A transmission method based on polar code and chaotic CCDM multiplexing encryption

Abstract

The application discloses a transmission method based on Polar code and chaotic CCDM multi-path encryption, which comprises the following steps: (1) converting an original data stream into a relatively short multi-channel parallel data stream after serial-parallel conversion; (2) obtaining a five-dimensional hyperchaotic system by using a five-dimensional chaotic model after the data is converted by serial-parallel conversion; (3) dividing a first group of chaotic sequences into three groups of data; (4) merging the three groups of data, sequentially scrambling subcarriers by using a fifth group of chaotic sequences, performing the last encryption, and finally obtaining safe data after multi-round encryption; (5) at a receiving end, performing demodulation and decryption operations on the encrypted signal by using a process opposite to that of a sending end, decrypting the received information by an ONU with all the keys, and finally obtaining correct information after decryption; the application can optimize constellation probability distribution, improve BER performance, improve security performance, and effectively reduce complexity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data transmission, and particularly relates to a transmission method based on a polar code and chaotic CCDM multi-encryption. BACKGROUND

[0002] With the development of information society, the security of information transmission is increasingly important, especially for PON, a broadcast mechanism communication architecture, the downlink signal is sent to multiple different ONUs in a broadcast manner, so that each ONU has the opportunity to crack the information of other users. Compared with the encryption method based on the transmission layer or the protocol stack layer, the physical layer encryption faces the optical fiber transmission channel, which can fundamentally guarantee the security of the communication system, and has become the research hotspot of many researchers. The research on optical chaos encryption, quantum encryption, digital chaos encryption and other encryption methods is in full swing. Among them, digital chaos encryption is based on DSP technology, without the support of complex hardware system, with obvious advantages in cost and complexity. The flexibility and stability of digital chaos encryption technology promote its integration with other existing technologies, and it is expected to realize the synchronous improvement of system effectiveness, reliability and security. Therefore, under this technical background, how to realize the synchronous improvement of various performances of the mechanism is the key scientific problem to be studied at present.

[0003] Reliability and security are two key characteristics of OFDM-PON systems. In optical communication systems, loss and noise can significantly affect the quality of information transmission, so it is necessary to use error correction coding to encode and modulate the signal. Soft detection forward error correction (FEC) is considered one of the most promising solutions, which can achieve power reduction and cost efficiency. In 2009, Arikan proposed a new FEC scheme, polar code. Polar code is based on channel polarization theory, which can be divided into two processes: channel coupling and channel splitting. With the infinite increase of code length, some sub-channels tend to be noiseless, while other sub-channels tend to be pure noise. In theory, polar code can achieve the Shannon limit with relatively low decoding complexity. The error correction performance and complexity advantage of polar code become more obvious with the increase of code length. Considering the excellent performance of polar code, it is necessary to further study its performance in OFDM optical access systems.

[0004] The probability shaping can obtain flexible spectrum efficiency by changing the constellation point probability distribution, and can increase the channel capacity to more approximate the Shannon limit in combination with the FEC technology; on the other hand, from the perspective of the CFM, the probability shaping can effectively reduce the average power of the constellation under the condition that the constellation point position is unchanged, i.e., the minimum Euclidean distance is fixed, obtain a certain degree of CFM gain, and the BER performance of the constellation is obviously improved; the emergence of the probability shaping technology provides a new way for improving the effectiveness and reliability of the communication system, so how to solve the above problems becomes a difficult problem to be solved at present.

[0005] In the current chaotic encryption technology, a transmission system composed of a low-dimensional chaotic model + a single encoding technology or a multi-dimensional chaotic model + a single encoding technology is often adopted, so that the system security is improved, but the complexity is significantly increased, the transmission error rate is increased, and the transmission efficiency is greatly reduced. Therefore, it is a key problem to be solved at present to improve the system security while ensuring the synchronous improvement of the effectiveness and reliability of the system. SUMMARY

[0006] The purpose of the application is to provide a transmission method based on Polar code and chaotic CCDM multi-path encryption, which realizes the synchronous improvement of transmission performance and security performance by using a five-dimensional chaotic model for multi-path hybrid encryption of transmission data.

