Optical transmission method, device and system based on polar code embedded irregular QC-LDPC concatenated TCM coding

Abstract

The application discloses an optical transmission method, device and system based on a polar code embedded irregular QC-LDPC concatenated TCM coding and decoding, which comprises the following steps: sending randomly generated information bits into a polar encoder; transmitting the information bits to an irregular QC-LDPC encoder through a reliable channel in the polar encoder; encoding the information bits by the irregular QC-LDPC encoder to obtain a first encoded signal; performing serial-parallel conversion on the first encoded signal to obtain a parallel bit stream; sending the parallel bit stream into a two-dimensional trellis coding and modulation unit to perform coding and modulation, thereby obtaining constellation symbol information; sending the constellation symbol information into a carrier amplitude and phase modulation unit to obtain a modulation signal; and modulating a to-be-sent light source signal by using the modulation signal to complete optical transmission. The application firstly embeds an irregular QC-LDPC code in a polar code, and then concatenates a two-dimensional trellis code, thereby realizing high-speed, stable and reliable transmission of an optical communication system.

Description

Technical Field

[0001] This invention belongs to the field of optical transmission, specifically relating to an optical transmission method, apparatus, and system based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding. Background Technology

[0002] The development of technologies such as the Internet of Things, virtual reality, cloud computing, and blockchain has led to a rapid increase in the demand for communication data traffic. However, the slow growth rate of fiber optic communication system transmission capacity in recent years has fallen far short of meeting this rapidly increasing demand. Under limited bandwidth, coding and modulation techniques, through high-order modulation and reliable coding, can effectively improve channel spectral efficiency, becoming an effective means to improve the transmission performance of fiber optic communication systems and approach the channel capacity limit.

[0003] Compared to traditional electrical interconnect networks, passive optical networks (PONs) offer advantages such as high flexibility, low power consumption, and high transmission rates, meeting the rapidly growing bandwidth and capacity demands of optical access networks. Combined with advanced modulation formats, PONs hold the promise of further improving the spectral efficiency and transmission capacity of optical communication systems. Currently widely used modulation formats include Pulse Amplitude Modulation (PAM), Orthogonal Frequency Division Multiplexing (OFDM), Discrete Multi-Frequency Modulation (DMT), and Carrier Amplitude-Phase Modulation (CAP). CAP uses digital filtering to generate multiplexed signals, achieving multi-level and multi-dimensional modulation without requiring complex mixers and RF sources for down-conversion. Therefore, CAP is one of the most attractive modulation formats for short-range communication scenarios and can work with other modulation formats to drive the development of PON technology.

[0004] Polar codes are a forward error correction coding scheme, and theoretically proven to reach the Shannon limit in Shannon's theorem. The core of their construction is channel polarization processing. On the coding side, methods are employed to make each sub-channel exhibit different reliability. As the code length continuously increases, some channels tend towards perfect channels with a capacity close to 1 (error-free), while others tend towards pure noise channels with a capacity close to 0. Information is directly transmitted on channels with a capacity close to 1 to approximate the channel capacity. On the decoding side, the polarized channels can be decoded using a simple successive interference cancellation method, achieving performance similar to maximum natural decoding with lower complexity. Quasi-cyclic low-density parity-check codes (QC-LDPC codes), as an important classification of LDPC codes, are characterized by their quasi-cyclic structure. Its parity check matrix can be divided into multiple square matrices of equal size, each of which is a cyclic shift matrix of the identity matrix or an all-zero matrix. This facilitates memory storage and addressing, thus greatly reducing the encoding and decoding complexity of LDPC codes. Furthermore, quasi-cyclic low-density parity check codes with a repeating cumulative structure can achieve fast encoding with linear complexity. The encoding can be implemented using shift registers, making hardware implementation relatively easy. However, due to the cyclic nature of QC-LDPC codes, there are more short cycles in the Tanner diagram, resulting in fewer codewords satisfying the conditions compared to LDPC codes, leading to a higher system error rate.

