPC) is an optimized technical solution. The thomlinson-Harashima Precoding (THP) can not only realize the DPC technical scheme, but also the THP technology has the characteristics of simple realization, good performance and the like.

The system model of THP is shown in fig. 1.

The interrelationship between the transceiving of the system model in fig. 1 can be represented as: y is GHFB^-1v + Gn, where G is a power scaling matrix, H is channel information from a transmitting antenna at a transmitting end to a user, F is a feed-forward matrix, B is a feedback matrix, v is a transmitted signal vector, and n is a noise vector on a receiving antenna of the user.

The implementation principle of THP is described below with reference to fig. 1.

Generally, in a multi-user MIMO broadcast channel, signals transmitted to multiple users interfere with each other after passing through a channel H, and in order to eliminate the mutual interference of the signals between the users, a THP system performs linear precoding on a transmitting end, that is, performs linear precoding on an information stream a according to channel information. After the channel is subjected to orthogonal triangular decomposition, the channel can be equivalent to a form that the channel of the orthogonal matrix is cascaded with the channel of a lower triangular matrix, so that the channel can be equivalent to the channel of the lower triangular matrix after the transmitting end multiplies the transmitting signal by the conjugate of the orthogonal matrix of the channel for conversion. In this case, the interference characteristics between the transmission signals of the layers of the triangular matrix can be used by the formulaPerforming linear precoding, wherein b_k,lK is the number of users for the elements in the feedback matrix B. When the linear pre-coded transmission signal x passes through F and channel H, the interference between layers of the transmission signal x is eliminatedIn addition, each user can independently decode the data. Since linear precoding causes power increase, the THP system introduces MOD (modulo) operation to reduce the transmit power of the transmit signal. The modulo operation changes the original linear precoding into a nonlinear precoding.

The inventors have found that the above prior art has at least the following problems: in a MIMO Broadcast Downlink (MIMO Broadcast), and in a scenario where each user receives a single stream, the number of receiving users cannot exceed the number of transmitting antennas because THP is limited by a channel space; that is, the existing THP can only be applied to an application scenario in which the number of users does not exceed the number of transmitting antennas and each user configures a single receiving antenna, and the problem of how to perform THP when the number of receiving antennas exceeds the number of transmitting antennas cannot be solved.

Disclosure of Invention

According to the precoding method and device provided by the embodiment of the invention, under the condition that a plurality of antennas are arranged at a transmitting end, the number of the antennas configured by two users can be unlimited.

The precoding method provided by the embodiment of the invention comprises the following steps:

a transmitting terminal acquires channel information of a plurality of antennas of the transmitting terminal from two users respectively, and acquires a channel correlation matrix according to the channel information;

the transmitting terminal obtains the generalized eigenvector of the channel correlation matrix;

the transmitting terminal determines the transmitting pre-coding vectors of the two users according to the generalized eigenvector, obtains the receiving vectors of the two users according to the transmitting pre-coding vectors of the two users, and obtains equivalent channel matrixes respectively corresponding to the two users according to the receiving vectors of the two users and the channel information;

and the transmitting terminal acquires a power scaling matrix, a feedback matrix and a feedforward matrix respectively corresponding to the two users according to the equivalent channel matrixes respectively corresponding to the two users, and performs Thomlinson-Harashima precoding (THP) on a system consisting of the two users according to the receiving vector, the power scaling matrix, the feedback matrix and the feedforward matrix.

The precoding device provided by the embodiment of the invention comprises:

the system comprises a channel correlation matrix module, a channel correlation matrix module and a channel estimation module, wherein the channel correlation matrix module is used for acquiring channel information from a plurality of antennas of a transmitting end to two users respectively and acquiring a channel correlation matrix according to the channel information;

the eigenvector module is used for acquiring the generalized eigenvector of the channel correlation matrix;

an equivalent channel matrix module, configured to obtain the transmitting precoding vectors of the two users according to the generalized eigenvector, obtain the receiving vectors of the two users according to the transmitting precoding vectors of the two users, and obtain equivalent channel matrices corresponding to the two users respectively according to the receiving vectors of the two users and the channel information;

and the precoding module is used for acquiring a power scaling matrix, a feedback matrix and a feedforward matrix which respectively correspond to the two users according to the equivalent channel matrix, and carrying out THP (total harmonic distortion) on a system consisting of the two users according to the receiving vector, the power scaling matrix, the feedback matrix and the feedforward matrix.

