A Chaotic Communication Method and System Based on Initial Value Modulation

Abstract

The present invention proposes a chaotic communication method and system based on initial value modulation, which relates to the technical field of signal transmission, including a chaotic transmission signal modulation process based on initial value modulation and a chaotic reception signal demodulation process based on initial value modulation; the chaotic transmission signal modulation process divides the initial information bits to be transmitted into modulation bits and sequence number bits, the modulation bits are carried by the polarity of the chaotic signal, and the sequence number bits are transmitted by using the initial value of the chaotic sequence; the chaotic reception signal demodulation process demodulates the modulation bits and the sequence number bits respectively, merges the estimated information bits obtained by demodulating the modulation bits and the sequence number bits, obtains the estimated information bits of all information bits, uses the initial state of the chaotic sequence to carry information, and can realize parallel transmission of multiple information bits without using multiple subcarriers, and improves the energy efficiency of the system by assisting with chaotic initial value modulation.

Description

Technical Field

[0001] The present invention relates to the technical field of signal transmission, and more specifically, to a chaotic communication method and system based on initial value modulation. Background Art

[0002] With the development of Internet of Things technology, the application scenarios of short-range wireless communication technology are increasing. Chaotic communication is a spread spectrum communication technology. By utilizing the broadband characteristics of chaotic signals, chaotic broadband communication systems can be easily constructed. Due to the inherent broadband characteristics, chaotic communication systems have potential advantages in resisting multipath interference and multi-user interference. Therefore, chaotic communication technology has received widespread attention. Based on this, Kolumban et al. proposed a differential chaotic keying communication system based on incoherent demodulation. The carrier signal used in differential chaotic keying technology is a chaotic signal. The reference carrier signal and the information carrier signal are sent to the receiving user in a transmission reference manner. It has good correlation, long-term unpredictability, noise-like performance, etc. It is difficult to be intercepted or intercepted, and has strong confidentiality. In addition, differential chaotic keying technology also has the characteristics of spread spectrum communication, can resist multipath fading interference, and its receiver structure is simple and can recover the target information without channel estimation.

[0003] The prior art discloses a frequency domain chaotic cognitive radio system based on subcarrier shifting, including a transmitting end and a receiving end. At the transmitting end, a frequency domain chaotic signal generator generates a chaotic signal c(t) based on the frequency domain, and then a subcarrier corresponding module realizes a dynamic change in the corresponding relationship between the chaotic sequence C(k) and the subcarrier. The data information is modulated by BPSK to obtain b(t), and b(t) is modulated by c(t) into s(t) and then modulated by the carrier to be sent to a wireless channel in an available frequency band; at the receiving end, after carrier coherent demodulation, a frequency domain chaotic signal generator also generates a chaotic signal c(t) based on the frequency domain. After synchronization, the chaotic signal demodulates the received signal r(t) to obtain d(t), and then a zero-crossing judgment is performed on d(t) to obtain an estimated value of the information bit. However, this scheme requires that information bits be distributed among multiple carriers for transmission, and multiple matched filters are required in the receiver, which makes the system more complex and less energy efficient. Summary of the invention

[0004] In order to solve the current problem, the present invention proposes a chaotic communication method and system based on initial value modulation, which utilizes chaotic initial value modulation to assist the realization of modulation and demodulation in the chaotic communication system, and can realize parallel transmission of multiple information bits without using multiple subcarriers, and effectively improves the energy efficiency of the 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 based on initial value modulation, including a chaotic transmission signal modulation process based on initial value modulation and a chaotic reception signal demodulation process based on initial value modulation;

[0007] The chaotic signal transmission modulation process divides the initial information bits to be transmitted into modulation bits and sequence number bits, wherein the modulation bits are carried by the polarity of the chaotic signal, and the sequence number bits are transmitted by using the initial value of the chaotic sequence;

[0008] The chaotic received signal demodulation process demodulates the modulation bits and the sequence number bits respectively, and combines the estimated information bits obtained by demodulating the modulation bits and the sequence number bits to obtain the estimated information bits of all information bits.

