A high spectral efficiency and low power consumption joint channel coding modulation optical transmission method and system

Abstract

The present invention discloses a high spectral efficiency and low power consumption joint channel coding modulation optical communication method and system, and relates to the field of high-speed optical fiber communication technology. It includes a data acquisition step, a symbol multiplexing joint channel coding modulation step, a signal light transmission step, a channel equalization step, and a symbol demultiplexing step. The present invention aims to improve the problems of relative independence of forward error correction channel coding FEC and high-order modulation function modules in optical transmission, dependence on FEC long code length, limited spectrum efficiency improvement under the limitation of optical fiber nonlinear effects, and high FEC decoding delay and power consumption, which is beneficial to improving the spectrum efficiency and capacity of coherent optical transmission systems and optimizing system delay and power consumption.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a high-spectral-efficiency, low-power-consumption joint channel coding modulation optical transmission method and system. Background Art

[0002] High-order modulation is an inevitable way to improve the spectrum efficiency within the fiber bandwidth resources and realize large-capacity optical transmission. However, the larger the high-order modulation order, the shorter the Euclidean distance between the constellation points, the greater the signal is affected by channel damage such as fiber dispersion, nonlinearity, polarization mode dispersion, and the shorter the effective transmission distance, thus limiting the improvement of the overall capacity of optical transmission. At the same time, since forward error correction channel coding (FEC) can improve the signal-to-noise ratio gain of the received light and effectively improve the transmission reliability of the signal, it is a key technology for obtaining a high-spectral efficiency and large-capacity optical transmission system. Shannon information theory gives the basic relationship between spectrum efficiency (channel capacity) and signal-to-noise ratio, but at present, the FEC and high-order modulation functional modules are relatively independent, and the degree of mathematical correlation between the two has not been clarified. The optical transmission capacity model of joint channel coded high-order modulation is still unclear. Therefore, using joint coded high-order modulation to construct the mathematical correlation between the coded bits and the modulation symbols and realize the fusion between the coding module and the high-order modulation module is a key technology to improve the spectrum efficiency within the limited fiber bandwidth resources and obtain a high-spectral efficiency and large-capacity optical transmission system. At the same time, in theory, the larger the channel coding code length, the greater the optical transmission signal-to-noise ratio gain, and the greater the receiver delay, which limits the application scenarios of joint channel coding modulation technology. Therefore, the joint channel coding technology with high spectral efficiency and low delay has the main research value in high-speed optical transmission systems.

[0003] As the demand for communication capacity continues to increase, various new technologies are urgently needed to improve transmission capacity and performance. Polarization channel coding is one of the topics that has attracted much attention. Polar code is a channel coding method based on channel polarization theory. It has a short code length, can theoretically reach the Shannon limit, has a simple coding structure, and has a flexible and adjustable code rate. It has been selected as the coding method for 5G-NR control channels. The coding and decoding design based on parallel iteration of Polar short codes, combined with joint channel coding and modulation technology, is a key technology for realizing high spectral efficiency and low latency optical transmission systems.

[0004] Therefore, it is an urgent problem for those skilled in the art to propose a high spectral efficiency and low power consumption joint channel coding modulation optical communication method and system to solve the problems existing in the prior art. Summary of the invention

[0005] In view of this, the present invention provides a high spectral efficiency and low power consumption joint channel coding modulation optical communication method and system, which can improve the optical transmission capacity and system spectrum efficiency while reducing system delay and power consumption.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A high spectral efficiency and low power consumption joint channel coding modulation optical communication method and system, comprising the following steps:

[0008] Data acquisition step: acquiring signal source data generated by user information;

[0009] Symbol multiplexing step: The forward error correction encoder based on the polar code performs channel coding and rate matching on the signal source data, and then sends it to the interleaver for interleaving, and then sends it to the symbol multiplexer for "many-to-one" mapping high-order modulation to obtain a high-spectral-efficiency symbol multiplexing signal with high spectral efficiency and short code joint channel coding modulation;

[0010] Signal transmission steps: The high-spectral-efficiency symbol multiplexing signal is then converted from digital to analog and polarization multiplexing IQ modulation is used to achieve electro-optical conversion, and the generated optical signal is sent into the optical fiber for transmission to the optical receiver. The receiver uses a coherent detector to receive the signal, and then performs analog-to-digital conversion to collect data and obtain the analog-to-digital converted signal;

[0011] Channel equalization step: The signal after analog-to-digital conversion undergoes clock recovery, dispersion compensation, polarization demultiplexing, frequency offset compensation, and phase recovery to initially obtain the constellation information of the transmission signal;

[0012] Symbol demultiplexing step: obtain the signal constellation point of the constellation information of the transmission signal, implement the bit-interleaved polarization demodulation and iterative decoding process through multi-module iterative decoding based on soft information interaction, realize joint symbol demultiplexing and FEC decoding, and restore the information bit data of the data source.