[0005] Higher-order modulation formats offer the advantage of increasing the transmission capacity of optical communication systems, but reduced channel spacing leads to increased inter-channel crosstalk, reducing the reliability of the communication system. Meanwhile, while channel coding techniques improve the system's anti-interference capability, they sacrifice system effectiveness. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes an optical transmission method, apparatus, and system based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding. First, an irregular QC-LDPC code is embedded within the polar code, and then a two-dimensional grid encoding is concatenated, achieving high-speed, stable, and reliable transmission in the optical communication system.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides an optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, comprising:

[0009] Randomly generated information bits are fed into a polar encoder. The information bits are transmitted to an irregular QC-LDPC encoder via a reliable channel within the polar encoder. The irregular QC-LDPC encoder encodes the information bits to obtain a first encoded signal.

[0010] Perform a serial-to-parallel conversion on the first encoded signal to obtain a parallel bit stream;

[0011] The parallel bit stream is fed into a two-dimensional trellis coding modulation unit for encoding and modulation to obtain constellation symbol information;

[0012] The constellation symbol information is sent to the carrier amplitude-phase modulation unit to obtain the modulation signal;

[0013] The light source signal to be transmitted is modulated using the modulation signal to complete the optical transmission.

[0014] Optionally, the check matrix of the irregular QC-LDPC encoder is constructed based on the quasi-cyclic construction method. The check matrix is ​​constructed as a combination of a cyclic submatrix and a non-singular submatrix, and its mathematical expression is:

[0015]

[0016] Where H is the parity check matrix, H1 is the cyclic submatrix, H2 is the non-singular submatrix, I is the q×q identity matrix, and 0 is the q×q all-zero matrix. xi It involves circularly shifting each row of the identity matrix I to the right by x. i The cyclic shift matrix obtained by bit, a i b i Let H1 be a non-zero element over the finite field GF(q). In each row or column of the H1 matrix, there is at most one zero element over GF(q), and any two rows have at least k-1 distinct values.

[0017] Optionally, the step of feeding the parallel bit stream into a two-dimensional trellis coding modulation unit to obtain constellation symbol information includes the following steps:

[0018] The parallel bitstream is divided into two groups of bit data. One group of bit data is fed into a convolutional encoder with a code rate of R = m / n, outputting n encoded bits, which are equally likely to be selected from 2... n Choose one subset of constellations from the set of constellations;

[0019] Based on a selected subset of constellations, another set of bit data is mapped to constellation symbols to generate constellation symbol information.

[0020] Optionally, when the parallel bit stream is a parallel four-bit binary bit stream and the code rate is R = 2 / 3, the parallel bit stream is divided into two groups of bit data, each group of bit data being a two-bit binary bit stream. The convolutional encoder outputs 3 encoded bits, which, together with the remaining two-bit binary bit stream, yield a five-bit parallel binary bit stream.

[0021] Optionally, based on the sub-minimum Euclidean distance partitioning criterion, the preset constellation map is divided into constellation point subsets, and constellation points with the same minimum Euclidean distance in the constellation map are divided into different constellation point subsets.

[0022] Optionally, the preset constellation diagram is a 32QAM constellation diagram.

[0023] Optionally, the carrier amplitude-phase modulation unit includes a first upsampling module, a first filter module, a second upsampling module, a second filter module, and an adder module;

[0024] The first upsampling module is connected in series with the first filter module;

[0025] The second upsampling module is connected in series with the second filter module;

[0026] The two input terminals of the adder module are respectively connected to the output terminals of the first filter module and the second filter module;

[0027] The input terminals of both the first upsampling module and the second upsampling module are used to access the constellation symbol information.

[0028] Optionally, the first upsampling unit and the second upsampling unit respectively perform M-fold upsampling on the constellation symbol information to achieve M-fold periodic expansion of the signal in the spectrum; the filter unit uses an orthogonal digital filter bank to filter and shape the upsampled constellation symbol information; and the modulation signal is generated.

[0029] Secondly, the present invention provides an optical transmission device based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, comprising:

[0030] The encoding unit is used to send randomly generated information bits to the polar encoder. The information bits are transmitted to the irregular QC-LDPC encoder through a reliable channel in the polar encoder, and the irregular QC-LDPC encoder encodes the information bits to obtain the first encoded signal.

