CN102710310B - SLR (Signal-To-Leakage Ratio)-based multiple-user safety communication precoding method - Google Patents

Abstract

The invention provides an SLR (Signal-To-Leakage Ratio)-based multiple-user safety communication precoding method. The SLR-based multiple-user safety communication precoding method comprises the following steps of: firstly, carrying out channel estimation on a downlink by a transmitter Alice; secondly, constructing an equivalent heterogeneous joint channel matrix of each user according to the known channel matrixes of all legal users Bob and carrying out generalized singular value decomposition on the channel matrix of each user and the equivalent heterogeneous joint channel matrix corresponding to each channel matrix to obtain a corresponding generalized eigenvalue and generalized eigenvector by the Alice; thirdly, simultaneously transmitting d data streams to each user, selecting generalized eigenvectors corresponding to maximum d generalized eigenvalues in the second step, transmitting a signal of each user to a corresponding generalized eigenvector space and transmitting man-made noise to null spaces of all channel matrixes by the Alice; and fourthly, decoding an information sink D by a Wiener filter. The experiment result shows that the secrecy capacity of the scheme approaches to that of the optimal scheme but the complexity of the scheme is far lower than that of the optimal scheme.

Description

The method for precoding of the multi-user's secure communication based on SLR

Technical field

The present invention relates to wireless communication field, especially based on SLR(signal-to-leakage ratio, letter leakage ratio) MUME-MIMO(multiple-user multiple-eavesdropper, multiple-input multiple-put, the many listener-ins of multi-user enter to have more more) a kind of Precoding Design scheme in multi-user's secure communication, be specifically related to the method for precoding of the multi-user's secure communication based on SLR.

Background technology

Along with the development of the communication technology, people are more and more higher to performance requirements such as transmission rate, transmission reliability, resource utilization and communication securities.Due to the broadcast characteristic of radio communication, communication security becomes a basic problem of radio communication.A potential listener-in may intercept the information that originator sends in the situation that not being detected, thereby threatens to secure wireless communication.Communication security can be by realizing by encryption technology traditionally.On the other hand, according to information-theoretical research, find also can realize secure communication not needing to use under the prerequisite of privacy key.

In information-theoretical research, Wyner has introduced a kind of tapping channel model in early days, and in this model, listener-in's channel is defined by the degeneration version of validated user.As long as listener-in's channel quality does not have the good of validated user, so just may obtain the secrecy capacity of a non-zero.Csiszar and Korner have expanded to a more general channel condition the problem of secure communication: a public information is sent to two users simultaneously, and the secret signal of another one is only sent in them.Even if the situation more far short of what is expected than listener-in for the channel quality legal recipient is issued to secure communication, the technology of various physical layers is used.Wherein being used the most widely one of technology is exactly to come while transmitted signal and man made noise to confuse listener-in with many antennas.

If many antennas have been installed, originator just can launch the object that useful information signal and man made noise reach secure communication simultaneously.Wherein man made noise launches immediately, is used for " shielding " useful signal to send to legitimate receiver, at user side, can disturbedly eliminate, and causes very large interference in listener-in one end.Meanwhile, in the design of the secure communication with man made noise based on many antennas, the transmit power allocations between useful signal and man made noise is also a very important problem.

What research majority was in the past paid close attention to is all single user system.Yet the communication system of most of reality has a more than user.In addition listener-in may not be also to exist individually, and this can take the mode of combining or not combining to eavesdrop with regard to meaning them.Here it is many listener-ins of so-called MUME(multi-user) system.Reach communication security, must guarantee that any one legal user is not ravesdropping, this former few people's research.In many listener-ins of multi-user situation, the secrecy capacity of system is also different with single user system.Y.Liang in 2007, H.V.Poor, and S.Shamai has discussed the realization with the secrecy capacity of man made noise's MUME secret signalling in " Compoundwire-tap channels, ".Y.Liang in 2008, H.V.Poor, has given a rough definition about MUME system secrecy capacity in " the Secure communication over fadingchannels " of and S.Shamai on IEEE Trans.Inf.Theory.Within 2009, A.Mukherjee and A.Swindlehurst is at Proc.47th AllertonConf.on Communication, two kinds of ZF beamforming strategies under multiuser MIMO tapping channel have been discussed in " Utility of Beamforming Strategiesfor Secrecy in Multiuser MIMOWiretap Channels, " on Control and Computing.Wherein author's selective analysis SNR and the BER of Bob and Eve, but they only analyze the situation of single data stream.

