CN101286823A - Data-transmission method and system for MIMO system - Google Patents

Abstract

The invention discloses a data transmission method used for a multi-input and multi-output system and a data transmission system, wherein, the data transmission method of the multi-input multi-output system comprises the steps that: S102, space-time coding is carried out by a data sending terminal to data needing to be sent; S104, the data sending terminal estimates the channels and obtains channel matrices as well as the eigenvalue of channel matrices; S106, the data sending terminal carries out beam forming towards data on at least one antenna by making use of the eigenvalue and sends the data after beam forming to a data receiving terminal; S108, the data receiving terminal receives the data and carries out space-time decoding according to the eigenvalue to obtain data. The method and the system of the invention can improve transmission efficiency, reduce transmission power and suppress interference among different users.

Description

The data transmission method and the data transmission system that are used for multi-input multi-output system

Technical field

The present invention relates to the communications field, relate more specifically to a kind of data transmission method and a kind of data transmission system that is used for multi-input multi-output system.

Background technology

In recent years, Space Time Coding effectively overcomes and improves the method for existing multipath fading and received signal performance in the wireless communications environment and receive much attention as a kind of.At document [Asimple transmit diversity technique for wireless communications[J] .IEEE J.Select.Areas Commun, 1998,16 (10): 1451-1458, Oct.] in, Alamouti has proposed a kind of space-time coding method based on two transmit antennas, and this method can realize the diversity gain of maximum possible by the maximum-likelihood decoding algorithm of simple linear complexity.Space Time Coding combines the advantage of space diversity and time diversity, but it requires the channel fading correlation of different antennae very little, and when having correlation between the channel fading, the performance of Space Time Coding can variation.Transmitter Unknown Channel information is mostly supposed in existing research about Space Time Coding, and the channel fading between the dual-mode antenna is separate arbitrarily.And in the wireless communications environment of reality, because the base station is all set up than higher usually, the spacing between the antenna for base station is also little, so the channel fading between the different dual-mode antenna has correlation, no longer satisfies separate condition.Therefore, the system that adopts Space Time Coding separately in actual applications performance can become relatively poor.

Wave beam forms and utilizes correlation between channels just, selects suitable weights, at transmitting terminal transmitting of different antennae is weighted, and improves the signal to noise ratio of receiving terminal by the through-put power of distributing different antennae.Can improve efficiency of transmission like this, reduce transmitted power, can reduce the interference between different user again.

Transmitter is if utilizing the more accurate channel information of receiver feedback to carry out classical wave beam forms, and then system can reach best performance.But, when path number is big, needing accurately to estimate the deflection of each paths, system can be difficult to because of complexity is too high realize.Particularly become condition following time when quick when channel is in, by feedback to channel estimate be unrealistic also be nonsensical because the channel information that feedback obtains can lag behind the channel of variation.

Therefore, a kind of new data transmission method that is used for multi-input multi-output system and a kind of data transmission system need be provided.

Summary of the invention

In view of above one or more problems, the invention provides a kind of new data transmission method that is used for multi-input multi-output system and a kind of data transmission system.

The data transmission method that is used for multi-input multi-output system according to the present invention may further comprise the steps: S102, and data sending terminal carries out Space Time Coding to the data that needs send; S104, data sending terminal estimate channel and obtain channel matrix, and the characteristic value of obtaining channel matrix; S106, data sending terminal utilize characteristic value the data at least one antenna are carried out that wave beam forms and wave beam formed after data be sent to data receiver; And S108, when receiving data and carry out sky according to characteristic value, deciphers data receiver, to obtain data.

Wherein, step S106 comprises: S1062, data sending terminal obtain characteristic value characteristic of correspondence vector, and with characteristic vector as weight vector; S1064, data sending terminal utilize weight vector that the data at least one antenna are weighted; And S1066, the data after the weighting are sent to data receiver.

Wherein, step S108 comprises: S1082, data receiver estimate and obtain the characteristic value of channel matrix to channel; S1084, data receiver obtains the characteristic of correspondence vector according to characteristic value; And S1086, when carrying out sky according to characteristic vector to received data, deciphers data receiver.

