CN116614202B - Mixed coding and decoding method and device based on sub-constellation space - Google Patents

Mixed coding and decoding method and device based on sub-constellation space

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CN116614202B
CN116614202B CN202310520556.2A CN202310520556A CN116614202B CN 116614202 B CN116614202 B CN 116614202B CN 202310520556 A CN202310520556 A CN 202310520556A CN 116614202 B CN116614202 B CN 116614202B
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polarization
bit
signal
dimension
sub
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CN116614202A (en
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忻向军
田凤
郭千卉
武天泽
张琦
姚海鹏
高然
田清华
王拥军
王富
黄鑫
张文全
武瑞德
李志沛
郭栋
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Yatigers Shanghai Communication Technology Co ltd
Beijing Institute of Technology BIT
Beijing University of Posts and Telecommunications
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Yatigers Shanghai Communication Technology Co ltd
Beijing Institute of Technology BIT
Beijing University of Posts and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0057—Block codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0061—Error detection codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/345—Modifications of the signal space to allow the transmission of additional information
    • H04L27/3461—Modifications of the signal space to allow the transmission of additional information in order to transmit a subchannel
    • H04L27/3483—Modifications of the signal space to allow the transmission of additional information in order to transmit a subchannel using a modulation of the constellation points
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Error Detection And Correction (AREA)

Abstract

本发明提供一种基于子星座空间下的混合编译码方法及装置，所述方法的步骤包括生成比特信息，并分离为两路信号；对两路信号分别进行LDPC和Polar编码，并进行偏振复用处理得到X偏振和Y偏振；基于X偏振和Y偏振的星座分割结果确定是否对Y偏振进行幅度平移，输出信号；加载到激光上，进行传输；接收时，将信号分离为X偏振产生的4D信号、Y偏振产生的4D信号和四相相移键控信号三部分；计算每个符号中每一比特的对数似然比；基于对数似然比确定每个符号的比特数据，得到X偏振和幅度平移的Y偏振；并基于四相相移键控信号的比特信息对Y偏振的幅度平移进行还原，得到Y偏振，进一步对X偏振和Y偏振进行解调和译码，输出比特信息。

The present invention provides a hybrid coding method and device based on a sub-constellation space. The method comprises the following steps: generating bit information and separating it into two signals; performing LDPC and Polar coding on the two signals respectively, and performing polarization multiplexing processing to obtain X polarization and Y polarization; determining whether to perform amplitude shift on the Y polarization based on the constellation segmentation results of the X polarization and the Y polarization, and outputting the signal; loading the signal onto a laser for transmission; during reception, separating the signal into three parts: a 4D signal generated by the X polarization, a 4D signal generated by the Y polarization, and a quaternary phase shift keying (QPSK) signal; calculating the log-likelihood ratio of each bit in each symbol; determining the bit data of each symbol based on the log-likelihood ratio to obtain the X polarization and the amplitude-shifted Y polarization; restoring the amplitude shift of the Y polarization based on the bit information of the QPSK signal to obtain the Y polarization; further demodulating and decoding the X polarization and the Y polarization to output the bit information.