In order to limit the cochannel from he user coming, disturb (co-channel interference) and protect useful user profile not disturbed simultaneously, conventionally there are at present two kinds of practical linear transfer technology: (i) X.Zhou in 2010, M.R.McKay has delivered " Secure Transmission with Artificial Noiseover Fading Channels:Achievable Rate and Optimal Power Allocation " at IEEETrans.Vehicualr Technology, wherein used a kind of traditional SVD method, it carries out singular value decomposition (SVD) to each user's self channel matrix, then get the signal sending direction of maximum singular value characteristic of correspondence vector, thereby can obtain user's maximum channel gain of signal separately.(ii) A.Mukherjee and A.Swindlehurst in 2009 has adopted ZF wave beam to be formed for multi-user's safe communication system at " Utility of Beamforming Strategiesfor Secrecy inMultiuser MIMOWiretap Channels, ".Q.Spencer and A.Swindlehurst in 2004 delivers at EURASIP Journ.WirelessCommun.and Network " A hybrid approach to spatial multiplexing in multi-user MIMOdownlinks; " the fast diagonalization of evolution method (block diagonalization) of middle proposed ZF, and by it for multiuser mimo communication.In this method, all information will be sent in every other user's the kernel of receive channel matrix, thereby has effectively avoided the interference to other users.According to research in the past, show, SVD method and ZF beamforming method are relatively simple, but effect is not ideal enough.And block diagonalization (BD method) can be obtained good effect but shortcoming to be complexity too high.

Shortcoming and advantage in view of above-mentioned the whole bag of tricks, the present invention proposes a method, this method is based on A.Tarighat in 2005, M.Sadek, the letter that and A.H.Sayed proposes in paper " A multi user beamformingscheme for downlink MIMO channels based on maximizing signaltoleakageratios " leaks than (signal-to-leakage-ratio) concept.Inventor studies discovery, but the obtained secrecy capacity of this method approaches existing optimal case complexity far below existing optimal case, therefore can be used as a half-way house between secrecy capacity and complexity.In addition, inventor has also analyzed the optimal power allocation in secure communication, wherein not only comprises the power division between useful information and man made noise, has also comprised the power division between each user.Maximum secrecy capacity can be obtained according to the design of these power division parameters.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of precoding strategy of many listener-ins of the multi-user secure communication based on SLR be provided, to each user's channel with and corresponding isomery combined channel matrix carry out generalized singular value decomposition (GSVD).Then user's separately information transmitting to the incorgruous quantity space of the multipair generalized odd of answering of corresponding maximum generalized singular value, complete transmitting.

Application scenarios of the present invention includes 1 originator (Alice), J legal recipient (Bob) and individual listener-in (Eve).On Alice, Bob j and Eve k, the antenna number of configuration is respectively N _a, N _bjand N _ek.The present invention is by the following technical solutions---a kind of method for precoding of the multiuser MIMO secure communication based on SLR.

According to an aspect of the present invention, provide a kind of method for precoding of the multi-user's secure communication based on SLR, comprise the following steps:

Step 1: sender Alice carries out the channel estimating of down link;

Step 2:Alice is according to the channel matrix of known all user Bob, construct each user's equivalent isomery confederate matrix matrix, the confederate matrix that other all subscriber channel matrixes form except self, and to each user's channel matrix with and corresponding equivalent isomery combined channel matrix carry out generalized singular value decomposition (GSVD), draw corresponding generalized eigenvalue and the generalized eigenvector of each channel matrix;

Step 3:Alice sends d data flow to each user simultaneously, in step 2, select corresponding d the maximum generalized eigenvector that generalized eigenvalue is corresponding, then Alice is transmitted into corresponding generalized eigenvector space by each user's to be sent signal, and man made noise sends to the kernel of all channel matrixes at utmost to reduce the impact on Bob;

Step 4: stay of two nights D decodes with Wiener filter.

