CN101834815A - Method for resisting interception and inference for signals based on quadrinomial weighted fractional Fourier transform of multiple-path variable parameters - Google Patents

Abstract

The invention discloses a method for resisting interception and inference for signals based on quadrinomial weighted fractional Fourier transform of multiple-path variable parameters, relating to the communication technical field and solving the problems of poor interception resistance and poor interference resistance in the existing transmission resistance process of communication signals. The method comprises the following steps: at a transmitting end: digital signals are modulated by a baseband and then are subjected to spread spectrum encoding and quadrinomial weighted fractional Fourier transform under the control of a dynamic encryption parameter alphai and a dynamic encryption vector Vi, and encryption data synthesized by signals in multiple paths are subjected to digital carrier modulation and then are sent to a channel to transmit after D/A conversion and up-conversion; and at a receiving end: the data after down-conversion and A/D sampling is subjected to digital carrier coherent modulation, is decomposed by the signals in multiple paths, is subjected to quadrinomial weighted fractional Fourier transform for m times under the control of the dynamic encryption parameter alphai and dynamic encryption vector Vi, and is modulated by the baseband. The method is suitable for occasions of communication signal transmission.

Description

Intercept and capture and anti-interference method based on the signal of the four-item weight score Fourier conversion of multichannel variable element is anti-

Technical field

The present invention relates to communication technical field, be specifically related to anti-intercepting and capturing of a kind of signal of communication and anti-interference method.

Background technology

Current society, information has become the important wealth of society, and maintaining secrecy of information more and more is subject to people's attention.The purpose of secure communication is in the face of the assailant, guarantees the safety of communicating by letter when the dangerous channel of application communicates between communicating pair.In the process of secure communication, the two communication informations of not wishing or not allowing one's own side to send of sending out of communication are intercepted and captured by other party, and communication is divulged a secret, the disturbed even danger that destroyed otherwise just have.As content important in the modern secure communication, the anti-intercepting and capturing character of information has caused people's extensive attention.

(Fractional Fourier Transform is a kind of important time frequency analyzing tool FRFT) to fractional Fourier transform, has obtained comparatively extensive studies in the last few years, and has been used in some field of engineering technology.FRFT is the popularization to traditional F ourier conversion, and its essential characteristics can be understood as the fractionation to Fourier transform characteristics value.The continuity of parameter value, rotation additivity and be the fundamental property of FRFT to the uniformity of signal time-frequency form.Owing to, and, make FRFT have various definition form to the wide in range property that FRFT character retrains to the difference of characteristic value fractionation mode.According to these definition starting point and essential characteristic separately, can roughly it be divided into two classes, that is: classical class FRFT and weighting class FRFT.

(Weighted FRFT is to be proposed first in nineteen ninety-five by C.C.Shih WFRFT) to weighting class fractional Fourier transform.After this, multinomial and multi-parameter WFRFT successively is suggested again.According to existing theory, the WFRFT definition can be generalized to the WFRFT of discrete series continuously.The four-item weight score Fourier conversion (4-WFRFT) of discrete series is defined as follows after promoting:

Wherein

$w_l(\mathrm{\α},m_k,n_k)=\frac{1}{4}\underset{k=0}{\overset{3}{\mathrm{\Σ}}}\exp \{\±\frac{2\mathrm{\πi}}{4}[(4m_k+1)\mathrm{\α}(k+4n_k)-\mathrm{lk}\left]\right\},l=\mathrm{0,1,2,3}$

Be by α, MV=[m ₀, m ₁, m ₂, m ₃] and NV=[n ₀, n ₁, n ₂, n ₃] wait the common weight coefficient form of controlling of 9 parameters, wherein α is a real number, MV and NV are real vector; N counts for the DFT conversion; N is the sequential element sequence number, and is identical with the implication of n among the DFT and k.Make V=[MV, NV].X (n) and x (n) be discrete Fourier transform (DFT) (DFT) to (through substitution of variable n=k), DFT adopts following formal definition:

$\left\{\begin{array}{c}X\left(k\right)=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H201010301259120100205E000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{X}\mathrm{kn}}\\ x\left(n\right)=\frac{1}{\sqrt{N}}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}X\left(k\right){\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="H201010301259120100205E000021.png"\; state="\{\{state\}\}">e</figure-callout>}}^j\end{array}\right.$

Adopt the digital communication system of 4-WFRFT technology, its transmission information has class Gauss's feature, thereby has the anti-characteristic of intercepting and capturing of certain communication.