[0009] The technical solution adopts the initial state of the chaotic sequence to carry information, and can realize the parallel transmission of multiple information bits without using multiple subcarriers.

[0010] Preferably, in the chaotic transmission signal modulation process, the initial signal bits to be transmitted The first signal bit in Use the polarity of the chaotic signal to carry as the modulation bit; the remaining M-1 information bits The chaotic sequence initial value is used for transmission as the sequence number bit.

[0011] Preferably, in the chaotic transmission signal modulation process, based on the sequence number bit, the chaotic sequence initial value is selected to generate the chaotic sequence, and the process includes:

[0012] Sequence number bit Convert to decimal notation ;

[0013] Preset a length of The chaotic initial value vector , , the absolute values ​​of the chaos initial values ​​in the chaos initial value vector are all less than 1;

[0014] In the chaotic initial value vector, select As the initial value of the chaotic sequence ;

[0015] Will Transmitted to the chaotic signal generator, through the Logistic mapping, to generate a chaotic sequence .

[0016] Here, the Logistic chaotic signal with uniform probability density and ideal correlation characteristics is used for mapping, which is beneficial to improving the energy efficiency of communication.

[0017] Preferably, the transmission signal of the chaotic transmission signal modulation process is: .

[0018] Preferably, the received signal of the chaotic received signal demodulation process for:

[0019]

[0020] in, ; is the Rayleigh fading channel coefficient, which obeys the Rayleigh distribution; is a Gaussian white noise vector, , where each term has a mean of 0 and a variance of Gaussian distribution.

[0021] Here, a Rayleigh fading channel is used as a channel model, so that the communication environment is more in line with a real communication scenario, and the energy efficiency of the communication system in this environment is effectively improved.

[0022] Preferably, in the demodulation process of the chaotic received signal, the modulated bits are demodulated, and the process expression is as follows:

[0023]

[0024] The judgment process is as follows: is greater than 0, the estimated information bit of the modulated bit is 1, if is less than 0, the estimated information bit of the modulated bit is -1.

[0025] Preferably, in the demodulation process of the chaotic received signal, the sequence number bits are demodulated, and the process includes:

[0026] Based on the preset chaos initial value vector ,generate A chaotic sequence, chaotic sequences are all possible chaotic sequences used by the received signal, among which, ;

[0027] Using the generated chaotic sequence, the received signal is generated Correlation values , the generation process expression is as follows:

[0028]

[0029] To get The absolute values ​​of the correlation values ​​are sorted to obtain the serial number of the chaotic sequence corresponding to the maximum absolute value, that is, the serial number Q of the chaotic initial value selected in the chaotic initial value vector. The process expression is as follows:

[0030]

[0031] Perform symbol / bit conversion on Q to obtain the estimated information bit of the sequence bit .

[0032] Here, and By combining them, we can get all the estimated information bits.

[0033] The present invention also proposes a chaotic communication system based on initial value modulation, which includes a transmitter for implementing the chaotic transmission signal modulation process based on initial value modulation and a receiver for implementing the chaotic transmission signal demodulation process based on initial value modulation.

[0034] Preferably, the transmitter comprises a bit splitter, a chaotic sequence initial value selection module, and a chaotic signal modulator;

[0035] The bit splitter divides the transmitted initial information bits into modulation bits and sequence number bits;

[0036] The chaotic sequence initial value selection module selects a chaotic sequence initial value based on a sequence number bit in a preset chaotic sequence initial value vector to generate a chaotic sequence;

[0037] The chaotic signal modulator generates a chaotic sequence through Logistic mapping based on the chaotic sequence initial value and signal bits to obtain a transmission signal of the transmitter, so that the modulated bits are carried by the polarity of the chaotic signal and the sequence number bits are transmitted using the chaotic sequence initial value.

