CN101635592B - LTE MIMO 8-TX transmit diversity method - Google Patents

Abstract

The invention provides an LTE MIMO 8-TX transmit diversity method, relates to a communication technology and realizes the coding and decoding expansion from LTE MIMO 2-TX diversity and LTE MIMO 4-TX diversity to LTE-Advance 8-TX diversity. Diversity signals generated in a coding process are mutually orthometric, and the relativity between channel responses is minimum; and in a decoding process, a block decoding method is adopted to input a corresponding receiving signal and a channel estimation value which are extracted from two fixed antenna ports to a 2-TX decoder every time to finish decoding. The invention utilizes the block decoding method for independent decoding and greatly lowers the decoding complexity, thereby providing a simple and effective solution for the application of the 8-TX MIMO diversity.

Description

The 8-TX emission diversity method of a kind of LTE MIMO

Technical field

The present invention relates to the mobile communication technology field, specifically the emission diversity method of a kind of LTE (Long Term Evolution) MIMO (multiple-input and multiple-output).

Background technology

The cardinal principle of transmission diversity is to utilize the weak dependence of space channel, selectivity on binding time/frequency for the transmission of signal provides more copy, improves the reliability of signal transmission, thereby improve the signal to noise ratio that receives signal, improve transmission rate or coverage.The candidate technologies of the transmit diversity technique among the LTE is a lot, such as Space Time Coding (Space-Time Code, STC), circulation delay diversity (CyclicDelay Diversity, CDD) and antenna switching diversity technology etc.

At present, the maximum antenna in the down link support is configured to 4 * 4 (4 reception antennas of 4 transmit antennas) among the LTE.In order further to improve the system signal transmission performance, LTE-Advance proposes to be configured to 8 * 8 (8 reception antennas of 8 transmit antennas) at the maximum antenna of down link support.For 8 * 8 antenna configurations among the LTE-Advance, some have been proposed about candidate's diversity scheme of 8-TX, such as document (R1-090104, Discussions on 8-TX Diversity Schemes for LTE-A Downlink, Samsung) in propose based on the 8-TX diversity scheme of SFBC+FSTD (space frequency block coding+frequency exchange transmit diversity) and improvement project based on SFBC+PSD (space frequency block coding+phase deviation diversity).But under the uncorrelated and 8-TX diversity situation, most encoding schemes are very little to the properties influence of BLER (Block Error Rate) when channel.During the channel strong correlation, SFBC+PSD diversity encoding scheme has preferably BLER, simultaneously, compares with the improvement project based on SFBC+PSD based on the 8-TX diversity scheme of SFBC+FSTD, only has very little BLER performance gap.And based on the 8-TX emission diversity scheme of SFBC+FSTD more simply too much than the improvement project based on SFBC+PSD aspect coding, the decoding.But still there is its deficiency in the emission diversity scheme that proposes in above-mentioned document aspect channel relevancy, and decode procedure is comparatively complicated, the symbol arrangement of coding also with R8LTE in 2-TX, the 4-TX scheme is inconsistent, and is compatible relatively poor before and after namely.

Summary of the invention

The present invention is directed to the defects of prior art, design a kind of emission diversity method that is applicable to 8-TX MIMO.This emission diversity method can reduce the correlation of interchannel, reduces decoding complexity, thereby and keeps well compatible and reach good systematic function with diversity scheme among the R8LTE.

The technical scheme that the present invention solves the problems of the technologies described above is, designs a kind of emission diversity method that is applicable to 8-TX MIMO, and the method comprises following treatment step:

A. encoder utilizes grouping quadrature encoding when empty, and as processing unit, coding generates two data vectors, forms two diversity signals with two independent data pieces of a time slot in the input data.Two optimally diversified antennas of each selection send this two diversity signals simultaneously;

B. the signal after the block encoding is modulated to respectively on the different OFDM subcarriers, sends by transmitting antenna;

C. corresponding with block encoding, use the block decoding method to extract from corresponding reception antenna subcarrier successively and receive signal and obtain channel response estimated value on the corresponding subcarrier;

D. the channel response estimated value of the reception signal that extracts among the step C and acquisition is directly inputted to and finishes successively decoding in the 2-TX decoder.

