CN106374980A - Safe transmission method in MIMO Y eavesdropping network based on real interference alignment - Google Patents

Abstract

The invention discloses a safe transmission method in an MIMO Y eavesdropping network based on real interference alignment. According to the method, through utilization of a real interference alignment technology and an artificial noise technology, through construction of useful signal precoding matrixes and interference suppression matrixes, inter-user interference signals at legal user positions are located in null spaces of receiving suppression matrixes; and noise signals are completely eliminated through linear combination. Moreover, through construction of a noise signal coding matrix at a relay position, the noise signals are completely aligned to receiving signal spaces of eavesdropping users, so the eavesdropping users cannot eavesdrop the signals and the whole multi-user eavesdropping network can obtain multiple safe communication channels.

Description

A kind of based on do solid work disturb alignment mimo y eavesdrop network in safe transmission method

Technical field

The invention belongs to safety of physical layer field in radio communication and in particular to a kind of based on doing solid work the mimo disturbing alignment Y eavesdrops the safe transmission method in network.

Background technology

In recent years, the safety problem in radio communication progressively becomes study hotspot.Traditional AES is mainly used in Upper layer network, in transmitting terminal, using key come encryption information, plaintext is converted into ciphertext；In receiving terminal, deciphered using key Information, ciphertext is converted in plain text.Listener-in can analyze in plain text according to the ciphertext receiving.Therefore, AES needs constantly Improve and increase the length of key to tackle the ever-increasing computing capability of computer.Safety of physical layer technology is as to encryption skill The a kind of of art supplements, and has progressively been applied to wireless network and ad-hoc network.Its core concept is using legitimate channel and eavesdropping Different physical characteristics between channel are realizing safe transmission.At present, many researchs all concentrate on safety of physical layer technology, dimension Receive and demonstrate legitimate correspondence both sides first under conditions of there is no shared key, still can obtain perfect secure communications, with When point out, under discrete memoryless channel(DMC) model, safe rate is the difference of legitimate channel speed and tapping channel speed, and Propose wiener tapping channel model, this lays a good foundation for later research, existing document is generalized to Gaussian channel mould Type, broadcast channel model, all obtain identical safe rate formula.

In multi-user's eavesdropping network, the problem of the reliability and security of existence information transmission simultaneously.Dry between user Disturb the transmitting procedure inevitably affecting this system, thus reducing the data fluxion that system can be transmitted, i.e. degree of freedom (dof).Therefore, in order to weaken inter-user interference, interference alignment techniques cause extensive concern.The ultimate principle of interference alignment It is to less interference space it is desirable to signal, independent of this space, is then recovered by simple ZF by interference vector compression Desired signal, so that numerous user can communicate in the signal space of low-dimensional simultaneously.Prior art proposes to need less sky The interference alignment algorithm of line number, this algorithm can obtain and tradition interference alignment algorithm identical degree of freedom.It should be noted that We have found that cooperation signal scrambling technique is perfectly in harmony in thinking with interference alignment techniques.As the crucial skill in safety of physical layer One of art, cooperation signal scrambling technique typically the noise signal of transmission is placed in the kernel of channel so as to not disturb useful letter Number, only weaken the received signal to noise ratio at eavesdropping end；And disturb alignment also to expect receiving useful signal and interference signal End separates.Therefore, there is scholar's research to realize multi-user using interference alignment techniques and eavesdrop the secure communication in network.As In prior art, author combines the non-zero safety realizing k user Gaussian interference channel using interference alignment and network coding technique Data fluxion, i.e. (secrecy degree of freedom).

For the eavesdropping network of the multi-user containing relaying, technology is had to point out, it is possible to use interference alignment techniques are whole to realize The secure communication of individual system.The secrecy that the double jump that x.he and a.yener have studied with unreliable relaying is eavesdropped in network is free The problem of degree.But, the research in the secrecy degree of freedom that multichannel is relayed with eavesdropping network at this stage has also lacked.One typical case K user multichannel relaying eavesdropping network be mimo y tapping channel, in mimo y network, all users are multi-antenna nodes, Each user expects to be communicated by relaying with other all users, because its traffic model is similar in alphabetical " y ", and Its communication mode is by the way of one-to-many, therefore it is named as " y model ".Its communication process mainly contains multiple access and accesses (mac) stage and broadcast (bc) stage.In the mac stage, each user sends k-1 signal to relaying, simultaneously at relaying Carry out signal alignment；In the bc stage, k (k-1)/2 signal after alignment is broadcast to all users by relaying, and each user passes through certainly Interference elimination can obtain desired signal.In the present invention, we will propose a kind of to lead to based on doing solid work the safety disturbing alignment techniques Letter scheme, by designing pre-coding matrix, AF panel matrix and man made noise's encoder matrix, realizes the multi-user containing relaying and steals Listen the secure communication of system.