Wherein, the number of transmit antennas of data sending terminal equates with the reception antenna number of data receiver.Data transmission method according to the present invention is used for tdd systems.

Data transmission system according to the present invention comprises: data sending device, has at least one transmitting antenna, data sending device is used for the data that needs send are carried out Space Time Coding, the characteristic value of channel matrix and channel matrix is estimated and obtained to channel, utilize characteristic value the data at least one antenna are carried out that wave beam forms and wave beam formed after data be sent to data sink; And data sink, having at least one reception antenna, data sink is used to receive data, channel is estimated and is deciphered when carrying out sky according to the characteristic value of channel, to obtain data.

Wherein, data sending device also comprises: coding module, and the data that are used for the needs transmission are carried out Space Time Coding; First channel estimation module is used for channel is estimated and obtained the characteristic value of channel matrix and channel matrix; Wave beam forms module, be used to obtain characteristic value characteristic of correspondence vector, and with characteristic vector as weight vector, and utilize weight vector that the data at least one antenna are weighted, and be sent to data receiver by the data of at least one antenna after with weighting.

Wherein, data sink comprises: the second channel estimation module is used for channel is estimated and obtained the characteristic value of channel matrix; Decoding module is used for obtaining the characteristic of correspondence vector according to characteristic value, and deciphers when according to characteristic vector received data being carried out sky.

Wherein, the number of transmit antennas of data sending device can be for equating with the reception antenna number of data receiver.Can be used for tdd systems according to data transmission system of the present invention.

Description of drawings

Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:

Fig. 1 is the flow chart according to the data transmission method that is used for multi-input multi-output system of the embodiment of the invention;

Fig. 2 is the flow chart that is used for the data transmission method of multi-input multi-output system according to another embodiment of the present invention;

Fig. 3 is the simulated effect figure of embodiment illustrated in figures 1 and 2; And

Fig. 4 is the block diagram according to the data output system of the embodiment of the invention.

Embodiment

Below with reference to accompanying drawing, describe the specific embodiment of the present invention in detail.

With reference to figure 1, the data transmission method that is used for multi-input multi-output system according to the embodiment of the invention is described.As shown in Figure 1, this data transmission method may further comprise the steps: S102, and data sending terminal carries out Space Time Coding to the data that needs send; S104, data sending terminal estimate channel and obtain channel matrix, and the characteristic value of obtaining channel matrix; S106, data sending terminal utilize characteristic value the data at least one antenna are carried out that wave beam forms and wave beam formed after data be sent to data receiver; And S108, when receiving data and carry out sky according to characteristic value, deciphers data receiver, to obtain data.

Wherein, step S106 comprises: S1062, data sending terminal obtain characteristic value characteristic of correspondence vector, and with characteristic vector as weight vector; S1064, data sending terminal utilize weight vector that the data at least one antenna are weighted; And S1066, the data after the weighting are sent to data receiver.

Wherein, step S108 comprises: S1082, data receiver estimate and obtain the characteristic value of channel matrix to channel; S1084, data receiver obtains the characteristic of correspondence vector according to characteristic value; And S1086, when carrying out sky according to characteristic vector to received data, deciphers data receiver.

From above-mentioned description, as can be seen, used Space Time Coding according to the data transmission method that is used for multi-input multi-output system of the embodiment of the invention and formed method in conjunction with wave beam.And time division duplex (Time Division Duplex, abbreviation TDD) the maximum characteristics of system are that there is reciprocity in the up-downgoing channel, so the channel information that can utilize up channel to obtain is selected suitable weights, at transmitting terminal transmitting of different antennae is weighted, improves the signal to noise ratio of receiving terminal by the through-put power of distributing different antennae.Can improve efficiency of transmission like this, reduce transmitted power, can reduce the interference between different user again.