It can be known from the above description of the technical solution that, in the case that the transmitting end is provided with a plurality of antennas, the transmitting end obtains the channel correlation matrix by using the channel information from the plurality of antennas to the two users, and obtains the generalized eigenvector by using the channel correlation matrix, and then further obtains the receiving vectors of the two users by using the generalized eigenvector.

Drawings

FIG. 1 is a system model schematic of a prior art THP;

FIG. 2 is a flowchart of a precoding method according to a first embodiment of the present invention;

FIG. 3 is a model diagram of a MIMO system according to a first embodiment of the present invention;

FIG. 4 is a graph comparing BER performance of an embodiment of the present invention with that of the prior art;

FIG. 5 is a schematic diagram of a comparison of system capacity of an embodiment of the present invention with that of the prior art;

fig. 6 is a structural diagram of a precoding device according to a second embodiment of the present invention.

Detailed Description

The embodiment of the invention provides a precoding method. In this embodiment and the following embodiments, 2 transmitting antennas are provided at the transmitting end as an example for explanation.

In the MIMO system of the present embodiment, the transmitting end is provided with two antennas, i.e., the number N of transmitting antennas _t2, the sending end can obtain all channel state information; the number of users K in the MIMO system is 2, and the number of receiving antennas N of the users_rNot limited to and N_rWhich may be greater than 2, one data stream per user. In the above case, the flow of the method is shown in FIG. 2.

In fig. 2, S200, a transmitting end such as a base station acquires channel information from two transmitting antennas to two users, respectively, and acquires a channel correlation matrix according to the channel information.

If acquired by the transmitting endThe channel information from the two transmit antennas to the two users is denoted as H₁And H₂Then according to H₁And H₂The obtained channel correlation matrix isAnd

wherein,

is H₁The conjugate transpose matrix of (a) is,is H₂The conjugate transpose matrix of (2).

S210, the transmitting end obtains the generalized eigenvector of the channel correlation matrix.

Setting generalized eigenvectors as t₁And t₂Then t is₁And t₂Should satisfy respectively:and

i.e. according to the formula

Andcalculating and determining t₁And t₂。t₁And t₂Has symmetry.

S220, the transmitting end obtains transmitting pre-coding vectors of the two users according to the generalized characteristic vectors determined by the calculation.

If the transmitting end will t₁And t₂As linear precoding vectors for two users, according to the characteristics of the generalized eigenvectors,that is at this time

And

when the receivers of two users adopt

When the form receiving vector is received, the mutual interference of signals between two users can be realized to be 0.

In consideration of the system capacity problem, the transmitting end in this embodiment may use a system capacity maximization criterion to obtain the receiving vectors and the transmitting precoding vectors of the two users. For example, the transmitting end selects the optimal transmitting precoding vectors t for user 1 and user 2 respectively according to the following formula (1)_1,optAnd t_2,optTo maximize system capacity.

$\{t_{1,\mathrm{opt}},{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_{2,\mathrm{opt}}\}=\arg \underset{t,\stackrel{\&OverBar;}{t}\&Element;{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_2,t\&NotEqual;\stackrel{\&OverBar;}{t}}{\max }\{{\log }_2(1+\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">P</figure-callout>}}{2{\mathrm{\&sigma;}}_1^2}{\left|H_{1}t\right|}^2)+{\log }_2(1+\frac{P}{2{\mathrm{\&sigma;}}_2^2}{\left|H_2\stackrel{\&OverBar;}{t}\right|}^2)\},s.t,\left|\right|t_1\left|\right|=1,\left|\right|t_2\left|\right|=1$ Formula (1)

In equation (1): p is the signal transmission power, H₁And H₂Channel information from the two antennas to two users respectively, t is the generalized eigenvector of one of the users, sigma_iFor the receiver noise variance of the ith user,

to another oneGeneralized eigenvectors of individual users.

And S230, the transmitting terminal acquires receiving vectors of the two users according to the determined transmitting precoding vectors of the two users, and acquires equivalent channel matrixes respectively corresponding to the two users according to the receiving vectors of the two users and the channel information.

In this embodiment, the receiving matrix containing the receiving vectors of two users is W, and the use of the receiving matrix makes the whole system equivalent to the generalized eigenvector

And

thereby eliminating interference between users.

