CN103117780A - Method for eliminating multi-user interference in multiple input and multiple output (MIMO) system - Google Patents

Abstract

The invention discloses a method of eliminating multi-user interference in a multiple input and multiple output (MIMO) system. The method of eliminating the multi-user interference in the MIMO system is suitable for an X channel, wherein two transmitting ends of the X channel are respectively provided with two antennas. The transmitting ends utilizes a pace time block code (R2-STBC), wherein the rate of the space time block code is 2, and each encoding matrix is transmitted continuously two times. The multi-user interference can be eliminated by precoding each encoding matrix at the transmitting end and conducting the add and substract operation on receiving signals at the receiving end, so that transmitting signals of each user can be decoded respectively. The method of eliminating the multi-user interference in the MIMO system can not only reduce feedback quantity, but also improve transmission efficiency.

Description

A kind of method of eliminating multi-user interference in the mimo system

Technical field

The present invention relates to the communications field, especially a kind of method of eliminating multi-user interference in the mimo system.

Background technology

Multiple-input and multiple-output (MIMO, Multi-Input Multi-Output) technology refers to use respectively many transmit antennas and Duo Gen reception antenna at transmitting terminal and receiving terminal, by many antenna transmitted signals and multiple antenna receiving signal, improved user's service quality.

The transmission plan of MIMO technology can be divided into two classes, and first spatial multiplex scheme can improve the validity of system; It two is space diversity scheme, can improve the reliability of transfer of data.Studying one of more space diversity scheme is orthogonal space time packet (OSTBC, Orthogonal Space Time Block Code), and the Alamouti coding is typical OSTBC, and this coding comprises 2 independently symbols, and its code rate is 1.OSTBC has obtained full diversity gains, but can not obtain spatial multiplexing gain, and comparatively desirable encoding scheme should be able to obtain two kinds of gains simultaneously, takes into account reliability and the validity of system.So scholars had proposed Perfect space-time block codes afterwards, its spatial multiplexing gain equals the number of transmitting antenna, and can realize full-diversity, and namely diversity gain equals the product of number of transmit antennas and reception antenna quantity.Speed is that 2 Space-Time Block Coding (R2-STBC, Rate2Space Time Block Code) is a kind of of Perfect space-time block codes.

The number of users that supports from system is divided, and the MIMO technology can be divided into Single User MIMO technology and multiuser MIMO technology.The Single User MIMO technology has just obtained scholars' extensive concern from the MIMO technology is born, get after deliberation at present comparative maturity.Compare the Single User MIMO technology, the multiuser MIMO technology is the communication system of closing to reality more, is present research main flow about the MIMO technology.The greatest problem that the multiuser MIMO technology faces is cannot cooperate with each other between each user, and this is so that serious interference appears in receiving terminal, thus the reliability of reduction whole system, and therefore, interference cancellation techniques is one of key technology of multiuser MIMO.

The X channel that each user disposes many antennas is a kind of common multi-user MIMO system.The X channel comprises two transmitting terminals and two receiving terminals, and each transmitting terminal is respectively to two receiving terminal transmitted signals.Disturb alignment so that the useful signal of each receiving terminal drops on respectively in the different vector spaces with interference signal, to eliminate the effect of disturbing thereby reach.Li Liangbin proposes to adopt Space Time Coding and disturbs alignment to eliminate multi-user interference in the X channel in article " When alamouti codes meet interference alignment:transmission schemes for two-user X channel ", be applicable to the X channel of two transmitting antennas and two reception antennas, the method has obtained the diversity gain that Space Time Coding brings, and its reliability is better than not adopting the interference alignment scheme of Space Time Coding.The below simply introduces the method.

System model as shown in Figure 1, two transmitting terminals, 2 antennas of each transmitting terminal configuration, 2 receiving terminals, 2 antennas of each receiving terminal configuration.H ₁And H ₂Respectively that transmitting terminal 1 is to the channel matrix of receiving terminal 1 and receiving terminal 2, G ₁And G ₂Respectively that transmitting terminal 2 is to the channel matrix of receiving terminal 1 and receiving terminal 2.Transmitting terminal 1 sends respectively s ^k ₁₁And s ^k ₁₂To receiving terminal 1 and receiving terminal 2, transmitting terminal 2 sends respectively s ^k ₂₁And s ^k ₂₂To receiving terminal 1 and receiving terminal 2, k=1,2.s ^k ₁₁And s ^k ₂₁The useful reception signal of receiving terminal 1, s ^k ₁₂And s ^k ₂₂It is the interference signal to receiving terminal 1.s ^k ₁₂And s ^k ₂₂The useful reception signal of receiving terminal 2, s ^k ₁₁And s ^k ₂₁It is the interference signal to receiving terminal 2.Two transmitting terminals all adopt the Alamouti coding.The transmitted signal of two transmitting terminals is used respectively X ₁And X ₂Expression.

$X_1=\left[\begin{array}{cc}{s^1}_{11}& {s^2}_{11}\\ {{{-s}^2}_{11}}^{*}& {{s^1}_{11}}^{*}\\ 0& 0\end{array}\right]V_{11}+\left[\begin{array}{cc}0& 0\\ {{{-s}^2}_{12}}^{*}& {{s^1}_{12}}^{*}\\ {s^1}_{12}& {s^2}_{12}\end{array}\right]{\mathrm{<figure-callout\; id="12"\; label="V"\; filenames="130122170612.png"\; state="\{\{state\}\}">V</figure-callout>}}_{12}$

$X_2=\left[\begin{array}{cc}{s^1}_{21}& {s^2}_{21}\\ {{{-s}^2}_{21}}^{*}& {{s^1}_{21}}^{*}\\ 0& 0\end{array}\right]{\mathrm{<figure-callout\; id="21"\; label="V"\; filenames="130122170612.png"\; state="\{\{state\}\}">V</figure-callout>}}_{21}+\left[\begin{array}{cc}0& 0\\ {{{-s}^2}_{22}}^{*}& {{s^1}_{22}}^{*}\\ {s^1}_{22}& {s^2}_{22}\end{array}\right]V_{22}$

Wherein, V _IkPre-coding matrix, i, k=1,2.

