High-signal-quality physical layer encrypted free space optical communication method and system

Abstract

According to the high-signal-quality physical layer encrypted free space optical communication method and system provided by the invention, quantization noise can be effectively controlled through DSM modulation, high-frequency noise is removed, so that high quality and low distortion of signals are kept in the transmission process, and especially in long-distance and severe-environment communication, the high-quality and low-distortion performance of the signals is ensured. And the signal stability can be obviously improved. Wherein in the physical layer encryption process of quantum noise stream encryption and the like, quantum noise or random phase jump is used as a means for generating an encrypted signal to introduce certain noise, the noise shaping characteristic of DSM modulation plays an important role, the noise is concentrated in a high-frequency area to reduce low-frequency interference caused by the quantum noise, and the quantum noise stream encryption is realized. The signal quality is optimized, and the bit error rate is reduced. Interference caused by quantum noise and external environment factors can be effectively eliminated in the signal transmission process, and therefore the transmission stability of a system and the reliability of signals are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, and in particular to a high-signal-quality physical layer encryption free space optical communication method and system. BACKGROUND

[0002] With the rapid development of quantum computing and network attack technology, the security problem of free space optical communication (FSO) system is increasingly prominent. Due to its open transmission medium, FSO system is vulnerable to eavesdropping, interference and cracking. Therefore, how to realize efficient encryption mechanism in FSO system and ensure the security of transmitted information has become the focus of research. In recent years, researches include adding artificial noise to increase the security of the system. A double-layer encryption strategy using STM32 chip, laser emitter and photodiode is used to construct a secure FSO system, but its hardware implementation is complex and the cost is high. In addition, a double-channel encryption free space optical communication system based on compressed sensing and tilted fiber grating is proposed, which can reduce the amount of data acquisition while encrypting the data transmitted in free space.

[0003] These studies are still a blank in the research of the interaction between quantum noise and atmospheric turbulence for encryption. In the existing research, the application of quantum noise stream encryption (QNSC) and dynamic displacement operator quantum encryption (QEPS) in FSO system is still in the preliminary exploration stage. The essence of QNSC is to add information redundancy after the plaintext signal, so that the low-order signal becomes a high-order signal. QEPS is based on quantum random phase hopping, which changes the initial signal into a high-order phase modulation signal. Then, through the Delta-Sigma modulator (DSM), the high-order signal is changed into several low-order signals. However, under the complex channel conditions of atmospheric turbulence, signal attenuation, etc., the interaction between quantum noise and channel characteristics has not been deeply studied.

[0004] Especially under the condition of turbulence, the signal intensity fluctuation and phase distortion caused by turbulence may interfere with the decryption process of quantum noise encrypted signal, thereby affecting the communication performance. In addition, the implementation of QNSC and QEPS requires high-resolution digital-to-analog converters (DAC) and synchronization modules, which further limits its wide application in actual complex channels. SUMMARY

[0005] The first aspect of the present application provides a high-signal-quality physical layer encryption free space optical communication method, which comprises: mapping a plaintext signal into a high-order ciphertext at a sending end by using a quantum noise stream encryption algorithm or the like; DSM modulating the high-order ciphertext at the sending end to change a high-order signal in the high-order ciphertext into a plurality of low-order signals; At the transmitting end, the modulated encrypted signal is converted into an optical signal, and the optical signal is transmitted using free space light.

[0006] In one embodiment, the step of mapping the plaintext signal into higher-order ciphertext at the transmitting end using algorithms such as quantum noise stream encryption includes: Quantum noise is generated using a random number generator or a quantum noise source; The plaintext signal is superimposed with the quantum noise to obtain the higher-order ciphertext.

[0007] In one embodiment, after mapping the plaintext signal into high-order ciphertext using algorithms such as quantum noise stream encryption at the transmitting end; and before performing DSM modulation on the high-order ciphertext at the transmitting end to transform the high-order signals in the high-order ciphertext into multiple low-order signals; the method further includes: The higher-order ciphertext is upsampled at the sending end and filtered using a root-raised cosine filter.

