Physical layer security communication method and device based on constellation probability shaping and quantum noise encryption

Abstract

The invention relates to the technical field of physical layer security communication, in particular to a physical layer security communication method and device based on constellation probability shaping and quantum noise encryption. Comprising the following steps of: performing quantum noise encryption processing on 1-bit data and an n-bit key of original binary data; performing constellation probability shaping coding on the encrypted n-bit data to obtain (n + m)-bit data; converting the data into an analog signal, and amplifying and transmitting the analog signal; amplifying and filtering the received analog signal, and recovering the analog signal into a digital signal; performing constellation probability shaping decoding on the (n + m) bit data, and recovering the (n + m) bit data into n bit data; and performing quantum noise decryption on the n-bit data to obtain 1-bit original binary data. According to the design, high-speed, accurate and safe transmission of data can be realized; the constellation probability shaping technology and the quantum noise encryption technology are combined, the communication capacity can be improved, and the communication safety can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of physical layer security communication, and in particular to a physical layer security communication method and device based on constellation probability shaping and quantum noise encryption. Background Art

[0002] With the advent of the 6G era, data is growing explosively, and more and more sensitive data is transmitted through the network. Therefore, people have put forward higher requirements for the security of communication systems. At present, information encryption is mainly implemented at the data layer, and physical layer encryption technology is still in the laboratory stage. Therefore, it is considered to combine probability shaping technology and quantum noise encryption technology to further improve the security of communication systems.

[0003] In order to improve the security of the communication system, the data layer and the physical layer can be encrypted separately. The data layer encryption technology mainly includes: symmetric encryption, asymmetric encryption, elliptic curve encryption, etc. The physical layer encryption technology mainly includes: quantum noise encryption, channel feature extraction, channel authentication, etc. Quantum noise encryption technology has the advantages of simple implementation and high security.

[0004] Constellation probability shaping is to remap the signal after encoding, change the distribution probability of the constellation points, make the signal's spectrum characteristics more adaptable to the transmission characteristics of the channel, and improve the channel spectrum utilization. However, no application combining the above two technologies has been found so far.

[0005] Constellation probability shaping technology can improve the channel spectrum utilization, but it does not have encryption function. Quantum noise encryption technology can encrypt data, but the signals distributed at the edge of the constellation diagram are easy to be cracked. How to combine the advantages of these two technologies to meet the needs of large-capacity secure communication in optical fiber channels is an urgent problem to be solved. In view of this, we propose a physical layer secure communication method and device based on constellation probability shaping and quantum noise encryption. Summary of the invention

[0006] The object of the present invention is to provide a physical layer secure communication method and device based on constellation probability shaping and quantum noise encryption to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, one of the objectives of the present invention is to provide a physical layer security communication method based on constellation probability shaping and quantum noise encryption, comprising the following steps:

[0008] S1. The original binary data is processed synchronously and in parallel in a single channel or divided into multiple channels. 1 bit of data and n bit of key are respectively taken from each channel for quantum noise encryption. The 1 bit of data is XORed with the lowest bit of the n bit key. The obtained data replaces the highest bit of the n bit key to obtain the encrypted n bit data. Finally, the encrypted data of each channel is obtained.

[0009] S2, respectively performing constellation probability shaping encoding on each encrypted n-bit data to obtain (n+m)-bit data, where m represents the number of bits added to achieve constellation probability shaping; and finally obtaining each data after constellation probability shaping;

[0010] S3, converting each channel of data into an analog signal, amplifying and transmitting the analog signal;

[0011] S4, after receiving the analog signal, amplify and filter the analog signal, and restore the analog signal to digital signals of various channels;

[0012] S5, performing constellation probability shaping decoding on each channel data of (n+m) bits, and restoring them into each channel data of n bits respectively;

[0013] S6. Perform quantum noise decryption on each channel of n-bit data respectively to obtain 1-bit original binary data; finally, restore all the original binary data.

[0014] As a further improvement of the technical solution, in step S1, the method of dividing the original binary data into multiple data at least includes: parity bit division, equal bit division, equal byte division, and adaptive division;

[0015] The selection method of the n-bit key for each data path includes at least: random generation, based on hardware physical characteristics, pseudo-random number generation algorithm, pre-shared key, key negotiation protocol;

[0016] The process of quantum noise encryption includes the following steps:

[0017] Input: 1 bit of data for each channel, denoted as D, n bit key, denoted as K = k1, k2, k3, ..., k n ;

[0018] S1.1. Compare 1 bit of data D with the lowest bit k of the n bit key n Perform XOR operation to get

[0019] S1.2, replace the highest bit k1 of the n-bit key with E to obtain the encrypted n-bit data, that is, K′=E, k2, k3, ..., kn ;

[0020] Output: Encrypted n-bit data K′.

[0021] As a further improvement of the technical solution, in step S2, performing constellation probability shaping coding on the encrypted n-bit data specifically includes the following steps:

[0022] When 64QAM modulation is used, the probability of each point appearing when the constellation points are evenly distributed is P; when constellation probability shaping coding is performed, it is expected that the probability of the constellation points close to the center will be higher, while the probability of the constellation points far from the center will be lower;

[0023] Input: encrypted n-bit data K′;

[0024] S2.1. Determine the probability model of constellation point distribution; define a probability distribution function f(x), where x represents the distance from the constellation point to the center of the constellation diagram; f(x) can be designed according to actual needs, so that the closer the constellation point is to the center, the higher the probability corresponding to it;

[0025] S2.2, according to the input n bit data K′, calculate its corresponding constellation point index i through a certain mapping rule;

[0026] S2.3, according to the constellation point index i and the probability distribution function f(x), determine the probability P of the constellation point appearing in the shaped constellation diagram i ;

[0027] S2.4. According to the determined probability P i , remap the constellation points; specifically, according to the probability P i Randomly select one of all possible constellation points as the final mapping result;

[0028] S2.5, repeat steps S2.2-S2.4 until constellation probability shaping coding is completed for all n-bit data;

[0029] Output: (n+m) bit data after constellation probability shaping encoding, where m represents the number of bits added to achieve constellation probability shaping.