Summary of the invention

The present invention is in order to overcome the anti-intercepting and capturing poor performance in the anti-transmission course of existing communication signal, the problem of interference free performance difference, thereby a kind of anti-intercepting and capturing and anti-interference method of signal of the four-item weight score Fourier conversion based on the multichannel variable element is provided.

Intercept and capture and anti-interference method based on the signal of the four-item weight score Fourier conversion of multichannel variable element is anti-, it since following steps realize:

Transmitting terminal:

Step 1, the digital signal that data source is sent are carried out the digital baseband modulation, obtain the signal after the modulation;

Signal after step 2, the modulation that step 1 is obtained carries out m times of spread spectrum coding, obtains the signal behind the spread spectrum coding of m road;

Every road signal in the signal behind step 3, the m road spread spectrum coding that step 2 is obtained carries out four-item weight score Fourier conversion respectively, obtain the signal after the m road conversion, wherein to carry out the dynamic encryption parameter of four-item weight score Fourier conversion be α to i road signal _i, the dynamic encryption vector is V _i

Signal after step 4, the m road conversion that step 3 is obtained synthesizes, and obtains the signal after synthetic;

Step 5, with step 4 obtain synthetic after signal carry out the digital carrier modulation, obtain the signal after the modulation;

Signal after step 6, the modulation that step 5 is obtained carries out D/A conversion and filtering, obtains filtered signal;

Step 7, the filtered signal that step 6 is obtained carry out sending by channel after the upconversion process;

Receiving terminal:

Step 8, the signal that receives is carried out down-converted, obtain the signal after the down-converted;

Signal after step 9, the down-converted that step 8 is obtained carries out filtering and A/D conversion, obtains the signal after the conversion;

Signal after step 10, the conversion that step 9 is obtained carries out the digital carrier demodulation, obtains the signal after the demodulation;

Signal after step 11, the demodulation that step 10 is obtained is decomposed into m road signal, and every road signal is carried out four-item weight score Fourier conversion respectively, obtains the m road signal after the conversion; Wherein the signal dynamic encryption parameter of carrying out four-item weight score Fourier conversion in i road is-α _i, the dynamic encryption vector is V _i

Signal spread-spectrum decoding back, m road after step 12, the conversion that step 11 is obtained obtains the signal after the decoding;

Signal after step 13, the decoding that step 12 is obtained carries out the digital baseband signal demodulation, obtains result after the demodulation;

Described i=1,2 ... m;

M is a positive integer.

The parameter alpha of dynamic encryption described in the step 3 _iEstablishing method be: by clock source control pseudo-code generator output pseudo noise code, described pseudo noise code and predefined dynamic encryption parameter changing pattern are united, obtain concrete dynamic encryption parameter value.

The present invention is by carrying out repeatedly different parameters four-item weight score Fourier conversion simultaneously to same group of data, and repeatedly transformation results with staggered form output.And control the dynamic change of encryption parameter by pseudo random sequence, make the rule of conversion of encryption parameter present pseudo-random characteristics; Simultaneously, same data block adopted respectively behind the different encryption parameter parallel encryptions carry out serial transmission after synthetic, make and in long-time observation, have more noisy characteristics through the signal after the four-item weight score Fourier transform, can effectively resist at random and bursty interference, improve the anti-intercepting and capturing performance and the interference free performance of communication information transmission significantly.

Description of drawings

Fig. 1 is a signal processing flow schematic diagram of the present invention; Fig. 2 is that the dynamic encryption parameter in the specific embodiment of the invention one changes tactful schematic diagram; Fig. 3 is the synthetic schematic diagram of multiple signals in the embodiment one.