In the described steps A, the selection of grouping quadrature encoding and optimally diversified antenna when relating to sky.The coding that it is concrete and antenna selecting method are:

According to (the x that transmits ₁, x ₂, x ₃, x ₄, x ₅, x ₆, x ₇, x ₈), the conjugation (x that transmits ₁ ^*, x ₂ ^*, x ₃ ^*, x ₄ ^*, x ₅ ^*, x ₆ ^*, x ₇ ^*, x ₈ ^*), call the quadrature encoding that divides into groups when following formula adopts sky and select optimally diversified antenna,

$\left(\begin{array}{c}{s}_1\\ s_2\\ s_3\\ s_4\\ s_5\\ s_6\\ s_7\\ s_8\end{array}\right)=\frac{1}{\sqrt{2}}\left(\begin{array}{cccccccc}{x}_1& x_2& 0& 0& 0& 0& 0& 0\\ 0& 0& x_3& x_4& 0& 0& 0& 0\\ 0& 0& 0& 0& x_5& x_6& 0& 0\\ 0& 0& 0& 0& 0& 0& x_7& x_8\\ -x_2^{*}& x_1^{*}& 0& 0& 0& 0& 0& 0\\ 0& 0& -x_4^{*}& x_3^{*}& 0& 0& 0& 0\\ 0& 0& 0& 0& -x_6^{*}& x_5^{*}& 0& 0\\ 0& 0& 0& 0& 0& 0& -x_8^{*}& x_7^{*}\end{array}\right).$

Among described step C and the D, relate to the extraction and the diversity decode procedure that receive signal, its detailed process comprises: at every turn extract to estimate successively the decoder that corresponding reception signal and channel response estimated value be input to 2-TX from two fixed antenna ports and transmit, obtain the valuation of complex value MIMO decoded data, thereby obtain the valuation of one group of complex value MIMO decoded data.For example, the 2-TX decoder is according to i root reception antenna, and the channel response estimated value h on k and the individual subcarrier of k ' between j and j ' transmit antennas _{I, j, k}, h _{I, j ', k}, h _{I, j ', k},, h _{I, j, k '}, the reception signal r of i root reception antenna on k and the individual subcarrier of k ' _{I, k}, r _{I, k '}, call formula $\begin{array}{c}\sqrt{2}(h_{i,j,k^{\′}}^{*}{r}_{i,k}+h_{i,j^{\′},k}{r}_{i,k^{\′}}^{*})=(h_{i,j,k}{h}_{i,j,k^{\′}}^{*}+h_{i,j^{\′},k}{h}_{i,j^{\′},k^{\′}}^{*}){\tilde{x}}_j\\ \sqrt{2}(h_{i,j,k}^{*}{r}_{i,k^{\′}}+h_{i,j^{\′},k^{\′}}{r}_{i,k}^{*})=(h_{i,j,k}^{*}{h}_{i,j,k^{\′}}+h_{i,j^{\′},k}^{*}{h}_{i,j^{\′},k^{\′}}){\tilde{x}}_{j^{\′}}\end{array}$ The specified data valuation

Finish successively the data valuation to the 8-TX transmit diversity.

The present invention has realized the expansion from LTE MIMO 2-TX and 4-TX diversity to LTE-Advance 8-TX diversity coding and decoding.The present invention adopts independently data block as processing unit in cataloged procedure, and formed diversity signal is mutually orthogonal, and the correlation between channel response is minimum, the close and compatibility mutually of the Space Time Coding processing scheme that adopts among such processing method and the LTE; In decode procedure, utilize the block decoding method, extract the decoder that corresponding reception signal and channel estimation value be input to 2-TX from two fixed antenna ports at every turn and finish decoding, thus the lower decoding complexity of acquisition.

The 8-TX MIMO emission diversity scheme that adopts the present invention to propose, can in the transmit diversity of 8-TX MIMO, reach good performance with less complexity, for the application of 8-TX MIMO (multiple-input and multiple-outputs of 8 transmit antennas) diversity provides a kind of simple effectively solution.

