CN117938308A - Optical transmission method, device and system based on polarization code embedded irregular QC-LDPC cascade TCM (quasi-cyclic Low Density parity check) encoding and decoding - Google Patents

Abstract

The invention discloses an optical transmission method, a device and a system based on polarization code embedded irregular QC-LDPC cascade TCM (quasi-cyclic low density parity check) encoding and decoding, which comprise the steps of sending randomly generated information bits to a polarization encoder, transmitting the information bits to the irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and encoding the information bits by the irregular QC-LDPC encoder to obtain a first encoded signal; performing serial-parallel conversion on the first coded signal to obtain a parallel bit stream; the parallel bit stream is sent into a two-dimensional grid coding modulation unit for coding and modulating, and constellation symbol information is obtained; sending the constellation symbol information into a carrier amplitude phase modulation unit to obtain a modulation signal; and modulating a light source signal to be transmitted by using the modulation signal to finish optical transmission. The invention firstly embeds irregular QC-LDPC codes in the polarization codes, and then cascades two-dimensional grid codes, thereby realizing high-speed stable and reliable transmission of the optical communication system.

Description

Optical transmission method, device and system based on polarization code embedded irregular QC-LDPC cascade TCM (quasi-cyclic Low Density parity check) encoding and decoding

Technical Field

The invention belongs to the field of optical transmission, and particularly relates to an optical transmission method, device and system based on polarization code embedded irregular QC-LDPC cascade TCM coding and decoding.

Background

With the development of technologies such as the internet of things, virtual reality, cloud computing and blockchain, the communication data traffic demands are rapidly increased. Since the transmission capacity of the optical fiber communication system has been increased slowly in recent years, the requirement for a sharply increased transmission capacity has been far from satisfied. Under the limited bandwidth, the code modulation technology can effectively improve the frequency spectrum efficiency of the channel through high-order modulation and reliable coding, and becomes an effective means for improving the transmission performance of the optical fiber communication system and approaching the limit of the channel capacity.

Compared with the traditional electrical interconnection network, the passive optical network has the advantages of high flexibility, low power consumption, high transmission rate and the like, and can meet the requirements of rapid increase of bandwidth and capacity in an optical access network. In combination with advanced modulation formats, passive optical networks are expected to further improve the spectral efficiency and transmission capacity of optical communication systems. Modulation formats that are currently widely used include Pulse Amplitude Modulation (PAM), orthogonal Frequency Division Multiplexing (OFDM), discrete multi-frequency modulation (DMT), and carrier amplitude phase modulation (CAP). The carrier amplitude phase modulation adopts a digital filtering mode to generate multiplexing signals, so that multi-level and multi-dimensional modulation is realized, and a complex mixer and a radio frequency source are not needed to carry out down-conversion. Therefore, carrier amplitude phase modulation is one of the modulation formats attractive in the short-range communication scenario, and can drive the development of passive optical network technology together with other modulation formats.

The polarization code is a forward error correction coding mode and is a coding which can be strictly proved to reach Shannon limit in Shannon theorem in theory. The core of the construction is that through the channel polarization processing, the method is adopted on the encoding side to enable each sub-channel to present different reliability, when the code length is continuously increased, part of channels tend to be perfect channels with the capacity close to 1 (no error codes), the other part of channels tend to be pure noise channels with the capacity close to 0, and the direct transmission information on the channels with the capacity close to 1 is selected to approximate the capacity of the channels. On the decoding side, the polarized channel can obtain the performance similar to the maximum natural decoding with lower complexity by using a simple successive interference cancellation decoding method. While a quasi-cyclic low-density parity check code (QC-LDPC) code is an important class of LDPC codes, and is most characterized by having a quasi-cyclic structure. The parity check matrix can be divided into a plurality of square matrixes with equal size, each square matrix is a cyclic shift matrix or an all 0 matrix of the identity matrix, and the storage and addressing of a memory are very convenient, so that the coding and decoding complexity of the LDPC code is greatly reduced, the quasi-cyclic low-density parity check code with a repeated accumulation structure can realize the quick coding of the linear complexity, and the coding can be realized by using a shift register, so that the hardware realization complexity can be reduced more easily. However, due to the cyclic characteristic of the QC-LDPC code, the number of short rings in a tanner graph is large, so that the code words of the QC-LDPC code meeting the conditions are fewer than the LDPC code, and the system error rate is high.

