A probabilistic constellation shaping method and system, and an optical communication method and system

Abstract

The present invention discloses a probabilistic constellation shaping method and system, and an optical communication method and system. The present invention does not require the high-precision arithmetic process of traditional CCDM, and uses a table lookup method to select mapping symbols, thereby reducing the encoding and decoding complexity of the transceiver and improving cost-effectiveness. In addition, the Polar code with strong error correction performance is combined to suppress the error propagation and accumulation during decoding at the receiving end, thereby ensuring the reliability of the transmission system and being suitable for cost-sensitive scenarios such as short-distance optical access systems.

Description

Technical Field

[0001] The present invention relates to a probabilistic constellation shaping method and system, an optical communication method and system, and belongs to the field of optical fiber communication. Background Art

[0002] With the rapid development of the current network world and the explosive growth of data traffic demand, the capacity and reliability of optical communication systems are facing challenges. Advanced modulation formats help to improve the spectrum utilization, transmission rate, and dispersion robustness of optical communication systems. Currently, the widely used modulation formats include: pulse amplitude modulation (PAM), orthogonal frequency division multiplexing (OFDM), discrete multi-tone modulation (DMT) and carrier amplitude phase modulation (CAP). The CAP modulation format has higher spectrum efficiency and flexibility due to its multi-level signal constellation diagram and spectrum shaping capabilities, making it one of the most attractive modulation formats. The application of finite impulse response (FIR) filter groups can directly generate orthogonal signals, which can reduce the complexity of the system and equipment costs to a certain extent.

[0003] Probabilistic constellation shaping (PCS) technology is one of the important means to improve the transmission capacity of optical communication systems and approach the Shannon limit. Probabilistic constellation shaping technology changes the probability distribution of constellation points, increases the probability of low-energy symbols, and reduces the probability of high-energy symbols, achieving a smaller average transmission power at the same information rate, showing excellent anti-noise robustness, and improving the reliability of the transmission system.

[0004] The current constant component distribution matcher (CCDM) is an earlier proposed and relatively mature probability shaping technology, which can use high-precision arithmetic processes to convert independent Bernoulli distribution input bit information into output symbols of the desired distribution. However, the high computational complexity increases the cost of the communication system and limits its application in scenarios such as short-distance optical access systems. Summary of the invention

[0005] The present invention provides a probabilistic constellation shaping method and system, and an optical communication method and system, which solve the problems disclosed in the background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A probabilistic constellation shaping method, comprising:

[0008] Performing serial-to-parallel conversion on the binary data to be transmitted to obtain real binary data and imaginary binary data;

[0009] Perform distribution matching and Polar coding on the real binary data in sequence, combine and map the distribution matching results and Polar coding results to obtain the real part information of the constellation point; wherein the distribution matching is prefix-free codebook distribution matching;

[0010] Perform distribution matching and Polar coding on the imaginary binary data in sequence, combine and map the distribution matching results and Polar coding results to obtain the imaginary part information of the constellation point;

[0011] The real part information and the imaginary part information of the constellation points are combined into a probability distribution diagram of the constellation points.

[0012] The real binary data is distributed and matched and polar coded in turn, and the distribution matching result and polar coding result are combined and mapped to obtain the real part information of the constellation point, including:

[0013] Perform distribution matching on the real binary data, and convert information symbols with uniform probability distribution in the real binary data into coding symbols with target non-uniform probability distribution;

[0014] Polar encoding is performed on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits;

[0015] The coding symbols of the target non-uniform probability distribution and the redundant check bits are mapped to obtain the real part information of the constellation point.

[0016] The imaginary binary data is distributed and matched and polar coded in turn, and the distribution matching result and polar coding result are combined and mapped to obtain the imaginary part information of the constellation point, including:

[0017] Perform distribution matching on the imaginary binary data, and convert the information symbols with uniform probability distribution in the imaginary binary data into coding symbols with target non-uniform probability distribution;

[0018] Polar encoding is performed on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits;

[0019] The coding symbols of the target non-uniform probability distribution and the redundant check bits are combined and mapped to obtain the imaginary part information of the constellation point.