Description of drawings

The Space Time Coding of Fig. 1 during take data block as processing unit concerns schematic diagram (take 2-TX as example)

Fig. 2 is the data transmit-receive schematic diagram based on the MIMO-OFDM system

Fig. 3 is based on the data transmit-receive schematic diagram of MIMO-OFDM system in the 2-TX situation

Fig. 4 is general code word decoding process figure in many antenna configurations system

Fig. 5 is codeword decoding flow chart in the 8-TX situation

Embodiment

In LTE by 2-TX and 4-TX diversity in the expansion of 8-TX diversity, inevitablely when improving systematic function, will increase system complexity.Therefore, when considering to improve systematic function, also must consider the increase of system complexity.The present invention adopts independently data block as processing unit in encoding and decoding, just can not exist between the adjacent coding unit and the interference between the adjacent encoding block, for simplified decoding is provided by the condition that provides.Simultaneously, the such processing method to a great extent processing scheme with LTE 2-TX and 4-TX diversity Space Time Coding is close and compatible mutually, and when the 8-TX diversity was processed, decode procedure did not need to change substantially.

The emission diversity method that is applicable to 8-TX MIMO specifically comprises following treatment step.

The grouping quadrature encoding carried out block encoding when the encoder utilization was empty, and as processing unit, coding generates two data vectors, forms two diversity signals with two independent data pieces of a time slot in the input data.Can select two optimally diversified antennas to send simultaneously this two diversity signals at every turn; Diversity signal after the block encoding is modulated to respectively on the different OFDM subcarriers, sends by transmitting antenna; Corresponding with block encoding, use the block decoding method to extract from corresponding reception antenna subcarrier successively and receive signal and obtain channel response estimated value on the corresponding subcarrier; The channel response estimated value that obtains is directly inputted to the 2-TX decoder finishes successively decode procedure.

Space Time Coding referring to Fig. 1 during take data block as processing unit concerns schematic diagram, and two independent data pieces that send among the figure can be expressed as (x ₁, x ₂), can be expressed as through the diversity signal that produces behind the LTE 2-TX antennas transmit diversity scheme coding:

$\left(\begin{array}{c}{s}_1\\ s_2\end{array}\right)=\frac{1}{\sqrt{2}}\left(\begin{array}{cc}{x}_1& x_2\\ -x_2^{*}& x_1^{*}\end{array}\right)---\left(1\right)$

Diversity signal after the block encoding is modulated to respectively on the different OFDM subcarriers, sends by transmitting antenna.It may be noted that to be that relevant LTE aspect among the 3GPPRelease 8 by adopting OFDM and MIMO technology, so that data are not to send from antenna separately simply, but will be modulated to respectively on the different OFDM subcarriers.

Referring to the data transmit-receive schematic diagram of Fig. 2 based on the MIMO-OFDM system, wherein a kind of after the OFDM modulation, the transmission situation signal of data have been provided among the figure.Among Fig. 2, h _{I, j, k}, h _{I, j ', k}, h _{I, j ', k '}, h _{I, j, k '}Represent respectively i root reception antenna, and the channel response on k and the individual subcarrier of k ' between j and j ' transmit antennas.Can be expressed as through the reception signal behind the channel,

$r_{i,k}=\frac{1}{\sqrt{2}}(h_{i,j,k}{x}_j-h_{i,j^{\′},k}{x}_{j^{\′}}^{*})+n_k---\left(2\right)$

$r_{i,k^{\′}}=\frac{1}{\sqrt{2}}(h_{i,j,k^{\′}}{x}_{j^{\′}}+h_{i,j^{\′},k^{\′}}{x}_j^{*})+n_{k^{\′}}$

Here, r _{I, k}, r _{I, k '}Represent the reception signal of i root reception antenna on k and k ' subcarrier.

Use the block decoding method to extract from corresponding reception antenna subcarrier successively and receive signal and obtain channel response estimated value on the corresponding subcarrier, further, following formula is carried out linear transformation process, and ignore noise n _k, n _{K '}, then can obtain

$\begin{array}{c}\sqrt{2}(h_{i,j,k^{\′}}^{*}{r}_{i,k}+h_{i,j^{\′},k}{r}_{i,k^{\′}}^{*})=(h_{i,j,k}{h}_{i,j,k^{\′}}^{*}+h_{i,j^{\′},k}{h}_{i,j^{\′},k^{\′}}^{*}){\tilde{x}}_j\\ \sqrt{2}(h_{i,j,k}^{*}{r}_{i,k^{\′}}+h_{i,j^{\′},k^{\′}}{r}_{i,k}^{*})=(h_{i,j,k}^{*}{h}_{i,j,k^{\′}}+h_{i,j^{\′},k}^{*}{h}_{i,j^{\′},k^{\′}}){\tilde{x}}_{j^{\′}}\end{array},$ The specified data valuation

The complex value MIMO decoded data valuation that namely obtains.

