Chaotic communication method and system assisted by frequency point mode energy conversion

Abstract

The invention provides a frequency point mode energy conversion assisted chaotic communication method and system, and relates to the technical field of signal transmission, information bits b1 and b2 to be sent by a transmitting end are divided into two parts to be transmitted, a pre-generated chaotic sequence is preprocessed, two modes of monotonically increasing or monotonically decreasing frequency domain energy are constructed, and the frequency domain energy is converted into the frequency domain energy. One more information bit can be additionally transmitted, and the energy efficiency and bit error rate performance of a differential shift chaos keying modulation communication system are improved; in addition, the transmission of the information bits b1 and b2 is mutually independent, and the demodulation of the two information bits does not influence each other to cause error propagation.

Description

Technical Field

[0001] The present invention relates to the field of signal transmission technology, and more specifically, to a frequency point mode energy conversion-assisted chaotic communication method and system. Background Art

[0002] In the field of modern communications, fast and secure transmission of information is crucial. With the rapid development of information technology, traditional communication methods are facing problems such as low transmission efficiency and insufficient security. Especially in the fields of military, finance, government and other fields with extremely high requirements for information security, traditional communication technologies have been unable to meet the needs. Therefore, research and development of new communication technologies, especially chaos communication technology, has become a hot research direction in the field of communications.

[0003] Chaos communication technology is a communication method based on chaos theory, which uses the unpredictability and complexity of chaotic signals to improve the security of communication. The dynamic characteristics of chaotic signals make it difficult to be intercepted and decoded during transmission, thus providing a natural encryption method. However, chaos communication technology also faces some challenges in practical applications, such as signal synchronization, transmission efficiency, and energy consumption. In addition, in traditional communication systems, directly modulating or encoding chaotic signals will change their original chaotic characteristics, resulting in reduced signal security. Summary of the invention

[0004] In order to solve the problems of low transmission efficiency and low security of current chaotic communication technology, the present invention proposes a chaotic communication method and system assisted by frequency mode energy conversion, constructs a new information transmission dimension, transmits an additional information bit, and improves the energy efficiency, bit error rate performance and security of the differential shift chaotic keying modulation communication system.

[0005] In order to achieve the above technical effects, the technical solution of the present invention is as follows:

[0006] A chaotic communication method assisted by frequency point mode energy conversion, comprising:

[0007] The method includes a signal modulation process and a signal demodulation process;

[0008] The signal modulation process modulates the information bits to be sent by the transmitter to generate a transmission signal, and the steps include:

[0009] S1. Divide the information bits to be sent into two parts, b1 and b2;

[0010] S2. Using Logistic Mapping Generate a chaotic sequence of length β, where x is a positive integer greater than 0, let c = [c1,…,c j ,…,cβ ].

[0011] S3. Perform Fourier transform on sequence c to get c DFT .

[0012] S4. Based on information bits b1 and c DFT The signal energy of the sequence c DFT Rearrange and inverse Fourier transform to generate sequence c Θ .

[0013] S5. According to c Θ and information bit b2, generating a transmission signal s = [c Θ ,b2c Θ ].

[0014] The signal demodulation process is to receive the signal r = αs + n = [r1, ..., r 2β ] to demodulate, the steps include:

[0015] S6. Construct sequence Λ based on the received signal and perform Fourier transform to generate sequence Λ DFT ; Based on Λ DFT A decision variable of information bit b1 is constructed, and an estimated information bit corresponding to b1 is obtained based on the decision variable.

[0016] S7. Construct a decision variable for information bit b2 based on the received signal, and obtain the estimated information bit corresponding to b2 based on the decision variable.

[0017] This technical solution constructs different patterns of frequency domain energy by reordering the chaotic sequence after Fourier transform, which can transmit an additional information bit and improve the energy efficiency and bit error rate performance of the differential shift chaotic keying modulation communication system; in addition, the transmission of information bits b1 and b2 is independent of each other, and the demodulation of the two information bits will not affect each other and cause error propagation.

[0018] Preferably, in step S2, β is an integer power of 2, and c1 is a random number satisfying |c1|<1.

[0019] Preferably, in step S3, a discrete Fourier transform is performed on the sequence c to obtain in, i is a plural unit.