Embodiment

Embodiment one, this embodiment is described in conjunction with Fig. 1, based on anti-the intercepting and capturing and anti-interference method of signal of the four-item weight score Fourier conversion of multichannel variable element, it since following steps realize:

Transmitting terminal:

Step 1, the digital signal that data source is sent are carried out the digital baseband modulation, obtain the signal after the modulation;

Signal after step 2, the modulation that step 1 is obtained carries out m times of spread spectrum coding, obtains the signal behind the spread spectrum coding of m road;

Every road signal in the signal behind step 3, the m road spread spectrum coding that step 2 is obtained carries out four-item weight score Fourier conversion respectively, obtain the signal after the m road conversion, wherein to carry out the dynamic encryption parameter of four-item weight score Fourier conversion be α to i road signal _i, the dynamic encryption vector is V _i

Signal after step 4, the m road conversion that step 3 is obtained synthesizes, and obtains the signal after synthetic;

Step 5, with step 4 obtain synthetic after signal carry out the digital carrier modulation, obtain the signal after the modulation;

Signal after step 6, the modulation that step 5 is obtained carries out D/A conversion and filtering, obtains filtered signal;

Step 7, the filtered signal that step 6 is obtained carry out sending by channel after the upconversion process;

Receiving terminal:

Step 8, the signal that receives is carried out down-converted, obtain the signal after the down-converted;

Signal after step 9, the down-converted that step 8 is obtained carries out filtering and A/D conversion, obtains the signal after the conversion;

Signal after step 10, the conversion that step 9 is obtained carries out the digital carrier demodulation, obtains the signal after the demodulation;

Signal after step 11, the demodulation that step 10 is obtained is decomposed into m road signal, and every road signal is carried out four-item weight score Fourier conversion respectively, obtains the m road signal after the conversion; Wherein the signal dynamic encryption parameter of carrying out four-item weight score Fourier conversion in i road is-α _i, the dynamic encryption vector is V _i

Signal spread-spectrum decoding back, m road after step 12, the conversion that step 11 is obtained obtains the signal after the decoding;

Signal after step 13, the decoding that step 12 is obtained carries out the digital baseband signal demodulation, obtains result after the demodulation;

Described i=1,2 ... m;

M is a positive integer.

The parameter alpha of dynamic encryption described in the step 3 _iEstablishing method be: by clock source control pseudo-code generator output pseudo noise code, described pseudo noise code and predefined dynamic encryption parameter changing pattern are united, obtain concrete dynamic encryption parameter value.

The signal processing flow of present embodiment: the binary data information that data source provides is carried out spread spectrum coding after the digital baseband modulation, and the length of data block is increased to original m doubly behind the process spread spectrum coding; Encrypting module receives Data Dynamic encryption parameter α _i, the dynamic encryption vector V _i(i=1,2,3 ... m) carry out the four-item weight score Fourier transform under the control; The data encrypted signal synthesizes, and employing is read in, by capable mode of reading data handled by row; Again through sending into channel after digital carrier modulation, A/D conversion, filtering, the upconversion process.Signal decomposition is opposite with the front with spread spectrum decoding part.The multichannel composition principle figure of signal as shown in Figure 3.

Fig. 2 is that a kind of dynamic encryption parameter of the present invention changes tactful schematic diagram, the complete period B of parameter alpha _α=4 have been divided into 16 groups 32 parts, and wherein same group two parts at a distance of 2, correspond respectively to pseudo noise code and be 0 and the interval of 1 o'clock output parameter.B _FBe the size between each group parameter region, the parameter protection scope when also being each frame data conversion.T _FBe the time of same data block through continuing behind the spread spectrum coding, T _CBeing the cycle of parameter saltus step, also is the time that each data block continues.