Receiving matrix containing receiving vectors of two users $W=\left(\begin{array}{cc}{\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">w</figure-callout>}}_1& 0\\ 0& {\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">w</figure-callout>}}_2\end{array}\right);$

Wherein, w₁Is the received vector, w, of the 1 st user₂Is the received vector for the 2 nd user.

Transmitting end by using t_1,optAnd t_2,optA normalized received vector w can be obtained₁And w₂E.g. receiving vectors $w_1={\left(H_1{t}_{1,\mathrm{opt}}\right)}^H/{\left|\right|H_1{t}_{1,\mathrm{opt}}\left|\right|}_2^2,$ Receiving a vector $w_2={\left(H_2{t}_{2,\mathrm{opt}}\right)}^H/{\left|\right|H_2{t}_{2,\mathrm{opt}}\left|\right|}_2^2;$

Wherein, t_1,optAnd t_2,optTransmitting precoding vectors for two users, H₁And H₂Is the channel information to two users through two antennas of the transmitting end.

Transmitting end by using w₁And w₂According to the formula (2), the equivalent channel matrixes of the two users can be calculated

And

${\tilde{H}}_1=w_1{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1,$ ${\tilde{H}}_2=w_2{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">H</figure-callout>}}_2$ formula (2)

The equivalent channel matrix of the two users can be expressed as $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right].$

As can be seen from the above description, since the receiving vector is used in the process of determining the equivalent channel matrix, the order number of the equivalent channel matrix of two users is reduced, and the order number of the equivalent channel matrix is only related to the number of antennas at the transmitting end and the number of users, but not related to the number of receiving antennas of the users, so that the complexity of THP is not related to the number of receiving antennas of the users, and finally, the number of receiving antennas of the users can be unlimited.

S240, the transmitting terminal obtains a power scaling matrix G, a feedback matrix B and a feedforward matrix F respectively corresponding to the two users according to the equivalent channel matrixes respectively corresponding to the two users, namely, the equivalent channels are utilized $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ F, B and G are computed for the two users respectively.

The process of obtaining F, B and G using the equivalent channel matrix is: to pair $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ The conjugate transpose of (a) is subjected to orthogonal triangular decomposition such as QR decomposition to obtain:thus, F can be obtained, i.e. F is a unitary matrix obtained by orthogonal triangular decomposition of the conjugate transpose of the equivalent channel matrix. S above^HAnd carrying out conjugate transpose operation on the triangular matrix S obtained after orthogonal triangular decomposition is carried out on the conjugate transpose of the equivalent channel matrix to obtain the triangular matrix.

The power scaling matrix may be formulated

Obtaining wherein s₁₁,...，s_KKIs an equivalent channel matrix $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ And K is the number of users.

The feedback matrix B may be obtained by a formula B ═ GS, where G is a power scaling matrix and S is a triangular matrix obtained by performing orthogonal triangular decomposition on the equivalent channel matrix.

The triangular matrix S may be an upper triangular matrix or a lower triangular matrix according to the orthogonal triangular decomposition form adopted for the equivalent channel matrix.

And S250, carrying out THP on a system consisting of two users by the transmitting end according to the receiving vector, the power scaling matrix G, the feedback matrix B and the feedforward matrix F respectively corresponding to the two users.

The transmitting end can perform THP for a system composed of two users according to the system model shown in FIG. 3, the system in FIG. 3

Where a is the transmitted signal vector, d is the perturbation vector, d is such that B^-1(a + d) is equivalently B^-1and a is subjected to modular operation.

The interrelationship between the transceiving of the system model shown in fig. 3 can be expressed as: GWFFB^-1v + GWn, i.e. the transmitting end, according to the formula y-GWHFB^-1v + Gwn is THP carried out by a system consisting of two users;

wherein y is a transmit vector, G is a power scaling matrix, W is a receive vector matrix for the user, H is channel information for the user, v is a transmit signal vector, n is a noise vector on a receive antenna for the user, each component of n is independent and uncorrelated with each other, and

E[]it is shown that it is desirable to,

represents the variance of gaussian white noise, and I represents a unit matrix.

The system model shown in FIG. 3 can be designed using Zero-Forcing Criterion (ZFC), i.e., GWFFB^-1I. I denotes a unit matrix.