For the 2-TX transmit diversity, can directly make j=1, j '=2, k=1, k '=2.Namely in this case based on the data transmit-receive schematic diagram of MIMO-OFDM system referring to Fig. 3.Correspondingly, can be expressed as through the reception signal behind the channel,

$r_{i,1}=\frac{1}{\sqrt{2}}(h_{i,\mathrm{1,1}}{x}_1-h_{i,\mathrm{2,1}}{x}_2^{*})+n_1---\left(3\right)$

$r_i^{\mathrm{sc}2}=\frac{1}{\sqrt{2}}(h_{i,\mathrm{1,2}}{x}_2+h_{i,\mathrm{2,2}}{x}_1^{*})+n$

Use the block decoding method to extract from corresponding reception antenna subcarrier successively and receive signal and obtain channel response estimated value on the corresponding subcarrier, obtain determining the valuation of complex value MIMO decoded data

Formula (4)

$\sqrt{2}(h_{i,\mathrm{1,2}}^{*}{r}_{i,1}+h_{i,\mathrm{2,1}}{r}_{i,2}^{*})=(h_{i,\mathrm{1,1}}{h}_{i,\mathrm{1,2}}^{*}+h_{i,\mathrm{2,1}}{h}_{i,\mathrm{2,2}}^{*}){\tilde{x}}_1---\left(4\right)$

$\sqrt{2}(h_{i,\mathrm{1,1}}^{*}{r}_{i,2}+h_{i,\mathrm{2,2}}{r}_{i,1}^{*})=(h_{i,\mathrm{1,1}}^{*}{h}_{i,\mathrm{1,2}}+h_{i,\mathrm{2,1}}^{*}{h}_{i,\mathrm{2,2}}){\tilde{x}}_2$

Based on as front understanding to 2-TX, here can directly utilize the decoding scheme of 2-TX to process 4-TX, 8-TX transmit diversity, obviously this processing mode can reduce decoding complex degree, and has unified the decoder module in different antennae configuration (for example, 4-TX and the 8-TX etc.) situation.

Correspondingly, can do following processing for the situation of 4-TX, be (x when transmitting ₁, x ₂, x ₃, x ₄) time, have:

$\left(\begin{array}{c}{s}_1\\ s_2\\ s_3\\ s_4\end{array}\right)=\frac{1}{\sqrt{2}}\left(\begin{array}{cccc}{x}_1& x_2& 0& 0\\ 0& 0& x_3& x_4\\ -x_2^{*}& x_1^{*}& 0& 0\\ 0& 0& -x_4^{*}& x_3^{*}\end{array}\right)---\left(5\right)$

Formula (5) shows that this scheme can see as at 2 2-TX emission diversity schemes on the antenna port 1,3 and on the antenna port 2,4, so in the process of decoding, we only need corresponding data and channel estimation value be input in the decoder of 2-TX and finish decoding.

For the emission diversity method of 8-TX MIMO, the system of selection of grouping quadrature encoding and optimally diversified antenna is when relating to sky:

According to (the x that transmits ₁, x ₂, x ₃, x ₄, x ₅, x ₆, x ₇, x ₈), the conjugation (x that transmits ₁ ^*, x ₂ ^*, x ₃ ^*, x ₄ ^*, x ₅ ^*, x ₆ ^*, x ₇ ^*, x ₈ ^*), call the quadrature encoding that divides into groups when following formula adopts sky and select optimally diversified antenna to obtain diversity signal,

$\left(\begin{array}{c}{s}_1\\ s_2\\ s_3\\ s_4\\ s_5\\ s_6\\ s_7\\ s_8\end{array}\right)=\frac{1}{\sqrt{2}}\left(\begin{array}{cccccccc}{x}_1& x_2& 0& 0& 0& 0& 0& 0\\ 0& 0& x_3& x_4& 0& 0& 0& 0\\ 0& 0& 0& 0& x_5& x_6& 0& 0\\ 0& 0& 0& 0& 0& 0& x_7& x_8\\ -x_2^{*}& x_1^{*}& 0& 0& 0& 0& 0& 0\\ 0& 0& -x_4^{*}& x_3^{*}& 0& 0& 0& 0\\ 0& 0& 0& 0& -x_6^{*}& x_5^{*}& 0& 0\\ 0& 0& 0& 0& 0& 0& -x_8^{*}& x_7^{*}\end{array}\right).$

Diversity signal after the block encoding is modulated to respectively on the different OFDM subcarriers, sends by transmitting antenna.