[0031] A serial-to-parallel conversion unit is used to perform serial-to-parallel conversion on the first encoded signal to obtain a parallel bit stream;

[0032] The encoding and modulation unit is used to send the parallel bit stream into the two-dimensional grid encoding and modulation unit for encoding and modulation to obtain constellation symbol information;

[0033] A modulation unit is used to send the constellation symbol information into a carrier amplitude-phase modulation unit to obtain a modulation signal;

[0034] The transmission unit is used to modulate the light source signal to be transmitted using the modulation signal to complete the optical transmission.

[0035] Thirdly, the present invention provides an optical transmission system based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, characterized in that it includes a storage medium and a processor;

[0036] The storage medium is used to store instructions;

[0037] The processor is configured to operate according to the instructions to perform the method according to any one of the first aspects.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] This invention proposes to embed irregular QC-LDPC codes within polar codes to improve the system's error correction capability while approximating channel capacity; two-dimensional trellis coding modulation combines channel error correction coding and two-dimensional constellation modulation processes, and improves the reliability of the communication system through the high coding gain of convolutional codes. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0041] Figure 1 This is a schematic diagram illustrating the principle of an optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding according to an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of a polar code embedded irregular QC-LDPC code encoding structure according to an embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of the structure of a two-dimensional grid-coded modulation unit according to an embodiment of the present invention;

[0044] Figure 4 This is a diagram showing the constellation subset partitioning result of a constellation diagram according to an embodiment of the present invention;

[0045] Figure 5 This is a schematic diagram of a carrier amplitude-phase modulation module according to an embodiment of the present invention;

[0046] Figure 6 This is the 32QAM constellation diagram of the receiver in the simulation;

[0047] Figure 7 The bit error rate curves for different SNR values ​​are shown in the simulation. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0050] Example 1

[0051] This invention provides an optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, applied at the transmitting end, including the following steps:

[0052] (1) Randomly generated information bits are fed into a polar encoder. The information bits are transmitted to an irregular QC-LDPC encoder via a reliable channel within the polar encoder. The irregular QC-LDPC encoder encodes the information bits to obtain a first encoded signal. The irregular QC-LDPC encoder is... Figure 1 The Polar-irQC-LDPC encoding unit in;

[0053] (2) Perform serial-to-parallel conversion on the first encoded signal to obtain a parallel bit stream;

[0054] (3) The parallel bit stream is fed into a two-dimensional trellis coding modulation unit for encoding and modulation to obtain constellation symbol information; the two-dimensional trellis coding modulation unit is... Figure 1 2D-TCM encoding unit in;

[0055] (4) The constellation symbol information is sent to a carrier amplitude-phase modulation unit to obtain a modulation signal; the carrier amplitude-phase modulation unit is... Figure 1 The two-dimensional CAP modulation unit in the middle;

[0056] (5) Use the modulation signal to modulate the light source signal to be transmitted to complete the optical transmission.

[0057] In practical applications, a receiver is also required. The receiver performs digital matched filtering, Viterbi decoding, and soft-decision forward error correction decoding on the modulated signal received to recover the information bits from the transmitter. This invention, on the encoding side, uses a three-stage concatenated coding method to maximize coding gain, bringing the signal rate close to the channel capacity limit. This achieves a significant reduction in system complexity while lowering the system error rate and improving system performance.

[0058] In one specific embodiment of the present invention, such as Figure 2 As shown, channel combining can fuse N independent binary memoryless channels into an N-dimensional combined channel W. N :X N →Y N It can also be represented as: (x1, x2, ... x i …x N → (y1, y2, ...) i ...y N ), where N = 2 n Since n>0, and n is a positive integer, the N-dimensional combination channel can only be an integer power of 2. Channel combination is given recursively; the recursive operation mainly involves recombinating multiple input signals within the layer. After performing a combination transformation on the input u, it can be equivalently represented by an N-dimensional generator matrix G. N We can get X1 N =u1 N *G N Through similar operations, the channel polarization process is as follows: Figure 2 As shown in the figure, R N The input vector u is transposed, and the odd-numbered elements of the input sequence are placed in the first half of the sequence, while the even-numbered elements are placed in the second half. Through recursive polarization, the capacity of the sub-channels is polarized into two categories: a pure noise channel with a capacity of 0, and a noise-free channel with a capacity of 1. Furthermore, the polarization phenomenon becomes increasingly pronounced as the code length increases. Sub-channels with a capacity less than 0.5 are considered pure noise channels and are deemed unreliable; therefore, they are only used to transmit frozen bits of value 0. Sub-channels with a capacity greater than 0.95 are considered noise-free channels and are used to transmit useful information bits. These useful information bits are then encoded using embedded irregular QC-LDPC codes, which eliminates the need for interleaving during encoding and deinterleaving during decoding.