[0013] In the above method, optionally, the symbol multiplexing step is based on joint polar code channel coding modulation theory.

[0014] In the above method, optionally, in the symbol multiplexing step, every 5 binary codewords in the binary bit stream after polarization channel coding are modulated and mapped into a high-order modulation symbol. The traditional 5-bit codeword modulation requires a total of 32 different constellation symbols 32QAM to carry. The core of symbol multiplexing is the "many-to-one" overlapping mapping of joint channel coding. According to the principle of minimum Hamming distance between symbols and within symbols, every group of 4 high-order modulated 32QAM symbols are overlapped and mapped to 1 constellation point. Four 32QAM symbols are overlapped on each constellation point of the joint channel coding modulation to generate a symbol multiplexed 8QAM signal.

[0015] In the above method, optionally, during the signal transmission process, after optical fiber transmission, coherent detection and digital signal processing channel equalization, the symbol demultiplexing process for the symbol multiplexing step can be expressed as:

[0016] S De-SDM (t) = y(t)·ξ-1 (Υ,LLR ID );

[0017] Among them, y(t) represents the digital signal after signal equalization, ξ -1 (·) represents the demultiplexing process of the symbol multiplexed signal, γ represents the minimum Euclidean distance, and LLR ID is the prior information expressed as the log-likelihood ratio.

[0018] In the above method, optionally, in the symbol demultiplexing step, in the first round of high-order modulation and demodulation, each demodulated optical transmission symbol The posterior probability at time t is initialized with an equal probability value, and then its symbol soft information is continuously iterated in the Polar decoder for Polar decoding, and at the same time, The posterior probability information of ; specify is the deinterleaved external information and is the interleaved external information, and are the prior information of the Polar decoder and the symbol multiplexing QAM demapper, respectively. Through interweaving The difference is updated and sent back to the symbol multiplexing QAM demapper for the next round of parallel outer iteration.

[0019] The above method, optionally, in the symbol demultiplexing step, the external information obtained from the symbol multiplexing QAM demapper After deinterleaving, the root node RND passed to the Polar decoder is used as external information. The soft information is continuously iterated and updated between the polar root node and the polar leaf node LND. After each cycle, the LLRs are output from the Polar decoder to update Used for the next outer iteration.

[0020] A high spectral efficiency and low power consumption joint channel coding and modulation optical transmission system, characterized in that any one of the above-mentioned high spectral efficiency and low power consumption joint channel coding and modulation optical transmission methods comprises a data acquisition module, a symbol multiplexing module, a signal transmission module, a channel equalization module and a symbol demultiplexing module;

[0021] Data acquisition module: acquires signal source data generated by user information;

[0022] Symbol multiplexing module: The forward error correction encoder based on polar code performs channel coding and rate matching on the signal source data, and then sends it to the interleaver for interleaving, and then to the symbol multiplexer for "many-to-one" mapping high-order modulation, so as to obtain a high-spectral-efficiency symbol multiplexing signal with high spectral efficiency, short code and low delay combined with channel coding modulation;

[0023] Signal transmission module: The high-spectral-efficiency symbol multiplexing signal is converted from digital to analog and polarization multiplexing IQ modulation is used to achieve electro-optical conversion. The generated optical signal is sent into the optical fiber and transmitted to the optical receiver. The receiver uses a coherent detector to receive the signal, and then performs analog-to-digital conversion to collect data and obtain the analog-to-digital converted signal;

[0024] Channel equalization module: After analog-to-digital conversion, the signal undergoes clock recovery, dispersion compensation, polarization demultiplexing, frequency offset compensation, and phase recovery to initially obtain the constellation information of the transmission signal;

[0025] Symbol demultiplexing module: obtains the signal constellation point of the constellation information of the transmission signal, implements the bit-interleaved polarization demodulation and iterative decoding process through multi-module iterative decoding based on soft information interaction, realizes joint symbol demultiplexing and FEC decoding, and recovers the information bit data of the data source.