[0007] The technical scheme is characterized in that the transmission method based on Polar code and chaotic CCDM multi-path encryption comprises the following steps:

[0008] (1) converting the original data stream into a relatively short multi-channel parallel data stream after serial-parallel conversion;

[0009] (2) obtaining a five-dimensional hyperchaotic system by using a five-dimensional chaotic model after serial-parallel conversion of the data;

[0010] (3) dividing the first group of chaotic sequences into three paths of data; specifically comprising the following steps:

[0011] (31) sending the first path of data to a Polar encoding module, encrypting the frozen bits by using the second group of chaotic sequences, and realizing constellation mapping;

[0012] (32) sending the second path to a chaotic CCDM encryption module, performing chaotic CCDM operation by using the third group and the fourth group of chaotic sequences, obtaining the amplitude values after chaotic encryption, dividing the amplitude values into equal numbers of I paths and Q paths, and realizing constellation mapping;

[0013] (33) directly performing constellation mapping on the third path of data;

[0014] (4) The three groups of data are combined, and the fifth group of chaotic sequences is used to sequentially scramble the subcarriers for the last encryption, and finally the secure data after multiple rounds of encryption is obtained;

[0015] (5) At the receiving end, the demodulation and decryption operations of the encrypted signal are performed using the inverse process of the sending end, and the ONU with all the keys will decrypt the received information to finally obtain the correct information after decryption.

[0016] Further, the five-dimensional chaotic model of step (2) is based on the structure of a four-dimensional hyperchaotic system, introduces new state variables, and obtains a five-dimensional hyperchaotic system, which is as follows:

[0017]

[0018] Where x, y, z, w, and v are chaotic sequences generated by the chaotic system; a, b, c, d, e, and f are constants of the model;

[0019] Step (3) for dividing the first group of chaotic sequences into three groups of data is as follows: after the original data is subjected to serial-parallel conversion, a plurality of subcarriers are obtained, and the first group of chaotic sequences is used to determine which path each subcarrier passes through, and the generation rule is as follows:

[0020] k = floor(mod(x·10 18 , 3))

[0021] If k = 0, it goes to the first path, if k = 1, it goes to the second path, and if k = 2, it goes to the third path.

[0022] Further, the step (31) specifically includes the following:

[0023] First, the code word X of Polar coding is defined as:

[0024]

[0025] Where N is the code length, BN is the bit-reversal permutation matrix, and represents the nth(n = log2N) Kronecker power of the matrix;

[0026] Then, the frozen bits of each block group are determined using the chaotic sequence y; the length of y is equal to the number of block groups;

[0027] The generation rule is as follows:

[0028] l frocon = floor(mod(y·10 15 , 2))

[0029] Where l frozonFreeze bit, value is 0 or 1.

[0030] Further, the step (32) specifically comprises the following steps:

[0031] (321) The input second path data is divided into 3 bits groups, and there are two amplitude values {1, 3} for the PS-16QAM signal, and the distribution of the two amplitude values is: P(1) = 3 / 4, P(3) = 1 / 4, that is, the probability of amplitude 1 is 3 / 4, and the probability of amplitude 3 is 1 / 4; meanwhile, 8 kinds of 000, 001, 010, 100, 011, 101, 110, 111 bits are input, and the above bits are corresponded to different amplitude values, that is, 8 kinds of different signed amplitude value combinations are required: {1, 1}, {1, -1}, {-1, 1}, {-1, -1}, {1, 3}, {1, -3}, {-1, 3}, {-1, -3};

[0032] (322) The above bits data and amplitude value data are divided, specifically: 000, 001, 010, 100 are grouped and named as group A, 110, 101, 011, 111 are grouped and named as group B; {1, 1}, {1, -1}, {-1, 1}, {-1, -1} are grouped and named as group C, and {1, 3}, {1, -3}, {-1, 3}, {-1, -3} are grouped and named as group D;

[0033] (323) The third group of chaotic sequences is used to select the group-out mapping rule of bits and amplitude values, and the specific rule is as follows:

[0034] m = floor(mod(x·10 16 , 2))

[0035] If m = 0, A corresponds to C, and B corresponds to D; if m = 1, A corresponds to D, and B corresponds to C.