[0059] Compared to regular QC-LDPC codes, irregular QC-LDPC codes offer better error correction performance. The check-check matrix for irregular QC-LDPC codes is constructed using a quasi-cyclic construction method, combining a cyclic submatrix and a non-singular submatrix to create a double-diagonal structure for subsequent iterative encoding of information bits in the polar code. The mathematical expression for the check-check matrix is:

[0060]

[0061] Where H is the parity check matrix, H1 is the cyclic submatrix, H2 is the non-singular submatrix, I is the q×q identity matrix, and 0 is the q×q all-zero matrix. xi It involves circularly shifting each row of the identity matrix I to the right by x. i The cyclic shift matrix obtained by bit, a i b i Let H1 be a non-zero element over the finite field GF(q). In each row or column of the H1 matrix, there is at most one zero element over GF(q), and any two rows have at least k-1 distinct values.

[0062] The generator matrix G can be obtained by using the formula to solve the parity check matrix, thus completing the encoding process.

[0063] Because the parity check matrix constructed in this embodiment of the invention has a special double-diagonal structure, and due to its quasi-cyclic characteristics, the subsequent encoding and decoding complexity will be reduced. This irregular QC code parity check matrix is ​​based on a quasi-cyclic structure, and many elements of the parity check matrix are contained within the base matrix. Therefore, there is no need to design dedicated storage space to store the parity check matrix, thus reducing storage requirements and saving a significant amount of storage space.

[0064] In one specific embodiment of the present invention, such as Figure 3 As shown, the step of sending the parallel bit stream into a two-dimensional trellis coding modulation unit to obtain constellation symbol information includes the following steps:

[0065] The parallel bitstream is divided into two groups of bit data. One group of bit data is fed into a convolutional encoder with a code rate of R = m / n, outputting n encoded bits, which are equally likely to be selected from 2... n Choose one subset of constellations from the set of constellations;

[0066] Based on a selected subset of constellations, another set of bit data is mapped to constellation symbols to generate constellation symbol information.

[0067] When the parallel bit stream is a parallel four-bit binary bit stream and the code rate is R = 2 / 3, the parallel bit stream is divided into two groups of bit data, each group of bit data being a two-bit binary bit stream. The convolutional encoder outputs 3 encoded bits, which, together with the remaining two-bit binary bit stream, yield a five-bit parallel binary bit stream.

[0068] In one specific embodiment of the present invention, the constellation map is divided into constellation point subsets according to the sub-minimum Euclidean distance partitioning criterion, and constellation points with the same minimum Euclidean distance in the constellation map are divided into different constellation point subsets.

[0069] In one specific embodiment of the present invention, the preset constellation diagram is a 32QAM constellation diagram, and its constellation points are partitioned according to the second-minimum Euclidean distance partitioning criterion, such as... Figure 4 As shown in the figure, the 32QAM constellation diagram, after three subset partitions, yields eight constellation point subsets. The minimum Euclidean distance between the sub-constellation points after partitioning is twice that of the original 32QAM constellation diagram. The correspondence between the final 5-bit output bits of TC32QAM (i.e., TCM encoding using 32QAM modulation) and the constellation diagram is shown in Table 1.