Content of the invention

It is an object of the invention to overcoming above-mentioned deficiency, provide a kind of based on do solid work disturb alignment mimo y eavesdropping network in Safe transmission method, k user mimo y eavesdropping network in, carried out by the pam constellation symbol that all users are sent Precoding, and relay the man made noise's signal after sending coding, combine and disturb alignment techniques and the signal scrambling technique that cooperates using doing solid work, In the case that user meets Power Limitation with via node, realize whole network transfer of security data stream.

In order to achieve the above object, the present invention comprises the following steps:

Step one, before starting transmission signal, each user needs to select useful signal from pam constellation, at relaying The noise signal sending also is taken from a pam constellation；

Step 2, according to known global channel status information, each sends user and designs it according to interference aligned condition Related pre-coding matrix；

It is assumed that all users and node are all full-duplex modes, all users send the letter after coding to relaying to step 3 Number, relaying sends first time man made noise's signal simultaneously；

Step 4, man made noise is broadcasted simultaneously to all users with the useful signal amplifying by relaying again；

Step 5, each user receiving twice after signal, is manually made an uproar by what linear combining eliminated that relaying sent Acoustical signal, and suppress matrix to demodulate useful signal using the reception meeting certain restrictive condition, thus whole system obtains Obtain traffic rate necessarily.

The concrete grammar of described step one is as follows:

Disturb alignment techniques using doing solid work, all of channel is real channel matrix, and assume user u_iIssue user u_j's Signal sending signal s_ijIt is taken from pam constellation c (a defined below_u,q_u), that is,

c(a_u,q_u)=a_u{-q_u,-q_u+1,...,q_u-1,q_u}

In formula:

q_uOne and number of users k and each user's transmit power p_iRelated on the occasion of, for δ ＞ 0,

a_uThe sending signal making each user meets the real number that transmit power limits, for γ ＞ 0,

In the above description, each user u_iThe signal s sending_i=[s_i1,s_i2,...,s_ik]^t∈r^(k-1)×1It is through pre- Encoder matrix v_i∈r^m×(k-1)Signal x after coding_i∈r^m×1, that is,Therefore transmit power is limited toTherefore, q_uδ and a in expression formula_uγ in expression formula takes in the many class values meeting power limitation condition Any one group on the occasion of；

In mbwc mimo y model, relay sent interference noise b_i∈r^k(k-1)×1Comprise the individual symbol of k (k-1), It is taken from another pam constellation c (a_r,q_r), that is,

c(a_r,q_r)=a_r{-q_r,-q_r+1,...,q_r-1,q_r}

In formula:

q_rOne to number of users k and relaying transmit power p related on the occasion of, for δ ＞ 0,

a_rSo that sending signal meets the real number of transmit power restriction at relaying, for γ ＞ 0,

Sending b_iNeed it is encoded, encoder matrix is t before_i∈r^n×k(k-1)；So, relaying place sends Man made noise isIts sending signal Power Limitation is e [tr (zz^h)]≤βp；Therefore, q_rIn expression formula δ and a_rγ in expression formula take in the many class values meeting power limitation condition any one group on the occasion of.

The concrete grammar of described step 2 is as follows:

In order to eliminate produced inter-user interference during k user intercommunication, and demodulate and come from other k-1 use The signal at family, needs to design pre-coding matrix v in each user_i,It is tieed up by k-1 m × 1 Precoding vector v_ijComposition, each precoding vector v_ijWill be to each signal s_jiCarry out linear predictive coding, that is, v_ijs_ij；The dimension in the space that the n root antenna at relaying is opened be less than k (k-1) individual symbolic number when, part signal can in Continue place's generation aliasing, in order to avoid above-mentioned condition, using interference alignment techniques, when the antenna number of each node meetsWhen, by all paired signal such as s_ijWith s_jiSnap in the same dimension of relaying, Now, the individual useful signal of k (k-1) can be comprised in relayingIn dimension space, that is, need to meet equation:

Wherein, what the vector of the same dimension after channel was equivalent is denoted as u_i,j,I=1,2 ..., k is User u_iTo relaying, it is relayed to user u_iReal channel matrix；Now, aliasing will not occur at relaying between each signal；

At relaying, in order to ensure to expect that legal signal can not be ravesdropping, as known gcsi, design man made noise's letter Number pre-coding matrix t_iSo that its satisfactionI.e.

Wherein,I=1,2 ..., k represent between eavesdropping end and user, between eavesdropping end and relaying respectively Real channel matrix, g_iIt is the equivalent vector of the same dimension after tapping channel；Then encoded man made noise's signal It is expressed as

The concrete grammar of described step 3 is as follows:

All users by encode after signal x_iBe sent to via node, then relay reception to signal be:

In formula:

n_rLocal white Gaussian noise at relaying；

When all users are to relaying sending signal, the man made noise z for β p for the broadcasting power to user and steals relaying simultaneously Listen end, now, the signal that user received in this stage is

In formula:

Artifact power's partition coefficient at β relaying.