[0020] Preferably, step S4 includes the following process:

[0021] S41. When the information bit b1 is +1, c DFT The elements in are arranged from large to small according to energy, and a new sequence c is obtained.DFT,down .

[0022] When the information bit b1 is -1, c DFT The elements in are arranged in ascending order of energy to obtain a new sequence c DFT,up .

[0023] S42. Check the generated sequence. The process is as follows:

[0024] Judgement DFT,down and c DFT,up Center front The energy and the subsequent Is the energy difference of the sequences less than times, where T∈[3,5]; if so, assign c1 to a new random number and return to step S3; otherwise, go to step S43.

[0025] S43. for c DFT,Θ Perform inverse discrete Fourier transform to obtain the sequence c Θ .

[0026] Here, the technical solution constructs two modes of monotonically increasing or monotonically decreasing frequency domain energy, and transmits one more information bit b1 through these two different modes in the frequency domain; since the signal energy sorting operation is performed in the frequency domain, the waveform of the transmitted signal in the time domain can still maintain the noise-like characteristics of the chaotic sequence.

[0027] Preferably, in sequence c DFT In the elements The energy size is

[0028] Preferably, in step S43, the sequence Where Θ = {down, up},

[0029] Preferably, in step S6, a sequence Λ is constructed based on the received signal, and the expression is as follows:

[0030] Λ=[r β+1 ,…,r 2β ]=[Λ1,…,Λ j ,…,Λ β ]

[0031] Perform Fourier transform on the sequence Λ and get the sequence in,

[0032] Preferably, in step S6, the decision variables of the information bit b1 are constructed respectively and

[0033] If D1>D2, the estimated information bit corresponding to b1 is recorded as +1.

[0034] If D1≤D2, the estimated information bit corresponding to b1 is recorded as -1.

[0035] Preferably, in step S7, a decision variable Z of the information bit b2 is constructed, and the expression is as follows:

[0036]

[0037] If Z is greater than 0, the estimated information bit corresponding to b2 is recorded as +1; if Z is less than 0, the estimated information bit corresponding to b2 is recorded as -1.

[0038] A chaotic communication system assisted by frequency point mode energy conversion includes a modulator and a demodulator; the modulator is used to implement the signal modulation process of the chaotic communication method assisted by frequency point mode energy conversion, and the demodulator is used to implement the signal demodulation process of the chaotic communication method assisted by frequency point mode energy conversion.

[0039] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0040] The present invention proposes a frequency point pattern energy conversion assisted chaotic communication method and system, which divides the information bits b1 and b2 to be sent by the transmitter into two parts for transmission, and constructs two modes of monotonically increasing or monotonically decreasing frequency domain energy by preprocessing the pre-generated chaotic sequence, so that one more information bit can be transmitted, thereby improving the energy efficiency and bit error rate performance of the differential shift chaotic keying modulation communication system; in addition, the transmission of the information bits b1 and b2 is independent of each other, and the demodulation of the two information bits will not affect each other, causing error propagation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic flow chart showing a chaotic communication method assisted by frequency point mode energy conversion proposed in Embodiment 1 of the present invention;

[0042] Figure 2 A schematic diagram showing the comparison of the bit error rate performance of the frequency pattern energy conversion assisted chaotic communication system proposed in embodiments 2 and 3 of the present invention and the existing differential shift chaotic keying modulation communication system under single-path Rayleigh fading channel conditions. DETAILED DESCRIPTION

[0043] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0044] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual size;

[0045] It is understandable to those skilled in the art that descriptions of certain well-known contents in the drawings may be omitted.

[0046] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0047] The positional relationships described in the drawings are only for illustrative purposes and should not be construed as limiting the present patent;

[0048] Example 1

[0049] like Figure 1 As shown, this embodiment proposes a frequency point mode energy conversion assisted chaotic communication method, the method includes a signal modulation process and a signal demodulation process;

[0050] The signal modulation process modulates the information bits to be sent by the transmitter to generate a transmission signal, and the steps include:

[0051] S1. Divide the information bits to be sent into two parts, b1 and b2.

[0052] S2. Using Logistic Mapping Generate a chaotic sequence of length β, where x is a positive integer greater than 0, let c = [c1,…,c j ,…,c β ], β is an integer power of 2, and c1 is a random number satisfying |c1|<1.