[0036] (324) The fourth group of chaotic sequences is used to select the group-in mapping rule of bits and amplitude values, and the specific rule is as follows:

[0037] n = floor(mod(u·10 16 , 24)) + 1;

[0038] (325) The chaotic encrypted amplitude value is divided into two parts, the first half part data is sent to the I path, and the second half part data is sent to the Q path; the I data will be used as the real part of the output data, and the Q path data will be used as the imaginary part of the output data, and the two path data are combined by using QAM mapping, and finally the PS-16QAM data of the second path is obtained.

[0039] Further, the step (4) is specifically: merging three-way constellation point data, and then performing subcarrier sequence scrambling; the subcarrier sequence is encrypted by using the fifth group of chaotic sequences according to the rule shown in the following formula; the generated scrambling sequence is as follows:

[0040] Subcarriers new = fw{subcarriers(sort(mod(w n 1))))

[0041] Wherein subcarriers new , subcarriers represent the subcarrier sequence, f w {} is the rule of scrambling the subcarrier sequence.

[0042] Beneficial effects: compared with the prior art, the present application has the following remarkable advantages: the constellation probability distribution can be optimized, the BER performance can be improved, the security performance can be improved, and the complexity can be effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a transmission system operation schematic diagram of the present application;

[0044] Figure 2 It is a mapping rule schematic diagram of the present application;

[0045] Figure 3 It is an x-y-z space phase schematic diagram of the present application;

[0046] Figure 4 It is an x-y-v space phase schematic diagram of the present application;

[0047] Figure 5 It is an x-z-w space phase schematic diagram of the present application;

[0048] Figure 6 It is an x-w-v space phase schematic diagram of the present application;

[0049] Figure 7 It is a y-z-v space phase schematic diagram of the present application;

[0050] Figure 8 It is a z-w-v space phase schematic diagram of the present application

[0051] Figure 9 It is an x-y space phase schematic diagram of the present application;

[0052] Figure 10 It is an x-z space phase schematic diagram of the present application;

[0053] Figure 11 It is an x-w space phase schematic diagram of the present application. DETAILED DESCRIPTION

[0054] The technical solutions of the present application are further described below with reference to the accompanying drawings.

[0055] As Figures 1-11 shown, an embodiment of the present application is a transmission method based on Polar code and chaotic CCDM multi-path encryption, including the following steps:

[0056] (1) converting the original data stream into a relatively short multi-channel parallel data stream after serial-parallel conversion;

[0057] (2) after serial-parallel conversion, obtaining a five-dimensional hyperchaotic system by using a five-dimensional chaotic model; the five-dimensional chaotic model is based on the structure of a four-dimensional hyperchaotic system, introduces a new state variable to obtain a five-dimensional hyperchaotic system, and the formula is as follows:

[0058]

[0059] wherein x, y, z, w, and v are chaotic sequences generated by the chaotic system; a, b, c, d, e, and f are constants of the model;

[0060] When a = 20, b = 8, c = 5, d = -20, and f = -15, the five-dimensional hyperchaotic system has good randomness; the initial values (x0, y0, z0, w0, v0) are set to 1, 1, 0, 0, and 0; and the phase diagram (such as Figures 3-11 ) in different three-dimensional spaces shows that the five-dimensional chaotic system exhibits complex bifurcation dynamic characteristics and high-security chaotic characteristics.

[0061] (3) dividing the first group of chaotic sequences into three paths of data; specifically, after serial-parallel conversion of the original data, a plurality of subcarriers are obtained, and the first group of chaotic sequences is used to determine which path each subcarrier goes to, and the generation rule is as follows:

[0062] k = floor(mod(x·10 16 , 3))

[0063] If k = 0, it goes to the first path, if k = 1, it goes to the second path, and if k = 2, it goes to the third path; specifically including the following steps:

[0064] (31) sending the first path of data to the Polar encoding module, encrypting the frozen bits using the second group of chaotic sequences, and realizing constellation mapping; specifically, first, define the Polar code X as follows:

[0065]

[0066] wherein N is the code length, BN is the bit-reversal permutation matrix, and an nth (n=log2N) Kronecker power of the matrix;

[0067] Then, the frozen bits of each block group are determined using the chaotic sequence y; the length of y is equal to the number of block groups;

[0068] The generation rule is as follows:

[0069] l frocon = floor(mod(y·10 16 , 2))

[0070] wherein l frozon represents the frozen bits, and has a value of 0 or 1.

