Optical communication method, device and system based on probability shaping differential phase encoding

Abstract

The application discloses a differential phase encoding optical communication method, device and system based on probability shaping, relates to the technical field of optical communication, and the differential phase encoding optical communication method based on probability shaping comprises the following steps: at a sending end, the probability of differential phase occurrence is changed, so that the code type with small phase change has a large occurrence probability, and the code type with large phase change has a small occurrence probability, so as that the spectrum of a sending signal is compressed; and a sending signal with compressed spectrum is modulated and transmitted. The application can keep the signal processing structure of the original system unchanged, effectively reduce the signal bandwidth through the coding mode, reduce the ISI between code types, and improve the system performance.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, specifically to an optical communication method, device, and system based on probabilistic shaping and differential phase coding. Background Technology

[0002] Differential phase modulation is an advanced modulation method with high spectral efficiency and anti-fading performance. It can be detected using both coherent and incoherent reception methods.

[0003] In general, noncoherent reception is used more in the field of short-range optical communication based on cost considerations. Its noncoherent reception method is more often called signal self-coherent reception, that is, obtaining differential phase information to demodulate the signal by delaying and cohering with the signal itself.

[0004] In the field of cost-controlled optical communication, devices typically have low bandwidth, inevitably leading to ISI (Inter-Symbol Interference) effects. This significantly impacts differential phase modulation signals using self-coherent reception. To address this issue, signal bandwidth compression schemes such as Nyquist coding and partial response signal systems are commonly employed. However, these methods greatly increase system complexity at both the transmitting and receiving ends, contradicting the goal of low-cost self-coherent reception using differential phase coding. Summary of the Invention

[0005] This application provides an optical communication method, device, and system based on probabilistic shaping differential phase coding, which can maintain the original signal processing structure of the transceiver end of the system unchanged, effectively reduce the signal bandwidth by coding alone, reduce the ISI between symbols, and improve system performance.

[0006] In a first aspect, embodiments of this application provide an optical communication method based on probabilistic shaping and differential phase coding, wherein the optical communication method based on probabilistic shaping and differential phase coding includes:

[0007] At the transmitting end, the probability of differential phase occurrence is changed so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0008] The transmitted signal is modulated and compressed to compress the spectrum for transmission.

[0009] In conjunction with the first aspect, in one implementation, at the transmitting end, changing the probability of differential phase occurrence so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal, includes:

[0010] Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information.

[0011] Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

[0012] In conjunction with the first aspect, in one implementation, the step of determining the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding based on the modulation type and data stream, performing differential phase coding and probabilistic coding, and mapping the probabilistic coding information to different differential phase information includes:

[0013] When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11.

[0014] Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

[0015] In conjunction with the first aspect, in one implementation, the step of adjusting the probability of differential phase occurrence based on the relationship between differential phase coding and probabilistic coding, and analyzing the spectrum at each frequency from the perspective of symbol energy, includes:

[0016] Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously:

[0017] p1+p2+p3+p4=1;

[0018] p1≥p2≥p3≥p4; and

[0019] h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

[0020] Secondly, embodiments of this application provide an optical communication device based on probabilistic shaping differential phase coding, wherein the optical communication device based on probabilistic shaping differential phase coding includes:

[0021] An encoder is used at the transmitting end to change the probability of differential phase occurrence, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0022] A modulator is used to modulate a transmitted signal after compressing the spectrum for transmission.

[0023] In conjunction with the second aspect, in one embodiment, the encoder at the transmitting end changes the probability of differential phase occurrence, making the probability of code patterns with small phase changes high and the probability of code patterns with large phase changes low, so as to compress the spectrum of the transmitted signal, including:

[0024] Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information.

[0025] Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

[0026] In conjunction with the second aspect, in one implementation, the encoder determines the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding based on the modulation type and data stream, performs differential phase coding and probabilistic coding, and maps the probabilistic coding information to different differential phase information, including:

[0027] When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11.