Order $V_{11}=\sqrt{\frac{1}{\mathrm{tr}\left({H_2}^{-1}{H_2}^{-1*}\right)}}{H_2}^{-1},$ ${\mathrm{<figure-callout\; id="12"\; label="V"\; filenames="130122170612.png"\; state="\{\{state\}\}">V</figure-callout>}}_{12}=\sqrt{\frac{1}{\mathrm{tr}\left({H_1}^{-1}{H_1}^{-1*}\right)}}{H_1}^{-1},$ ${\mathrm{<figure-callout\; id="21"\; label="V"\; filenames="130122170612.png"\; state="\{\{state\}\}">V</figure-callout>}}_{21}=\sqrt{\frac{1}{\mathrm{tr}\left({G_2}^{-1}{G_2}^{-1*}\right)}}{G_2}^{-1},$ $V_{22}=\sqrt{\frac{1}{\mathrm{tr}\left({G_1}^{-1}{G_1}^{-1*}\right)}}{G_1}^{-1},$ The mark of tr () representing matrix, () ^*Expression complex conjugate, then the reception signal Y of receiving terminal 1 and receiving terminal 2 ₁And Y ₂Can be expressed as respectively

$Y_1=\left[\begin{array}{cc}{s^1}_{11}& {s^2}_{11}\\ {{{-s}^2}_{11}}^{*}& {{s^1}_{11}}^{*}\\ 0& 0\end{array}\right]V_{11}{H}_1+\left[\begin{array}{cc}{s^1}_{21}& {s^2}_{21}\\ {{{-s}^2}_{21}}^{*}& {{s^1}_{21}}^{*}\\ 0& 0\end{array}\right]V_{21}{G}_1+\left[\begin{array}{cc}0& 0\\ {{{-\mathrm{as}}^2}_{12}}^{*}-{{{\mathrm{bs}}^2}_{22}}^{*}& {{{\mathrm{as}}^1}_{12}}^{*}+{{{\mathrm{bs}}^1}_{22}}^{*}\\ {{\mathrm{as}}^1}_{12}+{{\mathrm{bs}}^1}_{22}& {{\mathrm{as}}^2}_{12}+{{\mathrm{bs}}^2}_{22}\end{array}\right]+W_1$

$Y_2=\left[\begin{array}{cc}0& 0\\ {{{-s}^2}_{12}}^{*}& {{s^1}_{12}}^{*}\\ {s^1}_{12}& {s^2}_{12}\end{array}\right]V_{12}{H}_2+\left[\begin{array}{cc}0& 0\\ {{{-s}^2}_{22}}^{*}& {{s^1}_{22}}^{*}\\ {s^1}_{22}& {s^2}_{22}\end{array}\right]V_{22}{G}_2+\left[\begin{array}{cc}0& 0\\ {{\mathrm{cs}}^1}_{11}+{{\mathrm{ds}}^1}_{21}& {{\mathrm{cs}}^2}_{11}+{{\mathrm{ds}}^2}_{21}\\ {{{-\mathrm{cs}}^2}_{11}}^{*}-{{{\mathrm{ds}}^2}_{21}}^{*}& {{{\mathrm{cs}}^1}_{11}}^{*}+{{{\mathrm{ds}}^1}_{21}}^{*}\end{array}\right]+W_2$

Wherein, W ₁And W ₂Be noise matrix.

" When alamouti codes meet interference alignment:transmission schemes for two-user X channel " knows by article, to Y ₁Element eliminated s after adding reducing ^k ₁₂And s ^k ₂₂To the interference of receiving terminal 1, to Y ₂Element eliminated s after adding reducing ^k ₁₁And s ^k ₂₁To the interference of receiving terminal 2, so this model equivalence is two multiple access access channels, and receiving terminal can be deciphered respectively the signal of each transmitting terminal, realizes the maximum-likelihood decoding of single symbol.

The transmitting terminal of this scheme needs known channel matrix or 4 pre-coding matrixes, and feedback quantity is higher, and its efficiency of transmission is

Symbols/channel use awaits improving.

Summary of the invention

For existing program feedback quantity height and the lower problem of efficiency of transmission, the present invention proposes a kind of method of eliminating multi-user interference in the mimo system, be applicable to the X channel that two transmitting terminals dispose respectively two antennas, the method has not only reduced feedback quantity, has also improved efficiency of transmission.

Realize that technical thought of the present invention is: transmitting terminal employing speed is 2 Space-Time Block Coding (R2-STBC), and each encoder matrix is sent twice continuously, by at transmitting terminal each encoder matrix being carried out precoding and adds to received signal reducing at receiving terminal, eliminate multi-user interference, thereby can decipher respectively each user's transmitted signal.

For realizing above-mentioned technical thought, a kind of method of eliminating multi-user interference in the mimo system that the present invention proposes comprises:

A, two receiving terminals calculate respectively the element of the pre-coding matrix of two transmitting terminals, this pre-coding matrix energy is so that transmitting terminal 1 sends to the useful signal of receiving terminal 1 or receiving terminal 2 and useful signal that transmitting terminal 2 sends to receiving terminal 1 or receiving terminal 2 keeps quadrature in transmission course, and so latter two receiving terminal quantizes respectively the element of pre-coding matrix and quantized value is fed back to two transmitting terminals;

B, transmitting terminal 1 is to its modulation signal c _k(k=1,2 ..., 8) and to carry out speed be 2 space-time block code, obtains sending to the encoder matrix C of the individual receiving terminal of i (i=1,2) _i, $C_i=\left[\begin{array}{cc}{\mathrm{\&alpha;}}_1{c}_{4i-3}-{{\mathrm{\&beta;}}_1{c}_{4i-2}}^{*}& {\mathrm{\&beta;}}_1{c_{4i-1}}^{*}+{\mathrm{\&alpha;}}_1{c}_{4i}\\ {\mathrm{\&alpha;}}_2{c}_{4i-1}-{\mathrm{\&beta;}}_2{c_{4i}}^{*}& {\mathrm{\&beta;}}_2{c_{4i-3}}^{*}+{\mathrm{\&alpha;}}_2{c}_{4i-2}\end{array}\right],$ α ₁, α ₂, β ₁And β ₂Be real number, they satisfy α ₁ ²+ β ₁ ²=1 and α ₂ ²+ β ₂ ²=1; Transmitting terminal 2 is to its modulation signal s _k(k=1,2 ..., 8) and to carry out speed be 2 space-time block code, obtains sending to the encoder matrix S of i receiving terminal _i, $S_i=\left[\begin{array}{cc}{\mathrm{\&alpha;}}_1{s}_{4i-3}-{{\mathrm{\&beta;}}_1{s}_{4i-2}}^{*}& {\mathrm{\&beta;}}_1{s_{4i-1}}^{*}+{\mathrm{\&alpha;}}_1{s}_{4i}\\ {\mathrm{\&alpha;}}_2{s}_{4i-1}-{\mathrm{\&beta;}}_2{s_{4i}}^{*}& {\mathrm{\&beta;}}_2{s_{4i-3}}^{*}+{\mathrm{\&alpha;}}_2{s}_{4i-2}\end{array}\right];$

C, transmitting terminal 1 obtains pre-coding matrix A according to feedback information and quantization method ₁And A ₂, transmitting terminal 2 obtains pre-coding matrix B according to feedback information and quantization method ₁And B ₂

D, transmitting terminal 1 utilizes A _iTo C _iCarry out precoding, i=1,2, obtain A _iC _i, transmitting terminal 2 utilizes B _iTo S _iCarry out precoding, obtain B _iS _i, so latter two transmitting terminal sends A with two antennas respectively ₁C ₁± A ₂C ₂And B ₁S ₁± B ₂S ₂

E, receiving terminal 1 is processed and is received signal, obtains receiving the another kind of expression-form y of signal, and receiving terminal 2 is processed and is received signal, obtains receiving the another kind of expression-form z of signal;

F, receiving terminal 1 decipher respectively the useful signal that transmitting terminal 1 and transmitting terminal 2 send to this receiving terminal according to y, channel matrix and pre-coding matrix;

G, receiving terminal 2 decipher respectively the useful signal that transmitting terminal 1 and transmitting terminal 2 send to this receiving terminal according to z, channel matrix and pre-coding matrix.