Correspondingly, the 8-TX transmit diversity can be seen 4 2-TX emission diversity schemes as.Selection has two antenna ports of same transmit information as the antenna port of 2-TX emission diversity scheme., can be regarded as 1-5,2-6,3-7,4-8 here, the 2-TX emission diversity scheme of 4 antenna ports has the port of same transmit information as the antenna port of 2-TX emission diversity scheme with above-mentioned respectively.Extract respectively (1,5) (2,6), (3,7), the reception signal on the corresponding subcarrier of (4,8) antenna port and respective channel response; The data of extracting are input to respectively in the 2-TX decoder finish decoding, thereby obtain respectively the valuation of complex value MIMO decoded data $({\tilde{x}}_1,{\tilde{x}}_2),({\tilde{x}}_3,{\tilde{x}}_4),({\tilde{x}}_5,{\tilde{x}}_6),({\tilde{x}}_7,{\tilde{x}}_8);$ Finally obtain the valuation of one group of complex value MIMO decoded data

Finish whole decode procedure.Therefore aspect the actual realization in decode procedure, corresponding data and channel estimation value directly can be finished decode procedure as the input of the decoder of 2-TX.This shows that interpretation method of the present invention has the advantages that amount of calculation is little, complexity is low.

Referring to code word flow chart shown in Figure 4, provided general decode procedure in many antenna configurations system among the figure.Specifically comprise the steps:

Step 41, the terminal receive data extracts from corresponding reception antenna subcarrier and to receive signal and to obtain channel response estimated value on the corresponding subcarrier;

Step 42, reception signal and the responsive channels extracted on the corresponding subcarrier of institute from two antenna ports with same transmit information successively respectively respond;

Step 43 is input to the 2-TX decoder successively with the data of extracting at every turn, obtains corresponding data valuation;

Step 44 finally obtains the valuation of one group of complex value MIMO decoded data, i.e. decode results.

Below specifically describe the 8-TX emission diversity scheme with an instantiation, Fig. 5 has provided the simplified decoding process under this concrete condition.

Step 51, the terminal receive data extracts from corresponding reception antenna subcarrier and to receive signal and to obtain channel response estimated value on the corresponding subcarrier;

Step 52 extracts first to the reception signal r on (1,5) antenna port 1,2 subcarriers _{I, 1}, r _{I, 2}And channel response h _{I, 1,1}, h _{I, 1,2}, h _{I, 5,1}, h _{I, 5,2}

Step 53 is input to the data (receiving the response of signal and responsive channels) of extracting in the step 52 in the decoder of 2-TX and finishes decoding, obtains the valuation of complex value MIMO decoded data

Step 54 extracts second to the reception signal r on (2,6) antenna port 3,4 subcarriers _{I, 3}, r _{I, 4}And channel response h _{I, 2,3}, h _{I, 2,4}, h _{I, 6,3}, h _{I, 6,4}

Step 55 is input to the data of extracting in the step 54 in the decoder of 2-TX and finishes decoding, thereby obtains the valuation of complex value MIMO decoded data

Step 56 extracts the 3rd to the reception signal r on (3,7) antenna port 5,6 subcarriers _{I, 5}, r _{I, 6}And responsive channels response h _{I, 3,5}, h _{I, 3,6}, h _{I, 7,5}, h _{I, 7,6}

Step 57 is input to the data of extracting in the step 56 in the decoder of 2-TX and finishes decoding, thereby obtains the valuation of complex value MIMO decoded data

Step 58 extracts the 4th to the reception signal r on (4,8) antenna port 7,8 subcarriers _{I, 7}, r _{I, 8}And responsive channels response h _{I, 4,7}, h _{I, 4,8}, h _{I, 8,7}, h _{I, 8,8}

Step 59 is input to the data of extracting in the step 58 in the decoder of 2-TX and finishes decoding, thereby obtains the valuation of complex value MIMO decoded data

Step 510 finally obtains the valuation of one group of complex value MIMO decoded data It is decode results.