It should be emphasized that the present embodiment is not limited to using the ZFC criterion in THP, and the present embodiment may support THP based on other criteria, for example, the present embodiment may support THP under MMSE (minimum mean square error) criterion, and the like.

Experimental data can be used to obtain: when the number of the receiving antennas of the user is different, the BER (bit error rate) performance obtained by adopting the technical scheme of the first embodiment is as shown in fig. 4.

In fig. 4, the horizontal coordinate represents SNR (signal-to-noise ratio) and the vertical coordinate represents bit error rate. The curve with the circle is a BER performance curve when one user has one receiving antenna, and the curve with the cross is a BER performance curve when one user has two receiving antennas.

As can be seen from the graph shown in fig. 4, with this embodiment, as soon as the bit error rate can be greatly improved, the diversity gain at the time of multi-antenna reception can be obtained.

In addition, experimental data can be used to obtain: the comparison between the solution of the first embodiment and the existing DPC solution in terms of system capacity is shown in fig. 5.

In fig. 5, the horizontal coordinate represents the transmission power, the vertical coordinate represents the rate. The circled curve is the system capacity curve of the DPC solution, and the cross curve is the system capacity curve of the above-described embodiment-solution.

As can be seen from the two curves shown in fig. 5, the system capacity of this embodiment one is very close to the system capacity using the DPC technique.

The second embodiment of the invention provides a precoding device. The transmitting end of the device is provided with two antennas. The structure of the device is shown in figure 6.

The apparatus 600 in fig. 6 comprises: a channel correlation matrix module 601, a feature vector module 602, an equivalent channel matrix module 603, and a precoding module 604.

The channel correlation matrix module 301 is configured to obtain channel information from two antennas of the transmitting end to two users, respectively, and obtain a channel correlation matrix according to the channel information.

If the channel information of two transmitting antennas respectively to two users acquired by the channel correlation matrix module 301 is represented as H₁And H₂Then the channel correlation matrix module 301 is based on H₁And H₂The obtained channel correlation matrix is

And

wherein,is H₁The conjugate transpose matrix of (a) is,

is H₂The conjugate transpose matrix of (2).

The eigenvector module 602 is used to obtain the generalized eigenvector of the channel correlation matrix.

The generalized eigenvector obtained by the eigenvector setting module 602 is t₁And t₂Then t is₁And t₂Should satisfy respectively: $t_2^H{H}_1^H{H}_1{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=0$ and $t_2^H{H}_2^H{H}_2{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=0,$ i.e., the feature vector module 602 according to the formula $t_2^H{H}_1^H{H}_1{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=0$ And $t_2^H{H}_2^H{H}_2{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1=0$ calculating and determining t₁And t₂，t₁And t₂Has symmetry.

The equivalent channel matrix module 603 is configured to obtain the transmit precoding vectors of the two users according to the generalized eigenvector, obtain the receive vectors of the two users according to the transmit precoding vectors of the two users, and obtain the equivalent channel matrices corresponding to the two users respectively according to the receive vectors and the channel information of the two users.

In consideration of the system capacity problem, the equivalent channel matrix module 603 in this embodiment may use a system capacity maximization criterion in the process of obtaining the transmission precoding vectors of two users. For example, the equivalent channel matrix module 603 selects the optimal transmit precoding vectors t for user 1 and user 2 according to the following formula (1)_1,optAnd t_2,optTo maximize system capacity.

$\{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_{1,\mathrm{opt}},{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_{2,\mathrm{opt}}\}=\arg \underset{t,\stackrel{\&OverBar;}{t}\&Element;{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_2,t\&NotEqual;\stackrel{\&OverBar;}{t}}{\max }\{{\log }_2(1+\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">P</figure-callout>}}{2{\mathrm{\&sigma;}}_1^2}{\left|H_{1}t\right|}^2)+{\log }_2(1+\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">P</figure-callout>}}{2{\mathrm{\&sigma;}}_2^2}{\left|H_2\stackrel{\&OverBar;}{t}\right|}^2)\},s.t,\left|\right|{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1\left|\right|=1,\left|\right|{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_2\left|\right|=1$ Formula (1)

In equation (1): p is the signal transmission power, H₁And H₂Transmitting precoding vectors for the two antennas to two users respectively, wherein t is the generalized characteristic of the first 1 user, sigma_iFor the receiver noise variance of the ith user,the transmitted generalized eigen precoding vector for another 2 nd user, s.t (subject to, constrained), represents the formula