For example, when the antenna number of transmitting terminal and receiving terminal equated (being made as N), channel matrix H was a square formation.Channel matrix H is carried out characteristic value decomposition, can obtain the diagonal matrix Λ=diag (λ that forms by the characteristic value of H ₁, λ ₂λ _N) and be matrix U=[u that column element is formed with the characteristic vector of character pair value ₁, u ₂U _N].Wherein, in U, choose λ ₁, λ ₂λ _NMiddle two maximum unequal characteristic values (might as well be designated as λ ₁, λ ₂) pairing characteristic vector is as weight vector W=(ω ₁, ω ₂]

${\mathrm{\ω}}_1=\left[\begin{array}{c}{\mathrm{\ω}}_{\mathrm{1,1}}\\ {\mathrm{\ω}}_{\mathrm{1,2}}\\ .\\ .\\ .\\ {\mathrm{\ω}}_{1,N}\end{array}\right],$ ${\mathrm{\ω}}_2=\left[\begin{array}{c}{\mathrm{\ω}}_{\mathrm{2,1}}\\ {\mathrm{\ω}}_{\mathrm{2,2}}\\ .\\ .\\ .\\ {\mathrm{\ω}}_{2,N}\end{array}\right]$

Through the matrix behind the Alamouti scheme coding be

$[{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1,s_2]\&RightArrow;\left[\begin{array}{cc}{s}_1& -{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}\\ s_2& {{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\end{array}\right]$

Here only consider to send symbol on preceding two subcarriers $\left[\begin{array}{cc}{s}_1& -{s_2}^{*}\\ s_2& {{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\end{array}\right]$ The transmission situation, other repeat this situation.

$x_1={\mathrm{\&omega;}}_1{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_2{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2=\left[\begin{array}{c}{\mathrm{\&omega;}}_{\mathrm{1,1}}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_{\mathrm{2,1}}{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2\\ {\mathrm{\&omega;}}_{\mathrm{1,2}}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_{\mathrm{2,2}}{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2\\ .\\ .\\ .\\ {\mathrm{\&omega;}}_{1,\mathrm{<figure-callout\; id="1"\; label="N\; s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">N</figure-callout>}}{s}_{}{}_1+{\mathrm{\&omega;}}_{2,\mathrm{<figure-callout\; id="2"\; label="N\; s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">N</figure-callout>}}{s}_{}{}_2\end{array}\right]$

$x_2=-{\mathrm{\&omega;}}_1{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_2{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}=\left[\begin{array}{c}{-\mathrm{\&omega;}}_{\mathrm{1,1}}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_{\mathrm{2,1}}{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\\ {-\mathrm{\&omega;}}_{\mathrm{1,2}}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_{\mathrm{2,2}}{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\\ .\\ .\\ .\\ -{\mathrm{\&omega;}}_{1,N}{s_2}^{*}+{\mathrm{\&omega;}}_{2,N}{s_1}^{*}\end{array}\right]$

Write as the form of matrix:

$X=[x_1,x_2]=[{\mathrm{\&omega;}}_1{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_2{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2,-{\mathrm{\&omega;}}_1{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_2{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}]=[{\mathrm{\&omega;}}_1,{\mathrm{\&omega;}}_2]\left[\begin{array}{cc}{s}_1& -{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}\\ s_2& {{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\end{array}\right]$

Suppose to remain unchanged at these two adjacent subcarrier upper signal channels, then pass through channel H after, the signal on these two subcarriers of receiving terminal can be written as at frequency domain

$R_1=H*x_{1_1}+n_1=H({\mathrm{\&omega;}}_1{s}_1+{\mathrm{\&omega;}}_2{s}_2)+n_1=\mathrm{HW}\left[\begin{array}{c}{s}_1\\ s_2\end{array}\right]+n_1$

$R_2=H*x_{1_1}+n_1=H*({-\mathrm{\&omega;}}_1{s_2}^{*}+{\mathrm{\&omega;}}_2{s_1}^{*})+n_2=\mathrm{HW}\left[\begin{array}{c}-{s_2}^{*}\\ {s_1}^{*}\end{array}\right]+n_2$

Wherein, n ₁, n ₂Be noise vector.So, equivalent channel

Can be written as:

$\tilde{H}=\mathrm{HW}=H*\left[\begin{array}{cc}{\mathrm{\&omega;}}_{\mathrm{1,1}}& {\mathrm{\&omega;}}_{\mathrm{2,1}}\\ {\mathrm{\&omega;}}_{\mathrm{1,2}}& {\mathrm{\&omega;}}_{\mathrm{2,2}}\end{array}\right]$

Character according to characteristic value and characteristic vector can obtain

$H*U=U*\mathrm{\&Lambda;}\&DoubleRightArrow;H*[{\mathrm{\&omega;}}_1,{\mathrm{\&omega;}}_2]=[{\mathrm{\&omega;}}_1,{\mathrm{\&omega;}}_2]*\mathrm{diag}({\mathrm{\&lambda;}}_1,{\mathrm{\&lambda;}}_2)$

The equivalent as can be known matrix H * [ω of character according to different characteristic value characteristic of correspondence phasor linear independences ₁, ω ₂] two amounts of lising uncorrelated.Just the channel through two data stream processes behind the SFBC coding has nothing to do, and this has just improved the diversity performance of SFBC.

With reference to figure 2, the data transmission method that is used for multi-input multi-output system according to another embodiment of the present invention is described.As shown in Figure 2, this method may further comprise the steps:

S202 is to the data flow [s after the modulation ₁, s ₂] carry out the STBC Space Time Coding, obtain $\left[\begin{array}{cc}{s}_1& -{s_2}^{*}\\ s_2& {{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\end{array}\right],$ Modulation wherein with the modulation before associative operation identical with traditional approach, no longer provide.

S204 estimates channel matrix, asks the characteristic root of channel matrix.The diagonal matrix of supposing the characteristic value composition of channel matrix H is Λ=diag (λ ₁, λ ₂λ _N), be that the matrix that column element is formed is U=[u with the characteristic vector of character pair value ₁, u ₂U _N].

S206, the structure weights also carry out wave beam formation.Here be example with 22 debit's formulas, in U, choose λ ₁, λ ₂λ _NMiddle two maximum unequal characteristic values (might as well be designated as λ ₁, λ ₂) pairing characteristic vector is as weight vector W=[ω ₁, ω ₂].Here only consider to send symbol on preceding two subcarriers $\left[\begin{array}{cc}{s}_1& -{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}\\ s_2& {{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\end{array}\right]$ The transmission situation, other repeat this situation, then transmitting of two antennas is respectively

$x_1={\mathrm{\&omega;}}_1{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_2{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2=\left[\begin{array}{c}{\mathrm{\&omega;}}_{\mathrm{1,1}}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_{\mathrm{2,1}}{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2\\ {\mathrm{\&omega;}}_{\mathrm{1,2}}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_{\mathrm{2,2}}{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2\\ .\\ .\\ .\\ {\mathrm{\&omega;}}_{1,\mathrm{<figure-callout\; id="1"\; label="N\; s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">N</figure-callout>}}{s}_{}{}_1+{\mathrm{\&omega;}}_{2,\mathrm{<figure-callout\; id="2"\; label="N\; s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">N</figure-callout>}}{s}_{}{}_2\end{array}\right]$

$x_2=-{\mathrm{\&omega;}}_1{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_2{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}=\left[\begin{array}{c}{-\mathrm{\&omega;}}_{\mathrm{1,1}}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_{\mathrm{2,1}}{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\\ {-\mathrm{\&omega;}}_{\mathrm{1,2}}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_{\mathrm{2,2}}{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\\ .\\ .\\ .\\ -{\mathrm{\&omega;}}_{1,N}{s_2}^{*}+{\mathrm{\&omega;}}_{2,N}{s_1}^{*}\end{array}\right]$

Write as the form of matrix:

$X=[x_1,x_2]=[{\mathrm{\&omega;}}_1{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1+{\mathrm{\&omega;}}_2{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2,-{\mathrm{\&omega;}}_1{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}+{\mathrm{\&omega;}}_2{{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}]=[{\mathrm{\&omega;}}_1,{\mathrm{\&omega;}}_2]\left[\begin{array}{cc}{s}_1& -{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}^{*}\\ s_2& {{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="A20071010059100171.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}^{*}\end{array}\right]$