Preferably, each user and man made noise's Precoding Design, specific as follows:

H _j, j=1,2 ... J, represents the channel matrix of the user Bob j, G _k, k=1,2 ..., K, represents the channel matrix of k listener-in Eve k; The equivalent isomery combined channel matrix that wherein defines user j is ${\tilde{H}}_j={[{H_1}^T,{H_2}^T,\·\·\·{H_{j-1}}^T,{H_{j+1}}^T,\·\·\·{H_J}^T]}^T;$

Then to H corresponding to each user Bob j _jwith carry out GSVD decomposition:

$[U,V,X,C,S]=\mathrm{GSVD}(H_j,{\tilde{H}}_j)$

H _j=U*C*X′

${\tilde{H}}_j=V*S*X^{\′}$

C′*C+S′*S=I

The pre-coding matrix of designing user Bob j is:

$W_j\∝\max \mathrm{generalizedeigenvectorof}(H_j^H{H}_j,{\tilde{H}}_j^H{\tilde{H}}_j)\mathrm{whend}=1.$

$W_j\∝\max \mathrm{dgeneralizedeigenvectorsof}(H_j^H{H}_j,{\tilde{H}}_j^H{\tilde{H}}_j)\mathrm{whend}>1.$

Preferably, in described step 1, sender Alice estimates to carry out the channel estimating of down link by time division duplex.

Accompanying drawing explanation

Fig. 1 illustrates many listener-ins of multi-user MIMO tapping channel model;

Fig. 2 illustrates and works as d _j=1, N _a=10, N _bj=3, N _ekthe secrecy capacity comparison of=4 o'clock 4 kinds of methods;

Fig. 3 illustrates and works as d _j=1, N _a=10, N _bj=3, N _ekthe power ratio for all Bob of=4 o'clock 4 kinds of methods;

Fig. 4 illustrates and works as N _a=10, N _bj=3 o'clock, SLR method secrecy capacity during Eve cooperation (K=1) and uncooperative (K=2);

Fig. 5 illustrates and works as N _a=10, N _bj, during Eve cooperation (K=1) and uncooperative (K=2), be used for the power ratio of all Bob at=3 o'clock;

Fig. 6 illustrates and works as N _a=10, N _b2=3, N _ek=4 o'clock, the secrecy capacity of obtaining of SLR method when Bob1 has different antennae;

Fig. 7 illustrates and works as N _a=10, N _b2=3, N _ek=4 o'clock, when Bob1 has different antennae, SLR method was distributed to the power ratio of Bob1.

Embodiment

Specific as follows according to the described precoding strategy in the method for precoding of the multi-user's secure communication based on SLR provided by the invention and corresponding matrix disposal method:

The MUME tapping channel model of the present embodiment hypothesis as shown in Figure 1, wherein has an information transmitter (Alice), J validated user (Bobs) and K listener-in (Eves).All terminals are all assembled many antennas, and Alice has N _aroot antenna, Bob j has N _bjroot antenna, Eve k has N _ekroot antenna.The channel information completely (CSI) of also supposing the known all Bob of Alice is not but known the information of Eves, because Eves itself has the feature of " hiding ".

The signal of Alice transmission is u wherein _jthe useful information signal vector of Bobj, V is for disturbing man made noise's signal vector of all Eve.H _j, j=1,2 ... J, is the channel matrix of j user (Bob j), G _k, k=1,2 ..., K, represents the channel matrix of k listener-in (Eve k).Wherein the equivalent isomery combined channel matrix of user j, is defined as ${{\tilde{H}}_j}^H={[{H_1}^T,{H_2}^T,\·\·\·{H_{j-1}}^T,{H_{j+1}}^T,\·\·\·{H_J}^T]}^T.$ Suppose channel matrix { H _j, G _k, j=1,2 ..., Jk=1,2 ..., K, information can be in base station (Alice) end obtain (for example, can pass through time division duplex (TDD) is estimated or Frequency Division Duplexing (FDD) (FDD) is fed back).But because listener-in itself has hiddenly, Alice does not also know the channel information of Eve.

In base station, data needed to carry out precoding processing before transmission, and then sent to mimo channel.

