CN106330382A - Safe transmission method based on multipath fading frequency selection characteristics in wireless network - Google Patents

Abstract

The invention relates to a safe transmission method based on multipath fading frequency selection characteristics in a wireless network. Firstly, an emission node generates artificial noise based on signal channel state information by using the signal channel information of a multipath fading frequency selection characteristic signal channel and others; the emission node performs up-sampling on a confidential signal vector to be transmitted, and fills the generated artificial noise to form a mixed emission signal; a target receiving node completes the receiving of the mixed emission signal, performs the matching filtering and down-sampling treatment, and outputs the confidential signal; above steps are repeated, and the safe transmission based on multipath fading frequency selection characteristics in the wireless network is completed. The artificial noise is generated on the basis of the signal channel information of a main signal channel; after the main signal channel transmission and the matching filtering treatment, the output at the sampling judge output moment is 0; after transmission of an eavesdroping signal channel and the same matching filtering treatment at the eavesdropping node, the output at the sampling judge moment is not 0; thus the eavesdroping signal channel is degraded, and the safe transmission is guaranteed.

Description

Safe transmission method based on multipath fading frequency selective characteristic in wireless network

[technical field]

The present invention relates to the safe transmission field in wireless network, particularly relate in wireless network based on multipath fading frequency The safe transmission method of selectivity characteristic.

[background technology]

Due to wireless channel vulnerability, secure wireless communication has become a hot research problem.In the past ten Nian Li, safety of physical layer based on theory of information concept and signal processing has attracted the huge interest of people.The safety of physical layer passes Transmission method is a key character of radio communication, because safe transmission method of physical layer application is information-theoretical safety reason Opinion rather than the encryption method of dependence higher.Higher-layer encryption method is largely dependent upon and calculates intensity about mathematical problem Hypothesis.But, the opening of wireless medium and the lifting of computing capability make radio communication seem the most crisp in face of eavesdropping Weak.

Shannon proposes the concept of perfect confidentiality in the literature, and a perfect password is only when password and pure literary composition Perfect confidentiality could be realized the when that this information being the longest.Therefore based on such it is assumed that all of use cryptogram form Cipher mode can be cracked in theory.

Wayner proposes the concept of tapping channel, it is achieved that almost ideal confidentiality.Main channel (believe by legitimate receiver Road) assume it is discrete memoryless channel(DMC), and tapping channel (listener-in's channel) assumes it is the degeneration version of main channel.Later carries If going out main channel and tapping channel being all additive white Gaussian noise channel (AWGN), secrecy capacity is exactly legitimate channel and eavesdropping Channel is in the difference of channel capacity.So far, safety of physical layer problem is studied on a large scale, to improve the guarantor of wireless medium Close capacity.Including: the secure communication under Gaussian broadcast channel, SISO fading channel secure communication.Low-density parity check code The problem being proposed for tapping channel in the literature.But, in these schemes, great majority are all based on some unpractical vacations If: such as listener-in's channel ratio legitimate channel is further worsened, or listener-in does not knows main channel.Negi and Goel in the literature Propose man made noise's concept for mimo system.The target of man made noise's householder method is to be guaranteed by generation interference signal Secure communication, this interference signal can be degenerated listener-in's channel and be had little to no effect intended recipient's channel.

Man made noise's householder method has obtained substantial amounts of concern, because not having in the method for MIMO/MISO system Make any unrealistic assumption.A transmitter distribution part in the power of signal transmission is used for producing interference signal, This interference signal can be degenerated listener-in's channel.

But, in reality there is the substantial amounts of simple network node not possessing multiple antennas or configuration complex protocol in people, as What realizes the safe transmission between these single antenna network nodes, is a problem demanding prompt solution.By man made noise's householder method Inspiration, Yang and Jiao improves man made noise's householder method SISO system under multidiameter fading channel.They propose If bolter knows the channel condition information CSI of legitimate receiver, bolter just can produce one can reduce legitimate receiver The signal of place's intersymbol interference (ISI), and this signal form with random noise at listener-in presents.But, if eavesdropping Person is it is also known that the CSI of main channel, and the program is the most no longer valid.