Further, described steps A specifically comprises:

A1, every row of pre-coding matrix are identical, and receiving terminal 1 is according to channel matrix H ₁And G ₁Calculate the element a of pre-coding matrix ₁₁ ¹, a ₂₁ ¹, b ₁₁ ¹And b ₂₁ ¹, then adopt the method for uniform quantization or non-uniform quantizing to quantize this four parameters, and with a ₁₁ ¹And a ₂₁ ¹Quantized value feed back to transmitting terminal 1, with b ₁₁ ¹And b ₂₁ ¹Quantized value feed back to transmitting terminal 2, wherein H ₁And G ₁Be respectively two transmitting terminals to the channel matrix of receiving terminal 1, their exponent number is N * 2, N is the number of reception antenna, N 〉=1;

A2, every row of pre-coding matrix are identical, and receiving terminal 2 is according to channel matrix H ₂And G ₂Calculate the element a of pre-coding matrix ₁₁ ², a ₂₁ ², b ₁₁ ²And b ₂₁ ², then adopt the method for uniform quantization or non-uniform quantizing to quantize this four parameters, and with a ₁₁ ²And a ₂₁ ²Quantized value feed back to transmitting terminal 1, with b ₁₁ ²And b ₂₁ ²Quantized value feed back to transmitting terminal 2, wherein H ₂And G ₂Be respectively two transmitting terminals to the channel matrix of receiving terminal 2, their exponent number is N * 2.

Further, described step C specifically comprises:

C1, transmitting terminal 1 at first obtain the value of pre-coding matrix element according to feedback information and quantization method, might as well still use a ₁₁ ¹, a ₂₁ ¹, a ₁₁ ²And a ₂₁ ²Then expression obtains pre-coding matrix A ₁And A ₂, $A_1=\left[\begin{array}{cc}{a_{11}}^1& {a_{11}}^1\\ {a_{21}}^1& {a_{21}}^1\end{array}\right],$ $A_2=\left[\begin{array}{cc}{a_{11}}^2& {a_{11}}^2\\ {a_{21}}^2& {a_{21}}^2\end{array}\right];$

C2, transmitting terminal 2 at first obtain the value of pre-coding matrix element according to feedback information and quantization method, might as well still use b ₁₁ ¹, b ₂₁ ¹, b ₁₁ ²And b ₂₁ ²Then expression obtains pre-coding matrix B ₁And B ₂, $B_1=\left[\begin{array}{cc}{b_{11}}^1& {b_{11}}^1\\ {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^1& {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^1\end{array}\right],$ $B_2=\left[\begin{array}{cc}{b_{11}}^2& {b_{11}}^2\\ {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^2& {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^2\end{array}\right].$

Further, described step D specifically comprises:

D1,1 couple of C of transmitting terminal _iCarry out precoding, i=1,2, obtain A _iC _i, 2 couples of S of transmitting terminal _iCarry out precoding, obtain B _iS _i

D2, within the identical time, two antennas of transmitting terminal 1 usefulness are with A ₁C ₁+ A ₂C ₂Send, two antennas of transmitting terminal 2 usefulness are with B ₁S ₁+ B ₂S ₂Send, the reception signal of two receiving terminals is respectively Y ₁And Z ₁

D3, within the identical time, two antennas of transmitting terminal 1 usefulness are with A ₁C ₁-A ₂C ₂Send, two antennas of transmitting terminal 2 usefulness are with B ₁S ₁-B ₂S ₂Send, the reception signal of two receiving terminals is respectively Y ₂And Z ₂

Further, described step e specifically comprises:

E1, receiving terminal 1 receive signal to it and carry out the phase add operation, obtain Y=Y ₁+ Y ₂, then obtain the equivalents form y of Y, y=[y ₁₁, y ₁₂ ^*..., y _N1, y _N2 ^*] ^T, y _MnThe element of the capable n row of the m of representing matrix Y, m=1,2 ..., N, n=1,2, () ^*The expression complex conjugate, () ^TThe expression transposition;

E2, receiving terminal 2 receive signal to it and carry out the phase reducing, obtain Z=Z ₁-Z ₂, then obtain the equivalents form z of Z, z=[z ₁₁, z ₁₂ ^*..., z _N1, z _N2 ^*] ^T, z _MnThe element of the capable n row of the m of representing matrix Z, m=1,2 ..., N, n=1,2.

Further, described step F specifically comprises:

F1, receiving terminal 1 calculates H according to channel matrix and pre-coding matrix ₁A ₁And G ₁B ₁, H ₁A ₁Every row identical, G ₁B ₁Every row also identical, might as well be expressed as $H_1{A}_1=\left[\begin{array}{cc}{h_{11}}^{1^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="h"\; filenames="130122170612.png"\; state="\{\{state\}\}">h</figure-callout>}}_{12}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{1^{\&prime;}}& {h_{N2}}^{1^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{h_{11}}^{1^{\&prime;}}& {h_{11}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{1^{\&prime;}}& {h_{N1}}^{1^{\&prime;}}\end{array}\right],$ $G_1{B}_1=\left[\begin{array}{cc}{g_{11}}^{1^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="g"\; filenames="130122170612.png"\; state="\{\{state\}\}">g</figure-callout>}}_{12}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{1^{\&prime;}}& {g_{N2}}^{1^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{g_{11}}^{1^{\&prime;}}& {g_{11}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{1^{\&prime;}}& {g_{N1}}^{1^{\&prime;}}\end{array}\right];$

F2 is according to H ₁A ₁And G ₁B ₁Element obtain F ₁And F ₂, be expressed as:

$F_1=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{h_{11}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{11}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{11}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{11}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{11}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{11}}^{1^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{h_{N1}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{N1}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{N1}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{N1}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{N1}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{N1}}^{1^{\&prime;}*}\end{array}\right]$

$F_2=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{g_{11}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{11}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{11}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{11}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{11}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{11}}^{1^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{g_{N1}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{N1}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{N1}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{N1}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{N1}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{N1}}^{1^{\&prime;}*}\end{array}\right]$

F3, receiving terminal 1 is processed y, obtains $y^{\&prime;}=\left[\begin{array}{c}{F_1}^T\\ {F_2}^T\end{array}\right]y;$

F4 is listed as equivalent received signals, with 2F with front 4 of y ' ₁ ^TF ₁As equivalent channel matrix, decoding transmitting terminal 1 sends to the useful signal of receiving terminal 1;

F5 is listed as equivalent received signals, with 2F with rear 4 of y ' ₂ ^TF ₂As equivalent channel matrix, decoding transmitting terminal 2 sends to the useful signal of receiving terminal 1.