The higher order modulation format has the advantage of improving the transmission capacity of the optical communication system, but the reduced channel spacing can cause increased inter-channel crosstalk, thereby reducing the reliability of the communication system. Meanwhile, the channel coding technology improves the anti-interference capability of the system, but sacrifices the effectiveness of the system.

Disclosure of Invention

Aiming at the problems, the invention provides an optical transmission method, device and system based on polarization code embedded irregular QC-LDPC cascade TCM coding, which are characterized in that firstly, the irregular QC-LDPC code is embedded in the polarization code, and then, two-dimensional grid coding is cascaded, so that the high-speed stable and reliable transmission of an optical communication system is realized.

In order to achieve the technical purpose and achieve the technical effect, the invention is realized by the following technical scheme:

In a first aspect, the present invention provides an optical transmission method based on polarization code embedded irregular QC-LDPC concatenated TCM encoding and decoding, including:

the method comprises the steps of sending randomly generated information bits to a polarization encoder, transmitting the information bits to an irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and encoding the information bits by the irregular QC-LDPC encoder to obtain a first encoded signal;

performing serial-parallel conversion on the first coded signal to obtain a parallel bit stream;

The parallel bit stream is sent into a two-dimensional grid coding modulation unit for coding and modulating, and constellation symbol information is obtained;

Sending the constellation symbol information into a carrier amplitude phase modulation unit to obtain a modulation signal;

and modulating a light source signal to be transmitted by using the modulation signal to finish optical transmission.

Optionally, the check matrix of the irregular QC-LDPC encoder is constructed based on a quasi-cyclic construction method, the check matrix being constructed as a combination of a cyclic submatrix and a non-singular submatrix, and the mathematical expression is:

Wherein, H is a check matrix, H ₁ is a cyclic submatrix, H ₂ is a non-singular submatrix, I is a q×q identity matrix, 0 is a q×q all-zero matrix, I _xi is a cyclic shift matrix obtained by circularly shifting each row of the identity matrix I by x _i bits to the right, a ⁱ、bⁱ is a non-zero element on a finite field GF (q), at most only one zero element on GF (q) exists in each row or each column of the H ₁ matrix, and at least k-1 different values exist in any two rows.

Optionally, the sending the parallel bit stream into a two-dimensional grid coding modulation unit to obtain constellation symbol information includes the following steps:

Dividing the parallel bit stream into two groups of bit data, wherein one group of bit data enters a convolution encoder with a code rate of R=m/n, n bits of encoded bits are output, and one constellation subset of the n bits of encoded bits is selected from 2 ⁿ constellation subsets with equal probability;

and performing constellation symbol mapping on the other group of bit data based on the selected constellation subset to generate constellation symbol information.

Optionally, when the parallel bit stream is a parallel four-bit binary bit stream, the code rate is r=2/3, the parallel bit stream is divided into two groups of bit data, each group of bit data is a two-bit binary bit stream, and the convolutional encoder outputs 3-bit coded bits, and obtains five-bit parallel binary bit streams together with Yu Erwei binary bit streams.

Optionally, according to a division criterion of the next-smallest euclidean distance, dividing the constellation point subsets of the preset constellation diagram, and dividing the constellation points with the same smallest euclidean distance in the constellation diagram into different constellation point subsets.

Optionally, the preset constellation is a 32QAM constellation.

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;

the first up-sampling module is connected with the first filter module in series;

the second up-sampling module is connected with the second filter module in series;

two input ends of the adder module are respectively connected with the output ends of the first filter module and the second filter module;

The input ends of the first up-sampling module and the second up-sampling module are used for accessing the constellation symbol information.

Optionally, the first upsampling unit and the second upsampling unit respectively upsample the constellation symbol information M times, so as to realize M times of period expansion of the signal on the frequency spectrum; the filter unit adopts a quadrature digital filter bank to filter and shape the constellation symbol information after up-sampling; the generating a modulated signal.