User u_jIn the local white Gaussian noise in mac stage, noise variance is

The concrete grammar of described step 4 is as follows:

After relaying receives k (k-1) individual signal, it is amplified being transmitted to all users, forward signal is x_r=α y_r, its Middle α is the amplification coefficient at relaying, and the Power Limitation sending useful signal isMeanwhile, further Secondary transmission and mac stage identical man made noise's signal, now, the receipt signal in this stage for each user is

In formula:

User u_jIn the local white Gaussian noise in bc stage, noise variance is

The concrete grammar of described step 5 is as follows:

The first step, the signal twice that legitimate receipt end is received with eavesdropping end is weighted merging, the letter after being merged Number it is:

Note:So, y_jIn do not comprise man made noise z, validated user will not be disturbed by man made noise The impact of signal；

After above-mentioned described interference alignment, by y_jAgain it is expressed as the stacking pattern of two groups of pair signals:

In formula:

Interference alignment matrix；

Dimension relaying pair signals,

For user u_j, signal that it receives is divided into two parts, required useful signalWith doing of other users Disturb signal

Second step, designs the reception suppression matrix of each user；After carrying out spacing wave alignment, user u_jNeed into one Step receives suppression matrix f with (k-1) × m dimension_i=[f_1if_2i...f_i-1,if_i+1,i...f_ki]^tTo y_jCarry out disturbing ZF, just receive To useful signal, that is, need to use f_jPremultiplication is with y_j,

In formula:

Dimension equivalent received suppression matrix；

Equivalent received suppresses matrix p_jSelection principle be

Wherein, the kernel of null { a } representing matrix a；Upper two formulas represent p_jIt is taken fromKernel, and p_jDo not existKernel in；

In order to choose the matrix p meeting mentioned above principle_jIt is necessary first to clearly such matrix whether there is；Assume each conjunction Csi known to method node, above formula is equivalent toIn order to meet this condition, the antenna number at relaying must is fulfilled forAnd this condition is already contained in the feasibility condition of interference alignment, that is,Cause This, necessarily set up when meeting interference aligned condition；In order to ensure existing,Represent ?There is a n × n- (k-1) in matrix and tie up kernel, be designated as q；Assume that q is by a series of n × 1 rank null vector q institutes group Become, that is,p_jIt is written as the form of column vector, p_j=[p_j,1p_j,2...p_j,k-1]；Now, and if only if has matrix a, It is made to meet a=[p_j,1p_j,2...p_j,k-1q_j], during rank (a)=k, this means that selected p_jIt is independently of kernel, I.e.In sum, the reception suppression matrix p at user_jOr f_jAlways exist；

So, under any circumstance, all choose qualified reception and suppress matrix, then eliminated by self-interference, user u_jDemodulate the signal receiving, that is,

In formula:

User u_jLegitimate receipt signal；

User u_jLegal signal pre-coding matrix；

3rd step: using Maximum Likelihood Detection scheme detection signal；

In user u_jPlace, estimated signal is denoted asWhen known receipt signalWhen, using Maximum Likelihood Detection side Method draws estimation signal,

Wherein,

χ is s_jThe set being taken, has (2q_u+1)^k-1Kind；

argmin||a||²The minima of two norms of matrix a.

Compared with prior art, the present invention is using doing solid work alignment techniques and the man made noise's technology of disturbing, by being configured with letter Number pre-coding matrix is with AF panel matrix it is achieved that at validated user, inter-user interference signal is in reception suppression matrix Kernel at, noise signal is completely eliminated by linear combining；Construct noise signal encoder matrix additionally by relaying, will In the perfectly aligned receipt signal space to eavesdropping user of noise signal, reach make its cannot tapped signal purpose, thus whole Individual multi-user's eavesdropping network can obtain multiple secure communication channels.

Brief description

Fig. 1 eavesdrops the schematic diagram in model mac stage for the present invention；

Fig. 2 eavesdrops the schematic diagram in model bc stage for the present invention；

Fig. 3 is the FB(flow block) of the present invention.

Specific embodiment

The present invention will be further described below in conjunction with the accompanying drawings.

The present invention propose a kind of using do solid work disturb alignment techniques with cooperate scramble safety of physical layer scheme, the program employing Amplification forwarding agreement, based on the physical channel of multi-user-relaying-multi-user, carries out precoding at user, sends at relaying Man made noise, this noise disturbs external eavesdropping node in the case of not disturbing user, in the bar of each user node Power Limitation Under part, obtain whole secure communication channels.