[summary of the invention]

It is an object of the invention to overcome defect present in prior art, it is provided that based on multipath fading frequency in wireless network The safe transmission method of rate selectivity characteristic, for single-input single-output (SISO) Radio Network System, the inventive method be based on Multipath fading frequency selective characteristic, confidentiality independent of the safe transmission method of the confidentiality of channel condition information (CSI), with Solve existing radio physical layer secure transmission technique and cannot be directly applied for single-input single-output (SISO) Radio Network System, or The confidentiality that person realizes cannot be independent of the problem of the confidentiality of the status information (CSI) of channel.

For reaching object above, the present invention adopts the following technical scheme that and is achieved: comprise the following steps:

Step 1, transmitting node calculates the multipath fading frequency selective characteristic channel between itself and purpose receiving node Channel information h_AB, and obtain the sequence information q of the matched filtering device of discrete time K tap number at purpose receiving node, and Sampling judgement makes policy information: the sampling number R of each information-carrying symbols_s, and utilize h_AB, q and R_sGenerate based on channel status The man made noise w of information；

Step 2, frame secret signal waiting for transmission vector is carried out increasing sampling by transmitting node, obtains increasing sampled signal s, Increase the man made noise w that in sampled signal, implantation step 1 generates and form mixing transmitting signal x；

Step 3, purpose receiving node completes to launch mixing the reception of signal, and carries out matched filtering process, filtered Ripple signal z_AB；

Step 4, purpose receiving node is to filtering signal z_ABCarry out subtracting sampling processing, export secret signal；

Step 5: repetition step 1, to step 4, completes safety based on multipath fading frequency selective characteristic in wireless network and passes Defeated.

Further, transmitting node and purpose receiving node are single antenna node.

Further, in step 1, the channel information h of multipath fading frequency selective characteristic channel_AB=[h₀,h₁,…,h_L], Its matrix form is H_AB；Sequence information q=[q₀,q₁,…,q_K]^T, its matrix form is Q；R_sMatrix form be S；Wherein:

Wherein, L represents the multipath number of multipath fading frequency selective characteristic channel；K represents discrete time matched filtering device Tap number；M × the R of matrix S_s+ 1 row diagonal entry is 1, and remaining element is all 0, m=0,1 ..., M, M are waiting for transmission The number of information-carrying symbols in secret signal vector.

Further, in step 1, the generation of man made noise w specifically includes: utilize h_AB, q and R_sBuild channel information matrix Γ_AB=SQH_AB, and design that safe transmission used be positioned at channel information matrix Γ_ABThe man made noise vector w=of kernel Zu, wherein Z is channel information matrix Γ_ABThe orthonormal basis of kernel, u is that independent identically distributed multiple Gaussian random variable is vowed Amount, the average of each of vector multiple gaussian variable element is 0, and variance is

Further, step 2 specifically includes: the secret signal that a frame is made up of by transmitting node M information-carrying symbols VectorIncrease sampling, obtain the increasing sampled signal s=[s of N-dimensional₁,s₂,…,s_N]^T, wherein have N=MR_s, R_s For the sampling number of every symbol, and inject the N-dimensional man made noise vector w=[w generated by w=Zu in step 1₁,w₂,…,w_N]^T, Generate mixing and launch signal x=s+w.

Further, it is y that signal is launched in the mixing that in step 3, purpose receiving node receives_AB=h_AB*x+v_B, wherein v_B For the purpose of additive white Gaussian noise at receiving node；Matched filtering processes the filtering signal z of postfilter output_AB=q*y_AB。

Further, step 4 specifically includes, and purpose receiving node is to filtering signal z_ABCarrying out subtracting sampling, sampling judgement is defeated Go out forWherein Γ_ABIt is to utilize h_AB, q and R_sThe channel information matrix built,It is that single antenna purpose receives This white noise component of band limit for height of node sample outfan.