Further, described step G specifically comprises:

G1, receiving terminal 2 calculates H according to channel matrix and pre-coding matrix ₂A ₂And G ₂B ₂, H ₂A ₂Every row identical, G ₂B ₂Every row also identical, might as well be expressed as $H_2{A}_2=\left[\begin{array}{cc}{h_{11}}^{2^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="h"\; filenames="130122170612.png"\; state="\{\{state\}\}">h</figure-callout>}}_{12}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{2^{\&prime;}}& {h_{N2}}^{2^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{h_{11}}^{2^{\&prime;}}& {h_{11}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{2^{\&prime;}}& {h_{N1}}^{2^{\&prime;}}\end{array}\right],$ $G_2{B}_2=\left[\begin{array}{cc}{g_{11}}^{2^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="g"\; filenames="130122170612.png"\; state="\{\{state\}\}">g</figure-callout>}}_{12}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{2^{\&prime;}}& {g_{N2}}^{2^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{g_{11}}^{2^{\&prime;}}& {g_{11}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{2^{\&prime;}}& {g_{N1}}^{2^{\&prime;}}\end{array}\right];$

G2 is according to H ₂A ₂And G ₂B ₂Element obtain F ' ₁And F ' ₂, be expressed as:

$F_1^{\&prime;}=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{h_{11}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{11}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{11}}^{}& {-\mathrm{\&beta;}}_2{h_{11}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{11}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{11}}^{2^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{h_{N1}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{N1}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{N1}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{N1}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{N1}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{N1}}^{2^{\&prime;}*}\end{array}\right]$

$F_2^{\&prime;}=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{g_{11}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{11}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{11}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{11}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{11}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{11}}^{2^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{g_{N1}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{N1}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{N1}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{N1}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{N1}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{N1}}^{2^{\&prime;}*}\end{array}\right]$

G3, receiving terminal 2 is processed z, obtains $z^{\&prime;}=\left[\begin{array}{c}{F_1^{\&prime;}}^T\\ {F_2^{\&prime;}}^T\end{array}\right]z;$

G4 is listed as equivalent received signals, with 2F ' with front 4 of z ' ₁ ^TF ' ₁As equivalent channel matrix, decoding transmitting terminal 1 sends to the useful signal of receiving terminal 2;

G5 is listed as equivalent received signals, with 2F ' with rear 4 of z ' ₂ ^TF ' ₂As equivalent channel matrix, decoding transmitting terminal 2 sends to the useful signal of receiving terminal 2.

Compare with existing scheme, technical scheme of the present invention has not only reduced feedback quantity, has also improved efficiency of transmission.

Description of drawings

Fig. 1 is the system model of existing program;

Fig. 2 is the system model of the embodiment of the invention;

Fig. 3 is flow chart of the present invention;

Fig. 4 is coding and the process of transmitting flow chart of transmitting terminal among the present invention;

Fig. 5 is the decode procedure flow chart of receiving terminal among the present invention;

Fig. 6 be modulation system the present invention and existing program when being 4QAM reliability ratio;

Fig. 7 be modulation system the present invention and existing program when being 16QAM reliability ratio.

Embodiment

The below provides a kind of embodiment of the present invention, and the present invention will be further described in detail.System model as shown in Figure 2.System comprises two transmitting terminals and two receiving terminal R _i(i=1,2), two antennas of each transmitting terminal configuration, each receiving terminal configuration N root antenna.H _iIt is transmitting terminal 1 to R _iChannel matrix, G _iIt is transmitting terminal 2 to R _iChannel matrix, their exponent number is N * 2.

It is 2 Space-Time Block Coding that two transmitting terminals all adopt speed, and transmitting terminal 1 is with the Space Time Coding Matrix C _iSend to R _i, i=1,2, transmitting terminal 2 is with the Space Time Coding matrix S _iSend to R _ic _k(k=1,2 ..., 8) and s _kRespectively the modulation signal of transmitting terminal 1 and transmitting terminal 2, encoder matrix C _i(i=1,2) and S _iBe respectively

$C_i=\left[\begin{array}{cc}{\mathrm{\&alpha;}}_1{c}_{4i-3}-{\mathrm{\&beta;}}_1{c_{4i-2}}^{*}& {\mathrm{\&beta;}}_1{c_{4i-1}}^{*}+{\mathrm{\&alpha;}}_1{c}_{4i}\\ {\mathrm{\&alpha;}}_2{c}_{4i-1}-{\mathrm{\&beta;}}_2{c_{4i}}^{*}& {\mathrm{\&beta;}}_2{c_{4i-3}}^{*}+{\mathrm{\&alpha;}}_2{c}_{4i-2}\end{array}\right]$ $S_i=\left[\begin{array}{cc}{\mathrm{\&alpha;}}_1{s}_{4i-3}-{\mathrm{\&beta;}}_1{s_{4i-2}}^{*}& {\mathrm{\&beta;}}_1{s_{4i-1}}^{*}+{\mathrm{\&alpha;}}_1{s}_{4i}\\ {\mathrm{\&alpha;}}_2{s}_{4i-1}-{\mathrm{\&beta;}}_2{s_{4i}}^{*}& {\mathrm{\&beta;}}_2{s_{4i-3}}^{*}+{\mathrm{\&alpha;}}_2{s}_{4i-2}\end{array}\right]$ α ₁, α ₂, β ₁And β ₂Be real number, they satisfy α ₁ ²+ β ₁ ²=1 and α ₂ ²+ β ₂ ²=1.α ₁, α ₂, β ₁And β ₂Value countless versions is arranged, might as well suppose their value herein so that the coding gain of R2-STBC reaches maximum, i.e. α ₁=β ₂=sin (arctan (2)), α ₂=β ₁=cos (arctan (2)), sin () and cos () represent respectively SIN function and cosine function, arctan () represents arctan function.

The transmission of information is divided into two steps.Step 1,1 couple of C of transmitting terminal _iCarry out precoding, i=1,2, obtain A _iC _i, and with A ₁C ₁+ A ₂C ₂Send to R _iMeanwhile, 2 couples of S of transmitting terminal _iCarry out precoding, obtain B _iS _i, and with B ₁S ₁+ B ₂S ₂Send to R _iR ₁Reception signal Y ₁And R ₂Reception signal Z ₁Be expressed as respectively

Y ₁=H ₁(A ₁C ₁+A ₂C ₂)+G ₁(B ₁S ₁+B ₂S ₂)+N ₁ (1)

Z ₁=H ₂(A ₁C ₁+A ₂C ₂)+G ₂(B ₁S ₁+B ₂S ₂)+W ₁ (2)

Wherein, N ₁And W ₁Be noise matrix, their exponent number is N * 2; A _iAnd B _iRespectively C _iAnd S _iPre-coding matrix, i=1,2, their exponent number is 2 * 2.It is constant in order to guarantee transmitting power, || A _i|| ²=|| B _i|| ²=0.5.

Step 2, within the identical time, transmitting terminal 1 is with A ₁C ₁-A ₂C ₂Send to R _i, transmitting terminal 2 is with B ₁S ₁-B ₂S ₂Send to R _i, i=1,2.R ₁Reception signal Y ₂And R ₂Reception signal Z ₂Be expressed as respectively

Y ₂=H ₁(A ₁C ₁-A ₂C ₂)+G ₁(B ₁S ₁-B ₂S ₂)+N ₂ (3)

Z ₂=H ₂(A ₁C ₁-A ₂C ₂)+G ₂(B ₁S ₁-B ₂S ₂)+W ₂ (4)

Wherein, N ₂And W ₂Be noise matrix, their exponent number is N * 2.