$X=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{U}_j+V=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{W}_j{u}_j+\mathrm{Wv}$

At receiving terminal, the signal that Bob and Eve receive is respectively:

$Y_j=H_j\underset{i=1}{\overset{J}{\mathrm{\Σ}}}{W}_i{u}_i+H_j\mathrm{Wv}+N_j$

$Z_k=G_k\underset{i=1}{\overset{J}{\mathrm{\Σ}}}{W}_i{u}_i+G_k\mathrm{Wv}+N_k$

Wherein, W _ja N _bj* d _jlinear precoding matrix, u _ja d _jthe data symbol vector immediately of * 1 Bob, d _jit is the number that base station Alice sends to the data flow of user j simultaneously.This data symbol vector must pass through pre-coding matrix W _jprocessing.V is that it also can be expressed as Wv, is wherein a matrix to symbolic vector v precoding immediately for man made noise's signal vector of the special Eve of interference.N _j, N _kfor additive white Gaussian noise, its variance is $E\left(N_j{N_j}^H\right)=$ ${\mathrm{\σ}}_{\mathrm{Bj}}^{2}I,$ $E\left(N_j{N_j}^H\right)={\mathrm{\σ}}_{\mathrm{Bj}}^{2}I.$

Under MUME environment, the common channel Bob of several many antennas communicates by letter with Alice with time slot at same frequency domain.In this case, must design certain transmission policy suppresses from the common-channel interference between Bob (co-channel interference, CCI).Before entering on, first introduce SLR(signal-to-leakage ratio) concept.The mean receiving power (S) that briefly SLR is received by targeted customer and leakage are to the ratio of other uncorrelated users' of common channel average power (L).The value of SLR has reflected the efficiency of transmitting terminal power utilization, with equation expression, is

$\mathrm{SLR}=\frac{S}{L}$

Main object be according to an actual channel information design non-zero with encoder matrix W ₁, W ₂..., W _j, W, makes them can form a N _a* N _asquare formation.

$\tilde{W}=[W_1{W}_2\·\·\·W_{J}W]$

Traditionally, Bob estimates that reception information is all to come from Y according to classical maximal possibility estimation _jmiddle estimation u _j.

${\hat{u}}_j=u_j+\frac{W_j^{*}{H}_j^{*}{H}_j{\mathrm{\Σ}}_{i=1}^J{W}_i{u}_i}{{\left|\right|H_j{W}_j\left|\right|}^2}+\frac{W_j^{*}{H}_j^{*}{H}_j\mathrm{Wv}}{{\left|\right|H_j{W}_j\left|\right|}^2}$

And then the capacity of the Bob j obtaining can represent with SINR:

${\mathrm{SINR}}_j=\frac{{\left|\right|H_j{W}_j{u}_j\left|\right|}^2}{{\mathrm{\σ}}_{\mathrm{Bj}}^2+\frac{{\mathrm{\Σ}}_{i=1,i\≠j}^J{\left|\right|W_j^{*}{H}_j^{*}{H}_j{W}_i{u}_i\left|\right|}^2}{{\left|\right|H_j{W}_j\left|\right|}^2}+\frac{{\left|\right|W^{*}{H}_j^{*}{H}_j\mathrm{Wv}\left|\right|}^2}{{\left|\right|H_j{W}_j\left|\right|}^2}},$ j=1,2，…J

As can be seen from the above equation, by making SINR maximum be used as selecting W _jstandard will produce the optimization problem of the heavy variable of J, complexity is very high.

Rethink and receive signal Y _jcan find the echo signal u receiving in Bob termination _jpower be || H _jw _ju _j|| ², be intended to send to the signal power that Bobj is but received by Bob i to be simultaneously || H _iw _ju _j|| ².In like manner, send to Bobj but by other users, received and cause total signal power of interference to be

$\underset{i=1,i\≠j}{\overset{J}{\mathrm{\Σ}}}\left|\right|H_i{W}_j{u}_j\left|\right|$

Now, the expression formula of Bobj end SLR can be written as again:

${\mathrm{SLR}}_j=\frac{{\left|\right|H_j{W}_j\left|\right|}^2}{{\left|\right|{\tilde{H}}_J{W}_j\left|\right|}^2}$