[0038] Preferably, the receiver receives the transmission signal from the transmitter and then performs demodulation, and includes a filter and a demodulator; includes a filter and a demodulator;

[0039] The filter is used to receive the transmission signal of the transmitter , after filtering operation, the received signal is obtained ;

[0040] The demodulator performs an integration operation on the received signal, that is, demodulates the modulation bits and the sequence number bits, combines the estimated signal values ​​obtained by demodulating the modulation bits and the sequence number bits, and obtains the estimated signal values ​​of all information bits.

[0041] Here, the energy efficiency of the chaotic communication system is improved by assisting with chaotic initial value modulation, and less energy can be used while achieving the same bit error rate of a multi-carrier differential shift keying communication system; in addition, the chaotic communication system does not require multiple subcarriers for transmission, and therefore does not require multiple matching filters, reducing the complexity of the system.

[0042] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0043] The present invention proposes a chaotic communication method and system based on initial value modulation, including a chaotic transmission signal modulation process based on initial value modulation and a chaotic reception signal demodulation process based on initial value modulation; the chaotic transmission signal modulation process divides the initial information bits to be transmitted into modulation bits and sequence number bits, the modulation bits are carried by the polarity of the chaotic signal, and the sequence number bits are transmitted by the initial value of the chaotic sequence; the chaotic reception signal demodulation process demodulates the modulation bits and the sequence number bits respectively, merges the estimated information bits obtained by demodulating the modulation bits and the sequence number bits, obtains the estimated information bits of all information bits, uses the initial state of the chaotic sequence to carry information, and can realize parallel transmission of multiple information bits without using multiple subcarriers, and improves the energy efficiency of the system with the assistance of chaotic initial value modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram showing a flow chart of a chaotic communication method based on initial value modulation proposed in Embodiment 1 of the present invention;

[0045] Figure 2 A schematic diagram showing a comparison of bit error rate performance between a chaotic communication system based on initial value modulation proposed in Embodiment 3 of the present invention and an existing multi-carrier differential shift keying communication system;

[0046] Figure 3 A schematic diagram showing a comparison of bit error rate performance between another chaotic communication system based on initial value modulation proposed in Example 3 of the present invention and an existing multi-carrier differential shift keying communication system. DETAILED DESCRIPTION

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

[0048] 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;

[0049] It is understandable to those skilled in the art that descriptions of certain well-known contents in the drawings may be omitted.

[0050] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0051] The positional relationships described in the drawings are only for illustrative purposes and should not be construed as limiting the present patent;

[0052] Example 1 Figure 1 As shown, this embodiment proposes a chaotic communication method based on initial value modulation, including:

[0053] Chaotic signal modulation, the initial information bits sent are divided into modulation bits and sequence bits, the modulation bits are carried by the polarity of the chaotic signal, and the sequence bits are transmitted using the initial value of the chaotic sequence, the steps are as follows:

[0054] S11. The initial signal bit of the serial The first signal bit in As modulation bits, the remaining M-1 information bits As a sequence number bit;

[0055] S12. Set the sequence number bit Convert to decimal notation ;

[0056] S13. Preset a length of The chaotic initial value vector , , the absolute values ​​of the chaos initial values ​​in the chaos initial value vector are all less than 1;

[0057] S14. Select the first value, as the initial value of the chaotic sequence ;

[0058] S15. Transmitted to the chaotic signal generator, through the Logistic mapping, to generate a chaotic sequence ; The expression of Logistic mapping is:

[0059]

[0060] S16. Generate a transmission signal of the chaotic transmission signal modulation process , the expression is as follows: .

[0061] The chaotic received signal is demodulated, and the estimated signal values ​​obtained by demodulating the modulation bits and the sequence number bits are combined to obtain the estimated information bits of all information bits. The steps are as follows:

[0062] S21. Receive transmission signal , get the received signal In this embodiment, a Rayleigh fading channel is used as a channel model, so that the communication environment is more in line with the real communication scenario, and the energy efficiency of the communication system in this environment is effectively improved; The expression is as follows:

[0063]

[0064] in, ; is the Rayleigh fading channel coefficient, which obeys the Rayleigh distribution; is a Gaussian white noise vector, , where each term has a mean of 0 and a variance of Gaussian distribution.