The present invention considers a mimo y eavesdropping model, a total of k user, and each user has m root antenna, relaying There is n root antenna at place, relays realization by an af and be in communication with each other between multiple users, and system contains an eavesdropping node, each The power of user's sending signal is p_i, the transmit power of all users and be p, at relaying send artificial noise signal power be β p, the power forwarding legal signal is (1- β) p, and wherein β is the power partition coefficient at relaying, 0 ＜ β ＜ 1.Entirely it is transmitted across Journey is described as follows:

As shown in Figure 1, Figure 2 and Figure 3, the invention provides a kind of disturb alignment techniques and the signal scrambling technique that cooperates based on doing solid work Safe transmission method of physical layer in k user mimo y eavesdropping system, comprises the following steps:

1) before starting transmission signal, each user needs to select useful signal from pam constellation, sends at relaying Noise signal is also taken from a pam constellation；

In the following analysis, in order to disturb alignment techniques using doing solid work, all of channel is real channel matrix, and assumes User u_iIssue user u_jSignal sending signal s_ijIt is taken from pam constellation c (a defined below_u,q_u), that is,

c(a_u,q_u)=a_u{-q_u,-q_u+1,...,q_u-1,q_u}

In formula:

q_uOne and number of users k and each user's transmit power p_iRelated on the occasion of, for δ ＞ 0,

a_uThe sending signal making each user meets the real number that transmit power limits, for γ ＞ 0, In the above description, each user u_iThe signal s sending_i=[s_i1,s_i2,...,s_ik]^t∈r^(k-1)×1It is through pre-coding matrix v_i∈r^m×(k-1)Signal x after coding_i∈r^m×1, that is,Therefore transmit power is limited to Therefore, q_uδ and a in expression formula_uγ in expression formula just can take in the many class values meeting power limitation condition any one group Value.

In mbwc mimo y model, relay sent interference noise b_i∈r^k(k-1)×1Comprise the individual symbol of k (k-1), its It is taken from another pam constellation c (a_r,q_r), that is,

c(a_r,q_r)=a_r{-q_r,-q_r+1,...,q_r-1,q_r}

In formula:

q_rOne to number of users k and relaying transmit power p related on the occasion of, for δ ＞ 0,

a_rSo that sending signal meets the real number of transmit power restriction at relaying, for γ ＞ 0,Sending b_iNeed it is encoded, encoder matrix is t before_i∈r^n×k(k-1), subsequently we need right t_iIt is designed.So, the man made noise of relaying place transmission isIts sending signal Power Limitation is e [tr(zz^h)]≤βp.Therefore, q_rδ and a in expression formula_rγ in expression formula can take the many class values meeting power limitation condition In any one group on the occasion of.

2) according to known global channel status information, each sends user needs to design its phase according to interference aligned condition The pre-coding matrix closing；It is also required at relaying design artificial noise code matrix, concrete grammar is as follows:

In order to eliminate produced inter-user interference during k user intercommunication, and demodulate and come from other k-1 use The signal at family, needs to design pre-coding matrix v in each user_i,It is by k-1 m × 1 The precoding vector v of dimension_ijComposition, each precoding vector v_ijWill be to each signal s_jiCarry out linear predictive coding, that is, v_ijs_ij.The dimension in the space that the n root antenna at relaying is opened be less than k (k-1) individual symbolic number when, part signal can in Continue place's generation aliasing, and in order to avoid above-mentioned condition, we adopt interference alignment techniques, when the antenna number of each node meetsWhen, by all paired signal such as s_ijWith s_jiSnap in the same dimension of relaying, Now, the individual useful signal of k (k-1) can be comprised in relayingIn dimension space, that is, need to meet equation

Wherein, what the vector of the same dimension after channel was equivalent is denoted as u_i,j,I=1,2 ..., k is User u_iTo relaying, it is relayed to user u_iReal channel matrix.Now, aliasing will not occur at relaying between each signal.

At relaying, in order to ensure to expect that legal signal can not be ravesdropping, as known gcsi, we design and manually make an uproar The pre-coding matrix t of acoustical signal_iSo that its satisfactionI.e.

Wherein,I=1,2 ..., k represent between eavesdropping end and user, between eavesdropping end and relaying respectively Real channel matrix, g_iIt is the equivalent vector of the same dimension after tapping channel.Then encoded man made noise's signal It is expressed as

3) assume that all users and node are all full-duplex modes, in the first stage, all users send coding to relaying Signal afterwards, the first time man made noise's signal of relaying transmission simultaneously；In second stage, relaying is again by man made noise and amplification Useful signal be broadcasted simultaneously to all users；

Concrete communication process is divided into step, and detailed process is as follows:

Step 1 (mac stage): all users by encode after signal x_iIt is sent to via node, then relay reception arrives Signal is:

In formula:

n_rLocal white Gaussian noise at relaying.