In a second aspect, the present invention provides an optical transmission device based on polarization code embedded irregular QC-LDPC concatenated TCM encoding and decoding, including:

The encoding unit is used for sending the randomly generated information bits to the polarization encoder, the information bits are transmitted to the irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and the information bits are encoded by the irregular QC-LDPC encoder to obtain a first encoded signal;

The serial-parallel conversion unit is used for carrying out serial-parallel conversion on the first coded signal to obtain a parallel bit stream;

the code modulation unit is used for sending the parallel bit stream into the two-dimensional grid code modulation unit for coding and modulating to obtain constellation symbol information;

the modulating unit is used for sending the constellation symbol information into the carrier amplitude phase modulating unit to obtain a modulating signal;

and the transmission unit is used for modulating the light source signal to be transmitted by using the modulation signal to finish optical transmission.

In a third aspect, the present invention provides an optical transmission system based on polarization code embedded irregular QC-LDPC concatenated TCM encoding and decoding, which is characterized by comprising a storage medium and a processor;

The storage medium is used for storing instructions;

the processor is configured to operate in accordance with the instructions to perform the method according to any one of the first aspects.

Compared with the prior art, the invention has the beneficial effects that:

The invention provides a method for embedding irregular QC-LDPC codes in polarized codes and improving the error correction capability of a system under the condition of approaching the channel capacity; the two-dimensional grid coding modulation combines the channel error correction coding and the two-dimensional constellation modulation process, and the reliability of the communication system is improved through the high coding gain of the convolutional code.

Drawings

For a clearer description of an embodiment of the invention or of the solutions of the prior art, the drawings that are needed in the embodiment will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art, in which:

FIG. 1 is a schematic diagram of an optical transmission method based on polarization code embedded irregular QC-LDPC concatenated TCM coding and decoding according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a structure of a polarized code embedded irregular QC-LDPC code according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a two-dimensional trellis-coded modulation unit in accordance with one embodiment of the present invention;

fig. 4 is a diagram of a constellation subset partitioning result of a constellation diagram according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a carrier amplitude phase modulation module according to an embodiment of the present invention;

fig. 6 is a 32QAM constellation for the receiving end in the simulation;

fig. 7 is a graph of bit error rate curves for different SNRs under simulation.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.

Example 1

The embodiment of the invention provides an optical transmission method based on polarization code embedded irregular QC-LDPC cascade TCM coding and decoding, which is applied to a transmitting end and comprises the following steps:

(1) The method comprises the steps of sending randomly generated information bits to a polarization encoder, transmitting the information bits to an irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and encoding the information bits by the irregular QC-LDPC encoder to obtain a first encoded signal; the irregular QC-LDPC encoder is a Polar-irQC-LDPC encoding unit in the figure 1;

(2) Performing serial-parallel conversion on the first coded signal to obtain a parallel bit stream;

(3) The parallel bit stream is sent into a two-dimensional grid coding modulation unit for coding and modulating, and constellation symbol information is obtained; the two-dimensional grid coding modulation unit is the 2D-TCM coding unit in FIG. 1;

(4) Sending the constellation symbol information into a carrier amplitude phase modulation unit to obtain a modulation signal; the carrier amplitude phase modulation unit is the two-dimensional CAP modulation unit in FIG. 1;

(5) And modulating a light source signal to be transmitted by using the modulation signal to finish optical transmission.

In the practical application process, a receiving end is also required to be designed, and the receiving end carries out the processes of digital matched filtering, viterbi decoding, soft decision forward error correction decoding and the like aiming at the modulation signals in the received signals, so as to recover the information bits of the transmitting end. The invention improves the coding gain as much as possible by a three-level cascade coding mode at the coding side, so that the signal rate approaches the limit of the channel capacity, and the system error rate can be reduced and the system performance can be improved under the condition of obviously reducing the system complexity.