[0071] (32) The second path is sent to the chaotic CCDM encryption module, chaotic CCDM operation is performed using the third and fourth groups of chaotic sequences, chaotic encrypted amplitude values are obtained, the amplitude values are divided into equal numbers of I paths and Q paths, and constellation mapping is realized; specifically comprising the following steps:

[0072] (321) The input second path data is divided into 3 bits per group, and for a PS-16QAM signal, there are two amplitude values {1, 3}, and the distribution of the two amplitude values is: P(1)=3 / 4, P(3)=1 / 4, i.e., the probability of amplitude 1 is 3 / 4, and the probability of amplitude 3 is 1 / 4; at the same time, 8 kinds of 000, 001, 010, 100, 011, 101, 110, and 111 bits are input, and the above bits are corresponded to different amplitude values, i.e., 8 kinds of different signed amplitude value combinations are required: {1, 1}, {1, -1}, {-1, 1}, {-1, -1}, {1, 3}, {1, -3}, {-1, 3}, and {-1, -3};

[0073] (322) The above bits data and amplitude value data are divided, specifically: 000, 001, 010, and 100 are grouped and named as group A, 110, 101, 011, and 111 are grouped and named as group B; {1, 1}, {1, -1}, {-1, 1}, and {-1, -1} are grouped and named as group C, and {1, 3}, {1, -3}, {-1, 3}, and {-1, -3} are grouped and named as group D;

[0074] (323) The third group of chaotic sequences is used to select the group mapping rule of bits and amplitude values, and the specific rule is as follows:

[0075] m = floor(mod(z·10 16 , 2))

[0076] If m=0, A corresponds to C, and B corresponds to D; if m=1, A corresponds to D, and B corresponds to C.

[0077] (324)The fourth group of chaotic sequences is used to select the mapping rule within the group of bits and amplitude values, and the chaotic encrypted amplitude values are obtained; the specific rule is as follows:

[0078] n = floor(mod(u·10 16 , 24))+1;

[0079] Here, the A→C, B→D mapping rule is taken as an example, and the mapping rule within the group based on chaotic sequence u encryption is listed, and the mapping rule of the other group is similar.

[0080] Table 1 Chaotic CCDM mapping table within the group (A→C)

[0081] n value 000 001 010 100 n value 000 001 010 100 1 1 1 1 -1 -1 1 -1 -1 13 -1 1 1 1 1 -1 -1 -1 2 1 1 1 -1 -1 -1 -1 1 14 -1 1 1 1 -1 -1 1 -1 3 1 1 -1 1 1 -1 -1 -1 15 -1 1 1 -1 1 1 -1 -1 4 1 1 -1 1 -1 -1 1 -1 16 -1 1 1 -1 -1 -1 1 1 5 1 1 -1 -1 1 -1 -1 1 17 -1 1 -1 -1 1 1 1 -1 6 1 1 -1-1 -1 1 1 -1 18 -1 1 -1 -1 1 -1 1 1 7 1 -1 1 1 -1 1 -1 -1 19 -1 -1 1 1 1 -1 -1 1 8 1 -1 1 1 -1 -1 -1 1 20 -1 -1 1 1 -1 1 1 -1 9 1 -1 -1 1 1 1 -1 -1 21 -1 -1 1 -1 1 1 -1 1 10 1 -1 -1 1 -1 -1 1 1 22 -1 -1 1 -1 -1 1 1 1 11 1 -1 -1 -1 1 1 -1 1 23 -1 -1 -1 1 1 1 1 -1 12 1 -1 -1 -1 -1 1 1 1 24 -1 -1 -1 1 1 -1 1 1

[0082] Table 2 Chaotic CCDM mapping table within the group (B→D)