[0065] S22. Demodulate the modulated bits. The process expression is as follows:

[0066]

[0067] The judgment process is as follows: is greater than 0, the estimated information bit of the modulated bit is 1, if is less than 0, the estimated information bit of the modulated bit is -1;

[0068] S23. Demodulate the sequence number bits, the process comprising:

[0069] Based on the preset chaos initial value vector ,generate A chaotic sequence, chaotic sequences are all possible chaotic sequences used by the received signal, among which, ;

[0070] Using the generated chaotic sequence, the received signal is generated The generation process expression is as follows:

[0071]

[0072] To get The absolute values ​​of the correlation values ​​are sorted to obtain the serial number of the chaotic sequence corresponding to the maximum absolute value, that is, the serial number Q of the chaotic initial value selected in the chaotic initial value vector. The process expression is as follows:

[0073]

[0074] Perform symbol / bit conversion on Q to obtain the estimated information bit of the sequence bit ;

[0075] S24. and Combine to get all estimated information bits.

[0076] Example 2 This example proposes a chaotic communication system based on initial value modulation, the system comprising a transmitter for implementing the above-mentioned chaotic transmission signal modulation process based on initial value modulation and a receiver for implementing the above-mentioned chaotic transmission signal demodulation process based on initial value modulation.

[0077] The transmitter includes a bit splitter, a chaotic sequence initial value selection module, and a chaotic signal modulator;

[0078] The bit splitter divides the transmitted initial information bits into modulation bits and sequence number bits;

[0079] The chaotic sequence initial value selection module selects a chaotic sequence initial value based on a sequence number bit in a preset chaotic sequence initial value vector to generate a chaotic sequence;

[0080] The chaotic signal modulator generates a chaotic sequence through Logistic mapping based on the chaotic sequence initial value and signal bits to obtain a transmission signal of the transmitter, so that the modulated bits are carried by the polarity of the chaotic signal and the sequence number bits are transmitted using the chaotic sequence initial value.

[0081] The receiver receives the transmission signal of the transmitter and then demodulates it, and includes a filter and a demodulator;

[0082] The filter is used to receive the transmission signal of the transmitter , after filtering operation, the received signal is obtained ;

[0083] The demodulator performs an integration operation on the received signal, that is, demodulates the modulation bits and the sequence number bits, combines the estimated signal values ​​obtained by demodulating the modulation bits and the sequence number bits, and obtains the estimated signal values ​​of all information bits.

[0084] Embodiment 3 In this embodiment, the chaotic communication system based on initial value modulation according to Embodiment 1 and Embodiment 2 ( =3, =60) and the existing multi-carrier differential shift keying communication system (M=4, = 60) to compare the bit error rate performance. Figure 2 As shown, in the Rayleigh fading channel environment, the bit error rate level is When the initial value modulation is used, the proposed chaotic communication system has a gain of 4dB compared with the existing multi-carrier differential shift keying communication system.

[0085] The chaotic communication system based on initial value modulation according to Embodiment 1 and Embodiment 2 ( =4, =60) and the existing multi-carrier differential shift keying communication system (M=5, = 60) to compare the bit error rate performance. Figure 3 As shown, in the Rayleigh fading channel environment, the bit error rate level is When the chaotic initial value modulation assisted differential chaotic shift keying communication system is proposed, it has a gain of 6dB compared with the existing multi-carrier differential shift keying communication system.