$\{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_{1,\mathrm{opt}},{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_{2,\mathrm{opt}}\}=\arg \underset{t,\stackrel{\&OverBar;}{t}\&Element;{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_2,t\&NotEqual;\stackrel{\&OverBar;}{t}}{\max }\{{\log }_2(1+\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">P</figure-callout>}}{2{\mathrm{\&sigma;}}_1^2}{\left|H_{1}t\right|}^2)+{\log }_2(1+\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">P</figure-callout>}}{2{\mathrm{\&sigma;}}_2^2}{\left|H_2\stackrel{\&OverBar;}{t}\right|}^2)\}$ Constrained to | t₁| 1 and | t₂‖＝1。

The receiving matrix composed of the receiving vectors of the two users obtained by the equivalent channel matrix module 603 can be represented as:

$W=\left(\begin{array}{cc}{\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">w</figure-callout>}}_1& 0\\ 0& {\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">w</figure-callout>}}_2\end{array}\right);$

wherein, w₁Is the received vector, w, of the 1 st user₂Is the connection of the 2 nd userAnd receiving the vector.

Equivalent channel matrix module 603 by using t_1,optAnd t_2,optA normalized received vector w can be obtained₁And w₂E.g. receiving vectors $w_{}$ ${}_1={\left(H_1{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_{1,\mathrm{opt}}\right)}^H/{\left|\right|H_1{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">t</figure-callout>}}_{1,\mathrm{opt}}\left|\right|}_2^2,$ Receiving a vector $w_{}$ ${}_2={\left(H_2{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_{2,\mathrm{opt}}\right)}^H/{\left|\right|H_2{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">t</figure-callout>}}_{2,\mathrm{opt}}\left|\right|}_2^2;$

Wherein, t_1,optAnd t_2,optTransmitting precoding vectors for two users, H₁And H₂Channel information from two antennas at the transmitting end to two users, respectively.

Equivalent channel matrix module 603 by using w₁And w₂According to the formula (2), the equivalent channel matrixes of the two users can be calculated

And

${\tilde{H}}_1=w_1{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="H2009101309948E00022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1,$ ${\tilde{H}}_2=w_2{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="H2009101309948E00022.png,H2009101309948E00031.png"\; state="\{\{state\}\}">H</figure-callout>}}_2$ formula (2)

The equivalent channel matrix of the two users can be expressed as $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right].$

The precoding module 604 is configured to obtain a power scaling matrix G, a feedback matrix B, and a feedforward matrix F corresponding to two users according to the equivalent channel matrices corresponding to the two users, and perform THP for a system formed by the two users according to the receiving vector, the power scaling matrix G, the feedback matrix B, and the feedforward matrix F corresponding to the two users.

The process of the precoding module 604 to obtain F, B and G using the equivalent channel matrix may be:

precoding module 604 pairs $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ The conjugate transpose of (a) is subjected to orthogonal triangular decomposition to obtain:

the precoding module 604 can thus obtain F, i.e., F is a unitary matrix obtained by performing orthogonal triangular decomposition on the equivalent channel matrix. S above^HAnd carrying out conjugate transpose operation on the triangular matrix S obtained after orthogonal triangular decomposition is carried out on the equivalent channel matrix to obtain the triangular matrix.

PrecodingModule 604 may utilize formulas

Obtaining a power scaling matrix, wherein s₁₁,...，s_KKIs an equivalent channel matrix $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ And K is the number of users.

The precoding module 604 may obtain a feedback matrix B by using a formula B ═ GS, where G is a power scaling matrix and S is a triangular matrix obtained by performing orthogonal triangular decomposition on the equivalent channel matrix.

It should be noted that the triangular matrix S may be an upper triangular matrix or a lower triangular matrix according to different orthogonal triangular decomposition forms adopted by the precoding module 604 for the equivalent channel matrix.

After obtaining the power scaling matrix G, the feedback matrix B, and the feedforward matrix, the precoding module 604 may perform THP for a system composed of two users according to the system model shown in fig. 3, where the system model in fig. 3 is used for THP

Where a is the transmitted signal vector, d is the perturbation vector, d is such that B^-1(a + d) is equivalently B^-1and a is subjected to modular operation.