[0083] n value 011 101 110 111 n value 011 101 110 111 1 1 3 1 -3 -1 3 -1 -3 13 -1 3 1 3 1 -3 -1 -3 2 1 3 1 -3 -1 -3 -1 3 14 -1 3 1 3 -1 -3 1 -3 3 1 3 -1 3 1 -3 -1 -3 15 -1 3 1 -3 1 3 -1 -3 4 1 3 -1 3 -1 -3 1 -3 16 -1 3 1 -3 -1 -3 1 3 5 1 3 -1 -3 1 -3 -1 3 17 -1 3 -1 -3 1 3 1 -3 6 1 3 -1 -3 -1 3 1 -3 18 -1 3 -1 -3 1 -3 1 3 7 1 -3 1 3 -1 3 -1 -3 19 -1 -3 1 3 1 -3 -1 3 8 1 -3 1 3 -1 -3 -1 3 20 -1 -3 1 3 -1 3 1 -3 9 1 -3 -1 3 1 3 -1 -3 21 -1 -3 1 -3 1 3 -1 3 10 1 -3 -1 3 -1 -3 1 3 22 -1 -3 1 -3 -1 3 1 3 11 1 -3 -1 -3 1 3 -1 3 23 -1 -3 -1 3 1 3 1 -3 12 1 -3 -1 -3 -1 3 1 3 24 -1 -3 -1 3 1 -3 1 3

[0084] Through step-by-step encryption of two groups of chaotic sequences, the security of data is significantly improved, and the complexity of the system is also relatively low.

[0085] (325)The chaotic encrypted amplitude values are divided into two parts, the first half of the data is sent to the I path, and the second half of the data is sent to the Q path; the I data will be used as the real part of the output data, and the Q path data will be used as the imaginary part of the output data, and the two paths of data are merged using QAM mapping, and finally the PS-16QAM data of the second path is obtained.

[0086] (33)The third path data is directly subjected to constellation mapping;

[0087] (4)The three groups of data are merged, and the fifth group of chaotic sequences is used to perform sequential scrambling on the subcarriers for the last encryption, and finally the secure data after multiple rounds of encryption is obtained; specifically: the three paths of constellation point data are merged, and then the subcarriers are sequentially scrambled; the fifth group of chaotic sequences is used to encrypt the subcarrier sequence according to the rule shown in the following formula; the generated scrambling sequence is as follows:

[0088] Subcarriers new =f w {subcarriers(sort(mod(w n 1))))

[0089] Where subcarriers new , subcarriers represent the subcarrier sequence, f w {} is the rule for scrambling the subcarrier sequence.

[0090] (5) In the receiving end, the demodulation and decryption operation of the encrypted signal is carried out using the inverse process of the sending end, and the ONU with all the keys will decrypt the received information to finally obtain the correct information after decryption.

Claims

1. A transmission method based on Polar codes and chaotic CCDM multi-channel encryption, characterized in that, Includes the following steps: (1) The original data stream is converted into a relatively short multi-channel parallel data stream after serial-parallel processing; (2) After the data undergoes serial-to-parallel transformation, a five-dimensional hyperchaotic system is obtained using a five-dimensional chaotic model; (3) The first chaotic sequence will be divided into three data streams; specifically, the following steps are included: (31) Send the first data to the Polar encoding module and use the second set of chaotic sequences to encrypt the frozen bits to realize constellation mapping; (32) Send the second path to the chaotic CCDM encryption module, use the third and fourth sets of chaotic sequences to perform chaotic CCDM operation, obtain the amplitude value after chaotic encryption, divide these amplitude values ​​into equal number of I paths and Q paths, and realize constellation mapping; (33) The third data path is directly mapped to the constellation; (4) Combine the three sets of data, use the fifth set of chaotic sequence to scramble the subcarrier sequence, perform the last encryption, and finally obtain secure data after multiple rounds of encryption. (5) At the receiving end, the encryption signal is demodulated and decrypted using the reverse process of the sending end. The ONU that has all the keys decrypts the received information and finally obtains the decrypted correct information.