[0008] In one embodiment, after converting the modulated encrypted signal into an optical signal at the transmitting end and transmitting the optical signal using free-space light, the method further includes: The receiving end receives the optical signal and converts the optical signal into an electrical signal; The electrical signal is processed at the receiving end to recover the higher-order ciphertext; The receiving end decrypts and demaps the higher-order ciphertext to recover the plaintext signal.

[0009] In one embodiment, processing the electrical signal at the receiving end to recover the higher-order ciphertext includes: The electrical signal is downsampled at the receiving end and matched filtering is performed using a root-raised cosine matched filter to recover the higher-order ciphertext.

[0010] In one embodiment, receiving the optical signal at the receiving end and converting the optical signal into an electrical signal includes: The optical signal is received by a photodetector at the receiving end and converted into an electrical signal.

[0011] In one embodiment, after converting the optical signal into an electrical signal; and before processing the electrical signal at the receiving end to recover the higher-order ciphertext; the method further includes: High-frequency quantization noise in the electrical signal is removed using a low-pass filter.

[0012] Based on the same inventive concept, a second aspect of this application provides a high-signal-quality physical layer encrypted free-space optical communication system, comprising: A quantum encryption module is used at the sending end to map plaintext signals into high-order ciphertext using algorithms such as quantum noise stream encryption. A modulation module is used to perform DSM modulation on the high-order ciphertext at the transmitting end to convert the high-order signal in the high-order ciphertext into multiple low-order signals. The first signal conversion module is used to convert the modulated encrypted signal into an optical signal at the transmitting end, and to transmit the optical signal using free space light.

[0013] Based on the same inventive concept, a third aspect of this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the high signal quality physical layer encrypted free space optical communication method as described in the first aspect above.

[0014] Based on the same inventive concept, a fourth aspect of this application provides a non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the high-signal-quality physical layer encrypted free-space optical communication method described in the first aspect.

[0015] As can be seen from the above, in the high-signal-quality physical layer encrypted free-space optical communication method provided in this application, DSM modulation can effectively control quantization noise and remove noise in the high-frequency part, thereby maintaining high quality and low distortion of the signal during transmission. Especially in long-distance and harsh environments, it can significantly improve the stability of the signal.

[0016] In quantum noise stream encryption, quantum noise, as part of the encrypted signal, introduces a certain amount of noise. In this case, the noise shaping characteristics of DSM modulation play a crucial role. By concentrating the noise in the high-frequency region, DSM modulation can reduce low-frequency interference caused by quantum noise, optimize signal quality, and reduce the bit error rate.

[0017] Meanwhile, FSO systems often face the effects of atmospheric turbulence and optical attenuation, leading to various noises and distortions during signal transmission. By combining DSM modulation, this invention can effectively eliminate interference caused by quantum noise and external environmental factors during signal transmission, thereby improving the system's transmission stability and signal reliability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a high-signal-quality physical layer encrypted free-space optical communication method provided in an embodiment of this application; Figure 2a is a schematic diagram of a quantum noise stream encryption algorithm provided in an embodiment of this application; Figure 2b is a schematic diagram of a dynamic displacement operator quantum encryption algorithm provided in an embodiment of this application; Figure 3 The principle of DSM modulation provided in an embodiment of this application Figure 1 ; Figure 4 Schematic diagram 2 of DSM modulation provided for an embodiment of this application; Figure 5 This is a schematic diagram of noise shaping provided in an embodiment of this application; Figure 6 A flowchart illustrating a high-signal-quality physical layer encrypted free-space optical communication method provided in another embodiment of this application; Figure 7 A schematic diagram of a high-signal-quality physical layer encrypted free-space optical communication system provided in another embodiment of this application; Figure 8 A schematic diagram of a high-signal-quality physical layer encrypted free-space optical communication system provided in another embodiment of this application; Figure 9 This is a schematic diagram of an electronic device according to another embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] Reference Figure 1 As shown, one embodiment of this application provides a high-signal-quality physical layer encrypted free-space optical communication method, which includes the following steps: Step S10: At the sending end, use algorithms such as quantum noise stream encryption to map the plaintext signal into high-order ciphertext; Step S20: At the transmitting end, perform DSM modulation on the high-order ciphertext to convert the high-order signal in the high-order ciphertext into multiple low-order signals. Step S30: At the transmitting end, the modulated encrypted signal is converted into an optical signal and the optical signal is transmitted using free space light.