In one embodiment of the present invention, as shown in fig. 2, the channel combination may merge N binary independent memoryless channels into an N-dimensional combined channel W _N:X^N→Y^N, which may also be expressed as: (x ₁,x₂,…x_i…x_N)→(y₁,y₂,.y_i...y_N) where n= ⁿ, N >0, N being a positive integer, meaning that the combined channel in N dimensions can only be an integer power of 2. The channel combination is given by way of recursion, the recursive operation mainly working to recombine multiple input signals within a layer. The input u is subjected to combination transformation operation, and an N-dimensional generation matrix G _N can be equivalently recorded, so that X ₁ ^N＝u₁ ^N*G_N can be obtained. By similar operations, the channel polarization process is shown in fig. 2, where R _N is a transposed matrix through which the input vector u passes to place the odd-numbered bit elements of the input sequence in the first half of the sequence and the even-numbered bit elements in the second half of the sequence. By recursive polarization, the capacity of the sub-channels is polarized into two categories, one being a pure noise channel with capacity 0 and the other being a noise-free channel with capacity 1. And simultaneously, as the code length increases, the polarization phenomenon becomes more and more obvious. Sub-channels with a capacity of less than 0.5 are considered as pure noise channels, and this part of the channel is considered unreliable and is therefore only used for transmitting frozen bits of 0. All sub-channels with the capacity larger than 0.95 are regarded as noiseless channels and are used for transmitting useful information bits, and then the useful information bits are encoded in a mode of embedding irregular QC-LDPC codes, so that interleaving during encoding and de-interleaving during decoding can be omitted.

The irregular QC-LDPC code may provide better error correction performance than the regular QC-LDPC code. The irregular QC-LDPC code check matrix is constructed based on a quasi-cyclic construction method, the check matrix is constructed as a combination of a cyclic submatrix and a non-singular submatrix, so that the check matrix has a double diagonal structure to carry out subsequent iterative coding on information bits in the polarized code, and the mathematical expression of the check matrix is as follows:

Wherein, H is a check matrix, H ₁ is a cyclic submatrix, H ₂ is a non-singular submatrix, I is a q×q identity matrix, 0 is a q×q all-zero matrix, I _xi is a cyclic shift matrix obtained by circularly shifting each row of the identity matrix I by x _i bits to the right, a ⁱ、bⁱ is a non-zero element on a finite field GF (q), at most only one zero element on GF (q) exists in each row or each column of the H ₁ matrix, and at least k-1 different values exist in any two rows.

The generation matrix G can be obtained by solving the check matrix by using a formula, and the coding process is completed.

Because the check matrix constructed in the embodiment of the invention has a special dual diagonal structure, the complexity of subsequent encoding and decoding can be reduced due to the quasi-cyclic characteristic of the check matrix. The check matrix of the irregular QC code is based on a quasi-cyclic structure, and a plurality of elements in the check matrix are contained in the base matrix, so that a special storage space is not required to be specially designed for storing the check matrix, the storage capacity can be reduced, and a large amount of storage space is saved.

In a specific implementation manner of the embodiment of the present invention, as shown in fig. 3, the sending the parallel bit stream into a two-dimensional trellis-coded modulation unit to obtain constellation symbol information includes the following steps:

Dividing the parallel bit stream into two groups of bit data, wherein one group of bit data enters a convolution encoder with a code rate of R=m/n, n bits of encoded bits are output, and one constellation subset of the n bits of encoded bits is selected from 2 ⁿ constellation subsets with equal probability;

and performing constellation symbol mapping on the other group of bit data based on the selected constellation subset to generate constellation symbol information.

And when the parallel bit stream is a parallel four-bit binary bit stream, and the code rate is R=2/3, dividing the parallel bit stream into two groups of bit data, wherein each group of bit data is a two-bit binary bit stream, and outputting 3-bit coded bits by the convolutional encoder to obtain a five-bit parallel binary bit stream together with the Yu Erwei binary bit stream.

In a specific implementation manner of the embodiment of the present invention, according to a division criterion of a secondary minimum euclidean distance, a preset constellation diagram is divided into constellation point subsets, and constellation points with the same minimum euclidean distance in the constellation diagram are divided into different constellation point subsets.

In a specific implementation manner of the embodiment of the present invention, the preset constellation is a 32QAM constellation, and the constellation point subset is divided according to a division criterion of the second smallest euclidean distance, as shown in fig. 4. Eight constellation point subsets are obtained after the 32QAM constellation map is divided by three subsets, and the minimum Euclidean distance between the divided sub-constellation points is 2 times of that of the original 32QAM constellation map. The correspondence of the 5-bit output bits, which are finally output via TC32QAM (i.e., TCM encoding using 32QAM modulation), to the constellation is shown in table 1.