$=\frac{\mathrm{tr}\left(W_j^H{H}_j{H}_j{W}_j\right)}{{\mathrm{\Σ}}_{i,i\≠j}^J\mathrm{tr}\left(W_j^H{H}_i{H}_i{W}_j\right)}$

If from improving the angle analysis of each subscriber signal energy capacity usage ratio, this has just become one makes each user's SLR maximum, wherein only relates to a variable W _j.This has just produced a new optimization problem:

Problem is described: first do not consider the power to each user assignment, design w _j, j=1,2 ... J, makes each user's SLR maximum:

$W_j=\arg \max {\mathrm{SLR}}_j=\frac{\mathrm{tr}\left(W_j^H{H}_j{H}_j{W}_j\right)}{{\mathrm{\Σ}}_{i,i\≠j}^J\mathrm{tr}\left(W_j^H{H}_i{H}_i{W}_j\right)}$

subject?to||W _j|| ²=1，j=1,2，…J

Obviously, this is an optimization problem that only relates to a known variables, than above-mentioned, based on SINR, selects W _jmethod want simple many.

In order to solve optimization problem above, quoted the Rayleigh-Ritz Quotient result in " Matrix Computations ".

$\frac{{\left|\right|H_j{W}_j\left|\right|}^2}{{\left|\right|{\tilde{H}}_J{W}_j\left|\right|}^2}\≤{\mathrm{\λ}}_{\max }(H_j^H{H}_j,{\tilde{H}}_j^H{\tilde{H}}_j)$

Wherein, λ _maxit is matrix pair with generalized singular value.Equally, W _jin the incorgruous quantity space of the corresponding generalized odd of maximum generalized singular value, obtain.Specifically be expressed as follows:

Channel matrix H to each user Bob j _jwith and corresponding equivalence after combined channel matrix carry out GSVD decomposition:

$[U,V,X,C,S]=\mathrm{GSVD}(H_j,{\tilde{H}}_j)$

H _j＝U*C*X′

${\tilde{H}}_j=V*S*X^{\′}$

C′*C+S′*S＝I

Pre-coding matrix that can designing user Bobj is:

$W_j\∝\max \mathrm{generalizedeigenvectorof}(H_j^H{H}_j,{\tilde{H}}_j^H{\tilde{H}}_j)\mathrm{whend}=1.$

$W_j\∝\max \mathrm{dgeneralizedeigenvectorsof}(H_j^H{H}_j,{\tilde{H}}_j^H{\tilde{H}}_j)\mathrm{whend}>1.$

Because Alice knows the CSI information of all Bob, in order to guarantee not affect targeted customer Bob, select the equivalence that man made noise is sent to all Bob to combine downlink combined channel matrix quadrature kernel in.Wherein,

${\tilde{H}}^H=[{H_1}^T,{H_2}^T,\·\·\·,{H_j}^T,\·\·\·,{H_J}^T]$

Then man made noise's pre-coding matrix is designed to because W is necessary for non-null matrix, in order to meet this requirement, the number of antennas that adequate condition is Alice must be greater than the antenna number summation of all Bob, again $N_A\≥{\mathrm{\Σ}}_{i=1}^J{N}_{\mathrm{Bi}}+1.$

Suppose that it is P that Alice has total through-put power.After by the noise variance standardization of Bob end, also can be using P as the SNR transmitting.Wherein having an important parameter is exactly the power proportions of distributing between each user Bob, is expressed as ρ _j(0≤ρ _j≤ 1) for sending man made noise's power proportions, be, α.Between these parameters, meet lower relation of plane:

$Q_{u_j}=E\left\{u_j{u_j}^H\right\}\mathrm{Tr}\left(Q_{u_j}\right)={\mathrm{\ρ}}_{j}P$

$Q_v=E\left\{{\mathrm{vv}}^H\right\}\mathrm{Tr}\left(Q_v\right)=\mathrm{\αP}$

$\mathrm{\α}=1-\underset{i=1}{\overset{J}{\mathrm{\Σ}}}{\mathrm{\ρ}}_j{N}_A\≥\underset{i=1}{\overset{J}{\mathrm{\Σ}}}{N}_{\mathrm{Bj}}+1$