S208, decoding when receiving terminal is empty.Suppose to remain unchanged at these two adjacent subcarrier upper signal channels, then pass through channel H after, the signal on these two subcarriers of receiving terminal can be written as at frequency domain:

$Y_1=H*x_{1_1}+n_1=H({\mathrm{\&omega;}}_1{s}_1+{\mathrm{\&omega;}}_2{s}_2)+n_1=\mathrm{HW}\left[\begin{array}{c}{s}_1\\ s_2\end{array}\right]+n_1$

$Y_2=H*x_{1_1}+n_1=H*({-\mathrm{\&omega;}}_1{s_2}^{*}+{\mathrm{\&omega;}}_2{s_1}^{*})+n_2=\mathrm{HW}\left[\begin{array}{c}-{s_2}^{*}\\ {s_1}^{*}\end{array}\right]+n_2$

Wherein, n ₁, n ₂Be noise vector.So, equivalent channel Can be written as:

$\tilde{H}=\mathrm{HW}=H*\left[\begin{array}{cc}{\mathrm{\&omega;}}_{\mathrm{1,1}}& {\mathrm{\&omega;}}_{\mathrm{2,1}}\\ {\mathrm{\&omega;}}_{\mathrm{1,2}}& {\mathrm{\&omega;}}_{\mathrm{2,2}}\end{array}\right]$

Character according to characteristic value and characteristic vector can obtain:

$H*U=U*\mathrm{\&Lambda;}\&DoubleRightArrow;H*[{\mathrm{\&omega;}}_1,{\mathrm{\&omega;}}_2]=[{\mathrm{\&omega;}}_1,{\mathrm{\&omega;}}_2]*\mathrm{diag}({\mathrm{\&lambda;}}_1,{\mathrm{\&lambda;}}_2).$

As shown in Figure 3, suppose that receiving terminal can obtain the definite information of channel, then more only use the method for STBC and use STBC+beamforming (being called for short STBC+BF) method, by the relation curve of bit error rate and signal to noise ratio as can be seen, when signal to noise ratio is relatively lower, the performance of STBC+BF is compared with only using STBC, and it is not too big improving.When signal to noise ratio was the 4dB left and right sides, the former was than the well about 2dB of latter performance.When signal to noise ratio when higher, the performance of STBC+BF has just improved much than STBC.When signal to noise ratio during in the 10dB left and right sides, the former has improved 4dB than latter performance.Obviously, the performance of STBC+BF is better than the system that only uses STBC.

With reference to figure 4, the data output system according to the embodiment of the invention is described.As shown in Figure 4, this data transmission system comprises: data sending device 402, has at least one transmitting antenna, data sending device is used for the data that needs send are carried out Space Time Coding, the characteristic value of channel matrix and channel matrix is estimated and obtained to channel, utilize characteristic value the data at least one antenna are carried out that wave beam forms and wave beam formed after data be sent to data sink; And data sink 404, having at least one reception antenna, data sink is used to receive data, channel is estimated and is deciphered when carrying out sky according to the characteristic value of channel, to obtain data.

Wherein, data sending device 402 comprises: coding module 4022, and the data that are used for the needs transmission are carried out Space Time Coding; First channel estimation module 4024 is used for channel is estimated and obtained the characteristic value of channel matrix and channel matrix; Wave beam forms module 4026, be used to obtain characteristic value characteristic of correspondence vector, and with characteristic vector as weight vector, and utilize weight vector that the data at least one antenna are weighted, and be sent to data receiver by the data of at least one antenna after with weighting.

Wherein, data sink 404 comprises: second channel estimation module 4042 is used for channel is estimated and obtained the characteristic value of channel matrix; Decoding module 4044 is used for obtaining the characteristic of correspondence vector according to characteristic value, and deciphers when according to characteristic vector received data being carried out sky.

Wherein, the number of transmit antennas of data sending device can be for equating with the reception antenna number of data receiver.Data transmission system according to present embodiment can be used for tdd systems.