Since the interrelationship between the transceiving of the system model shown in fig. 3 can be expressed as follows:

y＝GWHFB^-1v+GWn；

wherein y is a transmit vector, G is a power scaling matrix, W is a receive vector matrix for the user, H is channel information for the user, v is a transmit signal vector, n is a noise vector on a receive antenna for the user, each component of n is independent and uncorrelated with each other, and

E[ ]it is shown that it is desirable to,

represents the variance of gaussian white noise, and I represents a unit matrix.

Thus, the precoding module 604 may be GWHFB according to the formula y^-1v + Gwn performs THP for a system consisting of two users.

As can be seen from the description of the second embodiment, since the equivalent channel matrix module 603 utilizes the receiving vector in the process of determining the equivalent channel matrix, the order number of the equivalent channel matrix of two users is reduced, and the order number of the equivalent channel matrix is only related to the number of antennas at the transmitting end and the number of users, but not related to the number of receiving antennas of the users, so that the complexity of the THP operation performed by the precoding module 604 is not related to the number of receiving antennas of the users, and finally the number of receiving antennas of the users can be unlimited.

Through the above description of the embodiments, those skilled in the art will clearly understand that the present invention may be implemented by software plus a necessary hardware platform, and certainly may be implemented by hardware, but in many cases, the former is a better embodiment. With this understanding in mind, all or part of the technical solutions of the present invention that contribute to the background can be embodied in the form of a software product, which can be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods according to the embodiments or some parts of the embodiments of the present invention.

While the invention has been described with respect to the embodiments, those skilled in the art will appreciate that there are numerous variations and permutations of the present invention that are encompassed by the claims of the present application without departing from the spirit of the invention.

Claims (7)

1. A precoding method, comprising:

a transmitting terminal acquires channel information of a plurality of antennas of the transmitting terminal from two users respectively, and acquires a channel correlation matrix according to the channel information;

the transmitting terminal obtains generalized eigenvectors of the channel correlation matrix, wherein the generalized eigenvectors are t respectively₁And t₂And t is₁And t₂Respectively satisfy: $t_2^H{H}_1^H{H}_1{t}_1=0$ and $t_2^H{H}_2^H{H}_2{t}_1=0;$ wherein,

H₁and

H₂is a channel correlation matrix, H₁And H₂Channel information to two users for the multiple antennas respectively,

is H₁The conjugate transpose matrix of (a) is,

is H₂The conjugate transpose matrix of (a);

the transmitting terminal determines the transmitting pre-coding vectors t of the two users according to the generalized characteristic vector and by utilizing the system capacity maximization criterion_1,optAnd t_2,optAcquiring normalized receiving vectors of the two users according to the transmitting precoding vectors of the two users, and multiplying the normalized receiving vectors of the two users with the channel information respectively to acquire equivalent channel matrixes corresponding to the two users respectively; wherein the transmitting end obtains t according to the following formula_1,optAnd t_2,opt：

$\{t_{1,\mathrm{opt}},t_{2,\mathrm{opt}}\}=\arg \underset{t,\stackrel{-}{t}\&Element;t_1,t_2,t\&NotEqual;\stackrel{-}{t}}{\max }\{{\log }_2(1+\frac{P}{{2\mathrm{\&sigma;}}_1^2}{\left|H_{1}t\right|}^2)+{\log }_2(1+\frac{P}{{2\mathrm{\&sigma;}}_2^2}{\left|H_2\stackrel{-}{t}\right|}^2)\},s.t\left|\right|t_1|=1,|\left|t_2\right||=1;$

Wherein: p is signal transmitting power, t is generalized eigenvector of 1 user in the signal transmitting power, and sigma_iFor the receiver noise variance of the ith user,

a generalized eigenvector for another user;

and the transmitting terminal acquires a power scaling matrix, a feedback matrix and a feedforward matrix respectively corresponding to the two users according to the equivalent channel matrixes respectively corresponding to the two users, and performs Thomlinson-Harashima precoding (THP) on a system consisting of the two users according to the receiving vector, the power scaling matrix, the feedback matrix and the feedforward matrix.