When all users are to relaying sending signal, the man made noise z for β p for the broadcasting power to user and steals relaying simultaneously Listen end, now, the signal that user received in this stage is

In formula:

User u_jIn the local white Gaussian noise in mac stage, noise variance is

Step 2 (bc stage): after relaying receives k (k-1) individual signal, be amplified being transmitted to all users, forward Signal is x_r=α y_r, wherein α is the amplification coefficient at relaying, and the Power Limitation sending useful signal isMeanwhile, transmission again and mac stage identical man made noise's signal, now, each user Receipt signal in this stage is

In formula:

User u_jIn the local white Gaussian noise in bc stage, noise variance is ${{\mathrm{\σ}}_j}^2.$

4) each user is receiving twice after signal, eliminates the sent man made noise's letter of relaying by linear combining Number, and suppress matrix to demodulate useful signal using the reception meeting certain restrictive condition, thus whole system obtains one Fixed traffic rate.Specifically comprise the following steps that

Step 1: the signal twice that legitimate receipt end is received with eavesdropping end is weighted merging, after being merged Signal is:

Note:So, y_jIn do not comprise man made noise z, validated user will not be disturbed by man made noise The impact of signal.

After above-mentioned described interference alignment, can be by y_jAgain it is expressed as the stacking pattern of two groups of pair signals:

In formula:

Interference alignment matrix；

Dimension relaying pair signals,

For user u_j, signal that it receives is divided into two parts, required useful signalWith doing of other users Disturb signal

Step 2: design the reception suppression matrix of each user.After carrying out spacing wave alignment, user u_jNeed into one Step receives suppression matrix f with (k-1) × m dimension_i=[f_1if_2i...f_i-1,if_i+1,i...f_ki]^tTo y_jCarry out disturb ZF so that it may To receive useful signal, that is, need to use f_jPremultiplication is with y_j,

In formula:

(k-1) × n dimension equivalent received suppression matrix.

Equivalent received suppresses matrix p_jSelection principle be

Wherein, the kernel of null { a } representing matrix a.Upper two formulas represent p_jIt is taken fromKernel, and p_jDo not existKernel in.

In order to choose the matrix p meeting mentioned above principle_jIt is necessary first to clearly such matrix whether there is.Assume each conjunction Csi known to method node, above formula is equivalent toIn order to meet this condition, the antenna number at relaying must is fulfilled forAnd this condition is already contained in the feasibility condition of interference alignment, that is,Cause This, necessarily set up when meeting interference aligned condition.In order to ensure existing, it was noted thatThis representsThere is a n × n- (k-1) in matrix and tie up kernel, be designated as q.Assume that q is made up of a series of n × 1 rank null vector q, that is,p_jCan be written as the form of column vector, p_j= [p_j,1p_j,2...p_j,k-1].Now, and if only if has matrix a so as to meet a=[p_j,1p_j,2...p_j,k-1q_j], rank (a)= During k, this means that selected p_jIt is independently of kernel, that is,In sum, the reception suppression square at user Battle array p_jOr f_jAlways exist.

So, under any circumstance, we all can choose qualified reception and suppress matrix, then are disappeared by self-interference Remove, user u_jThe signal receiving can be demodulated, that is,

In formula:

User u_jLegitimate receipt signal.

User u_jLegal signal pre-coding matrix.

Step 3: using Maximum Likelihood Detection scheme detection signal.

In user u_jPlace, estimated signal is denoted asWhen known receipt signalWhen, using Maximum Likelihood Detection side Method draws estimation signal,

Wherein,

χ is s_jThe set being taken, has (2q_u+1)^k-1Kind；

argmin||a||²The minima of two norms of matrix a.

In sum, whole multi-user's relaying eavesdropping network can realize secure communication.

5) in order to verify the performance of the present invention, we will analyze under this programme, system institute from information-theoretical angle The number of obtainable secure data flow, i.e. the secrecy degree of freedom of derivation whole system.When secure data flow amount is more than zero, Whole system can be with secure communication.Specifically comprise the following steps that

Step 1: the data fluxion of first derivation validated user communication.The information rate that each user obtains is:

In formula:

The mutual information of two stochastic variable a and b of i (a, b)；

H () comentropy.

Wherein, due to s_jIn k-1 symbol be equiprobable to come from pam constellation c (a_u,q_u), therefore h (s_j)=log (2q_u+1)^k-1.In addition, we use Markov ChainTo limit with Fano inequalityIt is wrong The upper bound of probability is by mistake:

In formula: η_γWith p_iUnrelated on the occasion of.Herein it will be assumed that p_i=p/k, therefore, validated user and fast Rate is expressed asI.e.

r_sum≥k log(2q_u+1)^k-1-k-k pr_u(e)log(2q_u+1)^k-1

We are to r_sumValue carry out finding limit under conditions of high signal/noise ratio, you can to obtain the legal number of whole system According to fluxion,

This represents, when each user sends k-1 data, the legal data fluxion of k user of whole system is k (k-1).