[0023] In the physical layer encrypted free-space optical communication method provided in this application, DSM modulation can effectively control noise and reduce noise in the high-frequency part, thereby maintaining high quality and low distortion of the signal during transmission. Especially in long-distance and harsh environments, it can significantly improve the stability of the signal.

[0024] Taking quantum noise stream encryption as an example, quantum noise, as part of the encryption signal, introduces a certain amount of noise. In this case, the noise shaping characteristics of DSM modulation play an important role. By concentrating the noise in the high-frequency region, DSM modulation can reduce low-frequency interference caused by quantum noise, optimize signal quality, and reduce the bit error rate.

[0025] Meanwhile, FSO systems often face the effects of atmospheric turbulence and optical attenuation, leading to various noises and distortions during signal transmission. By combining DSM modulation, this invention can effectively eliminate interference caused by quantum noise and external environmental factors during signal transmission, thereby improving the system's transmission stability and signal reliability.

[0026] Reference Figure 2a and2b As shown, in one embodiment, step S10, mapping the plaintext signal into higher-order ciphertext at the transmitting end using quantum noise stream encryption or dynamic shift operator quantum encryption algorithms, includes the following steps: Step S11: Generate quantum noise using a random number generator or a quantum noise source; Step S12: Superimpose the plaintext signal with quantum noise to obtain higher-order ciphertext.

[0027] Based on the uncertainty principle in quantum mechanics, it states that the physical quantities of a quantum particle cannot be simultaneously measured precisely. Specifically, this includes: Generating quantum noise: Quantum noise stream encryption uses a random number generator or a quantum noise source to generate a random signal that is highly unpredictable and can be used to generate encryption keys.

[0028] Encryption process: The original plaintext is superimposed on the quantum noise in the encryption module of the quantum noise stream. This operation introduces quantum noise perturbation into the plaintext signal, making the encrypted signal undecryptable without the key. For example, if the transmitted data is (1, 1), the encryption base is (1011, 0101), and the encrypted data is (11011, 10101), the quantum noise is applied as an encryption "mask" to the data stream, ensuring that even if an eavesdropper obtains the encrypted signal, they cannot recover the data.

[0029] Decryption process: At the receiving end, a legitimate receiver can recover the data by using the reverse perturbation of quantum noise through the same quantum noise source and key synchronization mechanism. The quantum noise stream encryption algorithm at the receiving end reverses the quantum noise to recover the transmitted plaintext data.

[0030] Compared to traditional encryption methods, quantum noise stream encryption offers stronger security. Due to the unpredictability of quantum noise, it is difficult for eavesdroppers to obtain valid encryption keys. Compared to other quantum encryption methods, quantum noise stream encryption does not rely on complex quantum communication hardware; it uses existing noise sources and digital-to-analog converters for encryption, resulting in lower costs. Quantum noise stream encryption technology can support real-time data encryption and decryption, making it suitable for communication systems requiring low latency, and it performs particularly well in high-speed data transmission and high-bandwidth applications.

[0031] Reference Figures 3-4As shown, in step S20, DSM modulation is implemented through a DSM modulator. The output of the DSM modulator is a digital signal composed of successive iterations. Like the Nyquist ADC, the output signal contains quantization error. However, the impact of quantization error on it is different from that of the Nyquist ADC. In the Nyquist ADC, quantization error is usually regarded as white noise that is evenly distributed across all frequency bands. The generation of quantization error is completely random and irregular. However, in the DSM modulator, the quantization results cannot exist as white noise. Each residual will be fed back to the input, thereby affecting the quantization result of the next iteration.

[0032] In fact, DSM modulators reduce the impact of quantization noise by oversampling and dividing it evenly at higher frequencies, taking only a portion of it. If this method is used, the signal-to-noise ratio only improves by 3dB for every doubling of OSR (oversampling ratio). However, if noise shaping is used, the signal-to-noise ratio will improve by more than 3dB for every increase in OSR.