[0026] It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a high spectral efficiency and low power consumption joint channel coding modulation optical communication method and system, which has the following beneficial effects:

[0027] ① Using symbol multiplexing technology, the carrying capacity of high-order modulation symbols can be increased through "many-to-one" overlapping mapping, thereby improving the system spectrum efficiency;

[0028] ② At the same time, by reducing the number of high-order modulation constellation points, the Euclidean distance between constellation points is increased, and the system's tolerance to fiber dispersion and nonlinear effects is improved;

[0029] ③ The parallel iterative design of short code polarization code was invented, which broke through the dependence of high signal-to-noise ratio gain of optical transmission on long code long channel coding, and the system has low delay characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0031] Figure 1 A flow chart of a high spectral efficiency and low power consumption joint channel coding modulation optical communication method provided by the present invention;

[0032] Figure 2 A schematic diagram of symbol multiplexing combined with channel coding modulation provided by the present invention;

[0033] Figure 3 A flowchart of symbol demultiplexing provided by the present invention;

[0034] Figure 4 A flow chart of the high-speed optical transmission system receiving and sending ends provided by the present invention;

[0035] Figure 5 A flow chart of a high-speed optical transmission system receiving end provided by the present invention;

[0036] Figure 6 A structural diagram of a high spectral efficiency and low power consumption joint channel coding modulation optical communication system provided by the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0039] Reference Figure 1 As shown, the present invention discloses a high spectral efficiency and low power consumption joint channel coding modulation optical communication method, comprising the following steps:

[0040] Data acquisition step: acquiring signal source data generated by user information;

[0041] Symbol multiplexing step: The forward error correction encoder based on the polar code performs channel coding and rate matching on the signal source data, and then sends it to the interleaver for interleaving, and then sends it to the symbol multiplexer for "many-to-one" mapping high-order modulation to obtain a high-spectral-efficiency symbol multiplexing signal with high spectral efficiency and short code joint channel coding modulation;

[0042] Signal transmission steps: The high-spectral-efficiency symbol multiplexing signal is then converted from digital to analog and polarization multiplexing IQ modulation is used to achieve electro-optical conversion, and the generated optical signal is sent into the optical fiber for transmission to the optical receiver. The receiver uses a coherent detector to receive the signal, and then performs analog-to-digital conversion to collect data and obtain the analog-to-digital converted signal;

[0043] Channel equalization step: The signal after analog-to-digital conversion undergoes clock recovery, dispersion compensation, polarization demultiplexing, frequency offset compensation, and phase recovery to initially obtain the constellation information of the transmission signal;

[0044] Symbol demultiplexing step: obtain the signal constellation point of the constellation information of the transmission signal, realize the bit interleaved polarization demodulation and iterative decoding process through multi-module iterative decoding based on soft information interaction, realize joint symbol demultiplexing and FEC decoding, and recover the information bit data of the data source

[0045] Furthermore, the symbol multiplexing step is based on the joint polar code channel coded modulation theory.

[0046] Further, see Figure 2 As shown in the figure, in the symbol multiplexing step, every 5 binary code elements in the binary bit stream after polarization channel coding are modulated and mapped into a high-order modulation symbol. The traditional 5-bit information modulation requires a total of 32 different constellation symbols 32QAM to carry. The core of symbol multiplexing is the "many-to-one" overlapping mapping of joint channel coding. According to the principle of minimum Hamming distance between symbols and within symbols, every group of 4 high-order modulation symbols are overlapped and mapped to 1 constellation point. Four 32QAM symbols are time-domain multiplexed at each constellation point of joint channel coding modulation to generate a symbol multiplexed 8QAM signal.

[0047] Specifically, the mapping rules are:

[0048]

[0049] Wherein, A(t) is the constellation point symbol after symbol multiplexing, and s(t) is the binary symbol.

[0050] Furthermore, in the signal transmission process, after optical fiber transmission, coherent detection and digital signal processing channel equalization, the symbol demultiplexing process for the symbol multiplexing step can be expressed as:

[0051] S De-SDM (t) = y(t)·ξ -1 (Υ,LLR ID );

[0052] Among them, y(t) represents the digital signal after signal equalization, ξ -1 (·) represents the demultiplexing of the symbol multiplexed signal, γ represents the minimum soft decision, and LLR ID is the prior information expressed as the log-likelihood ratio.