[0030] As a further improvement of the technical solution, in step S3, the method of converting the data into an analog signal using quadrature amplitude modulation (QAM) specifically includes the following steps:

[0031] Input: (n+m) bit data after constellation probability shaping coding, denoted as s(n);

[0032] A3.1. Group the input data according to the modulation order;

[0033] A3.2. For each set of data, convert it into the corresponding constellation point coordinates (I, Q) according to the constellation mapping rule of 64QAM;

[0034] A3.3. Generate a carrier signal; use a sine wave as a carrier signal to generate an in-phase (I) carrier and a quadrature (Q) carrier respectively;

[0035] A3.4. Multiply the coordinates of the constellation point (I, Q) by the in-phase carrier and the quadrature carrier respectively to obtain the in-phase component I×sin(ωt) and the quadrature component Q×cos(ωt), where ω represents the carrier angular frequency and t represents time;

[0036] A3.5. Add the in-phase component and the quadrature component to obtain the modulated analog signal s(t)=I×sin(ωt)+Q×cos(ωt);

[0037] Output: modulated analog signal s(t);

[0038] The analog signal is amplified by a linear power amplifier, which specifically includes the following steps:

[0039] Input: modulated analog signal s(t);

[0040] B3.1. Set the gain parameter G of the amplifier. The gain represents the amplitude ratio of the output signal to the input signal.

[0041] B3.2. Calculate the amplified analog signal r(t) = G × s(t), that is, the input signal multiplied by the gain value;

[0042] B3.3. Perform power detection on the amplified signal to ensure that its output power does not exceed the rated power of the transmitter and complies with relevant laws, regulations and standards;

[0043] B3.4. Monitor and adjust the linearity of the amplified signal;

[0044] B3.5. Output and transmit the amplified analog signal that meets the requirements;

[0045] Output: amplified analog signal r(t).

[0046] As a further improvement of the technical solution, in step S4, the analog signal is amplified by a low noise amplifier LNA, which specifically includes the following steps:

[0047] Input: received amplified analog signal r(t);

[0048] A4.1. Set the initial gain value G0 of LNA. The selection of gain value needs to consider factors such as the strength of the received signal and the dynamic range of the subsequent processing circuit.

[0049] A4.2. Input the received analog signal r(t) into the LNA to obtain the amplified signal r′(t)=G0×r(t);

[0050] A4.3. Perform noise monitoring on the amplified signal; evaluate the noise level introduced by the LNA by measuring parameters such as the noise power of the amplifier output signal;

[0051] A4.4. Dynamically adjust the gain of LNA according to the noise monitoring results; if the noise level is too high, the gain can be appropriately reduced to reduce the impact of noise; if the signal strength is weak, the gain can be appropriately increased to improve the signal-to-noise ratio; the gain adjustment can be achieved using the Automatic Gain Control (AGC) algorithm;

[0052] A4.5. During the amplification process, the frequency response of the signal needs to be compensated to ensure that a relatively uniform amplification effect can be obtained over the entire frequency range of the received signal. This can be achieved by introducing a frequency compensation circuit into the amplifier or by using digital signal processing technology.

[0053] A4.6. Output the analog signal after amplification, noise control and frequency compensation for subsequent filtering and other operations;

[0054] Output: The amplified analog signal r′(t) has an improved signal-to-noise ratio and optimized frequency response characteristics;

[0055] The digital filter is used to filter the analog signal, which includes the following steps:

[0056] Input: amplified analog signal r′(t);

[0057] B4.1. Analog-to-digital conversion (ADC): The analog signal r′(t) is converted into a digital signal r′(n) through an analog-to-digital converter, where n represents a discrete time index;

[0058] B4.2. Filter design: Design a suitable digital filter based on the required filtering characteristics and cutoff frequency parameters;

[0059] B4.3. Filtering operation: Input the digital signal r′(n) into the designed digital filter for filtering operation:

[0060] The filtering operation can be expressed as:

[0061]

[0062] Wherein, y(n) represents the digital signal after filtering, h(k) is the coefficient sequence of the filter, k represents the index of the filter coefficient, k=0, 1, 2, ..., N-1, N is the filter order, and each coefficient h(k) corresponds to the weighted value of the input signal r′(nk) with different time delays;

[0063] B4.4. Output the filtered signal: obtain the filtered digital signal y(n);

[0064] Output: filtered digital signal y(n).

[0065] As a further improvement of the technical solution, in step S5, the process of performing constellation probability shaping decoding on the data includes the following steps:

[0066] Input: (n+m) bits of data restored to digital signal after demodulation, denoted as D sh aped =y(n);

[0067] S5.1. Determine the constellation point distribution model: According to the constellation point distribution probability model used in constellation probability shaping coding, obtain the occurrence probability information of each constellation point in the shaped constellation diagram;

[0068] S5.2, constellation point mapping: the input (n+m) bit data D sh aped According to certain rules, it is converted into a point coordinate in the constellation diagram (I sh aped , Q sh aped ); This rule corresponds to the mapping rule in constellation probability shaping coding, but in the opposite direction;

[0069] S5.3, Probability calculation and judgment: For the obtained constellation point coordinates (I sh aped , Q sh aped ), calculate the coordinates of each possible constellation point in the original uniformly distributed constellation diagram (I original , Q original ) on the probability;

[0070] According to the calculated probability, the coordinates of the constellation point with the largest probability are selected as the decoding result;

[0071] s5.4, bit conversion: select the constellation point coordinates (I original , Q original ) Convert back to n bit data according to the original bit mapping rule of modulation;

[0072] S5.5, repeat steps S5.2-S5.4: perform the above decoding operations on all (n+m) bit data in sequence until all n bit data are recovered;

[0073] Output: the recovered n-bit data, i.e. the original data after constellation probability shaping and decoding.

[0074] As a further improvement of the technical solution, in step S6, the process of performing quantum noise decryption on the data includes the following steps:

[0075] Input: n-bit data decoded after constellation probability shaping, denoted as K″;

[0076] S6.1. Extract the highest bit and the lowest bit of the encrypted key: extract the highest bit (denoted as E′) and the lowest bit (denoted as k′n) from the input encrypted n-bit data K″;

[0077] S6.2, XOR operation: extract the highest bit E' and the lowest bit k' n Perform XOR operation to get 1 bit of original data

[0078] S6.3, restore the original key: combine the remaining (n-1) bits of the encrypted key except the highest bit with the 1 bit of the original data obtained in step S6.2 to obtain the restored original n-bit key K0=D′, k′2, k′3, ..., k′ n ;

[0079] Output: 1-bit data D′ of the restored original binary data and the original n-bit key K0.