[0033] The transfer function of the DSM modulator is: ; After simplification, we get: ; After simplification, we know that the noise transfer function NTF(Z) = 1 - Z -1 For low-frequency noise, NTF(Z)→0, and the noise is suppressed. However, for high-frequency signals (Z=-1), NTF(Z)→2, and the quantization noise is amplified. Therefore, the quantization noise is "shaped" from the low-frequency (within the signal's bandwidth) to the high-frequency part.

[0034] Reference Figure 5 As shown, (c) is the original signal spectrum. (d) is the oversampled and unshaped noise spectrum; DSM modulation will produce noise at frequencies much higher than the Nyquist frequency (f...). s >>2fb) rate sampling, OSR·f s / 2 represents the Nyquist frequency after oversampling (oversampling rate OSR=f) s / (2f b The blue shading represents quantization noise (errors introduced during the ADC quantization process), whose spectrum was originally uniformly distributed across the entire sampling bandwidth (0~f). s White noise within / 2). At this time, the signal bandwidth f b The signal contains both signal energy and quantization noise, limiting the effective resolution of the ADC. Figure (d) shows the spectrum optimization after noise shaping. The feedback loop (integrator + quantizer) of DSM modulation changes the spectral distribution of quantization noise, reducing low-frequency noise (signal bandwidth f) b (Inner) "push" towards the high-frequency region. Signal bandwidth f bThe quantization noise within the filter is significantly reduced (the area of ​​the blue shading is reduced), retaining only a small amount of high-frequency noise. Subsequent low-pass filtering removes f. b The above noise can significantly improve the signal-to-noise ratio (SNR) of the signal, which is equivalent to improving the resolution of the ADC (e.g., a 1-bit quantizer can achieve an effective precision of more than 16 bits).

[0035] Furthermore, after step S20, mapping the plaintext signal into high-order ciphertext using the quantum noise stream encryption algorithm at the transmitting end; and before step S30, performing DSM modulation on the high-order ciphertext at the transmitting end to transform the high-order signals in the high-order ciphertext into multiple low-order signals; the following steps are also included: Step S21: Upsample the high-order ciphertext at the transmitting end and filter it using a root-raised cosine filter. Specifically, at the transmitting end, to adapt the high-order ciphertext to channel transmission, it is necessary to first perform an upsampling operation, that is, insert zero values ​​between discrete high-order ciphertext symbols to increase the signal sampling rate and increase the time domain resolution. Then, the upsampled signal is passed through a root-raised cosine filter. With the help of the characteristics of this filter, on the one hand, the signal is pulse shaped to limit the signal spectrum within the available bandwidth of the channel, suppress out-of-band radiation, and avoid interference with adjacent channel signals. On the other hand, its Nyquist characteristics are used to ensure that there is no inter-symbol interference at the sampling time of the receiving end, laying the foundation for subsequent reliable transmission and demodulation. Finally, the discrete ciphertext symbols are converted into a continuous baseband signal suitable for channel transmission.

[0036] Reference Figure 6 As shown, in one embodiment, after step S30, the following step is further included: Step S40: Receive the optical signal at the receiving end and convert the optical signal into an electrical signal; Step S50: Process the electrical signal at the receiving end to recover the higher-order ciphertext; Step S60: Decrypt and demap the high-order ciphertext at the receiving end to recover the plaintext signal.

[0037] In one embodiment, step S50, processing the electrical signal at the receiving end to recover the higher-order ciphertext, includes: downsampling the electrical signal at the receiving end and performing matched filtering using a root-raised cosine matched filter to recover the higher-order ciphertext. The downsampling is used to cancel the upsampling performed at the transmitting end.