[0053] Specifically, refer to Figure 3As shown, the transmitter includes a laser, a data generating arbitrary waveform generator AWG, an electric drive amplifier, an optical IQ modulator, a polarization multiplexer, and a waveform selector WSS; the optical fiber transmission unit is a commercial standard single-mode optical fiber and an erbium-doped optical fiber amplifier. Specifically, at the transmitter, a symbol multiplexing signal based on short code joint coding modulation is first generated. The specific process is to convert the input binary source sequence into serial and parallel signals and group map the codeword sequence after forward error correction coding and bit interleaving with a code rate of 3 / 4. The single-carrier ultra-800Gb / s 32QAM signal carries 6 bits of information per symbol for "many-to-one" mapping symbol multiplexing. Every four 32QAM symbols are mapped to the same constellation point to obtain a symbol multiplexing 8QAM signal. The electrical signal is pre-equalized and then a DAC is used to generate a symbol multiplexing 16QAM electrical signal, which is modulated onto the optical carrier generated by the laser through an IQ modulator. Next, polarization multiplexing is used to double the total channel rate, and the signal is sent into a single-mode optical fiber link and transmitted to the receiving end. At the same time, a waveform selector can be used to perform wavelength division multiplexing to achieve high-density, large-capacity optical transmission.

[0054] Specifically, refer to Figure 4 As shown, the receiving end is composed of a tunable optical filter, a local oscillator signal LO, an integrated coherent receiver including a 90° optical mixer and a balanced receiver, and a high-speed real-time oscilloscope analog-to-digital converter (DAC) for data acquisition. At the receiving end, the integrated coherent receiver, including a 90° optical mixer and a balanced receiver, first performs optical mixing and balanced photoelectric conversion on the local oscillator signal LO and the received optical symbol multiplexing signal. Then, a high-speed real-time oscilloscope with a sampling rate of 256GSa / s performs analog-to-digital conversion and data acquisition on the two polarization states of the signal and a total of four IQ electrical signals. Finally, the collected digital signal is sent to the offline digital signal processing DSP unit. The processing process mainly includes: clock synchronization, 2x resampling, dispersion compensation, polarization demultiplexing, channel equalization, frequency offset compensation and phase recovery, symbol demultiplexing, forward error correction decoding and bit error rate calculation.

[0055] Further, such as Figure 5 As shown, in the symbol demultiplexing step, in the first round of high-order modulation and demodulation, each demodulated optical transmission symbol The posterior probability at time t is initialized with an equal probability value, and then its symbol soft information is continuously iterated in the Polar decoder for Polar decoding, and at the same time, The posterior probability information of ; specify is the deinterleaved external information and is the interleaved external information, and are the prior information of the Polar decoder and the symbol multiplexing QAM demapper, respectively. Through interweaving The difference is updated and sent back to the symbol multiplexing QAM demapper for the next round of parallel outer iteration.

[0056] Furthermore, the external information obtained from the symbol multiplexing QAM demapper After deinterleaving, the root node (RND) passed to the Polar decoder is used as external information. The soft information is continuously iterated and updated between the polar root node and the polar leaf node (LND). After each cycle, the LLRs are output from the Polar decoder to update Used for the next outer iteration.

[0057] like Figure 5 As shown in the figure, module A is a Polar decoder, which consists of a root node decoder (RND) and a leaf node decoder (LND). The information exchange between RND and LND is called the inner loop, and the information exchange between module A and the symbol multiplexing QAM demapper is called the outer loop. The joint iterative decoding system adopts the maximum a posteriori probability (MAP) algorithm, and realizes joint demultiplexing and iterative decoding by continuously transmitting the log-likelihood ratio soft information between module A and the symbol multiplexing QAM demapper.

[0058] For each symbol to be demultiplexed The LLRs output by the symbol multiplexing QAM demapper can be expressed as:

[0059]

[0060] in, By subset and For SDM-8QAM, the subset size of each symbol is 5. In the first round of demodulation, Indicates each transmitted symbol Tx t The posterior probability of i at time t is initialized with equal probability values. Then, the soft information is iterated in module A for Polar decoding and generates The posterior probability information of . Specify is the deinterleaved external information and is the interleaved external information. Similarly, and They are the prior information of the Polar decoder and the symbol multiplexing QAM demapper respectively. By interweaving The symbol multiplexing QAM demapper is sent back for the next outer iteration. The prior information can be expressed as:

[0061]

[0062]

[0063] in, Represents each transmitted coded bit v t The prior probability of i. The external information obtained from the symbol multiplexing QAM demapper After deinterleaving, it is passed to the Polar RND decoder of module A as external information.