Prerequisite of the invention process is that interior channel of twice transmission time of each encoder matrix remains unchanged, and namely channel remains unchanged in step 1 and the step 2.

This scheme has been transmitted 16 modulation symbols in 4 time slots, its efficiency of transmission is 4symbols/channel use.Although each encoder matrix has transmitted twice in this scheme, its efficiency of transmission still is higher than the scheme that Li Liangbin proposes in article " When alamouti codes meet interference alignment:transmission schemes for two-user X channel ", this is because R2-STBC is a kind of of Perfect space-time block codes, each encoder matrix comprises 4 independently symbols, and its code rate is 2 times of Alamouti coding.

Can be drawn by formula (1)-Shi (4)

Y=Y ₁+Y ₂=2H ₁A ₁C ₁+2G ₁B ₁S ₁+N (5)

Z=Z ₁-Z ₂=2H ₂A ₂C ₂+2G ₂B ₂S ₂+W (6)

Wherein, N=N ₁+ N ₂, W=W ₁-W ₂

Can be found out by formula (5), to R ₁The reception signal carry out having eliminated C after the sum operation ₂And S ₂To R ₁Interference, and C ₁And S ₁The phase mutual interference.Can be found out by formula (6), to R ₂The reception signal carry out having eliminated C behind the additive operation ₁And S ₁To R ₂Interference, and C ₂And S ₂The phase mutual interference.Next, to eliminate C _iAnd S _iBetween interference be target, provide pre-coding matrix A _iAnd B _iMethod for designing, i=1,2.

Use respectively a _Mn ⁱAnd b _Mn ⁱExpression A _iAnd B _iThe element of the capable n of m row, m, n, i=1,2.Use respectively h ⁱ _MnAnd g ⁱ _MnExpression H _iAnd G _iThe element of the capable n of m row, m=1,2 ..., N, n, i=1,2.Suppose A _iFirst row and B identical with secondary series _iFirst row also identical with secondary series, i=1,2, H then _iA _iFirst row and G identical with secondary series _iB _iFirst row also identical with secondary series,

$H_i{A}_i=\left[\begin{array}{cc}{h_{11}}^{i^{\&prime;}}& {h_{12}}^{i^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{i^{\&prime;}}& {h_{N2}}^{i^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{h_{11}}^i& {h_{12}}^i\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^i& {h_{N2}}^i\end{array}\right]\left[\begin{array}{cc}{a_{11}}^i& {a_{11}}^i\\ {a_{21}}^i& {a_{21}}^i\end{array}\right]=\left[\begin{array}{cc}{h_{11}}^i{a_{11}}^i+{h_{12}}^i{a_{21}}^i& {h_{11}}^i{a_{11}}^i+{h_{12}}^i{a_{21}}^i\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^i{a_{11}}^i+{h_{N2}}^i{a_{21}}^i& {h_{N1}}^i{a_{11}}^i+{h_{N2}}^i{a_{21}}^i\end{array}\right]---\left(7\right)$

$G_i{B}_i=\left[\begin{array}{cc}{g_{11}}^{i^{\&prime;}}& {g_{12}}^{i^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{i^{\&prime;}}& {g_{N2}}^{i^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{g_{11}}^i& {g_{12}}^i\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^i& {g_{N2}}^i\end{array}\right]\left[\begin{array}{cc}{b_{11}}^i& {b_{11}}^i\\ {b_{21}}^i& {b_{21}}^i\end{array}\right]=\left[\begin{array}{cc}{g_{11}}^i{b_{11}}^i+{g_{12}}^i{b_{21}}^i& {g_{11}}^i{b_{11}}^i+{g_{12}}^i{b_{21}}^i\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^i{b_{11}}^i+{g_{N2}}^i{b_{21}}^i& {g_{N1}}^i{b_{11}}^i+{g_{N2}}^i{b_{21}}^i\end{array}\right]---\left(8\right)$

Use respectively d _MnAnd e _MnRepresenting matrix H ₁A ₁C ₁And G ₁B ₁S ₁The element of the capable n of m row, m=1,2 ..., N, n=1,2, then

F ₁And F ₂Exponent number be 2N * 4.The origin of formula (9-10) please refer to the formula (6-7) in the article " speed of phase rotating is 2 Space-Time Block Coding ".

Can draw according to formula (5), formula (9) and formula (10)

$y=2\left[\begin{array}{cc}{F}_1& F_2\end{array}\right]\left[\begin{array}{c}c\\ s\end{array}\right]+n---\left(11\right)$

Wherein, y=[y ₁₁, y ₁₂ ^*..., y _N1, y _N2 ^*] ^T, n=[n ₁₁, n ₁₂ ^*..., n _N1, n _N2 ^*] ^T, y _MnAnd n _MnThe element of the capable n row of the m of representing matrix Y and N, m=1,2 ..., N, n=1,2.Y is R ₁Equivalent received signals, c and s are respectively the equivalent transmitted signals of transmitting terminal 1 and transmitting terminal 2,2F ₁And 2F ₂Respectively transmitting terminal 1 and transmitting terminal 2 to R ₁Equivalent channel matrix.Can be found out by following formula, if F ₁All row and F ₂All row mutually vertical, then c and s keep quadrature in transmission course, thus C ₁And S ₁In transmission course, do not interfere with each other.

Use f _iExpression F ₁Each row, i=1,2,3,4, use f _kExpression F ₂Each row, k=5,6,7,8.Can be calculated, if A ₁And B ₁Satisfy following equation group

$\left\{\begin{array}{c}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}({h_{i1}}^1{a_{11}}^1+{h_{i2}}^1{a_{21}}^1)({g_{i1}}^1{b_{11}}^1+{g_{i2}}^1{{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^1)=0\\ {\left|\right|A_1\left|\right|}^2=0.5\\ {\left|\right|B_1\left|\right|}^2=0.5\end{array}\right.---\left(12\right)$

F then _iAnd f _kInner product＜f _i, f _k〉=0, namely c and s keep quadrature in transmission course, thus C ₁And S ₁Between do not interfere with each other.Equation group (12) comprises three equations, four unknown quantitys, must have or not the array solution.

In like manner can get A ₂And B ₂When satisfying equation group (13), C ₂And S ₂Between do not interfere with each other.

$\left\{\begin{array}{c}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}({h_{i1}}^2{a_{11}}^2+{h_{i2}}^2{a_{21}}^2)({g_{i1}}^2{b_{11}}^2+{g_{i2}}^2{{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^2)=0\\ {\left|\right|A_2\left|\right|}^2=0.5\\ {\left|\right|B_2\left|\right|}^2=0.5\end{array}\right.---\left(13\right)$

This equation group also exists without the array solution.

When equation group (12) is set up, formula (11) two ends be multiply by respectively $\left[\begin{array}{c}{F_1}^T\\ {F_2}^T\end{array}\right]$ Can get

$y^{\&prime;}=\left[\begin{array}{c}{F_1}^T\\ {F_2}^T\end{array}\right]y=2\left[\begin{array}{cc}{F_1}^T{F}_1& 0\\ 0& {F_2}^T{F}_2\end{array}\right]\left[\begin{array}{c}c\\ s\end{array}\right]+\left[\begin{array}{c}{F_1}^T\\ {F_2}^T\end{array}\right]n$

Thereby R ₁Can decipher respectively c and s, namely can decipher respectively two transmitting terminals and send to R ₁Useful signal.