[0080] The second object of the present invention is to provide a physical layer security communication device based on constellation probability shaping and quantum noise encryption, which is used to implement the steps of the above-mentioned physical layer security communication method based on constellation probability shaping and quantum noise encryption, including a quantum noise encryption / decryption module, a constellation probability shaping encoding / decoding module, a modulator, a transmitter, a channel, a receiver and a demodulator that are sequentially connected in signal connection;

[0081] The quantum noise encryption / decryption module includes a quantum noise encryption submodule and a quantum noise decryption submodule;

[0082] The constellation probability shaping encoding / decoding module includes a constellation probability shaping encoding submodule and a constellation probability shaping decoding submodule.

[0083] As a further improvement of the technical solution, the quantum noise encryption / decryption module is used to perform encryption / decryption operations on a binary data stream; wherein: the quantum noise encryption submodule is used to encrypt the binary data stream; the quantum noise decryption submodule is used to perform an inverse operation on the data encrypted by the quantum noise encryption submodule to decrypt the data, so as to restore the original binary data;

[0084] The constellation probability shaping encoding / decoding module is used to perform encoding / decoding operations on the encrypted data; wherein: the constellation probability shaping encoding submodule is used to encode the encrypted data; the constellation probability shaping decoding submodule is used to perform inverse operations on the data encoded by the constellation probability shaping encoding submodule to achieve decoding, restore the encrypted data, and restore the uniform distribution characteristics of the constellation diagram.

[0085] As a further improvement of the technical solution, the modulator is used to convert the digital signal of the data shaped and encoded by the constellation probability shaping and encoding submodule into an analog signal;

[0086] The transmitter is used to amplify the analog signal and transmit it to the channel for transmission;

[0087] The channel is used to connect the transmitter and the receiver to realize the transmission of analog signals;

[0088] The receiver is used to receive analog signals and amplify and filter the received signals;

[0089] The demodulator is used to restore the analog signal into a digital signal.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] 1. The physical layer secure communication method and device based on constellation probability shaping and quantum noise encryption can realize high-speed, accurate and secure data transmission; the constellation probability shaping technology is used at the physical layer to rearrange the probability of signal constellation point allocation, which can improve the spectrum utilization rate of the channel and increase the communication capacity; the constellation probability shaping is used to reduce the data distribution probability at the edge of the constellation diagram, which can further improve the security of the system;

[0092] 2. In the physical layer secure communication method and device based on constellation probability shaping and quantum noise encryption, the quantum noise encryption technology is used to encrypt the data, which can ensure the security of communication; the constellation probability shaping technology and the quantum noise encryption technology are combined, which is more secure than the communication system using the quantum noise encryption technology alone; it can improve the communication capacity and the security of communication;

[0093] 3. In the physical layer secure communication method and device based on constellation probability shaping and quantum noise encryption, only the coding and modulation process of the digital signal processing part of the existing communication system needs to be upgraded and modified. There is no need to change other equipment in the communication link or add additional transmission equipment. It is an economical and practical solution for improving communication capacity and security, suitable for large-scale promotion; it meets both the needs of large-capacity communication and the needs of secure communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 This is a structural connection diagram of an exemplary physical layer security communication device based on constellation probability shaping and quantum noise encryption in the present invention;

[0095] Figure 2 This is a flowchart of an exemplary physical layer secure communication method based on constellation probability shaping and quantum noise encryption in the present invention;

[0096] Figure 3 This is an exemplary block diagram of the quantum noise encryption principle in the present invention;

[0097] Figure 4 This is a constellation diagram after encryption of quantum noise exemplified in the present invention;

[0098] Figure 5 is a constellation diagram after constellation probability shaping mapping exemplified in the present invention;

[0099] 100, quantum noise encryption / decryption module; 101, quantum noise encryption submodule; 102, quantum noise decryption submodule; 200, constellation probability shaping encoding / decoding module; 201, constellation probability shaping encoding submodule; 202, constellation probability shaping decoding submodule; 300, modulator; 400, transmitter; 500, channel; 600, receiver; 700, demodulator. DETAILED DESCRIPTION

[0100] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0101] Example 1

[0102] like Figure 1As shown, this embodiment provides a physical layer security communication device based on constellation probability shaping and quantum noise encryption, including a quantum noise encryption / decryption module 100, a constellation probability shaping encoding / decoding module 200, a modulator 300, a transmitter 400, a channel 500, a receiver 600 and a demodulator 700 which are sequentially connected in signal connection;

[0103] The quantum noise encryption / decryption module 100 includes a quantum noise encryption submodule 101 and a quantum noise decryption submodule 102;

[0104] The constellation probability shaping encoding / decoding module 200 includes a constellation probability shaping encoding submodule 201 and a constellation probability shaping decoding submodule 202 .

[0105] In this embodiment, the quantum noise encryption / decryption module 100 is used to perform encryption / decryption operations on a binary data stream; wherein: the quantum noise encryption submodule 101 is used to encrypt the binary data stream; the quantum noise decryption submodule 102 is used to perform an inverse operation on the data encrypted by the quantum noise encryption submodule 101 to decrypt the data, so as to restore the original binary data;

[0106] The constellation probability shaping encoding / decoding module 200 is used to encode / decode the encrypted data; wherein: the constellation probability shaping encoding submodule 201 is used to encode the encrypted data; the constellation probability shaping decoding submodule 202 is used to perform an inverse operation on the data encoded by the constellation probability shaping encoding submodule 201 to achieve decoding, restore the encrypted data, and restore the uniform distribution characteristics of the constellation diagram.

[0107] Further, the modulator 300 is used to convert the digital signal of the data shaped and encoded by the constellation probability shaping and encoding submodule 201 into an analog signal;

[0108] The transmitter 400 is used to amplify the analog signal and transmit it to the channel 500 for transmission;

[0109] Channel 500 is used to connect transmitter 400 and receiver 600 to achieve transmission of analog signals;

[0110] The receiver 600 is used to receive analog signals and amplify and filter the received signals;

[0111] The demodulator 700 is used to restore the analog signal to a digital signal.

