Signal transmission method and device based on orthogonal matrix precoding

Abstract

The invention discloses a signal transmission method and device based on orthogonal matrix precoding. The method comprises the steps that four chaotic sequences X, Y, Z and W are generated through a four-dimensional chaotic model according to a key initial value; performing bit interleaving on the original data by using X and W to obtain first data; performing serial-to-parallel conversion and QPSK mapping to obtain a mapping signal; scrambling the subcarriers and symbols of the mapping signals by using Y and Z to obtain encrypted data; carrying out IFFT (Inverse Fast Fourier Transform) on the encrypted data, adding a cyclic prefix, and carrying out parallel-serial conversion to obtain an encrypted data stream; performing binary conversion and serial-parallel conversion on the key initial value to obtain a square matrix K, and shaping the square matrix K by using a public key to obtain a key matrix; performing serial-to-parallel conversion, QPSK mapping, IFFT, cyclic prefix addition and parallel-to-serial conversion on the key matrix to obtain a key stream; and performing linear superposition on the encrypted data stream and the key stream through power distribution to obtain a power division multiplexing orthogonal frequency division multiplexing signal, and transmitting the power division multiplexing orthogonal frequency division multiplexing signal.

Description

Technical Field

[0001] The present application belongs to the field of optical communication technology, and specifically relates to a signal transmission method and device based on orthogonal matrix precoding. Background Art

[0002] The introduction of power division multiplexing (PDM) technology into orthogonal frequency division multiplexing (OFDM) systems may pose security risks. PDM allows multiple signals to be transmitted at different power levels within the same frequency band. This can make low-power signals difficult to distinguish from noise, reducing protection against unauthorized access. If an attacker can use a receiving device to detect a weak signal, they can steal sensitive information from the system. Attackers can also exploit side-channel information in the power signal to infer communication content. By analyzing changes in signal power during transmission, attackers may be able to recover portions of encrypted data, or even infer and decrypt it. OFDM systems that incorporate PDM use multi-stage demodulation at the receiver end. Low-power signals must be demodulated to recover high-power signals before being recovered. If the high-power signal is not adequately encrypted, its content could be obtained by an eavesdropper, allowing them to decrypt low-power user data. Physical layer security is also challenged. Attackers could exploit certain physical layer characteristics, such as location attacks and directional jamming, to obtain internal system information or disrupt normal operation. This requires communication systems to take more detailed security measures when designing encryption to ensure the robustness of the system and the confidentiality of data.

[0003] Existing encryption schemes are primarily categorized into two main categories: network-layer encryption and physical-layer encryption. Network-layer encryption schemes, such as those using various security protocols, can provide a certain degree of security, but as the number of users increases, key management challenges and security risks become increasingly prominent. Physical-layer optical signal encryption schemes are currently widely adopted and include quantum key distribution, optical time-domain encryption, optical frequency encryption, and phase-coded encryption. Traditional physical-layer security technologies often employ single-dimensional encryption or scrambling mechanisms, such as bit interleaving based on pseudorandom sequences and scrambling algorithms using finite-order chaotic maps. These techniques struggle to cope with increasingly complex channel environments and eavesdropping attacks. Existing research has shown that while traditional bit interleaving can improve robustness against burst errors, it lacks a dynamic key association mechanism, limiting its security dimension. Conventional chaotic encryption systems, which often employ a single-layer scrambling structure, face theoretical bottlenecks in key space and plaintext sensitivity. Due to the limitations of these techniques, chaotic encryption technology has found applications in various fields, thanks to its high sensitivity to initial conditions, randomness, and vast key space. However, most existing chaotic encryption schemes assume that the receiver already knows the key. This key is often the initial value of the chaotic system, and this initial value is fixed. In the event of an illegal brute force attack, these schemes lack an emergency response mechanism, which can easily lead to persistent security threats and losses. Therefore, to further improve system security, dynamic keys and secure key transmission mechanisms must be implemented. Summary of the Invention

[0004] Purpose: In view of at least one of the above technical problems, the present application provides a signal transmission method and device based on orthogonal matrix precoding. While using a chaotic system to perform multi-dimensional perturbations on the original signal, the key is matrix-shaped to generate a dynamic key before key transmission, and then the encrypted data stream and the shaped key stream are merged at the physical layer through power division multiplexing and superposition transmission. In this way, the legitimate receiving end can accurately extract the key for demodulation, while the illegal receiving end cannot accurately calculate the key without knowing the public key and the matrix shaping method. This solves the pain points of key staticity and transmission exposure, and effectively ensures the security of the key transmission process.