[0038] Specifically, at the receiving end, the electrical signal transmitted through the channel is first downsampled, reducing the sampling rate from a high rate to a rate matching the transmitting end's rate, in order to reduce the amount of data and focus on the effective signal frequency band. Subsequently, a root-raised-cosine matched filter is used to filter the downsampled signal. This filter matches the characteristics of the root-raised-cosine filter at the transmitting end, which can further suppress out-of-band noise and interference, maximize the signal-to-noise ratio of the received signal through matched filtering, and eliminate inter-symbol interference by utilizing its Nyquist characteristics. Finally, the high-order ciphertext from the transmitting end is accurately recovered from the filtered signal.

[0039] In one embodiment, step S40, receiving an optical signal at the receiving end and converting the optical signal into an electrical signal, includes: receiving the optical signal at the receiving end using a photodetector and converting the optical signal into an electrical signal.

[0040] Among them, the photodetector is the core device. Its operation is based on the photoelectric effect. When the light signal is incident on the photosensitive surface of the detector, the photon interacts with the electron in the photosensitive material. The energy of the photon is absorbed by the electron, causing the electron to escape from the bound state of the material and become a free electron (or generate electron-hole pairs in the material). Through appropriate circuit design, the movement of these electrons generated by light excitation is converted into measurable current or voltage changes, thereby realizing the conversion of the light signal carrying information into an electrical signal. This provides the basis for subsequent signal processing in the electrical domain (such as amplification, filtering, demodulation, etc.) so as to recover the effective information carried in the light signal.

[0041] In one embodiment, after step S40, converting the optical signal into an electrical signal; and before step S50, processing the electrical signal at the receiving end to recover the higher-order ciphertext; the following steps are also included: Step S41: Remove high-frequency quantization noise from the electrical signal using a low-pass filter. At the transmitting end, DSM modulation amplifies high-frequency noise while suppressing low-frequency noise, leaving only the low-frequency portion of the signal. Therefore, at the receiving end, to demodulate the DSM-modulated signal, a low-pass filter is needed to remove high-frequency quantization noise before downsampling.

[0042] For live broadcast systems, especially in scenarios such as sporting events, news reporting, and large-scale performances, extremely high requirements are placed on real-time performance, stability, and security. Traditional broadcast communication systems suffer from problems such as susceptibility to interference, data leakage, and signal degradation. The encrypted communication system proposed in this invention, based on QNSC, QEPS, and DSM technologies, can provide robust technical support in high-voltage, high-speed, and complex environments. Specific application scenarios and advantages are as follows: Quantum noise encryption ensures the security of on-site data: In live broadcasts, especially those involving important events and sensitive information, information confidentiality is paramount. This invention utilizes high-order encryption methods such as QNSC or QEPS to encrypt live audio and video signals. By leveraging the unpredictability of quantum noise, it ensures that even if an unauthorized eavesdropper intercepts the signal, they cannot obtain valid original information. This encryption method does not rely on traditional encryption algorithms but provides encryption at the physical layer, significantly enhancing the security of broadcast signals.

[0043] DSM modulation improves signal quality and interference immunity: Live broadcasts often face various interference factors, such as wireless signal obstruction, electromagnetic interference, and excessively long transmission distances. DSM modulation technology effectively reduces noise in the signal and optimizes transmission quality through oversampling and noise shaping techniques. In live broadcasts, DSM can improve signal reliability, especially during long-duration, high-data-volume broadcasts, ensuring the clarity of audio and video signals and a low bit error rate.

[0044] Low latency and real-time transmission: In live broadcasts, especially in sporting events and news reporting, real-time performance is one of the most critical requirements. DSM modulation technology, with its low latency, enables rapid signal transmission while maintaining encryption. Furthermore, QNSC technology does not introduce significant latency during physical layer encryption and decryption, allowing broadcast data to reach viewers instantly.

[0045] Adaptable to various broadcasting environments: Live broadcast environments are complex and changeable, and temporary signal obstruction or instability may occur, especially in large stadiums or remote areas where signal attenuation and distortion are more severe. Encrypted communication systems combined with DSM can effectively adapt to these challenges, reducing the impact of atmospheric attenuation, electromagnetic interference, and other environmental factors on the signal, thus improving the stability of live broadcasts.