[0112] It is worth noting that both communicating parties are equipped with a quantum noise encryption / decryption module 100 and a constellation probability shaping encoding / decoding module 200, so that both communicating parties can perform data transmission and reception operations with each other.

[0113] like Figure 2-Figure 5As shown, this embodiment also provides a physical layer security communication method based on constellation probability shaping and quantum noise encryption, using the above-mentioned physical layer security communication device based on constellation probability shaping and quantum noise encryption, including the following steps:

[0114] S1, the original binary data is processed synchronously and in parallel according to a single channel or divided into multiple channels, 1 bit of data and n bit of key of each channel are respectively taken for quantum noise encryption processing through the quantum noise encryption submodule 101, the 1 bit of data and the lowest bit of the n bit key are XORed, and the obtained data replaces the highest bit of the n bit key to obtain the encrypted n bit data; and finally the encrypted data of each channel is obtained;

[0115] In this step, the method of dividing the original binary data into multiple data at least includes:

[0116] (1) Parity bit division: the original binary data is divided into two groups according to odd bits and even bits;

[0117] (2) Equal bit division: The original binary data is evenly divided into multiple paths according to a fixed number of bits. For example, if the original binary data has a total of 80 bits and is to be divided into 4 paths, each path contains 20 bits of data.

[0118] (3) Equal byte division: divide the original binary data into bytes (8 bits); if the original binary data has 64 bytes, it can be divided into 8 paths, each path has 8 bytes (i.e., 64 bits);

[0119] (4) Based on data content or structure: The data is divided according to its specific content or structural characteristics. For example, if the data is organized in a certain frame format, it can be divided according to the frame; or if the data contains different types of information, it can be divided into different paths according to the information type.

[0120] (5) Adaptive partitioning: Dynamically adjust the partitioning method according to channel conditions, transmission requirements or other real-time factors; for example, when the channel quality is poor, reduce the amount of data per channel to improve transmission reliability; when the channel quality is good, increase the amount of data per channel to improve transmission efficiency;

[0121] It should be noted that the specific division method should be weighed and selected according to the actual application scenario and system performance requirements to ensure the efficiency and security of the communication system.

[0122] Furthermore, the method for selecting the n-bit key for each data path at least includes:

[0123] (1) Random generation: A random binary sequence generated by a random number generator is used as the key. This method has good randomness and security, but the quality and security of the random number generator must be ensured to prevent the key from being predicted or cracked.

[0124] (2) Based on the physical characteristics of hardware: The key is generated by using certain physical characteristics of the hardware device. For example, the random signal generated by physical phenomena such as thermal noise, radioactive decay, and quantum state of electronic devices is used as the source of the key. The key generated by this method has higher security because physical characteristics are usually difficult to simulate or predict.

[0125] (3) Pseudo-random number generation algorithm: Use a proven and widely used pseudo-random number generation algorithm to generate a key using a given seed value. The seed value can be a parameter with a certain degree of randomness and uniqueness, such as the system time or a device unique identifier. This method achieves a good balance between computational efficiency and randomness.

[0126] (4) Pre-shared key: The two communicating parties agree on a set of keys in advance and then use these pre-shared keys during the communication process. This method requires ensuring the secure distribution and storage of keys to prevent key leakage.

[0127] (5) Key negotiation protocol: The two communicating parties jointly generate a key through a specific key negotiation protocol. For example, the Diffie-Hellman key exchange protocol is a commonly used key negotiation protocol that allows the two communicating parties to negotiate a shared key over an insecure channel.

[0128] In practical applications, the appropriate key selection method can be selected based on the system's security requirements, computing resources, communication environment, etc. At the same time, in order to further improve security, measures such as regular key replacement or key hierarchical management can be adopted.

[0129] In this embodiment, the process of performing quantum noise encryption processing by the quantum noise encryption submodule 101 includes the following steps:

[0130] Input: 1 bit of data for each channel, denoted as D, n bit key, denoted as K = k1, k2, k3, ..., k n ;

[0131] S1.1. Compare 1 bit of data D with the lowest bit k of the n bit key n Perform XOR operation to get

[0132] S1.2, replace the highest bit k1 of the n-bit key with E to obtain the encrypted n-bit data, that is, K′=E, k2, k3, ..., k n ;

[0133] Output: Encrypted n-bit data K′.

[0134] In this way, quantum noise encryption processing of each data channel is realized through simple XOR operation and bit replacement operation. In practical applications, the algorithm may be further optimized and improved according to specific needs and security requirements.

[0135] S2, respectively perform constellation probability shaping coding on each encrypted n-bit data through the constellation probability shaping coding submodule 201 to obtain (n+m)-bit data; and finally obtain each data after constellation probability shaping;

[0136] In this step, constellation probability shaping encoding is performed on the encrypted n-bit data, specifically including the following steps:

[0137] Assume that 64QAM modulation is used for illustration. When the constellation points are evenly distributed, the probability of each point appearing is P=0.015624. When constellation probability shaping coding is performed, it is hoped that the probability of the constellation points close to the center appearing is higher, while the probability of the constellation points far from the center appearing is reduced.

[0138] Input: encrypted n-bit data K′;

[0139] S2.1. Determine the probability model of constellation point distribution; define a probability distribution function f(x), where x represents the distance from the constellation point to the center of the constellation diagram; f(x) can be designed according to actual needs, so that the closer the constellation point is to the center, the higher the probability corresponding to it;

[0140] S2.2. Calculate the corresponding constellation point index i according to the input n-bit data K′; for example, for 64QAM, n=6, then K′ can be expressed as E, k2, k3, ..., k6, which is converted into the constellation point index i through a certain mapping rule;

[0141] S2.3, according to the constellation point index i and the probability distribution function f(x), determine the probability P of the constellation point appearing in the shaped constellation diagram i ;

[0142] S2.4. According to the determined probability P i , remap the constellation points; specifically, according to the probability P i Randomly select one of all possible constellation points as the final mapping result;

[0143] S2.5, repeat steps S2.2-S2.4 until constellation probability shaping coding is completed for all n-bit data;

[0144] Output: (n+m) bit data after constellation probability shaping encoding, where m represents the number of bits added to achieve constellation probability shaping.

[0145] In this way, through the above algorithm process, the encrypted n-bit data is constellation-probability shaped and coded, so that the distribution probability of the constellation points is rearranged according to the preset model, thereby improving the security of the communication system and the channel spectrum utilization rate. The constellation probability shaping coding algorithm in actual application may be more complex and will be optimized and adjusted according to the specific modulation mode and system requirements.