[0020] A probabilistic constellation shaping system, comprising:

[0021] A serial-to-parallel conversion module is used to perform serial-to-parallel conversion on the binary data to be transmitted to obtain real binary data and imaginary binary data;

[0022] A real part shaping module is used to perform distribution matching and Polar coding on the real part binary data in sequence, and map the distribution matching results and Polar coding results together to obtain the real part information of the constellation point; wherein the distribution matching is prefix-free codebook distribution matching;

[0023] The imaginary part shaping module is used to perform distribution matching and Polar coding on the imaginary part binary data in sequence, and map the distribution matching results and Polar coding results together to obtain the imaginary part information of the constellation point;

[0024] The combination module is used to combine the real part information and the imaginary part information of the constellation points into a probability distribution diagram of the constellation points.

[0025] The real part shaping module includes:

[0026] A real distribution matcher is used to perform distribution matching on the real binary data, and convert information symbols with uniform probability distribution in the real binary data into coding symbols with target non-uniform probability distribution;

[0027] A real part Polar encoder is used to perform Polar encoding on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits;

[0028] The real part mapping unit is used to map the coding symbols of the target non-uniform probability distribution and the redundant check bit combination to obtain the real part information of the constellation point.

[0029] The imaginary part shaping module includes:

[0030] An imaginary distribution matcher is used to perform distribution matching on the imaginary binary data, and convert information symbols with uniform probability distribution in the imaginary binary data into coding symbols with target non-uniform probability distribution;

[0031] An imaginary part Polar encoder is used to perform Polar encoding on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits;

[0032] The imaginary part mapping unit is used to map the coding symbols of the target non-uniform probability distribution and the redundant check bit combination to obtain the imaginary part information of the constellation point.

[0033] An optical communication method, comprising:

[0034] The probability distribution diagram of constellation points is obtained by using the probabilistic constellation shaping method;

[0035] Carrier amplitude phase modulation is performed on the probability distribution graph, and the probability distribution graph after carrier amplitude phase modulation is sent to the receiving end.

[0036] Carrier amplitude phase modulation of the probability distribution diagram includes:

[0037] Upsampling the constellation symbol information in the probability distribution diagram by several times;

[0038] Performing orthogonal filtering on the constellation symbol information after being upsampled several times;

[0039] The two outputs of the orthogonal filter are added together into one output.

[0040] An optical communication system, comprising:

[0041] A probabilistic constellation shaping module is used to obtain a probability distribution diagram of constellation points by adopting a probabilistic constellation shaping method;

[0042] The carrier amplitude phase modulation module is used to perform carrier amplitude phase modulation on the probability distribution diagram and send the probability distribution diagram after the carrier amplitude phase modulation to the receiving end.

[0043] The carrier amplitude phase modulation module includes:

[0044] An up-sampling module, used to up-sample the constellation symbol information in the probability distribution diagram by several times;

[0045] An orthogonal filter is used to perform orthogonal filtering on the constellation symbol information after being upsampled several times;

[0046] The adder is used to add the two outputs of the orthogonal filter into one output.

[0047] The beneficial effects achieved by the present invention are as follows: the present invention does not require the high-precision arithmetic process of traditional CCDM, and uses a table lookup method to select mapping symbols, thereby reducing the encoding and decoding complexity of the transceiver and improving cost-effectiveness. In combination with the Polar code with strong error correction performance, the error propagation and accumulation during decoding at the receiving end are suppressed, thereby ensuring the reliability of the transmission system and being suitable for cost-sensitive scenarios such as short-distance optical access systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a flow chart of the probabilistic constellation shaping method;

[0049] Figure 2 Flowchart for Polar coding;

[0050] Figure 3 is the probability distribution diagram of the constellation points;

[0051] Figure 4 It is a flow chart of carrier amplitude phase modulation;

[0052] FIG5( a ) is a constellation diagram after probability shaping obtained by the present invention;

[0053] Figure 5(b) shows the standard 16-CAP uniform probability distribution constellation diagram under the same parameters;

[0054] Figure 6(a) shows the symbol error rate curves of the receiving end under different signal-to-noise ratios (SNRs) of the three methods;