Therefore, when the emission function is known the second-order statistics information of channel by feedback, data transmission system can be utilized the covariance matrix of the snap data computation channel of channel estimating, and transmitting terminal can utilize the information of covariance matrix to carry out wave beam formation, receiving terminal can utilize the information of covariance matrix to synthesize new equivalent channel, maximum likelihood decoding algorithm with the Alautimo scheme is decoded, so can reduce the complexity of data transmission system greatly.

In sum, the Space Time Coding among the present invention combines the advantage of space diversity and time diversity and the characteristics of beam directional in conjunction with the wave beam generation type, does not need overhead, and is simple for structure; And operand is little, is easy to Project Realization.In addition, the present invention handles when empty really merely or beam-forming technology is compared, and has better robustness, can suppress the interference between different user simultaneously, is applicable to plurality of application scenes.

The above is embodiments of the invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within the claim scope of the present invention.

Claims (10)

1. a data transmission method that is used for multi-input multi-output system is characterized in that, may further comprise the steps:

S102, data sending terminal carries out Space Time Coding to the data that needs send;

S104, described data sending terminal estimate channel and obtain channel matrix, and the characteristic value of obtaining described channel matrix;

S106, described data sending terminal utilize described characteristic value the data at least one antenna are carried out that wave beam forms and wave beam formed after data be sent to data receiver; And

S108, described data receiver decipher when receiving described data and carrying out sky according to described characteristic value, to obtain described data.

2. data transmission method according to claim 1 is characterized in that, described step S106 comprises:

S1062, described data sending terminal obtain described characteristic value characteristic of correspondence vector, and with described characteristic vector as weight vector;

S1064, described data sending terminal utilize described weight vector that the data on described at least one antenna are weighted; And

S1066 is sent to described data receiver with the data after the weighting.

3. data transmission method according to claim 2 is characterized in that, described step S108 comprises:

S1082, described data receiver estimate and obtain the characteristic value of channel matrix to described channel;

S1084, described data receiver obtains the characteristic of correspondence vector according to described characteristic value; And

S1086, described data receiver decipher when according to described characteristic vector received data being carried out sky.

4. according to each described data transmission method in the claim 1 to 3, it is characterized in that the number of transmit antennas of described data sending terminal equates with the reception antenna number of described data receiver.

5. data transmission method according to claim 4 is characterized in that described data transmission method is used for tdd systems.

6. data transmission system is characterized in that comprising:

Data sending device, has at least one transmitting antenna, described data sending device is used for the data that needs send are carried out Space Time Coding, the characteristic value of channel matrix and described channel matrix is estimated and obtained to channel, utilize described characteristic value the data on described at least one antenna are carried out that wave beam forms and wave beam formed after data be sent to data sink; And

Data sink has at least one reception antenna, and described data sink is used to receive described data, described channel is estimated and is deciphered when carrying out sky according to the characteristic value of described channel, to obtain described data.

7. data transmission system according to claim 6 is characterized in that, described data sending device also comprises:

Coding module, the data that are used for the needs transmission are carried out Space Time Coding;

First channel estimation module is used for channel is estimated and obtained the characteristic value of channel matrix and described channel matrix; And

Wave beam forms module, be used to obtain described characteristic value characteristic of correspondence vector, and with described characteristic vector as weight vector, and utilize described weight vector that the data on described at least one antenna are weighted, and be sent to described data receiver by the data of described at least one antenna after with weighting.

8. data transmission system according to claim 7 is characterized in that, described data sink comprises:

The second channel estimation module is used for described channel is estimated and obtained the characteristic value of channel matrix;

Decoding module is used for obtaining the characteristic of correspondence vector according to described characteristic value, and deciphers when according to described characteristic vector received data being carried out sky.

9. according to each described data transmission system in the claim 6 to 8, it is characterized in that the number of transmit antennas of described data sending device equates with the reception antenna number of described data receiver.

10. data transmission system according to claim 9 is characterized in that described data transmission method is used for tdd systems.

Images