[0146] S3, converting each channel of data into an analog signal through the modulator 300, and then amplifying the analog signal through the transmitter 400 and sending it to the channel 500 for transmission;

[0147] In this step, the modulator 300 converts the data into an analog signal using a quadrature amplitude modulation (QAM) method, which specifically includes the following steps:

[0148] Input: (n+m) bit data after constellation probability shaping coding, denoted as s(n);

[0149] A3.1. Group the input data according to the modulation order. For 64QAM modulation, each group of data contains 6 bits (n+m=6).

[0150] A3.2. For each group of 6-bit data, convert it into the corresponding constellation point coordinates (I, Q) according to the constellation mapping rule of 64QAM; the constellation mapping rule is predefined, which determines the correspondence between each 6-bit data combination and a specific point in the constellation diagram;

[0151] A3.3. Generate a carrier signal. Usually, a sine wave is used as a carrier signal to generate an in-phase (I) carrier and a quadrature (Q) carrier. The frequency and phase of the carrier are set according to system requirements.

[0152] A3.4. Multiply the coordinates of the constellation point (I, Q) by the in-phase carrier and the quadrature carrier respectively to obtain the in-phase component I×sin(ωt) and the quadrature component Q×cos(ωt), where ω represents the carrier angular frequency and t represents time;

[0153] A3.5. Add the in-phase component and the quadrature component to obtain the modulated analog signal s(t)=I×sin(ωt)+Q×cos(ωt);

[0154] Output: modulated analog signal s(t).

[0155] Thus, through the above algorithm process, digital data is converted into analog signals for transmission in channel 500. Different modulation methods have different specific algorithms and parameter settings, and in actual applications, more detailed and complex processing may be performed according to specific modulation technology and system requirements.

[0156] Furthermore, the analog signal is amplified by the transmitter 400 using a linear power amplifier, which can maintain the linearity of the signal as much as possible while amplifying the signal and reduce signal distortion; specifically, the following steps are included:

[0157] Input: modulated analog signal s(t);

[0158] B3.1. Set the gain parameter G of the amplifier. The gain represents the amplitude ratio of the output signal to the input signal.

[0159] B3.2. Calculate the amplified analog signal r(t) = G × s(t), that is, the input signal multiplied by the gain value;

[0160] B3.3. Perform power detection on the amplified signal to ensure that its output power does not exceed the rated power of the transmitter and complies with relevant laws and regulations and standards. If the output power exceeds the limit, it is necessary to adjust the gain parameters or take other measures to limit the power.

[0161] B3.4. Monitor and adjust the linearity of the amplified signal; evaluate the linearity of the signal through some linearity indicators (such as error vector amplitude, etc.). If the linearity does not meet the requirements, the amplifier needs to be linearized, such as using feedback technology, pre-distortion technology, etc.

[0162] B3.5, outputting the amplified analog signal that meets the requirements to channel 500 for transmission;

[0163] Output: amplified analog signal r(t).

[0164] S4, after the receiver 600 receives the analog signal, it amplifies and filters the analog signal, and the demodulator 700 restores the analog signal into various digital signals;

[0165] In this step, the receiver 600 uses a low noise amplifier LNA to amplify the analog signal. A low noise amplifier (LNA) is usually used in the receiver to amplify the received analog signal. The main feature of the LNA is to reduce the noise introduced by itself as much as possible while amplifying the signal, so as to improve the signal-to-noise ratio of the received signal. The specific steps include:

[0166] Input: received amplified analog signal r(t);

[0167] A4.1. Set the initial gain value G0 of LNA. The selection of gain value needs to consider factors such as the strength of the received signal and the dynamic range of the subsequent processing circuit.

[0168] A4.2. Input the received analog signal r(t) into the LNA to obtain the amplified signal r′(t)=G0×r(t);

[0169] A4.3. Perform noise monitoring on the amplified signal; evaluate the noise level introduced by the LNA by measuring parameters such as the noise power of the amplifier output signal;

[0170] A4.4. Dynamically adjust the gain of LNA according to the noise monitoring results; if the noise level is too high, the gain can be appropriately reduced to reduce the impact of noise; if the signal strength is weak, the gain can be appropriately increased to improve the signal-to-noise ratio; the gain adjustment can be achieved using the Automatic Gain Control (AGC) algorithm;

[0171] A4.5. During the amplification process, the frequency response of the signal needs to be compensated to ensure that a relatively uniform amplification effect can be obtained over the entire frequency range of the received signal. This can be achieved by introducing a frequency compensation circuit into the amplifier or by using digital signal processing technology.

[0172] A4.6. Output the analog signal after amplification, noise control and frequency compensation for subsequent filtering and other operations;

[0173] Output: The amplified analog signal r′(t) has an improved signal-to-noise ratio and optimized frequency response characteristics.

[0174] The actual amplification process of the transmitter 400 and the receiver 600 may be more complicated, involving more circuit design, control and optimization techniques to ensure the quality and performance of the signal during the amplification process. At the same time, different types of power amplifiers and specific application scenarios may use different amplification methods and algorithms.

[0175] Among them, in step A4.4, the automatic gain control AGC algorithm specifically includes the following steps:

[0176] Input: amplified analog signal r′(t);

[0177] A4.4.1. Initialization: Set the initial gain value G1=G0, where G0 is a preset initial gain;

[0178] Set the target signal power P target and the permissible power fluctuation range ΔP;

[0179] A4.4.2 Signal power measurement: Perform periodic power measurement on the input analog signal r′(t) and calculate the average signal power P in a measurement period. in ;

[0180] A4.4.3. Gain adjustment: Compare the measured signal power P in and the target signal power P target ;

[0181] If |P in -P target |>AP, then adjust the gain G1 according to the following rules:

[0182] If P in >P target +ΔP, then the gain is reduced to G2 = G1 × α, where α < 1 is an attenuation factor;

[0183] If P in <P target -ΔP, then the gain is increased to G2 = G1 × β, where β>1 is an amplification factor;

[0184] A4.4.4. Update gain: Apply the adjusted gain value G2 to the amplifier to amplify the subsequent input signal;

[0185] A4.4.5. Repeat steps A4.4.2-A4.4.4: continue to monitor the input signal power and adjust the gain to keep the signal power within the allowable range near the target power;

[0186] Output: The amplified analog signal r″(t)=G2×r′(t) after automatic gain control, whose power is relatively stable within the target range.