[0055] Figure 6(b) shows the bit error rate curves of the three methods at different signal-to-noise ratios (SNRs). DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0057] like Figure 1 As shown, a probabilistic constellation shaping method includes the following steps:

[0058] Step 1, performing serial-to-parallel conversion on the binary data to be transmitted to obtain real binary data and imaginary binary data;

[0059] Step 2: Perform distribution matching and Polar coding on the real binary data in sequence, combine and map the distribution matching result and the Polar coding result to obtain the real information of the constellation point; perform distribution matching and Polar coding on the imaginary binary data in sequence, combine and map the distribution matching result and the Polar coding result to obtain the imaginary information of the constellation point; wherein the distribution matching is prefix-free codebook distribution matching;

[0060] Step 3: Combine the real part information and the imaginary part information of the constellation points into a probability distribution diagram of the constellation points.

[0061] The above method is implemented at the transmitting end of optical communication. It does not require the high-precision arithmetic process of traditional CCDM. It uses a table lookup to select mapping symbols, reduces the encoding and decoding complexity of the transmitting and receiving ends, improves cost-effectiveness, and combines the Polar code with strong error correction performance to suppress the error propagation and accumulation during decoding at the receiving end, thereby ensuring the reliability of the transmission system and being suitable for cost-sensitive scenarios such as short-distance optical access systems.

[0062] In an optical communication system, the binary data to be transmitted at the transmitter is a binary bit stream, and a series of binary bit streams needs to be converted from serial to parallel, that is, a series of binary bit streams is converted into parallel real binary data and imaginary binary data.

[0063] The serial-to-parallel conversion is to extract part of the digital bits in the binary bit stream to form the real binary data, and the rest constitute the imaginary binary data. The extraction principle is determined according to the actual situation. For example, the even bits can be extracted as the real binary data, and the odd bits can be extracted as the imaginary binary data.

[0064] The two columns of binary data use the same method to obtain the real part information of the constellation point and the imaginary part information of the constellation point respectively. The process can be as follows:

[0065] 1. First, perform distribution matching on the binary data. Specifically, the binary data is input into a distribution matcher (PCDM) without a prefix codebook. An example of the PCDM codebook is shown in Table 1.

[0066] Table 1 DM codebook example

[0067]

[0068]

[0069] The distribution matcher converts uniform probability distribution information symbols into coding symbol outputs of target non-uniform probability distribution, such as the input information symbol bit b∈B:={0,1}, and the probability of b=0 and b=1 is equal to 0.5. The coding symbol output after the distribution matcher is used to represent the unipolar amplitude information a∈X:={1,3,…,2M-1}.

[0070] Based on PCDM, the amplitude information of the target probability distribution can be directly obtained through the design and selection of the codebook to complete the probability amplitude shaping; the codebook of PCDM can be freely designed using Huffman coding. Assuming that the total number of input bit symbols of PCDM is k and the number of output coded symbols is n, the coding rate Rd can be expressed as: Rd = k / n.

[0071] Therefore, the purpose of information rate matching can be achieved by using the corresponding relationship between the input and output symbols of the codebook. Taking the codebook in Table 1 as an example, the coding rate Rd is calculated to be approximately 0.866 through the simulation process. When the input binary sequence entering the distribution matcher is long enough, all input bits will have corresponding coding symbols. It can be seen from the output coding symbols of the codebook that the probability of the symbol "1" appearing is much greater than "3", realizing probability amplitude shaping, so the probability of low-energy constellation symbols in the final constellation point will be much greater than that of high-energy constellation symbols.

[0072] 2. Perform Polar encoding on the target non-uniform probability distribution coded symbols to obtain redundant check bits.

[0073] Polar code is a forward error correction code (FEC) based on channel polarization theory proposed by Dr. Arikan. The process of channel polarization includes two stages: channel combination and channel splitting. The good channel with relatively high reliability obtained by channel polarization is used to transmit information, while the poor channel with low reliability is used to transmit fixed bit information. Research on Polar codes in recent years has shown that compared with non-systematic coding, systematically coded Polar codes have better performance. Through the cascaded list-cyclic redundancy check (CRC) decoding method, the systematic Polar coding using the serial cancellation list (SCL) decoder at the receiving end has excellent error correction capability comparable to low-density parity-check code (LDPC).