[0086] 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 based on initial value modulation, characterized in that: The method comprises a chaotic transmission signal modulation process based on initial value modulation and a chaotic reception signal demodulation process based on initial value modulation; The chaotic signal modulation process divides the initial information bits to be sent into modulation bits and sequence number bits, and divides the initial signal bits b1, ..., b M The first signal bit b1 in is used as the modulation bit and carried by the polarity of the chaotic signal; the remaining M-1 information bits b2,…,b M As the sequence number bit, the chaotic sequence initial value is used for transmission. The transmission signal of the chaotic transmission signal modulation process is: s = [c select , b1c select ]; The chaotic received signal demodulation process demodulates the modulation bit and the sequence number bit respectively, combines the estimated signal values ​​obtained by demodulating the modulation bit and the sequence number bit, and obtains the estimated information bits of all information bits; the received signal r of the chaotic received signal demodulation process is: r＝[r1,…,r 2β ] Where r = h·s+w; h is the Rayleigh fading channel coefficient, which obeys the Rayleigh distribution; w is the Gaussian white noise vector, w = [w1, w2, …, w 2β ], where each item obeys a Gaussian distribution with a mean of 0 and a variance of N0; in the demodulation process of the chaotic received signal, the sequence number bits are demodulated, and the process includes: Based on the preset chaos initial value vector generate A chaotic sequence, chaotic sequences are all possible chaotic sequences used by the received signal, among which, Using the generated chaotic sequence, the received signal is generated Correlation value Z j , the generation process expression is as follows: To get The absolute values ​​of the correlation values ​​are sorted to obtain the serial number of the chaotic sequence corresponding to the maximum absolute value, that is, the serial number Q of the chaotic initial value selected in the chaotic initial value vector. The process expression is as follows: Perform symbol / bit conversion on Q to obtain the estimated information bit of the sequence bit 2. The chaotic communication method based on initial value modulation according to claim 1, characterized in that: In the chaotic transmission signal modulation process, based on the sequence number bit, the initial value of the chaotic sequence is selected to generate the chaotic sequence. The process includes: Set the sequence number bits b2,…,b M Convert to decimal symbol D M ; Preset a length of The chaotic initial value vector 0≤D M ≤2 M-1 -1, the absolute values ​​of the chaos initial values ​​in the chaos initial value vector are all less than 1; Select the Dth M +1 as the initial value of the chaos sequence Will Transmitted to the chaotic signal generator, through the Logistic mapping, a chaotic sequence of length β is generated 3. The chaotic communication method based on initial value modulation according to claim 2, characterized in that: In the demodulation process of chaotic received signals, the modulated bits are demodulated, and the process expression is as follows: The decision process is as follows: If Z1 is greater than 0, the estimated information bit of the modulated bit is 1, if Z1 is less than 0, then the estimated information bit of the modulated bit is -1.

4. A chaotic communication system based on initial value modulation, characterized in that: The system includes a transmitter for implementing the chaotic transmission signal modulation process based on initial value modulation as described in claim 1 and a receiver for implementing the chaotic transmission signal demodulation process based on initial value modulation as described in claim 1.

5. The chaotic communication system based on initial value modulation according to claim 4, characterized in that: The transmitter includes a bit splitter, a chaotic sequence initial value selection module, and a chaotic signal modulator; The bit splitter divides the transmitted initial information bits into modulation bits and sequence number bits; The chaotic sequence initial value selection module selects a chaotic sequence initial value based on a sequence number bit in a preset chaotic sequence initial value vector to generate a chaotic sequence; The chaotic signal modulator generates a chaotic sequence through Logistic mapping based on the chaotic sequence initial value and signal bits to obtain a transmission signal of the transmitter, so that the modulated bits are carried by the polarity of the chaotic signal and the sequence number bits are transmitted using the chaotic sequence initial value.

6. The chaotic communication system based on initial value modulation according to claim 4, characterized in that: The receiver receives the transmission signal of the transmitter and then demodulates it, and includes a filter and a demodulator; The filter is used to receive a transmission signal s from a transmitter, and obtain a received signal r after filtering operation; The demodulator performs an integration operation on the received signal, that is, demodulates the modulation bits and the sequence number bits, and combines the estimated signal bits obtained by demodulating the modulation bits and the sequence number bits to obtain the estimated signal bits of all information bits.

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