2. The transmission method based on Polar codes and chaotic CCDM multi-channel encryption according to claim 1, characterized in that, The five-dimensional chaotic model described in step (2) is based on the structure of a four-dimensional hyperchaotic system. By introducing new state variables, a five-dimensional hyperchaotic system is obtained, as shown in the following formula: Where x, y, z, w, and v are chaotic sequences generated by the chaotic system; a, b, c, d, e, and f are constants of the model.

3. The transmission method based on Polar codes and chaotic CCDM multi-channel encryption according to claim 1, characterized in that, Step (3) involves dividing the first set of chaotic sequences into three data streams: after performing serial-to-parallel transformation on the original data, several subcarriers are obtained. The first set of chaotic sequences is used to determine which subcarrier leads to which path. The generation rules are as follows: k=floor(mod(x·10 16 ,3)) If k = 0, the path leads to the first path; if k = 1, the path leads to the second path; if k = 2, the path leads to the third path.

4. The transmission method based on Polar codes and chaotic CCDM multi-channel encryption according to claim 1, characterized in that, Step (31) involves sending the first data stream to the Polar encoding module and using the second set of chaotic sequences to encrypt the frozen bits to achieve constellation mapping. Specifically, this includes the following: First, the codeword X using Polar encoding is defined as follows: Where N is the code length, BN is the bit reversal permutation matrix, and Denotes the nth (n = log₂N) Kronecker power of a matrix; Then, a chaotic sequence y is used to determine the frozen bits for each block group; the length of y is equal to the number of block groups. The generation rules are as follows: l frozon =floor(mod(y·10 16 ,2)) Among them, l frozon This indicates the freeze bit, with a value of 0 or 1.

5. The transmission method based on Polar codes and chaotic CCDM multi-channel encryption according to claim 1, characterized in that, Step (32) specifically includes the following steps: (321) Divide the input second channel data into groups of 3 bits. For the PS-16QAM signal, there are two amplitude values: {1,3}. The distribution of the two amplitude values ​​is: P(1) = 3 / 4, P(3) = 1 / 4, that is, the probability of amplitude 1 is 3 / 4; the probability of amplitude 3 is 1 / 4. At the same time, input 8 kinds of 000, 001, 010, 100, 011, 101, 110, 111 bits, and assign the above bits to different amplitude values. That is, 8 different signed amplitude value combinations are needed: {1,1}, {1,-1}, {-1,1}, {-1,-1}, {1,3}, {1,-3}, {-1,3}, {-1,-3}. (322) Divide the above bits data and amplitude value data into the following groups: 000, 001, 010, 100 are grouped together and named Group A; 110, 101, 011, 111 are grouped together and named Group B; {1,1}, {1,-1}, {-1,1}, {-1,-1} are grouped together and named Group C; {1,3}, {1,-3}, {-1,3}, {-1,-3} are grouped together and named Group D. (323) Use the third set of chaotic sequences to select the out-of-group mapping rules for bits and amplitude values. The specific rules are as follows: m=floor(mod(x·10 16 ,2)) If m = 0, A corresponds to C, and B corresponds to D; if m = 1, A corresponds to D, and B corresponds to C. (324) Using the fourth set of chaotic sequences, select the intra-group mapping rules for bits and amplitude values ​​to obtain the amplitude values ​​after chaotic encryption; the specific rules are as follows: n=floor(mod(u·10 16 ,24))+1; (325) Divide the amplitude value after chaotic encryption into two parts, send the first half of the data to the I channel and the second half of the data to the Q channel; the I data will be used as the real part of the output data and the Q channel data will be used as the imaginary part of the output data. Use QAM mapping to merge the two data channels to finally obtain the PS-16QAM data of the second channel.

6. The transmission method based on Polar codes and chaotic CCDM multi-channel encryption according to claim 1, characterized in that, Step (4) specifically involves: merging the three constellation point data, then scrambling the subcarrier order; encrypting the subcarrier sequence using the fifth group of chaotic sequences according to the rules shown in the following formula; the generated scrambling sequence is shown below: Subcarriers new =f w {subcarriers(sort(mod(w n ,1)))} subcarriers new Subcarriers represent the subcarrier sequence, f w {} represents the rule for scrambling subcarrier sequences.

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