[0046] Future development and application prospects: With the advancement of modern broadcasting technology, the application of FSO will become increasingly widespread. In many future transmission environments, it will play a significant role in "last-mile" applications, such as inter-island communication and satellite-to-ground communication scenarios, which require strong security and confidentiality. In these cases, QNSC / QEPS encryption can be used to encrypt the FSO system, while DSM modulation can be used to improve the performance of the encrypted system. It should be noted that the method in this embodiment can be executed by a single device, such as a computer or server. The method can also be applied in a distributed scenario, where multiple devices cooperate to complete the task. In such a distributed scenario, one of these devices may execute only one or more steps of the method in this embodiment, and the multiple devices will interact with each other to complete the method.

[0047] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0048] Based on the same inventive concept, corresponding to any of the above embodiments, this application also provides a high-quality signal physical layer encryption free-space optical communication system, referring to... Figure 7 As shown, the system includes the following modules: A quantum encryption module is used at the sending end to map plaintext signals into high-order ciphertext using algorithms such as quantum noise stream encryption. The modulation module is used to perform DSM modulation on the high-order ciphertext at the transmitting end to transform the high-order signal in the high-order ciphertext into multiple low-order signals. The first signal conversion module is used to convert the modulated encrypted signal into an optical signal at the transmitting end, and to transmit the optical signal using free space light.

[0049] In the high-signal-quality physical layer encrypted free-space optical communication method provided in this application, DSM modulation can effectively control quantization noise and remove noise in the high-frequency part, thereby maintaining high quality and low distortion of the signal during transmission. Especially in long-distance and harsh environments, it can significantly improve the stability of the signal.

[0050] In quantum noise stream encryption, quantum noise, as part of the encrypted signal, introduces a certain amount of noise. In this case, the noise shaping characteristics of DSM modulation play a crucial role. By concentrating the noise in the high-frequency region, DSM modulation can reduce low-frequency interference caused by quantum noise, optimize signal quality, and reduce the bit error rate.

[0051] Meanwhile, FSO systems often face the effects of atmospheric turbulence and optical attenuation, leading to various noises and distortions during signal transmission. By combining DSM modulation, this invention can effectively eliminate interference caused by quantum noise and external environmental factors during signal transmission, thereby improving the system's transmission stability and signal reliability.

[0052] Reference Figure 8 As shown, the system also includes the following modules: The second signal conversion module is used to receive optical signals at the receiving end and convert the optical signals into electrical signals; The decryption module is used to process electrical signals at the receiving end to recover higher-order ciphertext; The demapping module is used at the receiving end to decrypt and demap high-order ciphertext to recover the plaintext signal.

[0053] The physical layer encrypted free-space optical communication system in this embodiment has the beneficial effects of the above-described method embodiments, which will not be repeated here.

[0054] Based on the same inventive concept, corresponding to any of the above embodiments, this application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the free space optical communication method with physical layer encryption of any of the above embodiments.

[0055] Figure 9 This embodiment illustrates a more specific hardware structure of an electronic device. The device may include a processor 1101, a memory 1102, an input / output interface 1103, a communication interface 1104, and a bus 1105. The processor 1101, memory 1102, input / output interface 1103, and communication interface 1104 are interconnected internally via the bus 1105.

[0056] The processor 1101 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0057] The memory 1102 can be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1102 can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program code is stored in the memory 1102 and is called and executed by the processor 1101.

[0058] Input / output interface 1103 is used to connect input / output modules to realize information input and output. Input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Input devices may include keyboards, mice, touch screens, microphones, various sensors, etc., and output devices may include displays, speakers, vibrators, indicator lights, etc.

[0059] The communication interface 1104 is used to connect the communication module (not shown in the figure) to enable communication between this device and other devices. The communication module can communicate via wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0060] Bus 1105 includes a pathway for transmitting information between various components of the device, such as processor 1101, memory 1102, input / output interface 1103, and communication interface 1104.

[0061] It should be noted that although the above-described device only shows the processor 1101, memory 1102, input / output interface 1103, communication interface 1104, and bus 1105, in specific implementations, the device may also include other components necessary for normal operation. Furthermore, those skilled in the art will understand that the above-described device may only include the components necessary for implementing the embodiments of this specification, and not necessarily all the components shown in the figures.