[0064]

[0065] Then, the soft information is continuously iteratively updated in Polar RND and Polar LND. This process is called the inner loop. The inner loop assists the outer loop, reducing the number of calculations and improving efficiency.

[0066]

[0067] Among them, the LLR transfer from LND to RND is defined as L l,f , the LLR transfer from RND to LND is defined as R l,f The function μ(·) is defined as

[0068] μ(x,y)=ln(1+xy)-ln(x+y);

[0069] After each inner loop, the LLRs are output from the Polar decoder to update For the next outer iteration. The final decoding output is based on R 1,f and L 1,f The decision is made based on the sum of soft information, that is, the sum of posterior probabilities.

[0070] and Figure 1 Corresponding to the method described above, an embodiment of the present invention further provides a high spectral efficiency and low power consumption joint channel coding modulation optical communication system for Figure 1 For the specific implementation of the method, refer to Figure 6 As shown, it includes a data acquisition module, a symbol multiplexing module, a data transmission module and a symbol demultiplexing module;

[0071] Data acquisition module: acquires signal source data generated by user information;

[0072] Symbol multiplexing module: The forward error correction encoder based on polar code performs channel coding and rate matching on the signal source data, and then sends it to the interleaver for interleaving, and then to the symbol multiplexer for "many-to-one" mapping high-order modulation, to obtain a high-spectral-efficiency symbol multiplexing signal with high spectral efficiency and short code joint channel coding modulation;

[0073] Signal transmission module: The high-spectral-efficiency symbol multiplexing signal is converted from digital to analog and polarization multiplexing IQ modulation is used to achieve electro-optical conversion. The generated optical signal is sent into the optical fiber and transmitted to the optical receiver. The receiver uses a coherent detector to receive the signal, and then performs analog-to-digital conversion to collect data and obtain the analog-to-digital converted signal;

[0074] Channel equalization module: After analog-to-digital conversion, the signal undergoes clock recovery, dispersion compensation, polarization demultiplexing, frequency offset compensation, and phase recovery to initially obtain the constellation information of the transmission signal;

[0075] Symbol demultiplexing module: obtains the signal constellation point of the constellation information of the transmission signal, implements the bit-interleaved polarization demodulation and iterative decoding process through multi-module iterative decoding based on soft information interaction, and then realizes joint symbol demultiplexing and FEC decoding to recover the information bit data of the data source.

[0076] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high spectral efficiency and low power consumption joint channel coding modulation optical transmission method, characterized in that: The following steps are involved: Data acquisition step: acquiring signal source data generated by user information; Symbol multiplexing step: The forward error correction encoder based on the polar code Polar performs channel coding and rate matching on the signal source data, then sends it to the interleaver for interleaving, and then sends it to the symbol multiplexer for "many-to-one" mapping high-order modulation to obtain a high-spectral-efficiency symbol multiplexing signal with high spectral efficiency and short code joint channel coding modulation; Signal transmission steps: The high-spectral-efficiency symbol multiplexing signal is then converted from digital to analog and polarization multiplexing IQ modulation is used to achieve electro-optical conversion. The generated optical signal is sent into the optical fiber and transmitted to the optical receiver. The receiver uses a coherent detector to receive the signal, and then performs analog-to-digital conversion to collect data to obtain the analog-to-digital converted signal; Channel equalization step: The signal after analog-to-digital conversion undergoes clock recovery, dispersion compensation, polarization demultiplexing, frequency offset compensation, and phase recovery to initially obtain the constellation information of the transmission signal; Symbol demultiplexing step: Obtain the constellation point information of the transmission signal, implement bit-interleaved polarization demodulation and iterative decoding process through multi-module iterative decoding based on soft information interaction, realize joint symbol demultiplexing and FEC decoding, and recover the information bit data of the data source; The mapping rules are: Among them, A(t) is the constellation point symbol after symbol multiplexing, s(t) is the binary symbol, The expression is: The core of symbol multiplexing is the "many-to-one" overlapping mapping technology based on joint channel coding. According to the principle of minimum Hamming distance between multiplexed symbols and within multiplexed symbols, each group of 4 high-order modulated 32QAM symbols are overlapped and mapped to one constellation point. Four 32QAM symbols are overlapped on each constellation point of joint channel coding modulation to generate a symbol multiplexing 8QAM signal. The LLRs output by the symbol multiplexing QAM demapper are expressed as: in, By subset and constitute.