[0005] The technical solutions adopted in this application are:

[0006] In a first aspect, the present application provides a signal transmission method based on orthogonal matrix precoding, comprising:

[0007] Get the original data, initial key value and public key;

[0008] Generate four chaotic sequences X, Y, Z, and W through a four-dimensional chaotic model according to the initial value of the key;

[0009] Using X and W to perform bit interleaving on the original data to obtain first data; performing serial-to-parallel conversion and QPSK mapping on the first data to obtain a mapped signal; using Y and Z to scramble the subcarriers and symbols of the mapped signal to obtain encrypted data; performing IFFT on the encrypted data, adding a cyclic prefix, and performing parallel-to-serial conversion to obtain an encrypted data stream;

[0010] The initial key value is converted into binary and serial-to-parallel to construct a square matrix K, and the public key is used to reshape the square matrix K to obtain a key matrix; the key matrix is ​​subjected to serial-to-parallel conversion, QPSK mapping, IFFT, adding a cyclic prefix, and parallel-to-serial conversion to obtain a key stream;

[0011] The encrypted data stream and key stream are linearly superimposed through power distribution to obtain a power division multiplexing orthogonal frequency division multiplexing signal;

[0012] The power division multiplexing orthogonal frequency division multiplexing signal is transmitted.

[0013] In a second aspect, the present application provides a signal transmission device based on orthogonal matrix precoding, including a processor and a storage medium;

[0014] The storage medium is used to store instructions;

[0015] The processor is configured to operate according to the instructions to perform the method according to the first aspect.

[0016] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which implements the method described in the first aspect when the computer program is executed by a processor.

[0017] Beneficial Effects: The signal transmission method and device based on orthogonal matrix precoding provided in this application have the following advantages: Unlike previous key transmission methods, this scheme transforms the key into a dynamic encryption key through matrix shaping, and the shaped key is transmitted. By employing a four-dimensional Chen chaotic system, the original data is distributed as a high-power signal after multi-dimensional perturbations of bit interleaving, subcarriers, and symbols, while the key is distributed as a low-power signal after matrix shaping. Superposition coding is used to superimpose the two different power signals. Because the key exhibits complexity and variability after matrix shaping, even if an attacker possesses partial information, it is difficult to deduce the key matrix. Specifically, regarding key processing, unlike previous key transmission methods, before key transmission, the key matrix is ​​first serial-to-parallel converted to form a square matrix. The key matrix is ​​then processed using the public key and a series of matrix operations to convert the original key into a new key for transmission. The shaped key matrix is ​​transmitted, and the original key is only known at the receiving end through the public key and matrix shaping process. This process enables efficient and secure communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a flow chart of a signal transmission method based on orthogonal matrix precoding according to an embodiment of the present application;

[0019] Figure 2 Schematic diagram of a phase diagram of a four-dimensional Chen chaos model according to an embodiment of the present application;

[0020] Figure 3 Schematic diagram of a bit interleaving process according to an embodiment of the present application;

[0021] Figure 4 A schematic diagram of binary conversion of the initial key value according to an embodiment of the present application;

[0022] Figure 5 Schematic diagram of a key matrix shaping process according to an embodiment of the present application;

[0023] Figure 6 Schematic diagram of the demodulation process at the receiving end according to one embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application.

[0025] In the description of this application, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0026] Throughout the description of this application, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0027] The term "and / or" simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " generally indicates an "or" relationship between the related objects.

[0028] Embodiment 1: This embodiment provides a signal transmission method based on orthogonal matrix precoding, such as Figure 1 Shown, including:

[0029] S1. Obtain original data, initial key value and public key;

[0030] S2. Generate four chaotic sequences X, Y, Z, and W through a four-dimensional chaotic model based on the initial value of the key;

[0031] S3. Use X and W to bit-interleave the original data to obtain first data; perform serial-to-parallel conversion and QPSK mapping on the first data to obtain a mapped signal; use Y and Z to scramble the subcarriers and symbols of the mapped signal to obtain encrypted data; perform IFFT on the encrypted data, add a cyclic prefix, and perform parallel-to-serial conversion to obtain an encrypted data stream;

[0032] S4. Perform binary conversion and serial-to-parallel conversion on the initial key value to obtain a square matrix K, and use the public key to reshape the square matrix K to obtain a key matrix; perform serial-to-parallel conversion, QPSK mapping, IFFT, add a cyclic prefix, and perform parallel-to-serial conversion on the key matrix to obtain a key stream;

[0033] S5. Linearly superimpose the encrypted data stream and the key stream through power distribution to obtain a power division multiplexing orthogonal frequency division multiplexing PD-OFDM signal;

[0034] S6. Transmit the power division multiplexing orthogonal frequency division multiplexing signal.