Compared with safety of physical layer transmission plan existing with prior art, it is an advantage of the current invention that:

1, the present invention is on safe transmission conceptual design, it is considered to and utilize the frequency selective characteristic that radio channel multi-path declines Information design a kind of judgement moment of sampling at purpose receiving node is the man made noise of 0, and the man made noise's scrambling that will generate To secret signal waiting for transmission to form noise signal；Purpose receiving node completes the reception launching signal, and reception is believed Number carry out matched filtering, subtract sampling judgement, finally export the secret signal of prosthetic influence of noise；Due to man made noise be based on The channel information of main channel generates, in sampling judgement output time output after processing through main channel transmission and matched filtering It is 0, and in sampling judgement moment output after the transmission and same matched filtering process of tapping channel at eavesdropping node It is not 0, deteriorates listener-in's channel, it is ensured that safe transmission；

2, on applicable situation, it is adaptable in reality, a large amount of existence does not configures multiple antennas or complex protocol simple nothing Line network node composition single-input single-output (SISO) communication system, the hardware required by wireless security transmission plan of the present invention sets Standby simple；

3, on security information safe transmission ensures, the present invention is merely with having arrived transmitting node between purpose receiving node Channel condition information (CSI), it is not necessary to carry out between the two parties complexity work in coordination with, feed back or share etc. operation, the resource of system Consuming low, efficiency of transmission is high；

4, in the independence of safe transmission confidentiality, although the present invention make use of transmitting node to the letter between destination node Channel state information (CSI), but the confidentiality of safety approach is independent of the confidentiality of channel condition information (CSI), effectively increases The strong safety of this safe transmission scheme.

[accompanying drawing explanation]

Fig. 1 (a) is the transmission system model of the present invention.Figure interior joint Alice is single-antenna transmission node, and node Bob is Single antenna purpose receiving node, node Eve is single antenna passive wiretapping node.

Fig. 1 (b) is the flow chart of the present invention.

Fig. 2 is the receiving node under different artifact power and the bit error rate comparison diagram of eavesdropping node.

Fig. 3 is wireless channel difference multipath number (L), the receiving node under L >=2 and the bit error rate comparison diagram eavesdropping node.

Fig. 4 is the different single antenna purpose receiving node increased under sampling rate (hits/every symbol) and eavesdropping node Bit error rate comparison diagram.

[detailed description of the invention]

Below in conjunction with the drawings and the specific embodiments, the present invention is described in further detail.

The present invention is safe transmission method based on multipath fading frequency selective characteristic in wireless network, including following step Rapid:

First, single-antenna transmission node estimates the frequency of wireless channel between itself and legal single antenna purpose receiving node Selectivity characteristic information, and utilize the design of these channel informations to generate man made noise based on channel condition information；

Then, single-antenna transmission node one frame secret signal waiting for transmission vector is carried out increase sampling obtain and inject above-mentioned The man made noise generated forms mixing and launches signal；

Secondly, single antenna purpose receiving node completes to launch mixing the reception of signal；

Finally, single antenna purpose receiving node carries out matched filtering, subtracts the process such as sampling the mixed signal received, and is adopting Sample outfan exports secret signal accurately.

Hereinafter the single antenna purpose receiving node Bob and eavesdropping node Eve of the present invention is received transmitting node Alice respectively The signal sent illustrates, and sees transmission system model and Fig. 1 (b) shown in Fig. 1 (a), and concrete steps include:

Step 1, before Secret Information Transmission is opened, single-antenna transmission node Alice first passes through error-free channel Feedback information calculates its channel letter arriving the multipath fading frequency selective characteristic channel between single antenna purpose receiving node Bob Breath h_AB=[h₀,h₁,…,h_L], its matrix form H_AB,L represents that multipath declines Fall the multipath number of frequency selective characteristic channel；The coupling of the discrete time K tap number at acquisition single antenna purpose receiving node Bob Sequence information q=[the q of wave filter₀,q₁,…,q_K]^T, its matrix form Q,K Represent the tap number of discrete time matched filtering device；And sampling judgement makes policy information: the sampled point of each information-carrying symbols Number R_s, its matrix form S,M × the R of matrix S_s+ 1 row diagonal entry is 1, Remaining element is all 0, m=0, and 1 ..., M, M are the number of information-carrying symbols in secret signal vector waiting for transmission；Utilize this A little channel informations build channel information matrix Γ_AB=SQH_AB, and design that safe transmission used be positioned at channel information matrix Γ_ABThe man made noise vector w=Zu of kernel, wherein Z is channel information matrix Γ_ABThe orthonormal basis of kernel, u is Independent identically distributed multiple Gaussian random variable vector, the average of each of vector multiple gaussian variable element is 0, and variance is Thus have Γ_ABW=0；Γ in each frame information transmits_ABWith channel fading information H_ABChange, the man made noise w also phase of generation Should change；