[0187] The AGC algorithm in actual application may be more complex, and may consider more factors, such as the dynamic range of the signal, noise characteristics, convergence speed, etc., and adopt more complex control strategies to achieve more accurate and stable gain control. Different communication systems and application scenarios may require corresponding adjustments and optimizations to the AGC algorithm.

[0188] Furthermore, the receiver 600 performs filtering processing on the analog signal by using a digital filter, which has the advantages of high precision, strong flexibility, and easy implementation. Specifically, the following steps are included:

[0189] Input: amplified analog signal r′(t);

[0190] B4.1. Analog-to-digital conversion (ADC): The analog signal r′(t) is converted into a digital signal r′(n) through an analog-to-digital converter, where n represents a discrete time index;

[0191] B4.2. Filter design: Design a suitable digital filter based on the required filtering characteristics (such as low-pass, high-pass, band-pass, etc.) and parameters such as cutoff frequency. Common digital filter design methods include finite impulse response (FIR) filters and infinite impulse response (IIR) filters. For example, for a low-pass FIR filter, a specific frequency response can be achieved by determining the filter order and coefficients.

[0192] B4.3. Filtering operation: Input the digital signal r′(n) into the designed digital filter for filtering operation:

[0193] For a low-pass FIR filter, the filtering operation can be expressed as:

[0194]

[0195] Wherein, y(n) represents the digital signal after filtering, h(k) is the coefficient sequence of the filter, k represents the index of the filter coefficient, k=0, 1, 2, ..., N-1, N is the filter order, and each coefficient h(k) corresponds to the weighted value of the input signal r′(nk) with different time delays;

[0196] The filtering operation of the input signal is realized by weighted summing these input signals with different delays; different k values ​​correspond to different time delays and weighting coefficients, which together determine the frequency response characteristics and filtering effect of the filter;

[0197] B4.4. Output the filtered signal: obtain the digital signal y(n) after filtering, which removes unnecessary frequency components and retains the useful signal part;

[0198] Output: filtered digital signal y(n);

[0199] The filtering process in actual applications may be more complicated, and it may be necessary to consider factors such as filter stability, real-time requirements, anti-aliasing, etc., and optimize and adjust according to the specific communication system and signal characteristics. In addition, there are other types of filtering methods and algorithms to choose from, and the specific implementation methods will vary depending on the actual situation.

[0200] S5, performing constellation probability shaping decoding on each channel data of (n+m) bits through the constellation probability shaping decoding submodule 202, and restoring each channel data of n bits;

[0201] In this step, the process of constellation probability shaping decoding submodule 202 performing constellation probability shaping decoding on data includes the following steps (taking 64QAM modulation as an example for explanation):

[0202] Input: (n+m) bits of data restored to digital signal after demodulation, denoted as D sh aped =y(n);

[0203] S5.1. Determine the constellation point distribution model: According to the constellation point distribution probability model used in constellation probability shaping coding, obtain the occurrence probability information of each constellation point in the shaped constellation diagram;

[0204] S5.2, constellation point mapping: the input (n+m) bit data D sh aped According to certain rules, it is converted into a point coordinate in the constellation diagram (I sh aped , Q sh aped ); This rule corresponds to the mapping rule in constellation probability shaping coding, but in the opposite direction;

[0205] S5.3, Probability calculation and judgment: For the obtained constellation point coordinates (I sh aped , Q sh aped ), calculate the coordinates of each possible constellation point in the original uniformly distributed constellation diagram (I original , Q original ) on the probability;

[0206] According to the calculated probability, the coordinates of the constellation point with the largest probability are selected as the decoding result;

[0207] S5.4, bit conversion: the selected constellation point coordinates (I original , Q original ) Convert back to n bit data according to the original bit mapping rule of 64QAM modulation;

[0208] S5.5. Repeat steps S5.2-S5.4:

[0209] The above decoding operation is performed on all (n+m) bit data in sequence until all n bit data are recovered;

[0210] Output: The recovered n-bit data, that is, the original data after constellation probability shaping and decoding.

[0211] The actual constellation probability shaping decoding algorithm may be more complexly processed and optimized according to the specific encoding method, constellation diagram structure and system design to improve the accuracy and efficiency of decoding.

[0212] S6, performing quantum noise decryption on each channel of n-bit data through the quantum noise decryption submodule 102 to obtain 1-bit original binary data; finally, all the original binary data are restored;

[0213] In this step, the process of quantum noise decryption submodule 102 performing quantum noise decryption on data includes the following steps:

[0214] Input: n bit data decoded after constellation probability shaping, denoted as K″;

[0215] S6.1. Extract the highest bit and the lowest bit of the encrypted key: extract the highest bit (denoted as E′) and the lowest bit (denoted as k′n) from the input encrypted n-bit data K″;

[0216] S6.2, XOR operation: extract the highest bit E' and the lowest bit k' n Perform XOR operation to get 1 bit of original data

[0217] S6.3, restore the original key: combine the remaining (n-1) bits of the encrypted key except the highest bit with the 1 bit of the original data obtained in step S6.2 to obtain the restored original n-bit key K0=D′, k′2, k′3, ..., k′ n ;

[0218] Output: 1-bit data D′ of the restored original binary data and the original n-bit key K0.

[0219] In this way, through the above simple algorithm process, the decryption operation of quantum noise encrypted data is realized, and the original binary data and key are restored. In practical applications, in order to ensure security and reliability, the encryption and decryption algorithms may be more complexly designed and optimized.