[0053] S3. Perform Fourier transform on sequence c, and perform discrete Fourier transform on sequence c to obtain in, i is a plural unit.

[0054] It should be noted that is the new sequence c obtained by performing discrete Fourier transform on sequence c DFT The jth element in , where j ranges from 1 to β, and p represents a variable whose range is from 1 to β.

[0055] S4. Based on information bits b1 and c DFT The signal energy of the sequence c DFT Rearrange and inverse Fourier transform to generate sequence c Θ , the specific process is as follows:

[0056] S41. When the information bit b1 is +1, c DFT The elements in are arranged from large to small according to energy, and a new sequence c is obtained.DFT,down ;

[0057] When the information bit b1 is -1, c DFT The elements in are arranged in ascending order of energy to obtain a new sequence c DFT,up ;

[0058] Among them, in sequence c DFT In the elements The energy size is

[0059] S42. Check the generated sequence. The process is as follows:

[0060] Judgement DFT,down and c DFT,up Center front The energy and Is the energy difference of the sequences less than times, where T∈[3,5]; if so, assign c1 to a new random number and return to step S3; otherwise, proceed to step S43;

[0061] S43. for c DFT,Θ Perform inverse discrete Fourier transform to obtain the sequence Where Θ = {down, up},

[0062] S5. According to c Θ and information bit b2, generating a transmission signal s = [c Θ ,b2c Θ ];

[0063] The signal demodulation process is to receive the signal r = αs + n = [r1, ..., r 2β ] to demodulate, the steps include:

[0064] S6. Construct a sequence Λ based on the received signal, the expression is as follows:

[0065] Λ=[r β+1 ,…,r 2β ]=[Λ1,…,Λ j ,…,Λ β ]

[0066] Perform Fourier transform on the sequence Λ and get the sequence in,

[0067] Based on Λ DFT Construct the decision variables of information bit b1 respectively and χ represents a variable ranging from 1 to 2.

[0068] If D1>D2, the estimated information bit corresponding to b1 is recorded as +1.

[0069] If D1≤D2, the estimated information bit corresponding to b1 is recorded as -1.

[0070] S7. Construct a decision variable Z for information bit b2 based on the received signal, expressed as follows:

[0071]

[0072] If Z is greater than 0, the estimated information bit corresponding to b2 is recorded as +1; if Z is less than 0, the estimated information bit corresponding to b2 is recorded as -1. β ] represents the first half of the received signal sequence, Represents the transpose of the second half of the received signal.

[0073] Example 2

[0074] This embodiment proposes a frequency point mode energy conversion assisted chaotic communication system, including a modulator and a demodulator;

[0075] The modulator is used to implement the signal modulation process of the chaotic communication method assisted by frequency point mode energy conversion as described in Example 1, modulating the information bits to be sent by the transmitter to generate a transmission signal, including:

[0076] S1. Divide the information bits to be sent into two parts, b1 and b2;

[0077] S2. Using Logistic Mapping Generate a chaotic sequence of length β, where x is a positive integer greater than 0, let c = [c1,…,c j ,…,c β ].

[0078] S3. Perform Fourier transform on sequence c to get c DFT .

[0079] S4. Based on information bits b1 and c DFT The signal energy of the sequence c DFT Rearrange and inverse Fourier transform to generate sequence c Θ .

[0080] S5. According to c Θ and information bit b2, generating a transmission signal s = [c Θ ,b2c Θ ].

[0081] The demodulator is used to implement the signal demodulation process of the chaotic communication method assisted by frequency point mode energy conversion as described in the first embodiment, and the received signal r = αs + n = [r1, ..., r 2β ] for demodulation, including:

[0082] S6. Construct sequence Λ based on the received signal and perform Fourier transform to generate sequence Λ DFT ; Based on Λ DFT Constructing a decision variable of information bit b1, and obtaining an estimated information bit corresponding to b1 based on the decision variable;

[0083] S7. Construct a decision variable for information bit b2 based on the received signal, and obtain the estimated information bit corresponding to b2 based on the decision variable.

[0084] Example 3

[0085] In this embodiment, in a single-path Rayleigh fading channel environment, the bit error rate performance of the frequency point mode energy conversion assisted chaotic communication system (β=60, T=3) based on Example 2 is compared with the existing differential shift chaotic keying modulation communication system (β=60).