Step 2, after primary signal is modulated into the secret signal vector being made up of M information-carrying symbols, single antenna is sent out Penetrate node Alice at pulse shaping filter outfan by a frame modulated secret signal vectorIncrease It is sampled as N-dimensional dope vector s=[s₁,s₂,…,s_N]^T, wherein have N=MR_s, R_sFor the sampling number of each information-carrying symbols, Inject the N-dimensional man made noise vector w=[w generated by w=Zu in step 1 afterwards₁,w₂,…,w_N]^T, generate mixing for transmission Close and launch signal phasor x=s+w, and perform the preparation before signal is launched；

Step 3, single antenna purpose receiving node Bob and eavesdropping node Eve are respectively completed and send transmitting node Alice The reception of signal is launched in mixing: the signal that single antenna purpose receiving node Bob receives is y_AB=h_AB*x+v_B, write as convolution shape Formula is: each item receiving mixed signal isCorresponding matrix form is y_AB= H_ABx+v_B, wherein h_AB(matrix form H_AB) it is the channel letter of multipath fading frequency selective characteristic channel between Alice to Bob Breath, v_BFor receiving the additive white Gaussian noise at some Bob；Accordingly, the signal received at eavesdropping node Eve is y_AE=h_AE*x +v_E, being write as convolution form is: each item receiving mixed signal isCorresponding square Formation formula is y_AE=H_AEx+v_E, wherein h_AE(matrix form H_AE) it is the multipath fading frequency selective characteristic letter between Alice to Eve The channel information in road, v_EFor the additive white Gaussian noise at eavesdropping point Eve；

The signal received is done matched filtering by step 4, single antenna purpose receiving node Bob and eavesdropping node Eve respectively Processing, wave filter is output as z=q*y, single antenna purpose receiving node and eavesdropping node and is respectively z_AB=q*y_AB,z_AE=q*y_AE, Convolution form is respectivelyCorresponding matrix form is z_AB=Q [H_ABx+v_B], z_AE=Q [H_AEx+v_E], wherein q=[q₀,q₁,…,q_k]^T(matrix form Q) represents discrete time K The sequence information of the matched filtering device of tap number, it is assumed that legal single antenna purpose receiving node Bob and eavesdropping node Eve adopts With identical matched filtering device；

Step 5, single antenna purpose receiving node Bob and eavesdropping node Eve respectively matched filtering device outfan to The output result joining wave filter carries out subtracting sampling, and sampling judgement is output asSingle antenna purpose Receiving node and eavesdropping node are respectively Corresponding matrix form:

$z_{s,b}=SQ\[H_{AB}x+v_{AB}\]={\mathrm{\Γ}}_{AB}x+{\tilde{v}}_b={\mathrm{\Γ}}_{AB}s+{\tilde{v}}_b,$

$z_{s,e}=SQ\[H_{AE}x+v_{AE}\]={\mathrm{\Γ}}_{AE}x+{\tilde{v}}_e={\mathrm{\Γ}}_{AE}s+{\mathrm{\Γ}}_{AE}w+{\tilde{v}}_e,$

Wherein z [i] is the i-th symbol of the wave filter output vector z in step 4, and δ is unit impulse function, [i-mR_s] Variable for δ；Parameter R_sIdentical with each information-carrying symbols sampling number in step 2, z_s[i] vows for sampling output result Amount z_sI-th symbol；I.e. z_AB[i] is filtering signal z_ABI-th symbol, z_s,B[i] is sampling judgement output result z_s,B's I-th symbol.It is this white noise component of band limit for height of single antenna purpose receiving node sampled output,It is that eavesdropping node is adopted This white noise component of band limit for height of sample outfan；Receiver sampling judgement after to output signalComplete all Weighing apparatus, demodulation etc. process, and carry out Maximum Likelihood Detection judgement obtain secret signalSo far, a frame is completed The transmission of security information；

Step 6, when proceeding to the transmission stage of next frame secret signal, the automatic repeat the above steps of system 1 to step 5 In safe transmission step.