${\mathrm{\σ}}_{u_j}^2=\frac{P_j}{d_j}=\frac{{\mathrm{\ρ}}_{j}P}{d_j}{\mathrm{\σ}}_v^2=\frac{(1-\mathrm{\ρ})P}{N_A-{\mathrm{\Σ}}_{j=1}^J{d}_j}=\frac{(1-{\mathrm{\Σ}}_{j=1}^J{\mathrm{\ρ}}_j)P}{N_A-{\mathrm{\Σ}}_{j=1}^J{d}_j}$

In order to analyze better secrecy capacity, the signal that Bob j can be received is reduced to:

$Y_j=H_j\underset{i=1}{\overset{J}{\mathrm{\Σ}}}{W}_i{u}_i+H_j\mathrm{Wv}+N_j$

$=H_j{W}_j{u}_j+H_j\underset{i=1,i\≠j}{\overset{J}{\mathrm{\Σ}}}{W}_i{u}_i+H_j\mathrm{Wv}+N_j$

$={\stackrel{\·\·\·}{H}}_{\mathrm{jj}}{u}_j+{\mathrm{\Σ}}_{i\≠j}^J{\stackrel{\·\·\·}{H}}_{\mathrm{ji}}{u}_i+{\stackrel{\·\·\·}{H}}_{j}v+N_j$

In like manner, Evek intercepts the information u about Bobj _jsignal can be reduced to:

$Z_{\mathrm{kj}}=G_k\underset{i=1}{\overset{J}{\mathrm{\Σ}}}{W}_i{u}_i+G_k\mathrm{Wv}+N_k$

$=G_k{W}_j{u}_j+G_k\underset{i=1,i\≠j}{\overset{J}{\mathrm{\Σ}}}{W}_i{u}_i+G_k\mathrm{Wv}+N_k$

$={\stackrel{\·\·\·}{G}}_{\mathrm{kj}}{u}_j+{\mathrm{\Σ}}_{i=1,i\≠j}^J{\stackrel{\·\·\·}{G}}_{\mathrm{ki}}{u}_i+{\stackrel{\·\·\·}{G}}_{k}v+N_k$

Wherein, definition ${\stackrel{\·\·\·}{H}}_{\mathrm{ji}}=H_j{W}_i,$ ${\stackrel{\·\·\·}{H}}_j=H_{j}W=0,$ k=1,2，...，K

${\stackrel{\·\·\·}{G}}_{\mathrm{ki}}=G_k{W}_i,$ ${\stackrel{\·\·\·}{G}}_k=G_{k}W,$ i，j=1,2，...，J

According to the definition of MUME tapping channel secrecy capacity, must guarantee that any one user Bob is not ravesdropping, one of them coboundary that so just can obtain system secrecy secrecy capacity is C _jk=[C _bj-C _ek] ⁺, the secrecy capacity of whole system is by { C _jka middle minimum decision, that is, and C _se=min{C _jk, j=1,2 ..., J and k=1,2 ..., K.

By above discussion, can obtain the system for MUME-MIMO, its a traversal secrecy capacity is:

$C_{\mathrm{se}}={\max }_{j,k}^{\min }\left[{\left(E_{\tilde{H}}\right\{{\log }_2|I+\frac{{\mathrm{\ρ}}_{j}P}{d_{\mathrm{Bj}}}{\stackrel{\·\·\·}{H}}_{\mathrm{jj}}{{\stackrel{\·\·\·}{H}}_{\mathrm{jj}}}^H(I+\underset{i=1,i\≠j}{\overset{J}{\mathrm{\Σ}}}\frac{{\mathrm{\ρ}}_{i}P}{d_{\mathrm{Bi}}}{\stackrel{\·\·\·}{H}}_{\mathrm{ji}}{{\stackrel{\·\·\·}{H}}_{\mathrm{ji}}}^H)}^{-1}\right|\}$