[0086] like Figure 2 As shown in the figure, under the condition of single-path Rayleigh fading channel, the bit error rate level is 10 -3 When the frequency point mode energy conversion assisted chaotic communication system proposed in this embodiment has a gain of 4dB compared with the existing differential shift chaotic keying modulation communication system.

[0087] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A chaotic communication method assisted by frequency mode energy conversion, characterized in that: The method includes a signal modulation process and a signal demodulation process; The signal modulation process modulates the information bits to be sent by the transmitter to generate a transmission signal, and the steps include: S1. Divide the information bits to be sent into two parts, b1 and b2; S2. Using Logistic Mapping Generate a chaotic sequence of length β, where x is a positive integer greater than 0, let c = [c1,…,c j ,…,c β ]; S3. Perform Fourier transform on sequence c to get c DFT ; S4. Based on information bits b1 and c DFT The signal energy of the sequence c DFT Rearrange and inverse Fourier transform to generate sequence c Θ ; S5. According to c Θ and information bit b2, generating a transmission signal s = [c Θ ,b2c Θ ]; The signal demodulation process is to receive the signal r = αs + n = [r1, ..., r 2β ] to demodulate, the steps include: S6. Construct sequence Λ based on the received signal and perform Fourier transform to generate sequence Λ DFT ; Based on Λ DFT Constructing a decision variable of information bit b1, and obtaining an estimated information bit corresponding to b1 based on the decision variable; S7. Construct a decision variable for information bit b2 based on the received signal, and obtain the estimated information bit corresponding to b2 based on the decision variable.

2. The frequency point mode energy conversion assisted chaotic communication method according to claim 1, characterized in that: In step S2, β is an integer power of 2, and c1 is a random number satisfying |c1|<1.

3. The frequency point mode energy conversion assisted chaotic communication method according to claim 2, characterized in that: In step S3, the sequence c is subjected to discrete Fourier transform to obtain in, i is a plural unit.

4. The frequency point mode energy conversion assisted chaotic communication method according to claim 3, characterized in that: Step S4 The process includes: S41. When the information bit b1 is +1, c DFT The elements in are arranged from large to small according to energy, and a new sequence c is obtained. DFT,down ; When the information bit b1 is -1, c DFT The elements in are arranged in ascending order of energy to obtain a new sequence c DFT,up ; S42. Check the generated sequence. The process is as follows: Judgement DFT,down and c DFT,up Center front The energy and the subsequent Is the energy difference of the sequences less than times, where T∈[3,5]; if so, assign c1 to a new random number and return to step S3; otherwise, proceed to step S43; S43. DFT,Θ Perform inverse discrete Fourier transform to obtain the sequence c Θ .

5. The frequency point mode energy conversion assisted chaotic communication method according to claim 4, characterized in that: In sequence c DFT In the element The energy size is 6. The frequency point mode energy conversion assisted chaotic communication method according to claim 4, characterized in that: In step S43, the sequence Where Θ = {down, up}, 7. The frequency point mode energy conversion assisted chaotic communication method according to claim 4, characterized in that: In step S6, a sequence Λ is constructed based on the received signal, and the expression is as follows: Λ=[r β+1 ,…,r 2β ]=[Λ1,…,Λ j ,…,L β ] Perform Fourier transform on the sequence Λ and get the sequence in, 8. The frequency point mode energy conversion assisted chaotic communication method according to claim 7, characterized in that: In step S6, the decision variables of information bit b1 are constructed respectively and If D1>D2, the estimated information bit corresponding to b1 is recorded as +1; If D1≤D2, the estimated information bit corresponding to b1 is recorded as -1.

9. The frequency point mode energy conversion assisted chaotic communication method according to claim 4, characterized in that: In step S7, the decision variable Z of the information bit b2 is constructed, and the expression is as follows: If Z is greater than 0, the estimated information bit corresponding to b2 is recorded as +1; If Z is less than 0, the estimated information bit corresponding to b2 is recorded as -1.

10. A frequency point mode energy conversion assisted chaotic communication system, characterized in that: It includes a modulator and a demodulator; the modulator is used to implement the signal modulation process of the chaotic communication method assisted by the frequency point mode energy conversion as described in claim 1, and the demodulator is used to implement the signal demodulation process of the chaotic communication method assisted by the frequency point mode energy conversion as described in claim 1.

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