2. The high spectral efficiency and low power consumption combined channel coding modulation optical transmission method according to claim 1, characterized in that: The symbol multiplexing step is based on the joint polar code channel coded modulation theory.

3. The high spectral efficiency and low power consumption combined channel coding modulation optical transmission method according to claim 1, characterized in that: In the symbol multiplexing step, every 5 binary codewords in the binary bit stream after polarization channel coding are modulated and mapped into a high-order modulation symbol. Traditional 5-bit codeword modulation requires a total of 32 different constellation symbols 32QAM to carry.

4. The high spectral efficiency and low power consumption combined channel coding modulation optical transmission method according to claim 1, characterized in that: During the signal transmission process, after optical fiber transmission, coherent detection and digital signal processing channel equalization, the symbol demultiplexing process for the symbol multiplexing step is expressed as: S De-SDM (t)=y(t)·ξ -1 (Υ,LLR ID ); Among them, y(t) represents the digital signal after signal equalization, ξ -1 (·) represents the demultiplexing of symbol multiplexed signals, γ represents the soft decision rule, and LLR ID is the prior information expressed as the log-likelihood ratio.

5. The high spectral efficiency and low power consumption combined channel coding modulation optical transmission method according to claim 1 is characterized in that In the symbol demultiplexing step, in the first round of high-order modulation and demodulation, each demodulated optical transmission symbol The posterior probability at time t is initialized with an equal probability value, and then its symbol soft information is continuously iterated in the Polar decoder for Polar decoding, and at the same time, The posterior probability information of ; specify is the deinterleaved external information and is the interleaved external information, and are the prior information of the Polar decoder and the symbol multiplexing QAM demapper, Through interweaving The difference is updated and sent back to the symbol multiplexing QAM demapper for the next round of parallel outer iteration.

6. A high spectral efficiency and low power consumption combined channel coding modulation optical transmission method according to claim 5, characterized in that In the symbol demultiplexing step, the extrinsic information obtained from the symbol multiplexing QAM demapper After deinterleaving, the root node RND passed to the Polar decoder is used as external information. The soft information is continuously iterated and updated between the polar root node and the polar leaf node LND. After each cycle, the LLRs are output from the Polar decoder to update Used for the next outer iteration.

7. A high spectral efficiency and low power consumption joint channel coding modulation optical transmission system, characterized in that A high spectral efficiency and low power consumption joint channel coding modulation optical transmission method according to any one of claims 1 to 6 is applied, comprising a data acquisition module, a symbol multiplexing module, a signal transmission module, a channel equalization module and a symbol demultiplexing module; Data acquisition module: acquires signal source data generated by user information; Symbol multiplexing module: The forward error correction encoder based on polar code performs channel coding and rate matching on the signal source data, and then sends it to the interleaver for interleaving, and then to the symbol multiplexer for "many-to-one" mapping high-order modulation, to obtain a high-spectral-efficiency symbol multiplexing signal with high spectral efficiency and short code joint channel coding modulation; Signal transmission module: The high-spectral-efficiency symbol multiplexing signal is converted from digital to analog and polarization multiplexing IQ modulation is used to realize electro-optical conversion. The generated optical signal is sent into the optical fiber and transmitted to the optical receiver. The receiver uses a coherent detector to receive the signal, and then performs analog-to-digital conversion to collect data to obtain the analog-to-digital converted signal. Channel equalization module: After analog-to-digital conversion, the signal undergoes clock recovery, dispersion compensation, polarization demultiplexing, frequency offset compensation, and phase recovery to initially obtain the constellation information of the transmission signal; Symbol demultiplexing module: obtains the signal constellation point of the constellation information of the transmission signal, implements the bit-interleaved polarization demodulation and iterative decoding process through multi-module iterative decoding based on soft information interaction, realizes joint symbol demultiplexing and FEC decoding, and recovers the information bit data of the data source.

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