In above-mentioned steps 5, at legal single antenna purpose receiving node Bob, the signal of detection judgement input isUtilize the methods such as Maximum Likelihood Detection, it is possible to from z_s,bIn estimate secret signal exactlyAnd on the other hand, owing to transmitting node Alice is to the channel information matrix H of eavesdropping node Eve_AEWith Minor channel information matrix H_ABDifference, cause Γ_AEW ≠ 0, is rendered as interference noise form at eavesdropping node receiving terminal, thus moves back Change tapping channel, made listener-in cannot correctly estimate security informationCause the significantly increasing of the bit error rate Add.

As a example by the wireless communication system of 16-QAM modulation system, Fig. 2,3,4 respectively describe legal under different scene connecing Receipts person and the bit error rate (BER) comparison diagram of listener-in, quantitatively illustrate present invention single-input single-output in ensureing wireless network (SISO) system carries out effect of safe transmission.

Fig. 2 is the curve comparison figure of the bit error rate (BER) of legitimate receiver and listener-in under different artifact power.Examine Considering and control to transmitter power in actual scene, artifact power is from 0.1 × E_sChange to E_s, i.e. 0.1 times modulated signal Power to 1 times modulated signal power.It can be seen that the bit error rate of listener-in Eve trends towards increasing with the power increase of man made noise Add, and the bit error rate of legitimate receiver Bob is not affected by artifact power and keeps constant.These bit error rate results be Bob with Eve is in and obtains under the conditions of a certain identical average signal-to-noise ratio (signal power/white Gaussian noise), be respectively 18dB, 22dB and 26dB.

Fig. 3 is legitimate receiver and the ber curve comparison diagram of listener-in under different multipath number (L).It can be seen that recognized The multipath fading frequency selective characteristic in source of the disaster for being communication system can be used as radio communication provides safety.Solid line Being the ber curve of legitimate receiver Bob, dotted line is the ber curve of listener-in Eve.Bit error rate result be at Bob and Eve obtains under the conditions of being in same average signal-to-noise ratio, and in this example, average signal is made an uproar than selecting is 26dB, the merit of man made noise Rate is from 0.1 × E equally_sChange to E_s。

Fig. 4 is legitimate receiver and the mistake of listener-in under the hits that at transmitting terminal pulse shaping filter, every symbol is different Rate curve comparison diagram.It can be seen that the bit error rate of listener-in Eve rises along with the increase of hits/every symbol, and legal The bit error rate receiving Bob keeps constant.But, there is one to trade off between system secrecy performance and complexity.System security Energy and system complexity all rely on the hits of every symbol, need the most between to select an optimal equilibrium point. In figure, the result of the bit error rate obtains under the conditions of Bob and Eve is in same signal to noise ratio, in this example average signal make an uproar ratio select be 26dB, that artifact power selects simultaneously is 0.5 × E_s。

The present invention is directed to single-input single-output (SISO) Radio Network System, propose a kind of based on the selection of multipath fading frequency Characteristic, confidentiality are independent of the safe transmission method of the confidentiality of channel condition information (CSI), to solve existing radio physical Layer secure transmission technique cannot be directly applied for single-input single-output (SISO) Radio Network System, or the confidentiality realized without Method is independent of the problem of the confidentiality of the status information (CSI) of channel.

In the present invention, single-antenna transmission node utilizes the multipath fading frequency selective characteristic information of main channel, design one to exist At legal single antenna purpose receiving node, the sampling judgement moment is the man made noise of 0, and the man made noise of generation is scrambled and treat The secret signal of transmission is to form noise signal；Single antenna purpose receiving node completes the reception launching signal, and will receive Signal carries out matched filtering, subtracts sampling judgement, finally exports the secret signal of prosthetic influence of noise.Owing to man made noise is base Channel information in main channel generates, defeated at sampling judgement output time after processing through main channel transmission and matched filtering Go out is 0.And it is defeated in the sampling judgement moment after the transmission and same matched filtering process of tapping channel at eavesdropping node Going out not is 0, deteriorates listener-in's channel.Thus the single-input single-output (SISO) under final effective guarantee multidiameter fading channel The safe transmission of system.