$-E_{\tilde{H},G_k}\left\{{\log }_2\right|+\frac{{\mathrm{\ρ}}_{j}P}{d_{\mathrm{Bj}}}{\stackrel{\·\·\·}{G}}_{\mathrm{ki}}{{\stackrel{\·\·\·}{G}}_{\mathrm{kj}}}^H{(\underset{i=1,i\≠j}{\overset{J}{\mathrm{\Σ}}}\frac{{\mathrm{\ρ}}_{i}P}{d_{\mathrm{Bi}}}{\stackrel{\·\·\·}{G}}_{\mathrm{ki}}{{\stackrel{\·\·\·}{G}}_{\mathrm{ki}}}^H+\frac{(1-\mathrm{\ρ})P}{(N_A-{\mathrm{\Σ}}_{j=1}^J{N}_{\mathrm{Bj}})}{\stackrel{\·\·\·}{G}}_k{{\stackrel{\·\·\·}{G}}_k}^H)}^{-1}\left|\right\}{)}^{+}]$

Below the secrecy capacity and the complexity that mainly SLR method are provided analyze, and compare with method in the past.

Accompanying drawing 2,3 has provided the obtained secrecy capacity of above-mentioned four kinds of distinct methods and for the comparison of the power ratio of all Bob.As can be seen from Figure 2, SLR method effect is a little less than current best BD method, but more much better than conventional method and ZFBeamforming method, yet its complexity is more much lower than BD method.Therefore SLR method can realize a kind of compromise between high secrecy capacity and low complex degree.Fig. 3 shows that SLR method is with respect to other method, and its power utilization efficiency is lower, and namely more power is used to send man made noise.But the gross power that they use is all the same, therefore can not be considered as a kind of shortcoming.

The SLR method that provided accompanying drawing 4,5 obtains secrecy capacity and for the comparison of the power ratio of all Bob in Eve cooperation and uncooperative situation.If Eve selects information sharing, think that they are in cooperation, otherwise uncooperative.Fig. 4 shows that secure communication is by more difficult obtaining if cooperated between Eve.Fig. 5 shows, when existing in the situation of selecting cooperation between more Eve or Eve, should distribute more power for sending man made noise.

Accompanying drawing 6,7 considered when having two Bob and 3 Eve, and the secrecy capacity obtained while having different antenna radicals of Bob1 and the power division between each Bob.What inventor thought research is that how the power between them should distribute when the antenna number between Bob is different.Fig. 6 shows that the secrecy capacity of MUME safe communication system is mainly determined by the user with minimum antenna number, even and the have greatly increased secrecy capacity of entire system of the antenna number of other Bob do not have how many liftings yet.Fig. 7 shows that the antenna of Bob is more, and the required power proportions of distributing to it is just fewer.And when the antenna number of all Bob is identical, power is mean allocation between each Bob.

Although content of the present invention has partly been done detailed introduction in the above, will be appreciated that above-mentioned description should not be considered to limitation of the present invention.Those skilled in the art, read after foregoing, for multiple modification of the present invention with to substitute will be all apparent.Therefore, protection scope of the present invention should be limited to the appended claims.

Claims (3)

1. a method for precoding for the multi-user's secure communication based on SLR, is characterized in that comprising the following steps:

Step 1: sender Alice carries out the channel estimating of down link;

Step 2:Alice, according to the channel matrix of known all user Bob, constructs each user's equivalent isomery combined channel matrix, the confederate matrix that other all subscriber channel matrixes form except self; And to each user's channel matrix with and corresponding equivalent isomery combined channel matrix carry out generalized singular value decomposition, draw corresponding generalized eigenvalue and the generalized eigenvector of each channel matrix;

Step 3:Alice sends d data flow to each user simultaneously, in step 2, select corresponding d the maximum generalized eigenvector that generalized eigenvalue is corresponding, then Alice is transmitted into corresponding generalized eigenvector space by each user's to be sent signal, and man made noise sends to the kernel of all channel matrixes at utmost to reduce the impact on Bob;

Step 4: stay of two nights D decodes with Wiener filter.

2. the method for precoding of the multi-user's secure communication based on SLR according to claim 1, is characterized in that, in described step 1, sender Alice estimates to carry out the channel estimating of down link by time division duplex.

3. the method for precoding of the multi-user's secure communication based on SLR according to claim 1, is characterized in that, in described step 1, sender Alice carries out the channel estimating of down link by the feedback of Frequency Division Duplexing (FDD).