[0070] Subset A Subset B Subset C Subset D Subset E Subset F Subset G Subset H 1 00000 00100 01000 01100 10000 10100 11000 11100 2 00001 00101 01001 01101 10001 10101 11001 11101 3 00010 00110 01010 01110 10010 10110 11010 11110 4 00011 00111 01011 01111 10011 10111 11011 11111

[0071] In one specific embodiment of the present invention, such as Figure 5 As shown, the carrier amplitude-phase modulation unit includes a first upsampling module, a first filter module, a second upsampling module, a second filter module, and an adder module;

[0072] The first upsampling module is connected in series with the first filter module;

[0073] The second upsampling module is connected in series with the second filter module;

[0074] The two input terminals of the adder module are respectively connected to the output terminals of the first filter module and the second filter module;

[0075] The input terminals of both the first upsampling module and the second upsampling module are used to access the constellation symbol information.

[0076] The first upsampling unit and the second upsampling unit respectively perform M-fold upsampling on the constellation symbol information to achieve M-fold periodic expansion of the signal in the spectrum; the filter unit uses an orthogonal digital filter bank to filter and shape the upsampled constellation symbol information; and the modulation signal is generated.

[0077] The 32QAM constellation diagram obtained at the receiver with a signal-to-noise ratio of 16dB is as follows: Figure 6 As shown. Among them, Figure 6 (A) is the 32QAM constellation diagram obtained by the method of the present invention through concatenated coding modulation of polar code, irregular QC-LDPC and TCM, and (B) is the constellation diagram obtained by conventional 32QAM modulation.

[0078] like Figure 7 The figure shows the bit error rate curves of the proposed method (Polar-irQC-LDPC+TC32QAM), conventional TC32QAM modulation (Normal TC32QAM), and conventional 32QAM modulation (Normal32QAM). Comparison Figure 7 As shown in the bit error rate curves of the three schemes, the optical transmission method proposed in this invention has a 1.6 dB improvement in receiver sensitivity compared to the traditional TC32QAM modulation (@BER=10). -3 Compared to traditional 32QAM modulation, it offers a 7.6dB improvement in receiver sensitivity (@BER=10). -3 ).

[0079] Example 2

[0080] Based on the same inventive concept as Embodiment 1, this embodiment of the invention provides an optical transmission device based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, comprising:

[0081] The encoding unit is used to send randomly generated information bits to the polar encoder. The information bits are transmitted to the irregular QC-LDPC encoder through a reliable channel in the polar encoder, and the irregular QC-LDPC encoder encodes the information bits to obtain the first encoded signal.

[0082] A serial-to-parallel conversion unit is used to perform serial-to-parallel conversion on the first encoded signal to obtain a parallel bit stream;

[0083] The encoding and modulation unit is used to send the parallel bit stream into the two-dimensional grid encoding and modulation unit for encoding and modulation to obtain constellation symbol information;

[0084] A modulation unit is used to send the constellation symbol information into a carrier amplitude-phase modulation unit to obtain a modulation signal;

[0085] A transmission unit is used to modulate the light source signal to be transmitted using the modulation signal.

[0086] The rest are the same as in the example.

[0087] Example 3

[0088] This invention provides an optical transmission system based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, characterized in that it includes a storage medium and a processor;

[0089] The storage medium is used to store instructions;

[0090] The processor is configured to operate according to the instructions to execute the method according to any one of Embodiment 1.

[0091] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied 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.

[0092] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0093] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0094] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0095] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

[0096] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, characterized in that, include: Randomly generated information bits are fed into a polar encoder. The information bits are transmitted to an irregular QC-LDPC encoder via a reliable channel within the polar encoder. The irregular QC-LDPC encoder encodes the information bits to obtain a first encoded signal. Perform a serial-to-parallel conversion on the first encoded signal to obtain a parallel bit stream; The parallel bit stream is fed into a two-dimensional trellis coding modulation unit for encoding and modulation to obtain constellation symbol information; The constellation symbol information is sent to the carrier amplitude-phase modulation unit to obtain the modulation signal; The modulation signal is used to modulate the light source signal to be transmitted; The check matrix of the irregular QC-LDPC encoder is constructed based on the quasi-cyclic construction method. The check matrix is ​​constructed as a combination of a cyclic submatrix and a non-singular submatrix, and its mathematical expression is: ， in, For the verification matrix, For cyclic submatrices, It is a non-singular submatrix. yes The identity matrix, 0 is A matrix of all zeros It is the identity matrix Each row moves to the right in a circular fashion. The resulting cyclic shift matrix , For a finite field The non-zero element on In each row or column of the matrix, there is at most one The zero element on the array, and at least two rows have A number of distinct values; The step of feeding the parallel bitstream into a two-dimensional trellis coding modulation unit to obtain constellation symbol information includes the following steps: The parallel bitstream is divided into two groups of bit data. One group of bit data is fed into a convolutional encoder with a code rate of R=m / n, outputting n encoded bits, which are equally likely to be selected from 2... n Choose one subset of constellations from the set of constellations; Based on a selected subset of constellations, another set of bit data is mapped to constellation symbols to generate constellation symbol information.