[0074] Due to the use of Polar coding, such as Figure 2 As shown in the figure, after the coded symbols obtained by PCDM are forward error correction coded, the information coded symbols and redundant check bits after Polar coding are separated by an interleaver; in the figure, {U In} represents the information encoding symbol set of the target non-uniform probability distribution, {U Fn} represents the set of redundant check bits added after Polar coding, and the characteristics of the non-uniform probability distribution of the final encoded symbols can be retained.

[0075] Polar coding, as a forward error correction code, is placed inside the PCDM mapping. The error correction capability of Polar coding can effectively suppress the error propagation and synchronization errors caused by the DM decoder during decoding, thus ensuring the transmission reliability of the optical communication system to a certain extent.

[0076] 3. Map the coding symbols and redundant check bits of the target non-uniform probability distribution to obtain the real / imaginary information of the constellation point, that is, the coding symbols a∈X:={1, 3, ..., 2M-1} obtained by PCDM and the redundant check bits after Polar coding are mapped into the real or imaginary information of the constellation point.

[0077] The process of obtaining the real part information of the constellation point can be described as: performing distribution matching on the real part binary data, converting the information symbols of the uniform probability distribution in the real part binary data into the coding symbols of the target non-uniform probability distribution; performing Polar coding on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits; and mapping the combination of the coding symbols of the target non-uniform probability distribution and the redundant check bits to obtain the real part information of the constellation point.

[0078] The process of obtaining the imaginary part information of the constellation point can be described as: performing distribution matching on the imaginary part binary data, converting the information symbols of the uniform probability distribution in the imaginary part binary data into coding symbols of the target non-uniform probability distribution; performing Polar coding on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits; and mapping the combination of the coding symbols of the target non-uniform probability distribution and the redundant check bits to obtain the imaginary part information of the constellation point.

[0079] Finally, the real part information and imaginary part information of the constellation point are combined into a probability distribution diagram of the constellation point, as shown in the following figure: Figure 3 ,After probability shaping, the probabilities of constellation points with the same radius are approximately the same, and the probabilities of constellation points with different radii approximately obey the Maxwell Boltzmann distribution.

[0080] Based on the same technical solution, the present invention also discloses a software system of the above method, a probabilistic constellation shaping system, comprising:

[0081] The serial-to-parallel conversion module is used to perform serial-to-parallel conversion on the binary data to be transmitted to obtain real binary data and imaginary binary data.

[0082] The real part shaping module is used to perform distribution matching and Polar coding on the real part binary data in sequence, and map the distribution matching results and the Polar coding results together to obtain the real part information of the constellation point; wherein the distribution matching is prefix-free codebook distribution matching.

[0083] The real part shaping module includes:

[0084] A real distribution matcher is used to perform distribution matching on the real binary data, and convert information symbols with uniform probability distribution in the real binary data into coding symbols with target non-uniform probability distribution;

[0085] A real part Polar encoder is used to perform Polar encoding on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits;

[0086] The real part mapping unit is used to map the coding symbols of the target non-uniform probability distribution and the redundant check bit combination to obtain the real part information of the constellation point.

[0087] The imaginary part shaping module is used to perform distribution matching and Polar coding on the imaginary part binary data in sequence, and map the distribution matching results and the Polar coding results together to obtain the imaginary part information of the constellation point.

[0088] The imaginary part shaping module includes:

[0089] An imaginary distribution matcher is used to perform distribution matching on the imaginary binary data, and convert information symbols with uniform probability distribution in the imaginary binary data into coding symbols with target non-uniform probability distribution;

[0090] An imaginary part Polar encoder is used to perform Polar encoding on the coding symbols of the target non-uniform probability distribution to obtain redundant check bits;

[0091] The imaginary part mapping unit is used to map the coding symbols of the target non-uniform probability distribution and the redundant check bit combination to obtain the imaginary part information of the constellation point.