[0220] Exemplarily, the physical layer security communication method based on constellation probability shaping and quantum noise encryption in this embodiment includes the following steps:

[0221] S1. Divide the original binary data into two data paths, I and Q. Take 1 bit of I data and n bit key for quantum noise encryption. Perform XOR operation on the lowest bit of 1 bit data and n bit key, such as Figure 3As shown, the obtained data replaces the highest bit of the n-bit key to obtain the encrypted n-bit data; similarly, the Q-channel data is processed in the same way; and finally the encrypted I-channel and Q-channel data are obtained;

[0222] S2, perform constellation probability shaping encoding on the encrypted n-bit I-channel data to obtain (n+m)-bit data; similarly, perform the same processing on the Q-channel data to finally obtain constellation probability shaped I-channel and Q-channel data;

[0223] For example, when n=3, the I-channel and Q-channel data form 6-bit data, corresponding to the 64QAM signal. At this time, the constellation points are evenly distributed, and the probability of each point appearing is P=0.015624. Figure 4 As shown in the figure; when m=2, the 10-bit data after constellation probability shaping is obtained and mapped to the 64QAM constellation diagram. At this time, the corresponding constellation points are no longer evenly distributed, but the probability of appearing close to the center constellation point is high, and the probability of appearing far from the center of the constellation diagram is low, as shown in the figure. Figure 5 As shown;

[0224] S3, converting the I-channel and Q-channel data into analog signals through a modulator, and then amplifying the signals through a transmitter 400 and sending them to a channel 500 for transmission;

[0225] S4, after receiving the signal, the receiver 600 amplifies and filters the signal, and the demodulator 700 restores the analog signal into I-channel and Q-channel digital signals;

[0226] S5, performing constellation probability shaping decoding on the (n+m)-bit I-channel data to restore it to n-bit I-channel data. Similarly, n-bit Q-channel data can be obtained.

[0227] S6. Perform quantum noise decryption on n-bit I-channel data to obtain 1-bit original binary data. Similarly, perform quantum noise decryption on Q-channel data. Finally, all original binary data are restored.

[0228] Those skilled in the art will appreciate that the process of implementing all or part of the steps of the above embodiments may be completed by hardware, or may be completed by instructing related hardware through a program.

[0229] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A physical layer secure communication method based on constellation probability shaping and quantum noise encryption, characterized in that: The steps include: S1. The original binary data is processed synchronously and in parallel in a single channel or divided into multiple channels. 1 bit of data and n bit of key are respectively taken from each channel for quantum noise encryption. The 1 bit of data is XORed with the lowest bit of the n bit key. The obtained data replaces the highest bit of the n bit key to obtain the encrypted n bit data. Finally, the encrypted data of each channel is obtained. S2. Perform constellation probability shaping encoding on each encrypted n-bit data to obtain (n+m)-bit data, where m represents the number of bits added to achieve constellation probability shaping; Finally, the data of each channel after constellation probability shaping is obtained; S3, converting each channel of data into an analog signal, amplifying and transmitting the analog signal; S4, after amplifying and filtering the received analog signal, the analog signal is restored to each channel of digital signal; S5, performing constellation probability shaping decoding on each channel data of (n+m) bits, and restoring them into each channel data of n bits respectively; S6. Perform quantum noise decryption on each channel of n-bit data respectively to obtain 1-bit original binary data; finally, restore all the original binary data.

2. The physical layer secure communication method based on constellation probability shaping and quantum noise encryption according to claim 1, characterized in that: In step S1, the process of quantum noise encryption processing includes the following steps: Input: 1 bit of data for each channel, denoted as D, n bit key, denoted as K = k1, k2, k3, ..., k n ; S1.

1. Compare 1 bit of data D with the lowest bit k of the n bit key n Perform XOR operation to get S1.2, replace the highest bit k1 of the n-bit key with E to obtain the encrypted n-bit data, that is, K'=E,k2,k3,...,k n ; Output: Encrypted n-bit data K'.

3. The physical layer secure communication method based on constellation probability shaping and quantum noise encryption according to claim 2, characterized in that: In step S2, performing constellation probability shaping coding on the encrypted n-bit data specifically includes the following steps: When 64QAM modulation is used, the probability of each point appearing when the constellation points are evenly distributed is P; when constellation probability shaping coding is performed, it is expected that the probability of the constellation points close to the center will be higher, while the probability of the constellation points far from the center will be lower; Input: encrypted nbit data K'; S2.

1. Determine the probability model of constellation point distribution: define a probability distribution function f(t), where x represents the distance from the constellation point to the center of the constellation diagram; S2.2, according to the input n-bit data K', calculate its corresponding constellation point index i through the mapping rule; S2.3, according to the constellation point index i and the probability distribution function f(x), determine the probability P of the constellation point appearing in the shaped constellation diagram i ; S2.4, according to the determined probability C, the constellation points are remapped; that is, according to the probability P i Randomly select one of all possible constellation points as the final mapping result; S2.5, repeat steps S2.2-S2.4 until constellation probability shaping coding is completed for all n-bit data; Output: (n+m) bit data after constellation probability shaping encoding, where m represents the number of bits added to achieve constellation probability shaping.

4. The physical layer secure communication method based on constellation probability shaping and quantum noise encryption according to claim 3 is characterized in that: In step S3, the data is converted into an analog signal using a quadrature amplitude modulation (QAM) method, which specifically includes the following steps: Input: (n+m) bit data after constellation probability shaping coding, denoted as s(n); A3.

1. Group the input data according to the modulation order; A3.

2. For each set of data, convert it into the corresponding constellation point coordinates (I, Q) according to the constellation mapping rules; A3.

3. Generate carrier signal: Use a sine wave as a carrier signal to generate an in-phase (I) carrier and a quadrature (Q) carrier respectively; A3.

4. Multiply the coordinates of the constellation point (I, Q) by the in-phase carrier and the quadrature carrier respectively to obtain the in-phase component I×sin(ωt) and the quadrature component Q×cos(ωt), where ω represents the carrier angular frequency and t represents time; A3.

5. Add the in-phase component and the quadrature component to obtain the modulated analog signal s(t)=I×sin(ωt)+Q×cos(ωt); Output: modulated analog signal s(t); The analog signal is amplified by a linear power amplifier, which specifically includes the following steps: Input: modulated analog signal s(t); B3.

1. Set the gain parameter G of the amplifier. The gain represents the amplitude ratio of the output signal to the input signal. B3.

2. Calculate the amplified analog signal r(t) = G × s(t), that is, the input signal multiplied by the gain value; B3.

3. Perform power detection on the amplified signal; B3.

4. Monitor and adjust the linearity of the amplified signal; B3.

5. Output and transmit the amplified analog signal that meets the requirements; Output: amplified analog signal r(t).

5. The physical layer secure communication method based on constellation probability shaping and quantum noise encryption according to claim 4, characterized in that: In step S4, the analog signal is amplified by a low noise amplifier LNA, which specifically includes the following steps: Input: received amplified analog signal r(t); A4.