Present embodiment is an example with m=3, T in the strategy shown in the figure _F=3T _C, this ratio can be adjusted as required.The order of parameter transformation is in the strategy:

α ₅，α ₁₁，α ₇，α ₁₄，α ₁₂，α ₈，α ₁，α ₂，α ₄，α ₉，α ₃，α ₆，α ₁₃，α ₁₀，α ₁₆，α ₁₅，α ₅，α ₁₁，α ₇，α ₁₄，α ₁₂……

This is predefined in proper order, also can adjust as required in good time.As can be seen from Figure 2, each data block of information source all has been transmitted 3 times, has also promptly carried out 3 times spread spectrum transmission, reaches the purpose of anti-random disturbances and raising systematic function.

Fig. 3 is the synthetic block diagram of the packet configuration signal of n * m.As shown in the figure, packet configuration is a matrix of nm data bit being put into the capable m row of n, nm data bit is synthesized at every turn.Data block wherein

{a ₁，0，a _1，1，…，a _1，n-1}，{a _2，0，a _2，1，…，a _2，n-1}，……，{a _m，0，a _m，1，…，a _m，n-1}

The information source information unanimity of representative has just been carried out the four-item weight score Fourier transform of different conversion exponent numbers respectively.Signal synthesizer is inserted data in the matrix unit by row when work, and reads by row when sending.So just having produced initial data is the effect of separating in the cycle with m bit.

Present embodiment all can be realized by DSP, FPGA or FPGA+DSP.Present embodiment can adopt the system configuration of parallel or serial, and wherein parallel organization is more suitable in FPGA, and serial structure is more suitable in DSP; If adopt FPGA+DSP or other hardware structures, then can be according to the suitable Adjustment System structure of actual conditions.

Claims (2)

1. intercept and capture and anti-interference method based on the signal of the four-item weight score Fourier conversion of multichannel variable element is anti-, it is characterized in that: it since following steps realize:

Transmitting terminal:

Step 1, the digital signal that data source is sent are carried out the digital baseband modulation, obtain the signal after the modulation;

Signal after step 2, the modulation that step 1 is obtained carries out m times of spread spectrum coding, obtains the signal behind the spread spectrum coding of m road;

Every road signal in the signal behind step 3, the m road spread spectrum coding that step 2 is obtained carries out four-item weight score Fourier conversion respectively, obtain the signal after the m road conversion, wherein to carry out the dynamic encryption parameter of four-item weight score Fourier conversion be α to i road signal _i, the dynamic encryption vector is V _i

Signal after step 4, the m road conversion that step 3 is obtained synthesizes, and obtains the signal after synthetic;

Step 5, with step 4 obtain synthetic after signal carry out the digital carrier modulation, obtain the signal after the modulation;

Signal after step 6, the modulation that step 5 is obtained carries out D/A conversion and filtering, obtains filtered signal;

Step 7, the filtered signal that step 6 is obtained carry out sending by channel after the upconversion process;

Receiving terminal:

Step 8, the signal that receives is carried out down-converted, obtain the signal after the down-converted;

Signal after step 9, the down-converted that step 8 is obtained carries out filtering and A/D conversion, obtains the signal after the conversion;

Signal after step 10, the conversion that step 9 is obtained carries out the digital carrier demodulation, obtains the signal after the demodulation;

Signal after step 11, the demodulation that step 10 is obtained is decomposed into m road signal, and every road signal is carried out four-item weight score Fourier conversion respectively, obtains the m road signal after the conversion; Wherein the signal dynamic encryption parameter of carrying out four-item weight score Fourier conversion in i road is-α _i, the dynamic encryption vector is V _i

Signal spread-spectrum decoding back, m road after step 12, the conversion that step 11 is obtained obtains the signal after the decoding;

Signal after step 13, the decoding that step 12 is obtained carries out the digital baseband signal demodulation, obtains result after the demodulation

Described i=1,2 ... m;

M is a positive integer.

2. the signal of the four-item weight score Fourier conversion based on the multichannel variable element according to claim 1 is anti-to be intercepted and captured and anti-interference method, it is characterized in that the parameter alpha of dynamic encryption described in the step 3 _iEstablishing method be: by clock source control pseudo-code generator output pseudo noise code, described pseudo noise code and predefined dynamic encryption parameter changing pattern are united, obtain concrete dynamic encryption parameter value.

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