In like manner, when equation group (13) is set up, R ₂Can decipher respectively two transmitting terminals and send to R ₂Useful signal.

According to above analytic process, when pre-coding matrix satisfied equation group (12) and (13), the scheme that the present invention proposes can be eliminated all multi-user interference, sends to R thereby can decipher respectively each transmitting terminal _iUseful signal, i=1,2.Because the first row of pre-coding matrix is identical with secondary series, therefore, receiving terminal only need to feed back the element of the first row of each pre-coding matrix, thereby has reduced feedback information.

Below in conjunction with the method for designing of accompanying drawing and pre-coding matrix, specific implementation process of the present invention is described further.

Be Fig. 3 in conjunction with flow chart of the present invention, the concrete steps that receiving terminal calculates the method for each element of pre-coding matrix and feedback method are as follows:

A1, receiving terminal 1 known channel matrix H ₁And G ₁, and the first row of supposition pre-coding matrix is identical with secondary series, and solving equations (12) obtains one group of solution wherein, makes this group separate and is the element a of pre-coding matrix ₁₁ ¹, a ₂₁ ¹, b ₁₁ ¹And b ₂₁ ¹, then adopt the method for uniform quantization or non-uniform quantizing to quantize this four parameters, and with a ₁₁ ¹And a ₂₁ ¹Quantized value feed back to transmitting terminal 1, with b ₁₁ ¹And b ₂₁ ¹Quantized value feed back to transmitting terminal 2, wherein H ₁And G ₁Be respectively two transmitting terminals to the channel matrix of receiving terminal 1, their exponent number is N * 2, N is the number of reception antenna, N 〉=1;

A2, receiving terminal 2 known channel matrix H ₂And G ₂, and the first row of supposition pre-coding matrix is identical with secondary series, and solving equations (13) obtains one group of solution wherein, makes this group separate and is the element a of pre-coding matrix ₁₁ ², a ₂₁ ², b ₁₁ ²And b ₂₁ ², then adopt the method for uniform quantization or non-uniform quantizing to quantize this four parameters, and with a ₁₁ ²And a ₂₁ ²Quantized value feed back to transmitting terminal 1, with b ₁₁ ²And b ₂₁ ²Quantized value feed back to transmitting terminal 2, wherein H ₂And G ₂Be respectively two transmitting terminals to the channel condition information of receiving terminal 2, their exponent number is N * 2.

Fig. 4 is coding and the process of transmitting flow chart of transmitting terminal among the present invention.In conjunction with Fig. 3 and Fig. 4, the coding of transmitting terminal and process of transmitting are as follows among the present invention:

B, transmitting terminal 1 is to its modulation signal c _k(k=1,2 ..., 8) and to carry out speed be 2 space-time block code, obtains sending to the encoder matrix C of the individual receiving terminal of i (i=1,2) _i, $C_i=\left[\begin{array}{cc}{\mathrm{\&alpha;}}_1{c}_{4i-3}-{\mathrm{\&beta;}}_1{c_{4i-2}}^{*}& {\mathrm{\&beta;}}_1{c_{4i-1}}^{*}+{\mathrm{\&alpha;}}_1{c}_{4i}\\ {\mathrm{\&alpha;}}_2{c}_{4i-1}-{\mathrm{\&beta;}}_2{c_{4i}}^{*}& {\mathrm{\&beta;}}_2{c_{4i-3}}^{*}+{\mathrm{\&alpha;}}_2{c}_{4i-2}\end{array}\right],$ α ₁, α ₂, β ₁And β ₂Be real number, they satisfy α ₁ ²+ β ₁ ²=1 and α ₂ ²+ β ₂ ²=1; Transmitting terminal 2 is to its modulation signal s _k(k=1,2 ..., 8) and to carry out speed be 2 space-time block code, obtains sending to the encoder matrix S of i receiving terminal _i, $S_i=\left[\begin{array}{cc}{\mathrm{\&alpha;}}_1{s}_{4i-3}-{\mathrm{\&beta;}}_1{s_{4i-2}}^{*}& {\mathrm{\&beta;}}_1{s_{4i-1}}^{*}+{\mathrm{\&alpha;}}_1{s}_{4i}\\ {\mathrm{\&alpha;}}_2{s}_{4i-1}-{\mathrm{\&beta;}}_2{s_{4i}}^{*}& {\mathrm{\&beta;}}_2{s_{4i-3}}^{*}+{\mathrm{\&alpha;}}_2{s}_{4i-2}\end{array}\right];$

C1, transmitting terminal 1 at first obtain the value of pre-coding matrix element according to feedback information and quantization method, might as well still use a ₁₁ ¹, a ₂₁ ¹, a ₁₁ ²And a ₂₁ ²Then expression obtains pre-coding matrix A ₁And A ₂, $A_1=\left[\begin{array}{cc}{a_{11}}^1& {a_{11}}^1\\ {a_{21}}^1& {a_{21}}^1\end{array}\right],$ $A_2=\left[\begin{array}{cc}{a_{11}}^2& {a_{11}}^2\\ {a_{21}}^2& {a_{21}}^2\end{array}\right];$

C2, transmitting terminal 2 at first obtain the value of pre-coding matrix element according to feedback information and quantization method, might as well still use b ₁₁ ¹, b ₂₁ ¹, b ₁₁ ²And b ₂₁ ²Then expression obtains pre-coding matrix B ₁And B ₂, $B_1=\left[\begin{array}{cc}{b_{11}}^1& {b_{11}}^1\\ {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^1& {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^1\end{array}\right],$ $B_2=\left[\begin{array}{cc}{b_{11}}^2& {b_{11}}^2\\ {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^2& {{\mathrm{<figure-callout\; id="21"\; label="b"\; filenames="130122170612.png"\; state="\{\{state\}\}">b</figure-callout>}}_{21}}^2\end{array}\right];$

D1,1 couple of C of transmitting terminal _iCarry out precoding, i=1,2, obtain A _iC _i, 2 couples of S of transmitting terminal _iCarry out precoding, obtain B _iS _i

D2, within the identical time, two antennas of transmitting terminal 1 usefulness are with A ₁C ₁+ A ₂C ₂Send, two antennas of transmitting terminal 2 usefulness are with B ₁S ₁+ B ₂S ₂Send, the reception signal of two receiving terminals is respectively Y ₁And Z ₁

D3, within the identical time, two antennas of transmitting terminal 1 usefulness are with A ₁C ₁-A ₂C ₂Send, two antennas of transmitting terminal 2 usefulness are with B ₁S ₁-B ₂S ₂Send, the reception signal of two receiving terminals is respectively Y ₂And Z ₂

Fig. 5 is the decode procedure flow chart of receiving terminal among the present invention.In conjunction with Fig. 3 and Fig. 5, the decode procedure of receiving terminal is as follows among the present invention:

E1, receiving terminal 1 receive signal to it and carry out the phase add operation, obtain Y=Y ₁+ Y ₂, then obtain the equivalents form y of Y, y=[y ₁₁, y ₁₂ ^*..., y _N1, y _N2 ^*] ^T, y _MnThe element of the capable n row of the m of representing matrix Y, m=1,2 ..., N, n=1,2, () ^*The expression complex conjugate, () ^TThe expression transposition;

E2, receiving terminal 2 receive signal to it and carry out the phase reducing, obtain Z=Z ₁-Z ₂, then obtain the equivalents form z of Z, z=[z ₁₁, z ₁₂ ^*..., z _N1, z _N2 ^*] ^T, z _MnThe element of the capable n row of the m of representing matrix Z, m=1,2 ..., N, n=1,2;

F1, receiving terminal 1 calculates H according to channel matrix and pre-coding matrix ₁A ₁And G ₁B ₁, H ₁A ₁Every row identical, G ₁B ₁Every row also identical, might as well be expressed as $H_1{A}_1=\left[\begin{array}{cc}{h_{11}}^{1^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="h"\; filenames="130122170612.png"\; state="\{\{state\}\}">h</figure-callout>}}_{12}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{1^{\&prime;}}& {h_{N2}}^{1^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{h_{11}}^{1^{\&prime;}}& {h_{11}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{1^{\&prime;}}& {h_{N1}}^{1^{\&prime;}}\end{array}\right],$ $G_1{B}_1=\left[\begin{array}{cc}{g_{11}}^{1^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="g"\; filenames="130122170612.png"\; state="\{\{state\}\}">g</figure-callout>}}_{12}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{1^{\&prime;}}& {g_{N2}}^{1^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{g_{11}}^{1^{\&prime;}}& {g_{11}}^{1^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{1^{\&prime;}}& {g_{N1}}^{1^{\&prime;}}\end{array}\right];$

F2 is according to H ₁A ₁And G ₁B ₁Element obtain F ₁And F ₂, be expressed as:

$F_1=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{h_{11}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{11}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{11}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{11}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{11}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{11}}^{1^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{h_{N1}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{N1}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{N1}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{N1}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{N1}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{N1}}^{1^{\&prime;}*}\end{array}\right]$

$F_2=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{g_{11}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{11}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{11}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{11}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{11}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{11}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{11}}^{1^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{g_{N1}}^{1^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{N1}}^{1^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{N1}}^{1^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{N1}}^{1^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{N1}}^{1^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{N1}}^{1^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{N1}}^{1^{\&prime;}*}\end{array}\right]$

F3, receiving terminal 1 is processed y, obtains $y^{\&prime;}=\left[\begin{array}{c}{F_1}^T\\ {F_2}^T\end{array}\right]y;$

F4 is listed as equivalent received signals, with 2F with front 4 of y ' ₁ ^TF ₁As equivalent channel matrix, decoding transmitting terminal 1 sends to the useful signal of receiving terminal 1;

F5 is listed as equivalent received signals, with 2F with rear 4 of y ' ₂ ^TF ₂As equivalent channel matrix, decoding transmitting terminal 2 sends to the useful signal of receiving terminal 1;

G1, receiving terminal 2 calculates H according to channel matrix and pre-coding matrix ₂A ₂And G ₂B ₂, H ₂A ₂Every row identical, G ₂B ₂Every row also identical, might as well be expressed as $H_2{A}_2=\left[\begin{array}{cc}{h_{11}}^{2^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="h"\; filenames="130122170612.png"\; state="\{\{state\}\}">h</figure-callout>}}_{12}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{2^{\&prime;}}& {h_{N2}}^{2^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{h_{11}}^{2^{\&prime;}}& {h_{11}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {h_{N1}}^{2^{\&prime;}}& {h_{N1}}^{2^{\&prime;}}\end{array}\right],$ $G_2{B}_2=\left[\begin{array}{cc}{g_{11}}^{2^{\&prime;}}& {{\mathrm{<figure-callout\; id="12"\; label="g"\; filenames="130122170612.png"\; state="\{\{state\}\}">g</figure-callout>}}_{12}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{2^{\&prime;}}& {g_{N2}}^{2^{\&prime;}}\end{array}\right]=\left[\begin{array}{cc}{g_{11}}^{2^{\&prime;}}& {g_{11}}^{2^{\&prime;}}\\ .& .\\ .& .\\ .& .\\ {g_{N1}}^{2^{\&prime;}}& {g_{N1}}^{2^{\&prime;}}\end{array}\right];$

G2 is according to H ₂A ₂And G ₂B ₂Element obtain F ' ₁And F ' ₂, be expressed as:

$F_1^{\&prime;}=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{h_{11}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{11}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{11}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{11}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{11}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{11}}^{2^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{h_{N1}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{h_{N1}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{h_{N1}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{h_{N1}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{h_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{h_{N1}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{h_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{h_{N1}}^{2^{\&prime;}*}\end{array}\right]$

$F_2^{\&prime;}=\left[\begin{array}{cccc}{\mathrm{\&alpha;}}_1{g_{11}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{11}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{11}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{11}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{11}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{11}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{11}}^{2^{\&prime;}*}\\ .& .& .& .\\ .& .& .& .\\ .& .& .& .\\ {\mathrm{\&alpha;}}_1{g_{N1}}^{2^{\&prime;}}& -{\mathrm{\&beta;}}_1{g_{N1}}^{2^{\&prime;}}& {\mathrm{\&alpha;}}_2{g_{N1}}^{2^{\&prime;}}& {-\mathrm{\&beta;}}_2{g_{N1}}^{2^{\&prime;}}\\ {\mathrm{\&beta;}}_2{g_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_2{g_{N1}}^{2^{\&prime;}*}& {\mathrm{\&beta;}}_1{g_{N1}}^{2^{\&prime;}*}& {\mathrm{\&alpha;}}_1{g_{N1}}^{2^{\&prime;}*}\end{array}\right]$

G3, receiving terminal 2 is processed z, obtains $z^{\&prime;}=\left[\begin{array}{c}{F_1^{\&prime;}}^T\\ {F_2^{\&prime;}}^T\end{array}\right]z;$

G4 is listed as equivalent received signals, with 2F ' with front 4 of z ' ₁ ^TF ' ₁As equivalent channel matrix, decoding transmitting terminal 1 sends to the useful signal of receiving terminal 2;

G5 is listed as equivalent received signals, with 2F ' with rear 4 of z ' ₂ ^TF ' ₂As equivalent channel matrix, decoding transmitting terminal 2 sends to the useful signal of receiving terminal 2.