[0035] In some embodiments, in step S2, four chaotic sequences X, Y, Z, and W are generated by a four-dimensional chaotic model according to the initial value of the key, including:

[0036] The four-dimensional chaos model adopts the four-dimensional Chen chaos model, which is expressed as:

[0037] ,

[0038] Among them, X, Y, Z, W are state variables, a, b, c, d, e, m, g, k are system parameters, represents the number of iterations, 、 、 Respectively indicate the The chaotic sequence X, Y, Z obtained by iteration, 、 、 、 Respectively indicate the The chaotic sequence X, Y, Z, W obtained by iteration.

[0039] Furthermore, in this embodiment, the initial values ​​of the keys x0, y0, z0, and w0 of the four-dimensional Chen chaos model are set to 0.3512345678901234, 0.2198765432109876, 0.4356789012345678, and 0.8901234567890123, respectively. This partial differential equation can be solved by the fourth-order Runge-Kutta method, and the phase diagram of the four-dimensional Chen chaos model is as follows: Figure 2 As shown. Figure 2 It can be seen that the value ranges of the four chaotic sequences X, Y, Z, and W of the four-dimensional Chen chaos model are (-78, 86), (-71, 67), (-118, 112), and (-8, 8), respectively.

[0040] The original data is a randomly generated binary data stream representing the user's information. Applying chaotic sequences X and W to the bit interleaving process primarily leverages the randomness and sensitivity of chaotic sequences to alter the order of the original data bits, disrupting adjacent bit positions and thus increasing the signal's concealment and anti-interference capabilities.

[0041] In some embodiments, in step S3, bit-interleaving the original data using X and W to obtain the first data includes:

[0042] Generate a first chaotic index sequence and a second chaotic index sequence according to X and W respectively;

[0043] X, W both have N elements. First, linear mapping is performed on X, W to normalize them to the interval (0, 1); then , Normalize and convert into an index suitable for bit position, that is, , Each value in maps to an integer position.

[0044] ;

[0045] ;

[0046] in, 、 is the chaotic sequence X, W is the normalized sequence, N is the bit length of the original data; floor(-) is the rounding function, 、 They are the first chaotic index sequence and the second chaotic index sequence respectively;

[0047] Based on the bit interleaving rule, the first chaotic index sequence is used The original data is interleaved and rearranged in the first round to obtain rearranged data, and then the second chaotic index sequence is used to The rearranged data is subjected to a second round of interleaving and rearrangement to obtain the first data, thereby achieving a double bit interleaving process for the original data.

[0048] Furthermore, if Figure 3 As shown, the bit interleaving rules include:

[0049] The Ath bit data of the original data is rearranged according to the value B of the Ath sequence corresponding to the first chaotic index sequence, and all N bits of the original data are rearranged to obtain rearranged data; wherein the Ath bit data of the original data is located at the Cth bit position of the rearranged data after the first round of interleaving and rearrangement, where C=1+B;

[0050] The Ath bit data of the rearranged data is rearranged according to the value B of the Ath sequence corresponding to the second chaotic index sequence, and all N bits of the rearranged data are rearranged to obtain the first data; wherein the Ath bit data of the rearranged data is located at the Cth bit position of the first data after the second round of interleaving and rearrangement, and C=1+B.

[0051] like Figure 3 As shown, the first bit data "1" is rearranged according to the first sequence "4" corresponding to the chaotic index sequence, that is, the first bit data "1" is arranged to the "1+4=5" position. Similarly, the second bit data is rearranged in sequence until the Nth bit data is rearranged.

[0052] In some embodiments, in step S3, scrambling the subcarriers and symbols of the mapped signal using Y and Z to obtain encrypted data includes:

[0053] Sort Y in ascending order and then take the inverse to generate a matrix, and then multiply it with Y to generate the first scrambled matrix Y1; Sort Z in ascending order and then take the inverse to generate a matrix, and then multiply it with Z to generate the second scrambled matrix Z1;

[0054] ;

[0055] ;

[0056] Among them, sort(-) is the ascending sort function;

[0057] Extract the positions of 1 in the first scrambled matrix Y1 and the second scrambled matrix Z1 respectively to generate the first scrambled sequence and the second scrambled sequence;

[0058] The subcarriers and symbols of the mapping signal are scrambled using the first scrambling sequence and the second scrambling sequence respectively to obtain encrypted data.