[0092] The combination module is used to combine the real part information and the imaginary part information of the constellation points into a probability distribution diagram of the constellation points.

[0093] Based on the same technical solution, the present invention also discloses an optical communication method, comprising:

[0094] S1) A probability distribution diagram of constellation points is obtained by adopting a probability constellation shaping method.

[0095] S2) Carrier Amplitude Phase (CAP) modulation is performed on the probability distribution graph, and the probability distribution graph after the carrier amplitude phase modulation is sent to the receiving end.

[0096] After obtaining the probability distribution diagram of the constellation points, it is also necessary to perform carrier amplitude phase modulation on them, such as Figure 4 Specifically, it can be:

[0097] 31) upsampling the constellation symbol information in the probability distribution diagram by several times to achieve a multiple period expansion of the signal on the spectrum to obtain the upsampled symbol information;

[0098] 32) performing orthogonal filtering on the constellation symbol information after multiple upsampling;

[0099] The main process is to input the symbol information into two mutually orthogonal FIR filters for orthogonal filtering. The tap coefficients of the filters can be adjusted according to the actual situation.

[0100] 33) The two outputs of the orthogonal filter are added together to complete CAP modulation.

[0101] The above is the process of the transmitting end of the optical communication method. The receiving end is a reverse operation. The serial cancellation list decoding (SCL) algorithm and solution distribution matching are used to restore the original data. Specifically, the Polar decoder and PCDM decoder are used. Among them, the Polar decoder is before the PCDM decoder, which can effectively correct the bit errors during transmission, ensure the accuracy of the symbols entering the DM decoding, and ensure the reliability of the transmission system.

[0102] The constellation diagram of the receiving end is obtained through simulation. Figure 5(a) is the constellation diagram after probability shaping obtained by the present invention, and Figure 5(b) is the standard 16-CAP uniform probability distribution constellation diagram under the same parameters. It can be seen from the distribution of constellation points that the probability of occurrence of constellation points with low energy (inner) in Figure 5(a) is much greater than that of constellation points with high energy (outer) and constellation probability shaping is achieved; compared with the 18-CAP constellation points with uniform probability distribution, the constellation points obtained by the present invention are more concentrated and have better effects.

[0103] FIG6(a) is a receiving end symbol error rate curve of the present invention, probability constellation shaping based on prefix-free codebook distribution matcher and standard 16-CAP under different signal-to-noise ratios (SNRs). It can be seen from the figure that the symbol error rate of the constellation symbol after shaping by the prefix-free codebook distribution matcher is better than that of the standard 16-CAP, and the probability shaping improves the symbol error rate by about 1 dB; and since the Polar coding as forward error correction plays a role after receiving the constellation symbol, there is no obvious difference in the symbol error rate curves of the two methods with and without forward Polar coding in FIG6(a); wherein, the square PCDM w / i Polar represents the PCDM scheme of joint Polar coding (the present invention), the circular PCDM w / o Polar represents the pure PCDM scheme without joint Polar coding, and the triangular Normal w / o Polar represents the standard 16CAP modulation scheme.

[0104] FIG6(b) is a graph of the bit error rate of the three schemes. The bit error rate of the present invention quickly drops below 1E-5 as the signal-to-noise ratio increases. In the absence of Polar coding, the PCDM decoder receives more erroneous symbols at low signal-to-noise ratios, which causes error propagation and ultimately results in a received bit error rate close to 0.5. The bit error rate curve of the standard 16-CAP decreases as the signal-to-noise ratio increases, and the bit error rate drops below 1E-3 when the signal-to-noise ratio is greater than 6. Compared with the bit error rate curve of the standard 16-CAP, the present invention has a very high signal-to-noise ratio gain.

[0105] Based on the same technical solution, the present invention also discloses a software system of the above optical communication method, an optical communication system, comprising:

[0106] The probabilistic constellation shaping module is used to obtain the probability distribution diagram of the constellation points by adopting the probabilistic constellation shaping method.

[0107] The carrier amplitude phase modulation module is used to perform carrier amplitude phase modulation on the probability distribution diagram and send the probability distribution diagram after the carrier amplitude phase modulation to the receiving end.