Effect of the present invention can further specify by following emulation experiment.Fig. 6 and Fig. 7 respectively emulation modulation system proposed a plan in 2011 reliability of (scheme of mentioning in the technical background) of the present invention and Li Liangbin when being 4QAM and 16QAM.In the emulation, suppose that channel is obeyed independently Rayleigh fading and within twice transmission time of each encoder matrix channel remain unchanged, noise is white Gaussian noise, N=2, the value of pre-coding matrix element is ${a_{11}}^i=\frac{{-q}^i}{\sqrt{2({\left|p^i\right|}^2+{\left|q^i\right|}^2)}},$ ${a_{21}}^i=\frac{p}{\sqrt{2({\left|p^i\right|}^2+{\left|q^i\right|}^2)}},$ b ₂₁ ⁱ=0, b ₁₁ ⁱ=0.5, wherein, $p^i=\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\left({h_{j1}}^i{g_{j1}}^i\right),$ $q^i=\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\left({h_{j2}}^i{g_{j1}}^i\right),$ i=1,2。

Abscissa among Fig. 6 and Fig. 7 represents the signal to noise ratio of each transmitting terminal.As can be seen from the figure, the BER of present embodiment significantly is lower than the scheme that Li Liangbin proposed in 2011.If adopt the 4QAM modulation, the error rate is 10 ^-4The time, the embodiment of the invention has obtained the gain of about 6dB than existing program.If adopt the 16QAM modulation, the error rate is 10 ^-4The time, the embodiment of the invention has obtained the gain of about 5dB than existing program.

Above embodiment illustrates of the present invention, and those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (7)

1. a method of eliminating multi-user interference in the mimo system is applicable to the X channel that two transmitting terminals dispose respectively two antennas, it is characterized in that, comprises the steps:

A, two receiving terminals calculate respectively the element of the pre-coding matrix of two transmitting terminals, this pre-coding matrix energy is so that transmitting terminal 1 sends to the useful signal of receiving terminal 1 or receiving terminal 2 and useful signal that transmitting terminal 2 sends to receiving terminal 1 or receiving terminal 2 keeps quadrature in transmission course, and so latter two receiving terminal quantizes respectively the element of pre-coding matrix and quantized value is fed back to two transmitting terminals;

B, transmitting terminal 1 is to its modulation signal

Carry out speed and be 2 space-time block code, obtain sending to

The encoder matrix of individual receiving terminal

,

, ,

,

With

Be real number, they satisfy

And

Transmitting terminal 2 is to its modulation signal

Carry out speed and be 2 space-time block code, obtain sending to

The encoder matrix of individual receiving terminal ,

C, transmitting terminal 1 obtains pre-coding matrix according to feedback information and quantization method

With

, transmitting terminal 2 obtains pre-coding matrix according to feedback information and quantization method

With

D, transmitting terminal 1 utilizes

Right

Carry out precoding,

, obtain , transmitting terminal 2 utilizes

Right Carry out precoding, obtain

, so latter two transmitting terminal sends with two antennas respectively

With

E, receiving terminal 1 is processed and is received signal, obtains receiving the another kind of expression-form of signal

, receiving terminal 2 is processed and is received signal, obtains receiving the another kind of expression-form of signal

F, receiving terminal 1 basis

, channel matrix and pre-coding matrix, decipher respectively the useful signal that transmitting terminal 1 and transmitting terminal 2 send to this receiving terminal;

G, receiving terminal 2 bases

, channel matrix and pre-coding matrix, decipher respectively the useful signal that transmitting terminal 1 and transmitting terminal 2 send to this receiving terminal.

2. a kind of method of eliminating multi-user interference in the mimo system according to claim 1 is characterized in that described steps A specifically comprises:

A1, every row of pre-coding matrix are identical, and receiving terminal 1 is according to channel matrix

With

Calculate the element of pre-coding matrix

,

,

With

, then adopt the method for uniform quantization or non-uniform quantizing to quantize this four parameters, and will

With

Quantized value feed back to transmitting terminal 1, will

With

Quantized value feed back to transmitting terminal 2, wherein

With

Be respectively two transmitting terminals to the channel matrix of receiving terminal 1, their exponent number is

,

The number of reception antenna,

A2, every row of pre-coding matrix are identical, and receiving terminal 2 is according to channel matrix

With

Calculate the element of pre-coding matrix ,

,

With , then adopt the method for uniform quantization or non-uniform quantizing to quantize this four parameters, and will With Quantized value feed back to transmitting terminal 1, will With

Quantized value feed back to transmitting terminal 2, wherein

With

Be respectively two transmitting terminals to the channel matrix of receiving terminal 2, their exponent number is

3. a kind of method of eliminating multi-user interference in the mimo system according to claim 1 is characterized in that described step C specifically comprises:

C1, transmitting terminal 1 at first obtain the value of pre-coding matrix element according to feedback information and quantization method, might as well still use

,

,

With Then expression obtains pre-coding matrix

With

,

,

C2, transmitting terminal 2 at first obtain the value of pre-coding matrix element according to feedback information and quantization method, might as well still use

,

,

With

Then expression obtains pre-coding matrix

With

,

,

4. a kind of method of eliminating multi-user interference in the mimo system according to claim 1 is characterized in that described step D specifically comprises:

D1,1 pair of transmitting terminal

Carry out precoding,

, obtain , 2 pairs of transmitting terminals

Carry out precoding, obtain

D2, within the identical time, two antennas of transmitting terminal 1 usefulness will

Send, two antennas of transmitting terminal 2 usefulness will

Send, the reception signal of two receiving terminals is respectively

With

D3, within the identical time, two antennas of transmitting terminal 1 usefulness will Send, two antennas of transmitting terminal 2 usefulness will

Send, the reception signal of two receiving terminals is respectively

With

5. a kind of method of eliminating multi-user interference in the mimo system according to claim 1 is characterized in that described step e specifically comprises:

E1, receiving terminal 1 receive signal to it and carry out the phase add operation, obtain

, then obtain

The equivalents form

,

,

Representing matrix

Row The element of row, ,

,

The expression complex conjugate,

The expression transposition;

E2, receiving terminal 2 receive signal to it and carry out the phase reducing, obtain

, then obtain

The equivalents form

,

,

Representing matrix

Row

The element of row,

,

6. a kind of method of eliminating multi-user interference in the mimo system according to claim 1 is characterized in that described step F specifically comprises:

F1, receiving terminal 1 calculates according to channel matrix and pre-coding matrix With

,

Every row identical,

Every row also identical, might as well be expressed as

,

F2, according to

With Element obtain

With

, be expressed as:

F3, receiving terminal 1 is processed

, obtain

F4, with

Front 4 row as equivalent received signals, with

As equivalent channel matrix, decoding transmitting terminal 1 sends to the useful signal of receiving terminal 1;

F5, with

Rear 4 row as equivalent received signals, with

As equivalent channel matrix, decoding transmitting terminal 2 sends to the useful signal of receiving terminal 1.

7. a kind of method of eliminating multi-user interference in the mimo system according to claim 1 is characterized in that described step G specifically comprises:

G1, receiving terminal 2 calculates according to channel matrix and pre-coding matrix

With ,

Every row identical,

Every row also identical, might as well be expressed as

,

G2, according to

With

Element obtain

With

, be expressed as:

G3, receiving terminal 2 is processed

, obtain

G4, with

Front 4 row as equivalent received signals, with

As equivalent channel matrix, decoding transmitting terminal 1 sends to the useful signal of receiving terminal 2;

G5, with

Rear 4 row as equivalent received signals, with

As equivalent channel matrix, decoding transmitting terminal 2 sends to the useful signal of receiving terminal 2.

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