2. The method of claim 1, wherein a receiving matrix composed of the receiving vectors of the two users is W, and the W is obtained by the following formula:

$W=\left(\begin{array}{cc}{w}_1& 0\\ 0& w_2\end{array}\right);$

wherein, the 1 st user normalized receiving vector

2 nd user normalized received vector $w_2={\left(H_2{t}_{2,\mathrm{opt}}\right)}^H/{\left|\right|H_2{t}_{2,\mathrm{opt}}\left|\right|}_2^2.$

3. The method of claim 1, wherein the multiplying the received vectors of the two users by the channel information to obtain equivalent channel matrices corresponding to the two users respectively comprises:

according to the formula $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ Acquiring equivalent channel matrixes corresponding to two users;

wherein,

w₁received vector for the 1 st user, w₂Received vector for the 2 nd user, H₁And H₂Channel information to two users for the plurality of antennas respectively.

4. The method of claim 1, wherein the power scaling matrix G is formulated by the formula

Obtaining wherein s₁₁,...,s_KKFor the equivalent channel matrix $H_{\mathrm{eff}}=\left[\begin{array}{c}{\tilde{H}}_1\\ {\tilde{H}}_2\end{array}\right]$ Go on toThe element on the diagonal line of the triangular matrix S obtained after the triangular decomposition, K is the number of users,w₁received vector for the 1 st user, w₂Received vector for the 2 nd user, H₁And H₂Channel information to two users for the plurality of antennas respectively.

5. The method of claim 1, wherein the feedback matrix B is obtained by a formula B ═ GS, where G is the power scaling matrix and S is a triangular matrix obtained by orthogonal triangular decomposition of an equivalent channel matrix; or

The feedforward matrix F is a unitary matrix obtained by performing orthogonal triangular decomposition on the equivalent channel matrix.

6. The method of any one of claims 1 to 5, wherein said performing THP for a system of two users according to said receive vector, power scaling matrix, feedback matrix and feedforward matrix comprises:

according to y ═ GWFFB^-1v + Gwn is THP carried out by a system consisting of two users;

y is a transmitting vector, G is a power scaling matrix, W is a receiving vector matrix of a user, H is channel information of the user, F is a feedforward matrix, B is a feedback matrix, v is a transmitting signal vector, and n is a noise vector on a receiving antenna of the user.

7. A precoding apparatus having a plurality of antennas provided in a transmitting end, the apparatus comprising:

the channel correlation matrix module is used for acquiring channel information from the plurality of antennas of the transmitting end to two users respectively and acquiring a channel correlation matrix according to the channel information;

an eigenvector module for obtaining generalized eigenvectors of the channel correlation matrixThe generalized eigenvectors are respectively t₁And t₂And t is₁And t₂Respectively satisfy: $t_2^H{H}_1^H{H}_1{t}_1=0$ and $t_2^H{H}_2^H{H}_2{t}_1=0;$ wherein,

H₁and

H₂is a channel correlation matrix, H₁And H₂Channel information to two users for the multiple antennas respectively,

is H₁The conjugate transpose matrix of (a) is,

is H₂The conjugate transpose matrix of (a);

an equivalent channel matrix module for obtaining the transmitting pre-coding vectors t of the two users according to the generalized eigenvector and by using the system capacity maximization criterion_1,optAnd t_2,optObtaining normalized receiving vectors of the two users according to the transmitting pre-coding vectors of the two users, and respectively combining the two usersMultiplying the receiving vector of user normalization by the channel information to obtain equivalent channel matrixes respectively corresponding to the two users; wherein the transmitting end obtains t according to the following formula_1,optAnd t_2,opt：

$\{t_{1,\mathrm{opt}},t_{2,\mathrm{opt}}\}=\arg \underset{t,\stackrel{-}{t}\&Element;t_1,t_2,t\&NotEqual;\stackrel{-}{t}}{\max }\{{\log }_2(1+\frac{P}{{2\mathrm{\&sigma;}}_1^2}{\left|H_{1}t\right|}^2)+{\log }_2(1+\frac{P}{{2\mathrm{\&sigma;}}_2^2}{\left|H_2\stackrel{-}{t}\right|}^2)\},s.t\left|\right|t_1|=1,|\left|t_2\right||=1;$

Wherein: p is signal transmitting power, t is generalized eigenvector of 1 user in the signal transmitting power, and sigma_iFor the receiver noise variance of the ith user,

a generalized eigenvector for another user;

and the precoding module is used for acquiring a power scaling matrix, a feedback matrix and a feedforward matrix which respectively correspond to the two users according to the equivalent channel matrix, and carrying out THP (total harmonic distortion) on a system consisting of the two users according to the receiving vector, the power scaling matrix, the feedback matrix and the feedforward matrix.

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