Claims (7)

1. safe transmission method based on multipath fading frequency selective characteristic in a wireless network, it is characterised in that include with Lower step:

Step 1, transmitting node calculates the channel of the multipath fading frequency selective characteristic channel between itself and purpose receiving node Information h_AB, and obtain the sequence information q of the matched filtering device of discrete time K tap number at purpose receiving node, and sampling Judgement makes policy information: the sampling number R of each information-carrying symbols_s, and utilize h_AB, q and R_sGenerate based on channel condition information Man made noise w；

Step 2, frame secret signal waiting for transmission vector is carried out increasing sampling by transmitting node, obtains increasing sampled signal s, adopts in increasing The man made noise w that in sample signal, implantation step 1 generates forms mixing and launches signal x；

Step 3, purpose receiving node completes to launch mixing the reception of signal, and carries out matched filtering process, obtains filtering letter Number z_AB；

Step 4, purpose receiving node is to filtering signal z_ABCarry out subtracting sampling processing, export secret signal；

Step 5: repetition step 1, to step 4, completes safe transmission based on multipath fading frequency selective characteristic in wireless network.

Safe transmission side based on multipath fading frequency selective characteristic in a kind of wireless network the most according to claim 1 Method, it is characterised in that transmitting node and purpose receiving node are single antenna node.

Safe transmission side based on multipath fading frequency selective characteristic in a kind of wireless network the most according to claim 1 Method, it is characterised in that in step 1, the channel information h of multipath fading frequency selective characteristic channel_AB=[h₀,h₁,...,h_L], its Matrix form is H_AB；Sequence information q=[q₀,q₁,...,q_K]^T, its matrix form is Q；R_sMatrix form be S；Wherein:

Wherein, L represents the multipath number of multipath fading frequency selective characteristic channel；K represents the tap of discrete time matched filtering device Number；M × the R of matrix S_s+ 1 row diagonal entry is 1, and remaining element is all 0, m=0,1 ..., M, M are secrecy waiting for transmission The number of information-carrying symbols in signal phasor.

Safe transmission side based on multipath fading frequency selective characteristic in a kind of wireless network the most according to claim 3 Method, it is characterised in that in step 1, the generation of man made noise w specifically includes: utilize h_AB, q and R_sBuild channel information matrix Γ_AB =SQH_AB, and design that safe transmission used be positioned at channel information matrix Γ_ABThe man made noise vector w=Zu of kernel, Wherein Z is channel information matrix Γ_ABThe orthonormal basis of kernel, u is independent identically distributed multiple Gaussian random variable vector, The average of each of vector multiple gaussian variable element is 0, and variance is

Safe transmission side based on multipath fading frequency selective characteristic in a kind of wireless network the most according to claim 1 Method, it is characterised in that step 2 specifically includes: the secret signal vector that a frame is made up of by transmitting node M information-carrying symbolsIncrease sampling, obtain the increasing sampled signal of N-dimensionalWherein there is N=MR_s, R_sFor often according with Number sampling number, and inject by step 1 w=Zu generate N-dimensional man made noise vector w=[w₁,w₂,…,w_N]^T, generate mixed Close and launch signal x=s+w.

Safe transmission side based on multipath fading frequency selective characteristic in a kind of wireless network the most according to claim 1 Method, it is characterised in that it is y that signal is launched in the mixing that in step 3, purpose receiving node receives_AB=h_AB*x+v_B, wherein v_BFor mesh Receiving node at additive white Gaussian noise；Matched filtering processes the filtering signal z of postfilter output_AB=q*y_AB。

Safe transmission side based on multipath fading frequency selective characteristic in a kind of wireless network the most according to claim 1 Method, it is characterised in that step 4 specifically includes, purpose receiving node is to filtering signal z_ABCarrying out subtracting sampling, sampling judgement is output asWherein Γ_ABIt is to utilize h_AB, q and R_sThe channel information matrix built,It it is single antenna purpose receiving node This white noise component of band limit for height of sampled output.