[0028] Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

[0029] In conjunction with the second aspect, in one implementation, the encoder, based on the relationship between differential phase coding and probabilistic coding, analyzes the spectrum at each frequency from the perspective of symbol energy, and adjusts the probability of differential phase occurrence, including:

[0030] Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously:

[0031] p1+p2+p3+p4=1;

[0032] p1≥p2≥p3≥p4; and

[0033] h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

[0034] Thirdly, embodiments of this application provide another optical communication method based on probabilistic shaping differential phase coding, the optical communication method based on probabilistic shaping differential phase coding including:

[0035] At the transmitting end, the probability of differential phase occurrence is changed so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0036] The transmitted signal is modulated and compressed to achieve transmission.

[0037] At the receiving end, signal demodulation is completed through self-coherent differential reception.

[0038] Fourthly, embodiments of this application provide an optical communication system based on probabilistic shaping and differential phase coding, wherein the optical communication system based on probabilistic shaping and differential phase coding includes:

[0039] Transmitting device, comprising:

[0040] An encoder is used at the transmitting end to change the probability of differential phase occurrence, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0041] A modulator is used to modulate a transmitted signal after its spectrum has been compressed for transmission.

[0042] A receiving device is used to demodulate a signal at the receiving end through self-coherent differential reception.

[0043] The beneficial effects of the technical solutions provided in this application include at least the following:

[0044] The optical communication method based on probabilistic shaping differential phase coding in this application compresses the spectrum of the transmitted signal by changing the probability of differential phase occurrence at the transmitting end, making the probability of code patterns with small phase changes high and the probability of code patterns with large phase changes low; and modulating the transmitted signal after compressing the spectrum for transmission.

[0045] This method, based on existing differential phase modulation and coding, reduces the effective bandwidth of the signal by setting different probabilities of differential phase occurrence, thereby achieving signal compression. The scheme in this application maintains the original signal processing structure at the transceiver end of the system, effectively reducing signal bandwidth and lowering ISI between symbols through coding alone, thus improving system performance. This scheme effectively enhances the practical applicability of systems based on differential phase coding self-coherent reception structures. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating an embodiment of the differential phase coding optical communication method based on probabilistic shaping according to this application;

[0047] Figure 2 This is a flowchart illustrating another embodiment of the optical communication method based on probability shaping differential phase coding of this application. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0049] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0050] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0051] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0052] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0054] In a first aspect, embodiments of this application provide an optical communication method based on differential phase coding using probabilistic shaping.

[0055] In one embodiment, reference is made to Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the optical communication method based on probabilistic shaping and differential phase coding according to this application. Figure 1 As shown, the optical communication method based on probabilistic shaping and differential phase coding includes:

[0056] S1. At the transmitting end, change the probability of differential phase occurrence so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0057] Specifically, step S1 includes:

[0058] S11. Based on the modulation type and data stream, determine the absolute phase information of the transmitted signal and the phase information corresponding to the differential coding, perform differential phase coding and probabilistic coding, and map the probabilistic coding information to different differential phase information.

[0059] S12. Based on the relationship between differential phase coding and probabilistic coding, analyze the spectrum at each frequency from the perspective of symbol energy, and adjust the probability of differential phase occurrence.

[0060] S2. The transmitted signal after modulation and compression of the spectrum is used for transmission.

[0061] In this embodiment, firstly, at the transmitting end, without changing the original transmitting end system structure, the different absolute phase information and the corresponding differentially encoded phase information required for the transmitted signal are determined. The raw data is mapped through a probabilistic encoder to obtain encoded information with different probabilities, and then mapped to different differential phase information. Next, the transmitted signal is encoded using conventional differential phase encoding to obtain a differentially phase encoded optical signal with the required probability shaping. Finally, this signal is modulated and sent into the optical fiber for transmission.

[0062] Because of the probabilistically shaped differential phase coding, the phase variation between signal symbols is significantly reduced, the effective bandwidth of the signal is decreased, the inter-symbol ISI is reduced, and the signal quality after transmission is improved. Furthermore, since the optical signal with probabilistically shaped differential phase coding is not fundamentally different in structure from the original differential phase signal, the original receiving method can be largely used at the receiving end. Phase symbols between different symbols are obtained through self-coherent reception, and the original digital sequence is recovered through demapping.