Step 2: the data fluxion that analysis eavesdropping end can intercept.Letter twice first received by analysis eavesdropping end Number.In the mac stage, eavesdropping the signal received by end is:

Wherein:

Eavesdrop end this Earth noise when first time receiving signal, noise variance is

In the bc stage, the signal that eavesdropping end receives for the second time is:

Wherein:

Eavesdrop end this Earth noise when receiving signal for the second time, noise variance is

For eavesdropping end, we cannot learn its interception method used, therefore, in the present invention it will be assumed that eavesdropping end Take a kind of method most useful for eavesdropping, that is, it can carry out linear combining to received signal twice.Assume listener-in Receiving matrix can be utilizedMerge tapped signal twice in order to obtain the eavesdropping signal to noise ratio of maximum, that is,The demodulated signal at eavesdropping end is represented as

In formula:

s_iThe sending signal of each user,

n_eEavesdropping end this Earth noise of equivalence, that is,

WhenWhen, the signal that eavesdropping end receives can be expressed as again

Section 1 in above formula represents the impact for each subscriber signal for the interference signal.We will be right with interference for signal Together in a dimension, so eavesdropping end cannot identify useful signal, just cannot eavesdrop.Now, eavesdropping information rate is

Work as w₁≠0,w₂≠ 0,Can be represented as

Now:

For eavesdropping end, orderThe equivalent expression of the number of tapping channel For:

This shows, eavesdropping end at most can interceptIndividual data flow, wherein symbolRepresent and take downwards Whole.

Step 3: weed out the data flow of eavesdropping in legitimate traffic, remaining is safe and secret data flow Number, when whole system has the data flow of safety, whole system can securely communicate.Therefore, k user mbwc model The minima of secure data fluxion is

This shows, when number of users is more than three, the data fluxion that system is obtained in that is minimum to beIndividual, wherein SymbolExpression rounds up.By proving, this data fluxion is always on the occasion of that is, whole system has the number of secure communication According to stream, the safety of system is ensured.

Proposed by the invention in k user mimo y tapping channel, disturb alignment techniques and the scrambling skill that cooperates based on doing solid work The scheme of the secure communication of art has the advantage that

The program, be applied to the eavesdropping network of the multidirectional relaying of multi-user, is directed to the precoding of different user by design Matrix, noise code matrix and receive suppression matrix, under the communication pattern of full duplex pass through design sending method it is achieved that The secure communication of whole system, this compensate for the vacancy of security of system in junction network.

Knowable to above-mentioned performance proves, the number of the safe lane that the method obtains is consistently greater than zero, and this also indicates that entirely System can realize secure communication.

Claims (6)

1. a kind of eavesdrop the safe transmission method in network it is characterised in that including following based on doing solid work the mimo y disturbing alignment Step:

Step one, before starting transmission signal, each user needs to select useful signal from pam constellation, sends at relaying Noise signal be also taken from a pam constellation；

Step 2, according to known global channel status information, each sends user and designs its correlation according to interference aligned condition Pre-coding matrix；

It is assumed that all users and node are all full-duplex modes, all users send the signal after coding to relaying to step 3, with Shi Zhongji sends first time man made noise's signal；

Step 4, man made noise is broadcasted simultaneously to all users with the useful signal amplifying by relaying again；

Step 5, each user is receiving twice after signal, eliminates the sent man made noise's letter of relaying by linear combining Number, and suppress matrix to demodulate useful signal using the reception meeting certain restrictive condition, thus whole system obtains one Fixed traffic rate.

2. according to claim 1 a kind of based on do solid work disturb alignment mimo y eavesdrop network in safe transmission method, It is characterized in that, the concrete grammar of described step one is as follows:

Disturb alignment techniques using doing solid work, all of channel is real channel matrix, and assume user u_iIssue user u_jSignal Sending signal s_ijIt is taken from pam constellation c (a defined below_u,q_u), that is,

c(a_u,q_u)=a_u{-q_u,-q_u+1,...,q_u-1,q_u}

In formula:

q_uOne and number of users k and each user's transmit power p_iRelated on the occasion of, for δ ＞ 0,

a_uThe sending signal making each user meets the real number that transmit power limits, for γ ＞ 0,

In the above description, each user u_iThe signal s sending_i=[s_i1,s_i2,...,s_ik]^t∈r^(k-1)×1It is through precoding Matrix v_i∈r^m×(k-1)Signal x after coding_i∈r^m×1, that is,Therefore transmit power is limited toTherefore, q_uδ and a in expression formula_uγ in expression formula takes in the many class values meeting power limitation condition Any one group on the occasion of；