1. Set the initial gain value G0 of LNA; A4.

2. Input the received analog signal r(t) into the LNA to obtain the amplified signal r'(t) = G0×r(t); A4.

3. Perform noise monitoring on the amplified signal; evaluate the noise level introduced by the LNA by measuring the noise power parameters of the amplifier output signal; A4.

4. Dynamically adjust the gain of LNA according to the noise monitoring results; if the noise level is too high, the gain can be appropriately reduced to reduce the impact of noise; if the signal strength is weak, the gain can be appropriately increased to improve the signal-to-noise ratio; A4.

5. During the amplification process, the frequency response of the signal needs to be compensated to ensure that a relatively uniform amplification effect can be obtained within the entire frequency range of the received signal; A4.

6. Output the analog signal after amplification, noise control and frequency compensation for subsequent filtering operations; Output: amplified analog signal r'(t); The digital filter is used to filter the analog signal, which includes the following steps: Input: amplified analog signal r'(t); B4.1, Analog-to-digital conversion ADC: Convert the analog signal r'(t) into a digital signal r'(n) through an analog-to-digital converter, where n represents a discrete time index; B4.

2. Filter design: Design a suitable digital filter based on the required filtering characteristics and cutoff frequency parameters; B4.

3. Filtering operation: Input the digital signal r'(n) into the designed digital filter for filtering operation: The filtering operation can be expressed as: Wherein, y(n) represents the digital signal after filtering, h(k) is the coefficient sequence of the filter, k represents the index of the filter coefficient, k=0,1,2,...,N-1, N is the filter order, and each coefficient h(k) corresponds to the weighted value of the input signal r'(nk) with different time delays; B4.

4. Output the filtered signal: obtain the filtered digital signal y(n); Output: filtered digital signal y(n).

6. The physical layer secure communication method based on constellation probability shaping and quantum noise encryption according to claim 5, characterized in that: In step S5, the process of performing constellation probability shaping decoding on the data includes the following steps: Input: (n+m) bits of data restored to digital signal after demodulation, denoted as D shaped =y(n); S5.

1. Determine the constellation point distribution model: According to the constellation point distribution probability model used in constellation probability shaping coding, obtain the occurrence probability information of each constellation point in the shaped constellation diagram; S5.2, constellation point mapping: the input (n+m) bit data D shaped Converted to a point coordinate in the constellation diagram (I shaped ,Q shaped ); This rule corresponds to the mapping rule in constellation probability shaping coding, but in the opposite direction; S5.3, Probability calculation and judgment: For the obtained constellation point coordinates (I shaped ,Q shaped ), calculate the coordinates of each possible constellation point in the original uniformly distributed constellation diagram (I original ,Q original ) on the probability; According to the calculated probability, the coordinates of the constellation point with the largest probability are selected as the decoding result; S5.4, bit conversion: the selected constellation point coordinates (I original ,Q original ) Convert back to nbit data according to the original bit mapping rule of modulation; S5.5, repeat steps S5.2-S5.4: perform the above decoding operations on all (n+m) bit data in sequence until all n bit data are recovered; Output: the recovered n-bit data, i.e. the original data after constellation probability shaping and decoding.

7. The physical layer secure communication method based on constellation probability shaping and quantum noise encryption according to claim 6, characterized in that: In step S6, the process of performing quantum noise decryption on the data includes the following steps: Input: n-bit data decoded after constellation probability shaping, denoted as "K"; S6.

1. Extract the highest and lowest bits of the encrypted key: From the input encrypted n-bit data K", extract the highest bit and record it as E' and the lowest bit and record it as k' n ; S6.2, XOR operation: extract the highest bit E' and the lowest bit k' n Perform XOR operation to get 1 bit of original data S6.3, restore the original key: combine the remaining (n-1) bits of the encrypted key except the highest bit with the 1 bit of the original data obtained in step S6.2 to obtain the restored original n-bit key K0 = D', k'2, k'3, ..., k' n ; Output: 1-bit data D' of the restored original binary data and the original n-bit key K0.

8. A physical layer security communication device based on constellation probability shaping and quantum noise encryption, used to implement the steps of the physical layer security communication method based on constellation probability shaping and quantum noise encryption according to any one of claims 1 to 7, characterized in that: It comprises a quantum noise encryption / decryption module (100), a constellation probability shaping encoding / decoding module (200), a modulator (300), a transmitter (400), a channel (500), a receiver (600) and a demodulator (700) which are sequentially signal-connected; The quantum noise encryption / decryption module (100) comprises a quantum noise encryption submodule (101) and a quantum noise decryption submodule (102); The constellation probability shaping encoding / decoding module (200) comprises a constellation probability shaping encoding submodule (201) and a constellation probability shaping decoding submodule (202).

9. The physical layer secure communication device based on constellation probability shaping and quantum noise encryption according to claim 8, characterized in that: The quantum noise encryption / decryption module (100) is used to perform encryption / decryption operations on a binary data stream; wherein: the quantum noise encryption submodule (101) is used to encrypt the binary data stream; the quantum noise decryption submodule (102) is used to perform an inverse operation on the data encrypted by the quantum noise encryption submodule (101) to achieve decryption, so as to restore the original binary data; The constellation probability shaping encoding / decoding module (200) is used to perform encoding / decoding operations on encrypted data; wherein: the constellation probability shaping encoding submodule (201) is used to encode the encrypted data; the constellation probability shaping decoding submodule (202) is used to perform an inverse operation on the data encoded by the constellation probability shaping encoding submodule (201) to achieve decoding, restore the encrypted data, and restore the uniform distribution characteristics of the constellation diagram.

10. The physical layer security communication device based on constellation probability shaping and quantum noise encryption according to claim 8, characterized in that: The modulator (300) is used to convert the digital signal of the data shaped and encoded by the constellation probability shaping and encoding submodule (201) into an analog signal; The transmitter (400) is used to amplify the analog signal and transmit it to the channel (500) for transmission; The channel (500) is used to connect the transmitter (400) and the receiver (600) to achieve transmission of analog signals; The receiver (600) is used to receive analog signals and amplify and filter the received signals; The demodulator (700) is used to restore the analog signal into a digital signal.

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