	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

In a specific implementation manner of the embodiment of the present invention, as shown in fig. 5, 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 up-sampling module is connected with the first filter module in series;

the second up-sampling module is connected with the second filter module in series;

two input ends of the adder module are respectively connected with the output ends of the first filter module and the second filter module;

The input ends of the first up-sampling module and the second up-sampling module are used for accessing the constellation symbol information.

The first up-sampling unit and the second up-sampling unit respectively perform M times up-sampling on constellation symbol information to realize M times period expansion of signals on a frequency spectrum; the filter unit adopts a quadrature digital filter bank to filter and shape the constellation symbol information after up-sampling; the generating a modulated signal.

The 32QAM constellation obtained at the receiving end at a signal-to-noise ratio of 16dB is shown in fig. 6. Fig. 6 (a) is a 32QAM constellation obtained by performing polarization code, irregular QC-LDPC and TCM cascade coded modulation according to the method of the present invention, and (B) is a constellation obtained by performing conventional 32QAM modulation.

Fig. 7 is a graph showing error rate of the proposed method (Polar-irQC-ldpc+tc32 QAM), conventional TC32QAM modulation (Normal TC32 QAM) and conventional 32QAM modulation (Normal 32 QAM). As can be seen from comparing the bit error rate graphs of the three schemes in fig. 7, the optical transmission method proposed by the present invention has a 1.6dB improvement (@ ber=10 ^-3) compared to the receiving sensitivity of the conventional TC32QAM modulation, and has a 7.6dB improvement (@ ber=10 ^-3) compared to the receiving sensitivity of the conventional 32QAM modulation.

Example 2

Based on the same inventive concept as embodiment 1, an embodiment of the present invention provides an optical transmission device based on polarization code embedded irregular QC-LDPC concatenated TCM encoding and decoding, including:

The encoding unit is used for sending the randomly generated information bits to the polarization encoder, the information bits are transmitted to the irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and the information bits are encoded by the irregular QC-LDPC encoder to obtain a first encoded signal;

The serial-parallel conversion unit is used for carrying out serial-parallel conversion on the first coded signal to obtain a parallel bit stream;

the code modulation unit is used for sending the parallel bit stream into the two-dimensional grid code modulation unit for coding and modulating to obtain constellation symbol information;

the modulating unit is used for sending the constellation symbol information into the carrier amplitude phase modulating unit to obtain a modulating signal;

And the transmission unit is used for modulating the light source signal to be transmitted by using the modulation signal.

The rest is the same as the examples.

Example 3

The embodiment of the invention provides an optical transmission system based on polarization code embedded irregular QC-LDPC cascade TCM coding and decoding, which is characterized by comprising a storage medium and a processor;

The storage medium is used for storing instructions;

the processor is configured to operate in accordance with the instructions to perform the method according to any one of embodiment 1.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may 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, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may 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, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are all within the protection of the present invention.

The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (10)

1. An optical transmission method based on polarization code embedded irregular QC-LDPC cascade TCM coding and decoding is characterized by comprising the following steps:

the method comprises the steps of sending randomly generated information bits to a polarization encoder, transmitting the information bits to an irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and encoding the information bits by the irregular QC-LDPC encoder to obtain a first encoded signal;

performing serial-parallel conversion on the first coded signal to obtain a parallel bit stream;

The parallel bit stream is sent into a two-dimensional grid coding modulation unit for coding and modulating, and constellation symbol information is obtained;

Sending the constellation symbol information into a carrier amplitude phase modulation unit to obtain a modulation signal;

And modulating a light source signal to be transmitted by using the modulation signal.

2. The optical transmission method based on polarization code embedded irregular QC-LDPC cascade TCM encoding and decoding according to claim 1, wherein the method is characterized by: the check matrix of the irregular QC-LDPC encoder is constructed based on a quasi-cyclic construction method, the check matrix is constructed as a combination of a cyclic submatrix and a non-singular submatrix, and the mathematical expression is as follows:

Wherein, H is a check matrix, H ₁ is a cyclic submatrix, H ₂ is a non-singular submatrix, I is a q×q identity matrix, 0 is a q×q all-zero matrix, I _xi is a cyclic shift matrix obtained by circularly shifting each row of the identity matrix I by x _i bits to the right, a ⁱ、bⁱ is a non-zero element on a finite field GF (q), at most only one zero element on GF (q) exists in each row or each column of the H ₁ matrix, and at least k-1 different values exist in any two rows.