In mbwc mimo y model, relay sent interference noise b_i∈r^k(k-1)×1Comprise the individual symbol of k (k-1), it is taken from In another pam constellation c (a_r,q_r), that is,

c(a_r,q_r)=a_r{-q_r,-q_r+1,...,q_r-1,q_r}

In formula:

q_rOne to number of users k and relaying transmit power p related on the occasion of, for δ ＞ 0,

a_rSo that sending signal meets the real number of transmit power restriction at relaying, for γ ＞ 0,

Sending b_iNeed it is encoded, encoder matrix is t before_i∈r^n×k(k-1)；So, what relaying place sent is artificial Noise isIts sending signal Power Limitation is e [tr (zz^h)]≤βp；Therefore, q_rδ in expression formula with a_rγ in expression formula take in the many class values meeting power limitation condition any one group on the occasion of.

3. according to claim 1 a kind of based on do solid work disturb alignment mimo y eavesdrop network in safe transmission method, It is characterized in that, the concrete grammar of described step 2 is as follows:

In order to eliminate produced inter-user interference during k user intercommunication, and demodulate and come from other k-1 user's Signal, needs to design pre-coding matrix v in each user_i,Its by k-1 m × 1 tie up pre- Coding vector v_ijComposition, each precoding vector v_ijWill be to each signal s_jiCarry out linear predictive coding, i.e. v_ijs_ij；When When the dimension in the space that the n root antenna at relaying is opened is less than k (k-1) individual symbolic number, part signal can occur at relaying Aliasing, in order to avoid above-mentioned condition, using interference alignment techniques, when the antenna number of each node meetsm≥k-1, During 2m ＞ n, by all paired signal such as s_ijWith s_jiSnap in the same dimension of relaying, now, the individual useful letter of k (k-1) Number can be comprised in relayingIn dimension space, that is, need to meet equation:

$h_{u_{i}r}{v}_{ij}=h_{u_{j}r}{v}_{ji}=u_{i,j},i\&notequal;j,i,j=1,2,...k$

Wherein, what the vector of the same dimension after channel was equivalent is denoted as u_i,j,I=1,2 ..., k is user u_iTo relaying, it is relayed to user u_iReal channel matrix；Now, aliasing will not occur at relaying between each signal；

At relaying, in order to ensure to expect that legal signal can not be ravesdropping, as known gcsi, design artificial noise signal Pre-coding matrix t_iSo that its satisfactionI.e.

$t_i=h_{re}^h{h}_{u_{i}e}{v}_i$

Wherein,I=1,2 ..., k represent the real channel between eavesdropping end and user, between eavesdropping end and relaying respectively Matrix, g_iIt is the equivalent vector of the same dimension after tapping channel；Then encoded man made noise's signal is expressed as

4. according to claim 1 a kind of based on do solid work disturb alignment mimo y eavesdrop network in safe transmission method, It is characterized in that, the concrete grammar of described step 3 is as follows:

All users by encode after signal x_iBe sent to via node, then relay reception to signal be:

$y_r=\underset{i=1}{\overset{k}{\σ}}{h}_{u_{i}r}{x}_i+n_r$

In formula:

n_rLocal white Gaussian noise at relaying；

When all users are to relaying sending signal, the man made noise z for β p for the broadcasting power to user and eavesdrops end to relaying simultaneously, Now, the signal that user received in this stage is

$y_j^{\[1\]}=h_{{\mathrm{ru}}_j}z+n_j^{\[1\]},i=1,2,...,k$

In formula:

Artifact power's partition coefficient at β relaying.

User u_jIn the local white Gaussian noise in mac stage, noise variance is

5. according to claim 1 a kind of based on do solid work disturb alignment mimo y eavesdrop network in safe transmission method, It is characterized in that, the concrete grammar of described step 4 is as follows:

After relaying receives k (k-1) individual signal, it is amplified being transmitted to all users, forward signal is x_r=α y_r, wherein α For the amplification coefficient at relaying, the Power Limitation sending useful signal isMeanwhile, again Send and mac stage identical man made noise's signal, now, the receipt signal in this stage for each user is

$\begin{array}{c}{y}_j^{\[2\]}=h_{{\mathrm{ru}}_j}{x}_r+n_j^{\[2\]}\\ =h_{{\mathrm{ru}}_j}\[\mathrm{\α}(\underset{i=1}{\overset{k}{\σ}}{h}_{u_{i}r}{x}_i+n_r)+z\]+n_j^{\[2\]}\\ ={\mathrm{\αh}}_{{\mathrm{ru}}_j}\underset{i=1}{\overset{k}{\σ}}{h}_{u_{i}r}{x}_i+h_{{\mathrm{ru}}_j}z+\widetilde{\mathrm{\α}}{h}_{{\mathrm{ru}}_j}{n}_r+n_j^{\[2\]}\end{array}$