2. The optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding according to claim 1, characterized in that: When the parallel bit stream is a parallel four-bit binary bit stream and the code rate is R=2 / 3, the parallel bit stream is divided into two groups of bit data, each group of bit data being a two-bit binary bit stream. The convolutional encoder outputs 3 encoded bits, which, together with the remaining two-bit binary bit stream, yield a five-bit parallel binary bit stream.

3. The optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding according to claim 1, characterized in that, The method for generating the constellation subset includes: Based on the sub-minimum Euclidean distance partitioning criterion, the preset constellation map is divided into constellation point subsets, and constellation points with the same minimum Euclidean distance in the constellation map are divided into different constellation point subsets.

4. The optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding according to claim 3, characterized in that, The preset constellation diagram is a 32QAM constellation diagram.

5. The optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding according to claim 1, characterized in that: The carrier amplitude-phase modulation unit includes a first upsampling module, a first filter module, a second upsampling module, a second filter module, and an adder module; The first upsampling module is connected in series with the first filter module; The second upsampling module is connected in series with the second filter module; The two input terminals of the adder module are respectively connected to the output terminals of the first filter module and the second filter module; The input terminals of both the first upsampling module and the second upsampling module are used to access the constellation symbol information.

6. The optical transmission method based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding according to claim 5, characterized in that: The first upsampling module and the second upsampling module respectively perform M-fold upsampling on the constellation symbol information to achieve M-fold period expansion of the signal in the spectrum; the first filter module and the second filter model use orthogonal digital filter banks to filter and shape the upsampled constellation symbol information.

7. An optical transmission device based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, characterized in that, include: The encoding unit is used to send randomly generated information bits to the polar encoder. The information bits are transmitted to the irregular QC-LDPC encoder through a reliable channel in the polar encoder, and the irregular QC-LDPC encoder encodes the information bits to obtain the first encoded signal. A serial-to-parallel conversion unit is used to perform serial-to-parallel conversion on the first encoded signal to obtain a parallel bit stream; The encoding and modulation unit is used to send the parallel bit stream into the two-dimensional grid encoding and modulation unit for encoding and modulation to obtain constellation symbol information; A modulation unit is used to send the constellation symbol information into a carrier amplitude-phase modulation unit to obtain a modulation signal; A transmission unit is used to modulate the light source signal to be transmitted using the modulation signal; The check matrix of the irregular QC-LDPC encoder is constructed based on the quasi-cyclic construction method. The check matrix is ​​constructed as a combination of a cyclic submatrix and a non-singular submatrix, and its mathematical expression is: ， in, For the verification matrix, For cyclic submatrices, It is a non-singular submatrix. yes The identity matrix, 0 is A matrix of all zeros It is the identity matrix Each row moves to the right in a circular fashion. The resulting cyclic shift matrix , For a finite field The non-zero element on In each row or column of the matrix, there is at most one The zero element on the array, and at least two rows have A number of distinct values; The step of feeding the parallel bitstream into a two-dimensional trellis coding modulation unit to obtain constellation symbol information includes the following steps: The parallel bitstream is divided into two groups of bit data. One group of bit data is fed into a convolutional encoder with a code rate of R=m / n, outputting n encoded bits, which are equally likely to be selected from 2... n Choose one subset of constellations from the set of constellations; Based on a selected subset of constellations, another set of bit data is mapped to constellation symbols to generate constellation symbol information.

8. An optical transmission system based on polar code embedded irregular QC-LDPC concatenated TCM encoding and decoding, characterized in that, Including storage media and processor; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method according to any one of claims 1-6.

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