[0063] The following is a specific example to illustrate this:

[0064] First, the data stream generates probabilistic coded symbols through mapping. The following explanation uses DQPSK modulation as an example. Other differential phase coding modulation methods are similar and will not be detailed here.

[0065] Typically, the output phases of DQPSK four-phase modulation symbols are 45°, 135°, 225°, and 315°.

[0066] When differential coding is used, the phase difference between consecutive symbols is:

[0067] When the output bit is 00, the phase difference is 0°; when the output bit is 01, the phase difference is 90°; when the output bit is 10, the phase difference is 180°; and when the output bit is 01, the phase difference is 270°.

[0068] This completes the standard differential phase encoding process. Since probabilistic encoding was also applied to the output sequence, the probability of output 00 is set as p1, output 01 as p2, output 10 as p3, and output 11 as p4. Because the signal's spectral distribution depends on the change in signal phase, i.e.:

[0069] f = Δφ / Δt

[0070] Where f is the signal frequency, Δφ is the phase change per unit time, and Δt is the time of change. Therefore, the smaller the phase change of the signal per unit time, the lower its frequency, and thus the smaller the signal bandwidth. Based on the above principle, this application modifies the probability of differential phase to achieve signal compression, thereby increasing the occurrence of code patterns with small phase changes and decreasing the occurrence of code patterns with large phase changes, and effectively reducing the signal bandwidth. Specifically, it needs to meet the following requirements:

[0071] p1+p2+p3+p4=1;

[0072] p1>=p2>=p3>=p4;

[0073] Assuming the energy of a single symbol is 1, then p1, p2, p3, and p4 represent the relative energies of the four symbols, respectively. Therefore, when the signal spectrum of the system at frequencies f1, f2, and f3 corresponds to h1, h2, and h3 respectively (i.e., the remaining energy after transmission at these three frequencies when the input energy is 1), the energy ratios at these frequencies indicate that, in order to achieve signal compression, the following must be satisfied:

[0074] h1>p2 / p1, h2>p3 / p1, h3>p4 / p1;

[0075] Where h1, h2 and h3 are the signal spectra of the transmitting device at f1, f2 and f3 respectively, and f1, f2 and f3 are the frequencies when the phase difference is 90°, 180° and 270° respectively.

[0076] After completing the coding that meets the probability requirements, the signal spectrum is effectively compressed, and the differential coding process of probability shaping is also completed. At the receiving end, the signal is demodulated through self-coherent differential reception, which is the same as the original system and will not be repeated.

[0077] In summary, the optical communication method based on probabilistic shaping differential phase coding in this application compresses the spectrum of the transmitted signal by changing the probability of differential phase occurrence at the transmitting end, making the probability of code patterns with small phase changes high and the probability of code patterns with large phase changes low; and modulating the transmitted signal after compressing the spectrum for transmission.

[0078] This invention employs a probability-shaping-based differential phase coding method. Building upon existing differential phase modulation, it compresses the effective spectrum of the signal by altering the probability of differential phase occurrence. Simultaneously, while maintaining the original system structure, it leverages its coding characteristics to preserve the original self-coherent reception properties, ensuring a low-cost reception method. This application is applicable to short-range self-coherent signal bandwidth-limited systems, optimizing the overall performance of optical transmission systems and improving their compatibility and stability.

[0079] Secondly, embodiments of this application also provide an optical communication device based on probability shaping differential phase coding, which includes:

[0080] An encoder is used at the transmitting end to change the probability of differential phase occurrence, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0081] A modulator is used to modulate a transmitted signal after compressing the spectrum for transmission.

[0082] Furthermore, in one embodiment, the encoder at the transmitting end changes the probability of differential phase occurrence, making the probability of code patterns with small phase changes high and the probability of code patterns with large phase changes low, in order to compress the spectrum of the transmitted signal, including:

[0083] Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information.