[0062] The electronic devices described above are used to implement the corresponding physical layer encrypted free space optical communication method in any of the foregoing embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0063] Based on the same inventive concept, corresponding to the methods of any of the above embodiments, this application also provides a non-transitory computer-readable storage medium that stores computer instructions for causing the computer to execute the physical layer encrypted free-space optical communication method as described in any of the above embodiments.

[0064] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0065] The computer instructions stored in the storage medium of the above embodiments are used to cause the computer to execute the physical layer encrypted free space optical communication method as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0066] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0067] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this application, the well-known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided drawings. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this application, and this also takes into account the fact that the details of the implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this application will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that the embodiments of this application can be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0068] Although this application has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0069] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A high-signal-quality physical layer encrypted free-space optical communication method, characterized in that, include: At the sending end, algorithms such as quantum noise stream encryption are used to map plaintext signals into higher-order ciphertext; At the transmitting end, the high-order ciphertext is subjected to DSM modulation to transform the high-order signal in the high-order ciphertext into multiple low-order signals. At the transmitting end, the modulated encrypted signal is converted into an optical signal, and the optical signal is transmitted using free space light.

2. The high-signal-quality physical layer encrypted free-space optical communication method according to claim 1, characterized in that, The step of mapping plaintext signals into higher-order ciphertext at the transmitting end using algorithms such as quantum noise stream encryption includes: Quantum noise is generated using a random number generator or a quantum noise source; The plaintext signal is superimposed with the quantum noise to obtain the higher-order ciphertext.

3. The high-signal-quality physical layer encrypted free-space optical communication method according to claim 1, characterized in that, After the plaintext signal is mapped into high-order ciphertext at the transmitting end using algorithms such as quantum noise stream encryption; Before performing DSM modulation on the high-order ciphertext at the transmitting end to convert the high-order signal in the high-order ciphertext into multiple low-order signals; Also includes: The higher-order ciphertext is upsampled at the sending end and filtered using a root-raised cosine filter.

4. The high-signal-quality physical layer encrypted free-space optical communication method according to claim 1, characterized in that, The process of converting the modulated encrypted signal into an optical signal at the transmitting end and transmitting the optical signal using free-space light further includes: The receiving end receives the optical signal and converts the optical signal into an electrical signal; The electrical signal is processed at the receiving end to recover the higher-order ciphertext; The receiving end decrypts and demaps the higher-order ciphertext to recover the plaintext signal.

5. The high-signal-quality physical layer encrypted free-space optical communication method according to claim 4, characterized in that, The step of processing the electrical signal at the receiving end to recover the higher-order ciphertext includes: The electrical signal is downsampled at the receiving end and matched filtering is performed using a root-raised cosine matched filter to recover the higher-order ciphertext.

6. The high-signal-quality physical layer encrypted free-space optical communication method according to claim 4, characterized in that, The step of receiving the optical signal at the receiving end and converting the optical signal into an electrical signal includes: The optical signal is received by a photodetector at the receiving end and converted into an electrical signal.

7. The high-signal-quality physical layer encrypted free-space optical communication method according to claim 4, characterized in that, After the optical signal is converted into an electrical signal; before the electrical signal is processed at the receiving end to recover the high-order ciphertext; the method further includes: High-frequency quantization noise in the electrical signal is removed using a low-pass filter.

8. A high-signal-quality physical layer encrypted free-space optical communication system, characterized in that, include: A quantum encryption module is used at the sending end to map plaintext signals into high-order ciphertext using algorithms such as quantum noise stream encryption. A modulation module is used to perform DSM modulation on the high-order ciphertext at the transmitting end to convert the high-order signal in the high-order ciphertext into multiple low-order signals. The first signal conversion module is used to convert the modulated encrypted signal into an optical signal at the transmitting end, and to transmit the optical signal using free space light.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the free-space optical communication method with high signal quality physical layer encryption as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that, The computer instructions are used to cause the computer to execute the high-signal-quality physical layer encrypted free-space optical communication method according to any one of claims 1 to 7.

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