[0059] Specifically, the mapped signal is subjected to a column-wise permutation (subcarrier) based on each column element of the first scrambling sequence, i.e., rearranged according to the elements in the first scrambling sequence. Simultaneously, the mapped signal is subjected to a row-wise permutation (symbol) based on the transposition of the second scrambling sequence. This completes the scrambling of the subcarriers and symbols, resulting in encrypted data.

[0060] This application designs a new form of key protection. This involves shaping the key before transmission, so that the shaped key is transmitted in the system. This process effectively protects the initial key. Even if it is cracked during transmission, the attacker cannot extract the key without knowing the public key and the specific matrix shaping process, thus effectively protecting the key. The specific shaping process increases the complexity of the operation and improves security by introducing matrix addition, matrix multiplication, matrix transposition, and submatrix rotation.

[0061] First, convert the key of the chaotic system, i.e. the initial value of the key of the chaotic model, into a binary number, such as Figure 4 As shown, the key has four initial key values. Each initial key value consists of a 16-digit decimal number, including the integer part, and has a total of 256 bits after conversion to binary. To facilitate subsequent calculations, the matrix after serial-to-parallel conversion is a 16×16 square matrix K. A random 16×16 self-inverse matrix P is generated through code as the public key, and the self-inverse matrix must meet two conditions: (1) it is a reversible matrix; (2) the matrix and its inverse matrix are completely equal.

[0062] In some embodiments, in step S4, the initial key value is converted into binary and serial-to-parallel to obtain a square matrix K, and the public key is used to reshape the square matrix K to obtain a key matrix, such as Figure 5 As shown, specifically including:

[0063] Convert the initial key value into binary and serial-to-parallel to obtain a 16×16 square matrix K;

[0064] Generate a random 16×16 self-inverse matrix P as the public key;

[0065] Divide the square matrix K into four 8×8 sub-matrices, denoted as the first sub-matrix K 11 , the second submatrix K 12 , the third submatrix K 21 , the fourth submatrix K 22 ; Rotate and permute the four sub-matrices to obtain matrix A (that is, matrix K rotated ); The rotation permutation rule is to transform K 11 Move to the upper right corner, K12 Move to the lower right corner, K 21 Move to the upper left corner, K 22 Move to the lower left corner;

[0066] Perform matrix multiplication and modulo 2 operation on matrix A and self-inverse matrix P to obtain matrix B;

[0067] B=(A×P) mod 2 ; Specifically, for each element B ij , which computes the dot product of the i-th row of A and the j-th row of P, and then takes the result modulo 2.

[0068] Perform a modulo-2 addition operation on matrix B and the self-inverse matrix P to obtain matrix C; perform a transpose operation on matrix C to obtain matrix D;

[0069] C=(B+P) mod2 ;D=C T ;

[0070] Perform element-by-element XOR operation on matrix D and self-inverse matrix P to obtain the key matrix K reshaped , that is, K reshaped =D⊕P.

[0071] The complete matrix shaping process and inverse process are as follows:

[0072]

[0073]

[0074] in represents an exclusive-or operation. The subtraction operation during the inverse shaping process is also a modulo-2 subtraction operation, and an inverse submatrix rotation process is also involved. After matrix shaping, the key becomes a 16×16 0-1 matrix, that is, a 256-bit key matrix. The 256-bit key matrix after shaping is then transmitted.

[0075] Both the encrypted data and the reshaped key matrix undergo an inverse Fourier transform (IFFT) to convert both signals from the frequency domain to the time domain. A cyclic prefix is ​​added to the OFDM signal in the time domain to prevent inter-symbol interference. Parallel-to-serial conversion then transforms the two signals into data streams that can be loaded into an arbitrary waveform generator. Finally, high and low power allocations are applied to the two signals, followed by linear superposition, which is then transmitted to the receiver.

[0076] In some embodiments, in step S5, linearly superimposing the encrypted data stream and the key stream through power distribution to obtain a power division multiplexing orthogonal frequency division multiplexing signal includes:

[0077] ;

[0078] ;

[0079] ;

[0080] in, is the power ratio of the encrypted data stream, is the power ratio of the key stream, To encrypt data streams, is the key stream, It is the power division multiplexing orthogonal frequency division multiplexing signal obtained by linear superposition.