[0084] Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

[0085] Further, in one embodiment, the encoder determines the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding based on the modulation type and data stream, performs differential phase coding and probabilistic coding, and maps the probabilistic coding information to different differential phase information, including:

[0086] When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11.

[0087] Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

[0088] Furthermore, in one embodiment, the encoder adjusts the probability of differential phase occurrence based on the relationship between differential phase coding and probabilistic coding, by analyzing the spectrum at each frequency from the perspective of symbol energy, including:

[0089] Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously:

[0090] p1+p2+p3+p4=1;

[0091] p1≥p2≥p3≥p4; and

[0092] h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

[0093] The functions of each module in the above-mentioned optical communication device based on probabilistic shaping differential phase coding correspond to the steps in the above-mentioned embodiment of the optical communication method based on probabilistic shaping differential phase coding. Their functions and implementation processes will not be described in detail here.

[0094] Thirdly, embodiments of this application provide another optical communication method based on probability shaping and differential phase coding.

[0095] In one embodiment, reference is made to Figure 2 , Figure 2 This is a flowchart illustrating another embodiment of the optical communication method based on probabilistic shaping and differential phase coding according to this application. Figure 2 As shown, the optical communication method based on probabilistic shaping and differential phase coding includes:

[0096] S1. At the transmitting end, change the probability of differential phase occurrence so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0097] S2. The transmitted signal after modulation and compression of the spectrum is used for transmission;

[0098] S3. At the receiving end, the signal is demodulated through self-coherent differential reception.

[0099] It is worth noting that the signal demodulation is completed at the receiving end through self-coherent differential reception, which is the same as the system in the prior art, so this application will not repeat it here.

[0100] Further, in one embodiment, the step of changing the probability of differential phase occurrence at the transmitting end, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal, includes:

[0101] Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information.

[0102] Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

[0103] Further, in one embodiment, the step of determining the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding based on the modulation type and data stream, performing differential phase coding and probabilistic coding, and mapping the probabilistic coding information to different differential phase information includes:

[0104] When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11.

[0105] Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

[0106] Furthermore, in one embodiment, the step of adjusting the probability of differential phase occurrence based on the relationship between differential phase coding and probabilistic coding, and analyzing the spectrum at each frequency from the perspective of symbol energy, includes:

[0107] Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously:

[0108] p1+p2+p3+p4=1;

[0109] p1≥p2≥p3≥p4; and

[0110] h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

[0111] Fourthly, embodiments of this application also provide an optical communication system based on probabilistic shaping differential phase coding, the optical communication system based on probabilistic shaping differential phase coding comprising:

[0112] Transmitting device, comprising:

[0113] An encoder is used at the transmitting end to change the probability of differential phase occurrence, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal.

[0114] A modulator is used to modulate a transmitted signal after its spectrum has been compressed for transmission.

[0115] A receiving device is used to demodulate a signal at the receiving end through self-coherent differential reception.

[0116] Furthermore, in one embodiment, the encoder at the transmitting end changes the probability of differential phase occurrence, making the probability of code patterns with small phase changes high and the probability of code patterns with large phase changes low, in order to compress the spectrum of the transmitted signal, including:

[0117] Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information.

[0118] Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

[0119] Further, in one embodiment, the encoder determines the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding based on the modulation type and data stream, performs differential phase coding and probabilistic coding, and maps the probabilistic coding information to different differential phase information, including:

[0120] When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11.

[0121] Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

[0122] Furthermore, in one embodiment, the encoder adjusts the probability of differential phase occurrence based on the relationship between differential phase coding and probabilistic coding, by analyzing the spectrum at each frequency from the perspective of symbol energy, including:

[0123] Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously:

[0124] p1+p2+p3+p4=1;

[0125] p1≥p2≥p3≥p4; and

[0126] h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

[0127] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An optical communication method based on differential phase coding using probabilistic shaping, characterized in that, The optical communication method based on probability shaping and differential phase coding includes: At the transmitting end, the probability of differential phase occurrence is changed so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal. The transmitted signal is modulated and compressed to compress the spectrum for transmission.