[0108] The carrier amplitude phase modulation module includes:

[0109] An up-sampling module, used to up-sample the constellation symbol information in the probability distribution diagram by several times;

[0110] An orthogonal filter is used to perform orthogonal filtering on the constellation symbol information after being upsampled several times;

[0111] The adder is used to add the two outputs of the orthogonal filter into one output.

[0112] Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform a probabilistic constellation shaping method or an optical communication method.

[0113] Based on the same technical solution, the present invention also discloses a computing device, including one or more processors, one or more memories and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a probabilistic constellation shaping method or an optical communication method.

[0114] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0115] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0117] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0118] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A probabilistic constellation shaping method, characterized in that: include: Performing serial-to-parallel conversion on the binary data to be transmitted to obtain real binary data and imaginary binary data; Perform distribution matching on the real binary data, convert the information symbols of the uniform probability distribution in the real binary data into the coding symbols of the target non-uniform probability distribution, perform Polar coding on the coding symbols of the target non-uniform probability distribution, obtain redundant check bits, and map the coding symbols of the target non-uniform probability distribution and the redundant check bits to obtain the real information of the constellation point; wherein the distribution matching is prefix-free codebook distribution matching; Perform distribution matching on the imaginary binary data, convert the information symbols of uniform probability distribution in the imaginary binary data into coding symbols of target non-uniform probability distribution, perform Polar coding on the coding symbols of target non-uniform probability distribution, obtain redundant check bits, map the coding symbols of target non-uniform probability distribution and redundant check bits, and obtain the imaginary information of the constellation point; The real part information and the imaginary part information of the constellation points are combined into a probability distribution diagram of the constellation points.

2. A probabilistic constellation shaping system, characterized in that: include: A serial-to-parallel conversion module is used to perform serial-to-parallel conversion on the binary data to be transmitted to obtain real binary data and imaginary binary data; The real part shaping module performs distribution matching on the real part binary data, converts the information symbols of the uniform probability distribution in the real part binary data into the coding symbols of the target non-uniform probability distribution, performs Polar coding on the coding symbols of the target non-uniform probability distribution, obtains redundant check bits, and maps the coding symbols of the target non-uniform probability distribution and the redundant check bits to obtain the real part information of the constellation point; wherein the distribution matching is prefix-free codebook distribution matching; The imaginary part shaping module performs distribution matching on the imaginary part binary data, converts the information symbols of uniform probability distribution in the imaginary part binary data into coding symbols of target non-uniform probability distribution, performs Polar coding on the coding symbols of target non-uniform probability distribution, obtains redundant check bits, and maps the coding symbols of target non-uniform probability distribution and redundant check bits to obtain the imaginary part information of the constellation point; The combination module is used to combine the real part information and the imaginary part information of the constellation points into a probability distribution diagram of the constellation points.

3. An optical communication method, characterized in that: include: Using the method of claim 1, obtaining a probability distribution diagram of constellation points; Carrier amplitude phase modulation is performed on the probability distribution graph, and the probability distribution graph after carrier amplitude phase modulation is sent to the receiving end.

4. An optical communication method according to claim 3, characterized in that: Carrier amplitude phase modulation of the probability distribution diagram includes: Upsampling the constellation symbol information in the probability distribution diagram by several times; Performing orthogonal filtering on the constellation symbol information after being upsampled several times; The two outputs of the orthogonal filter are added together into one output.

5. An optical communication system, characterized in that: include: A probabilistic constellation shaping module, used to obtain a probability distribution diagram of constellation points using the method described in claim 1; The carrier amplitude phase modulation module is used to perform carrier amplitude phase modulation on the probability distribution diagram and send the probability distribution diagram after the carrier amplitude phase modulation to the receiving end.

6. An optical communication system according to claim 5, characterized in that: The carrier amplitude phase modulation module includes: An up-sampling module, used to up-sample the constellation symbol information in the probability distribution diagram by several times; An orthogonal filter is used to perform orthogonal filtering on the constellation symbol information after being upsampled several times; The adder is used to add the two outputs of the orthogonal filter into one output.

Images