[0081] This invention uses power division multiplexing (PDM) technology to superimpose encrypted data stream S1 and key stream S2 in the digital domain. We define S1 as a high-power signal and S2 as a low-power signal. Since the OFDM system's transmitter superimposes signals from different users, the receiver distinguishes between user signals based on their power. Therefore, the power distribution ratio (PDR) between different users at the transmitter directly affects the receiver's demodulation performance and determines the system's transmission rate. PDR is defined as P1 / P2. To achieve optimal interference cancellation, this invention sets the PDR to a fixed value of 4.

[0082] The transmitting end uses superposition coding technology, and the receiving end uses serial interference elimination algorithm. Figure 6 As shown in the figure, the receiver first sorts the received data to determine the order of the received data. The higher the power, the easier it is for the receiver to identify. High-power data streams are decoded first, and low-power signals are treated as noise. Channel estimation is used to equalize the channel, and after demodulation, the encrypted high-power signal is obtained. Subsequently, the signal is remodulated based on the channel response generated by the channel estimation, and the remodulated signal is subtracted from the original signal to generate a new signal. This new signal is then subjected to channel estimation, channel equalization, and demodulation to recover the low-power signal, which is the matrix-shaped key signal. The original key information is then calculated through the public key and inverse matrix shaping process. This key information is used as the initial key value to drive the four-dimensional Chen chaotic system to decrypt the encrypted high-power signal, thereby recovering the original data.

[0083] In summary, the present invention proposes a signal transmission method based on orthogonal matrix precoding, which significantly improves the security of data through multiple encryption using chaotic encryption technology under OFDM transmission, and prevents data from being stolen or tampered with during transmission. Even if an illegal receiving end successfully cracks part of the key information, it will not be able to correctly restore the signal without obtaining the complete key. At the legal receiving end, due to the known public key and the matrix shaping method, the initial signal can still be correctly restored even when the signal-to-noise ratio is very poor. Compared with the traditional key transmission method, the present invention adopts another processing method for the key, which more effectively protects the transmission of the key, and the key will not affect the transmission performance of the signal itself during the transmission process. Even if part of the key information is cracked, this part of the information cannot be used to restore the original signal.

[0084] Embodiment 2: Based on Embodiment 1, this embodiment provides a signal transmission device based on orthogonal matrix precoding, including a processor and a storage medium;

[0085] The storage medium is used to store instructions;

[0086] The processor is configured to operate according to the instructions to execute the method according to embodiment 1.

[0087] Example 3: Based on Example 1, this example provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the method described in Example 1 is implemented.

[0088] Example 4: Based on Example 1, this example provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the method described in Example 1 when executing the computer program.

[0089] Example 5: Based on Example 1, this example provides a computer program product, including a computer program. When the computer program is executed by a processor, the method described in Example 1 is implemented.

[0090] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0091] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram and the combination of processes and / or blocks in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0092] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0093] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0094] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A signal transmission method based on orthogonal matrix precoding, characterized in that: include: Get the original data, initial key value and public key; Generate four chaotic sequences X, Y, Z, and W through a four-dimensional chaotic model according to the initial value of the key; Using X and W to perform bit interleaving on the original data to obtain first data; performing serial-to-parallel conversion and QPSK mapping on the first data to obtain a mapped signal; using Y and Z to scramble the subcarriers and symbols of the mapped signal to obtain encrypted data; performing IFFT on the encrypted data, adding a cyclic prefix, and performing parallel-to-serial conversion to obtain an encrypted data stream; Perform binary conversion and serial-to-parallel conversion on the initial key value to obtain a square matrix K, and use the public key to reshape the square matrix K to obtain a key matrix; Perform serial-to-parallel conversion, QPSK mapping, IFFT, adding a cyclic prefix, and parallel-to-serial conversion on the key matrix to obtain the key stream; The encrypted data stream and key stream are linearly superimposed through power distribution to obtain a power division multiplexing orthogonal frequency division multiplexing signal; The power division multiplexing orthogonal frequency division multiplexing signal is transmitted.