In formula:

User u_jIn the local white Gaussian noise in bc stage, noise variance is

6. according to claim 1 a kind of based on do solid work disturb alignment mimo y eavesdrop network in safe transmission method, It is characterized in that, the concrete grammar of described step 5 is as follows:

The first step, the signal twice that legitimate receipt end is received with eavesdropping end is weighted merging, and the signal after being merged is:

$y_j=y_j^{\[2\]}-y_j^{\[1\]}={\mathrm{\αh}}_{rj}\underset{i=1}{\overset{k}{\σ}}{h}_{ir}{x}_i+{\tilde{n}}_j$

Note:So, y_jIn do not comprise man made noise z, validated user will not be subject to man made noise's interference signal Impact；

After above-mentioned described interference alignment, by y_jAgain it is expressed as the stacking pattern of two groups of pair signals:

$\begin{array}{c}{y}_j={\mathrm{\αh}}_{{\mathrm{ru}}_j}{u}_r{s}_r+{\tilde{n}}_j\\ ={\mathrm{\αh}}_{{\mathrm{ru}}_j}({\tilde{u}}_j{\tilde{s}}_j+{\stackrel{\&overbar;}{u}}_j{\stackrel{\&overbar;}{s}}_j)+{\tilde{n}}_j\end{array}$

In formula:

Interference alignment matrix；

Dimension relaying pair signals,

For user u_j, signal that it receives is divided into two parts, required useful signalInterference signal with other users

Second step, designs the reception suppression matrix of each user；After carrying out spacing wave alignment, user u_jNeed to use further (k-1) × m dimension receives suppression matrix f_i=[f_1if_2i... f_i-1,if_i+1,i... f_ki]^tTo y_jCarry out disturbing ZF, just receive To useful signal, that is, need to use f_jPremultiplication is with y_j,

${\hat{y}}_j={\mathrm{\αf}}_j{h}_{{\mathrm{ru}}_j}({\tilde{u}}_j{\tilde{s}}_j+{\stackrel{\&overbar;}{u}}_j{\stackrel{\&overbar;}{s}}_j)+{\tilde{n}}_j={\mathrm{\αp}}_j{\tilde{u}}_j{\tilde{s}}_j+{\mathrm{\αp}}_j{\stackrel{\&overbar;}{u}}_j{\stackrel{\&overbar;}{s}}_j+{\tilde{n}}_j\·$

In formula:

(k-1) × n dimension equivalent received suppression matrix；

Equivalent received suppresses matrix p_jSelection principle be

$p_j\⊂null\left\{{\stackrel{\&overbar;}{u}}_j\right\}$

$p_j\&notsubset;null\left\{{\tilde{u}}_j\right\}$

Wherein, the kernel of null { a } representing matrix a；Upper two formulas represent p_jIt is taken fromKernel, and p_jDo not exist's In kernel；

In order to choose the matrix p meeting mentioned above principle_jIt is necessary first to clearly such matrix whether there is；Assume each legitimate node Known csi, above formula is equivalent toIn order to meet this condition, the antenna number at relaying must is fulfilled forAnd this condition is already contained in the feasibility condition of interference alignment, that is,Cause This, necessarily set up when meeting interference aligned condition；In order to ensure existing,Represent ?There is a n × n- (k-1) in matrix and tie up kernel, be designated as q；Assume that q is by a series of n × 1 rank null vector q institutes group Become, that is,p_jIt is written as the form of column vector, p_j=[p_j,1p_j,2... p_j,k-1]；Now, and if only if has matrix A is so as to meet a=[p_j,1p_j,2... p_j,k-1q_j], during rank (a)=k, this means that selected p_jIt is independently of zero Space, that is,In sum, the reception suppression matrix p at user_jOr f_jAlways exist；

So, under any circumstance, all choose qualified reception and suppress matrix, then eliminated by self-interference, user u_jDemodulation Go out the signal receiving, that is,

${\hat{y}}_j={\mathrm{\αp}}_j{\tilde{u}}_j{s}_j+{\tilde{n}}_j$

In formula:

User u_jLegitimate receipt signal；

User u_jLegal signal pre-coding matrix；

3rd step: using Maximum Likelihood Detection scheme detection signal；

In user u_jPlace, estimated signal is denoted asWhen known receipt signalWhen, obtained using maximum likelihood detection method Go out to estimate signal,

${\hat{s}}_j=\underset{s_j\&element;\mathrm{\χ}}{\mathrm{argmin}}\left|\right|{\hat{y}}_j-{\mathrm{\αp}}_j{\tilde{u}}_j{\hat{s}}_j|{|}^2$

Wherein,

χ is s_jThe set being taken, has (2q_u+1)^k-1Kind；

argmin||a||²The minima of two norms of matrix a.