2. The optical communication method based on differential phase coding according to probabilistic shaping as described in claim 1, characterized in that, At the transmitting end, changing the probability of differential phase occurrence so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal, includes: Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information. Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

3. The optical communication method based on differential phase coding according to claim 2, characterized in that, The process involves determining the absolute phase information of the transmitted signal and the corresponding phase information for differential coding based on the modulation type and data stream, performing differential phase coding and probabilistic coding, and mapping the probabilistic coding information to different differential phase information, including: When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11. Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

4. The optical communication method based on differential phase coding according to probabilistic shaping as described in claim 3, characterized in that, The step of adjusting the probability of differential phase occurrence based on the relationship between differential phase coding and probabilistic coding, and by analyzing the spectrum at each frequency from the perspective of symbol energy, includes: Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously: p1 + p2 + p3 + p4 = 1; p1≥p2≥p3≥p4; and h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

5. An optical communication device based on differential phase coding using probabilistic shaping, characterized in that, The optical communication device based on probability shaping and differential phase coding includes: An encoder is used at the transmitting end to change the probability of differential phase occurrence, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal. A modulator is used to modulate a transmitted signal after compressing the spectrum for transmission.

6. The optical communication device based on probabilistic shaping and differential phase coding as described in claim 5, characterized in that, The encoder at the transmitting end changes the probability of differential phase occurrence, making the probability of code patterns with small phase changes high and the probability of code patterns with large phase changes low, in order to compress the spectrum of the transmitted signal, including: Based on the modulation type and data stream, the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding are determined, differential phase coding and probabilistic coding are performed, and the probabilistic coding information is mapped to different differential phase information. Based on the relationship between differential phase coding and probabilistic coding, the spectrum at each frequency is analyzed from the perspective of symbol energy, and the probability of differential phase occurrence is adjusted.

7. The optical communication device based on probabilistic shaping and differential phase coding as described in claim 6, characterized in that, The encoder, based on the modulation type and data stream, determines the absolute phase information of the transmitted signal and the corresponding phase information of the differential coding, performs differential phase coding and probabilistic coding, and maps the probabilistic coding information to different differential phase information, including: When DQPSK modulation is used, differential phase encoding is performed so that the phase difference is 0° when the output bit is 00, 90° when the output bit is 01, 180° when the output bit is 10, and 270° when the output bit is 11. Let p1 be the probability of outputting 00, p2 be the probability of outputting 01, p3 be the probability of outputting 10, and p4 be the probability of outputting 11.

8. The optical communication device based on probabilistic shaping and differential phase coding as described in claim 7, characterized in that, The encoder, based on the relationship between differential phase coding and probabilistic coding, analyzes the spectrum at each frequency from the perspective of symbol energy and adjusts the probability of differential phase occurrence, including: Configure the sizes of p1, p2, p3, and p4 such that the following conditions are met simultaneously: p1 + p2 + p3 + p4 = 1; p1≥p2≥p3≥p4; and h1>p2 / p1, h2>p3 / p1, h3>p4 / p1, where h1, h2, and h3 are the signal spectra of the transmitting device at f1, f2, and f3, respectively, and f1, f2, and f3 are the frequencies when the phase difference is 90°, 180°, and 270°, respectively.

9. An optical communication method based on differential phase coding using probabilistic shaping, characterized in that, The optical communication method based on probability shaping and differential phase coding includes: At the transmitting end, the probability of differential phase occurrence is changed so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal. The transmitted signal is modulated and compressed to achieve transmission. At the receiving end, signal demodulation is completed through self-coherent differential reception.

10. An optical communication system based on probabilistic shaping and differential phase coding, characterized in that, The differential phase coding optical communication system based on probability shaping includes: Transmitting device, comprising: An encoder is used at the transmitting end to change the probability of differential phase occurrence, so that the probability of code patterns with small phase changes is high and the probability of code patterns with large phase changes is low, in order to compress the spectrum of the transmitted signal. A modulator is used to modulate a transmitted signal after compressing its spectrum for transmission. A receiving device is used to demodulate a signal at the receiving end through self-coherent differential reception.

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