3. The optical transmission method based on polarization code embedded irregular QC-LDPC cascade TCM encoding and decoding according to claim 1, wherein the method is characterized by: the parallel bit stream is sent to a two-dimensional grid coding modulation unit to obtain constellation symbol information, and the method comprises the following steps:

Dividing the parallel bit stream into two groups of bit data, wherein one group of bit data enters a convolution encoder with a code rate of R=m/n, n bits of encoded bits are output, and one constellation subset of the n bits of encoded bits is selected from 2 ⁿ constellation subsets with equal probability;

and performing constellation symbol mapping on the other group of bit data based on the selected constellation subset to generate constellation symbol information.

4. A polarization code embedded irregular QC-LDPC concatenated TCM coding based optical transmission method according to claim 3, wherein: and when the parallel bit stream is a parallel four-bit binary bit stream, and the code rate is R=2/3, dividing the parallel bit stream into two groups of bit data, wherein each group of bit data is a two-bit binary bit stream, and outputting 3-bit coded bits by the convolutional encoder to obtain a five-bit parallel binary bit stream together with the Yu Erwei binary bit stream.

5. An optical transmission method based on polarization code embedded irregular QC-LDPC concatenated TCM coding as defined in claim 1, wherein the constellation subset generation method comprises:

and dividing the constellation point subsets of the preset constellation diagram according to the dividing criterion of the secondary minimum Euclidean distance, and dividing the constellation points with the same minimum Euclidean distance in the constellation diagram into different constellation point subsets.

6. The method for optical transmission based on polarization code embedded irregular QC-LDPC concatenated TCM coding as claimed in claim 5, wherein the predetermined constellation is a 32QAM constellation.

7. The optical transmission method based on polarization code embedded irregular QC-LDPC cascade TCM encoding and decoding according to claim 1, wherein the method is characterized by: the carrier amplitude phase modulation unit comprises a first up-sampling module, a first filter module, a second up-sampling module, a second filter module and an adder module;

the first up-sampling module is connected with the first filter module in series;

the second up-sampling module is connected with the second filter module in series;

two input ends of the adder module are respectively connected with the output ends of the first filter module and the second filter module;

The input ends of the first up-sampling module and the second up-sampling module are used for accessing the constellation symbol information.

8. The optical transmission method based on polarization code embedded irregular QC-LDPC concatenated TCM coding according to claim 7, wherein the method comprises the following steps: the first up-sampling unit and the second up-sampling unit respectively perform M times up-sampling on constellation symbol information to realize M times period expansion of signals on a frequency spectrum; the filter unit adopts a quadrature digital filter bank to filter and shape the constellation symbol information after up-sampling; the generating a modulated signal.

9. An optical transmission device based on polarization code embedded irregular QC-LDPC cascade TCM encoding and decoding, comprising:

The encoding unit is used for sending the randomly generated information bits to the polarization encoder, the information bits are transmitted to the irregular QC-LDPC encoder through a reliable channel in the polarization encoder, and the information bits are encoded by the irregular QC-LDPC encoder to obtain a first encoded signal;

The serial-parallel conversion unit is used for carrying out serial-parallel conversion on the first coded signal to obtain a parallel bit stream;

the code modulation unit is used for sending the parallel bit stream into the two-dimensional grid code modulation unit for coding and modulating to obtain constellation symbol information;

the modulating unit is used for sending the constellation symbol information into the carrier amplitude phase modulating unit to obtain a modulating signal;

And the transmission unit is used for modulating the light source signal to be transmitted by using the modulation signal.

10. An optical transmission system based on polarization code embedded irregular QC-LDPC cascade TCM coding and decoding is characterized in that,

Including a storage medium and a processor;

The storage medium is used for storing instructions;

the processor is operative to perform the method according to any one of claims 1-8.