2. The method according to claim 1, characterized in that The initial key value is converted into binary and serial-to-parallel to construct a square matrix K. The public key is used to reshape the square matrix K to obtain the key matrix, including: Convert the initial key value into binary and serial-to-parallel to obtain a 16×16 square matrix K; Generate a random 16×16 self-inverse matrix P as the public key; Divide the square matrix K into four 8×8 sub-matrices, denoted as the first sub-matrix K 11 , the second submatrix K 12 , the third submatrix K 21 , the fourth submatrix K 22 ; Rotate and permute the four sub-matrices to obtain matrix A; the rotation and permute rule is to replace K 11 Move to the upper right corner, K 12 Move to the lower right corner, K 21 Move to the upper left corner, K 22 Move to the lower left corner; Perform matrix multiplication and modulo 2 operation on matrix A and self-inverse matrix P to obtain matrix B; Perform a modulo-2 addition operation on matrix B and the self-inverse matrix P to obtain matrix C; perform a transpose operation on matrix C to obtain matrix D; Perform element-by-element XOR operation on matrix D and self-inverse matrix P to obtain the key matrix.

3. The method according to claim 1, characterized in that According to the initial value of the key, four chaotic sequences X, Y, Z, and W are generated through a four-dimensional chaotic model, including: The four-dimensional chaos model adopts the four-dimensional Chen chaos model, which is expressed as: ， Among them, X, Y, Z, W are state variables, a, b, c, d, e, m, g, k are system parameters, represents the number of iterations, 、 、 Respectively indicate the The chaotic sequence X, Y, Z obtained by iteration, 、 、 、 Respectively indicate the The chaotic sequence X, Y, Z, W obtained by iteration.

4. The method according to claim 3, characterized in that The initial values ​​of the keys x0, y0, z0, and w0 of the four-dimensional Chen chaotic model are 0.3512345678901234, 0.2198765432109876, 0.4356789012345678, and 0.8901234567890123, respectively; And / or, the value ranges of the four chaotic sequences X, Y, Z, and W of the four-dimensional Chen chaotic model are (-78, 86), (-71, 67), (-118, 112), and (-8, 8), respectively.

5. The method according to claim 1, wherein Bit-interleaving the original data using X and W to obtain first data includes: Generate a first chaotic index sequence and a second chaotic index sequence according to X and W respectively; ； ； in, 、 is the chaotic sequence X, W is the normalized sequence, N is the bit length of the original data; floor(-) is the rounding function, 、 They are the first chaotic index sequence and the second chaotic index sequence respectively; Based on the bit interleaving rule, the first chaotic index sequence is used The original data is interleaved and rearranged in the first round to obtain rearranged data, and then the second chaotic index sequence is used to A second round of interleaving and rearrangement is performed on the rearranged data to obtain first data.

6. The method according to claim 5, characterized in that The bit interleaving rules include: The Ath bit data of the original data is rearranged according to the value B of the Ath sequence corresponding to the first chaotic index sequence, and all N bits of the original data are rearranged to obtain rearranged data; wherein the Ath bit data of the original data is located at the Cth bit position of the rearranged data after the first round of interleaving and rearrangement, where C=1+B; The Ath bit data of the rearranged data is rearranged according to the value B of the Ath sequence corresponding to the second chaotic index sequence, and all N bits of the rearranged data are rearranged to obtain the first data; wherein the Ath bit data of the rearranged data is located at the Cth bit position of the first data after the second round of interleaving and rearrangement, and C=1+B.

7. The method according to claim 1, characterized in that Using Y and Z to scramble the subcarriers and symbols of the mapped signal to obtain encrypted data, including: Sort Y in ascending order and then take the inverse to generate a matrix, and then multiply it with Y to generate the first scrambled matrix Y1; Sort Z in ascending order and then take the inverse to generate a matrix, and then multiply it with Z to generate the second scrambled matrix Z1; ； ； Among them, sort(-) is the ascending sort function; Extract the positions of 1 in the first scrambled matrix Y1 and the second scrambled matrix Z1 respectively to generate the first scrambled sequence and the second scrambled sequence; The subcarriers and symbols of the mapping signal are scrambled using the first scrambling sequence and the second scrambling sequence respectively to obtain encrypted data.

8. The method according to claim 1, characterized in that The encrypted data stream and key stream are linearly superimposed through power distribution to obtain a power division multiplexing orthogonal frequency division multiplexing signal, including: ； ； ； in, is the power ratio of the encrypted data stream, is the power ratio of the key stream, To encrypt data streams, is the key stream, It is the power division multiplexing orthogonal frequency division multiplexing signal obtained by linear superposition.

9. A signal transmission device based on orthogonal matrix precoding, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the method according to any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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