The 8-TX diversity coding and decoding extended method that the present invention proposes, the input data of participating in coding are as processing unit take data block independently, and has minimum correlation between the antenna of selection transmission diversity signal, it is low that corresponding simplified decoding method has a computation complexity, the characteristics of function admirable are for its application provides a kind of simple effectively solution.

Claims (4)

1. the 8-TX emission diversity method of a LTE MIMO is characterized in that, comprises following treatment step:

A. encoder utilizes grouping quadrature encoding when empty, and as processing unit, coding generates two data vectors, forms two diversity signals, according to (the x that transmits with two independent data pieces of a time slot in the input data ₁, x ₂, x ₃, x ₄, x ₅, x ₆, x ₇, x ₈), the conjugation that transmits Call formula:

$\left(\begin{array}{c}{s}_1\\ s_2\\ s_3\\ s_4\\ s_5\\ s_6\\ s_7\\ s_8\end{array}\right)=\frac{1}{\sqrt{2}}\left(\begin{array}{cccccccc}{x}_1& x_2& 0& 0& 0& 0& 0& 0\\ 0& 0& x_3& x_4& 0& 0& 0& 0\\ 0& 0& 0& 0& x_5& x_6& 0& 0\\ 0& 0& 0& 0& 0& 0& x_7& x_8\\ -x_2^1& x_1^{*}& 0& 0& 0& 0& 0& 0\\ 0& 0& {-x}_4^{*}& x_3^{*}& 0& 0& 0& 0\\ 0& 0& 0& 0& -x_6^{*}& x_5^{*}& 0& 0\\ 0& 0& 0& 0& 0& 0& {-x}_8^{*}& x_7^{*}\end{array}\right)$ The grouping quadrature encoding selects optimally diversified antenna to obtain diversity signal when adopting sky;

B. the diversity signal after the block encoding is modulated to respectively on the different OFDM subcarriers, then sends;

C. corresponding with block encoding, use block decoding to extract from corresponding reception antenna subcarrier successively and receive signal and obtain channel response estimated value on the corresponding subcarrier;

The reception signal that D. will extract and the channel response estimated value of acquisition are directly inputted to the 2-TX decoder and finish successively decoding.

2. 8-TX emission diversity method according to claim 1 is characterized in that, described step B further comprises, selects two optimally diversified antennas to send simultaneously two diversity signals at every turn.

3. 8-TX emission diversity method according to claim 1, it is characterized in that, step D specifically comprises, at every turn extract to estimate successively the decoder that corresponding reception signal and channel response estimated value be input to 2-TX from two fixed antenna ports and transmit, obtain the valuation of complex value MIMO decoded data, thereby obtain the valuation of one group of complex value MIMO decoded data.

4. 8-TX emission diversity method according to claim 1, it is characterized in that, the concrete steps that described 2-TX decoder is finished decoding comprise, according to i root reception antenna, and the channel response estimated value h on k and the individual subcarrier of k ' between j and j ' transmit antennas _{I, j, k}, h _{I, j ', k}, h _{I, j ', k '}, h _{I, j, k '}, the reception signal r of i root reception antenna on k and the individual subcarrier of k ' _{I, k}, r _{I, k}', call formula $\begin{array}{c}\sqrt{2}(h_{i,j,k^{\′}}^{*}{r}_{i,k}+h_{i,j^{\′},k}{r}_{i,k^{\′}}^{*})=(h_{i,j,k}{h}_{i,j,k^{\′}}^{*}+h_{i,j^{\′},k}{h}_{i,j^{\′},k^{\′}}^{*}){\tilde{x}}_j\\ \sqrt{2}(h_{i,j,k}^{*}{r}_{i,k^{\′}}+h_{i,j^{\′},k^{\′}}{r}_{i,k}^{*})=(h_{i,j,k}^{*}{h}_{i,j,k^{\′}}+h_{i,j^{\′},k}^{*}{h}_{i,j^{\′},k^{\′}}){\tilde{x}}_{j^{\′}}\end{array}$ The specified data valuation

Images