Description

Mixed coding and decoding method and device based on sub-constellation space
Technical Field
The present invention relates to the field of digital communications technologies, and in particular, to a method and apparatus for hybrid encoding and decoding based on a sub-constellation space.
Background
With the rapid development of the internet industry, services such as artificial intelligence, big data, internet of things and the like are on a large scale, the demand of human beings for information is rapidly increased, the demands for the speed, capacity and reliability of a communication system are continuously increased, and meeting the rapidly-increased demand for network capacity has become a serious challenge facing the communication technology. As a backbone component in a communication network, optical fiber transmission technology with faster research speed, larger capacity and better performance plays an important role in meeting information development requirements.
In the conventional communication system, the encoder and the modulator are independent of each other, and the functions of reducing the error rate and increasing the information transmission rate are respectively realized, while the Trellis Coded Modulation (TCM) breaks through the mode, so that excellent decoding performance can be obtained under the conditions of not increasing the system bandwidth and reducing the data transmission rate. The basic idea of TCM is to introduce check bits in the transmitted symbols consisting of a plurality of bits, and to divide the set of signal constellation points (SPs) by the introduced coding redundancy. The two-dimensional grid coding modulation scheme can improve the anti-interference capability of signals under the condition of not increasing the transmission bandwidth and not sacrificing the information transmission rate, obtain obvious coding gain, increase the minimum Euclidean distance of a constellation diagram under the condition of unchanged transmitting power, and reduce the bit error rate.
In optical fiber communication, a Polarization Multiplexing (PM) technology is generally adopted to transmit two paths of signals on X polarization and Y polarization respectively, so as to expand the system capacity, and the two polarization directions, the in-phase component and the quadrature component together form a four-dimensional signal. When the four-dimensional probability shaping TCM signal is generated, the signal transmission effect on the Y polarization is slightly worse than that of the X polarization due to the adoption of an amplitude translation technology on the Y polarization, so that a coding mode with a certain difference in performance can be adopted on the two polarizations during coding, and the signal performance on the Y polarization is consistent with that of the X polarization. Under the condition of medium and short code length, the error rate performance of the Polar code is obviously superior to that of LDPC, and the overall complexity is far lower than that of LDPC, so that the LDPC coding is adopted on X polarization, the Polar code is adopted on Y polarization, TCM mapping is carried out to constellation points respectively, and 4D symbols are formed for transmission. This scheme of performing TCM after hybrid coding is a reliable way to further improve the performance of the communication system. However, when Polarization Multiplexing (PM) technology and probability shaping technology are used in combination in the application process, a technique of amplitude shifting is required for Y polarization, but a method of efficiently decoding the coded signal after shifting is lacking in the prior art.
Disclosure of Invention
In view of the above, embodiments of the present invention provide a hybrid coding method based on sub-constellation space to obviate or ameliorate one or more of the disadvantages of the prior art.
An aspect of the present invention provides a hybrid coding method based on a sub-constellation space, the method comprising the steps of signal generation and signal reception demodulation:
The step of signal generation includes:
The method comprises the steps of generating bit information, adopting a bit distributor to separate the bit information into two paths of signals, respectively performing advanced FEC coding on the two paths of signals, namely adopting LDPC coding on bit data to form an X-polarized signal, adopting Polar coding on bit data to form a Y-polarized signal, and performing polarization multiplexing processing to obtain X-polarization and Y-polarization;
the step of signal reception demodulation includes:
the method comprises the steps of separating a signal into three parts of a 4D signal generated by X polarization, a 4D signal generated by Y polarization and a four-phase shift keying signal, carrying out hard judgment on the four-phase shift keying signal to obtain bit information of a carried mark bit, calculating the log likelihood ratio of each bit in the 4D signal generated by X polarization and the 4D signal generated by Y polarization, determining data of each bit based on the log likelihood ratio to obtain Y polarization of X polarization and amplitude translation, reducing the amplitude translation of the Y polarization of the amplitude translation based on the bit information obtained by demodulation of the four-phase shift keying signal to obtain Y polarization, demodulating and decoding the X polarization and the Y polarization, and outputting bit information.
By adopting the scheme, at a receiving end, the invention provides a multi-dimensional soft decision algorithm aiming at amplitude translation set segmentation, which is used for respectively carrying out bitwise decoding on data on X polarization and Y polarization. In the X polarization, the Euclidean distance can be directly calculated with a subset where a received symbol is located, namely constellation points in bit correlation dimension BRD, so as to obtain a log-likelihood ratio for decoding, in the Y polarization, each bit in two directions is decoded bit by bit according to the received sign bits in two directions of an in-phase component and a quadrature component, if the sign bit is 0, the decoding is carried out according to the log-likelihood ratio in the bit correlation dimension, and if the sign bit is 1, which bit is required to be changed according to Gray code mapping rules determined by a transmitting end, and the bit is reversed, so that the received signal point is translated back to the original position and then decoded in the bit correlation dimension. The algorithm has lower complexity, and has superior error rate performance due to the combination of probability amplitude shaping PAS and an integrated segmentation technology, and can be suitable for effectively decoding the translated encoded signal.
In some embodiments of the present invention, in the step of encoding two signals respectively and performing polarization multiplexing processing to obtain X-polarization and Y-polarization, LDPC encoding and Polar encoding are respectively applied to the two signals to compensate for the fact that the Y-polarization signal will have slightly worse effect than the X-polarization signal in subsequent processing.
In some embodiments of the present invention, the constellation points of the signals in each polarization are divided into a plurality of subsets, and in the step of performing constellation subset segmentation based on the signals of the X polarization and the Y polarization, the subsets to which the signals of the X polarization and the Y polarization belong are determined respectively. And combining the four subsets of each of the X polarization and the Y polarization according to the determined sub-family constraint condition to form a 4D sub-family.
In some embodiments of the present invention, in the step of determining whether to perform amplitude translation on the Y polarization based on the constellation segmentation result of the X polarization and the Y polarization, whether the sub-group formed by the subset of the X polarization and the Y polarization belongs to a combination corresponding to a preset sub-group constraint condition corresponding to the subset of the X polarization is determined based on the subset to which the X polarization belongs, if so, amplitude translation is not required, and if not, amplitude translation is performed on the Y polarization to a sub-group corresponding to the subset of the X polarization.
In some embodiments of the present invention, the output signal includes a quadrature phase shift keying signal, the Y polarization includes an in-phase component and a quadrature component (for the adopted 64QAM signal, each symbol carries 6 bits of information altogether, wherein the first 3 bits are in-phase component information and the last 3 bits are quadrature component information), in the step of outputting the output signal, if amplitude translation is not required, the bit information carried by the quadrature phase shift keying signal is 00, if amplitude translation is required and the in-phase component of the Y polarization is translated, the bit information carried by the quadrature phase shift keying signal is 10, if amplitude translation is required and the quadrature component of the Y polarization is translated, the bit information carried by the quadrature phase shift keying signal is 01, and if amplitude translation is required and the in-phase component and the quadrature component of the Y polarization are translated, the bit information carried by the quadrature phase shift keying signal is 11.
In some embodiments of the present invention, in the steps of calculating the log-likelihood ratio of each bit in the 4D signal generated by the X polarization and the 4D signal generated by the Y polarization, determining the data of each bit based on the log-likelihood ratio to obtain Y polarization of the X polarization and the amplitude translation, and restoring the amplitude translation of the Y polarization based on the bit data of the quadrature phase shift keying signal to obtain Y polarization, and further demodulating and decoding the X polarization and the Y polarization;
directly decoding to obtain bit information of a marker bit by adopting a hard decision mode when the quadrature phase shift keying signal is demodulated;
In the 4D signal generated by the X polarization, the Euclidean distance is directly calculated with the subset to obtain the log-likelihood ratio for decoding;
In the 4D signal generated by Y polarization, each bit in two directions is decoded bit by bit according to the received mark bits in two directions of the in-phase component and the quadrature component, namely, the two mark bits of the four-phase shift keying signal, if the mark bit is 0, the decoding is carried out according to the log likelihood ratio in the bit correlation dimension, and if the mark bit is 1, the bit which is changed in the symbol is determined according to the Gray code mapping rule determined by the transmitting end, and the bit is reversed and then decoded.
In some embodiments of the present invention, in the step of calculating the log likelihood ratio of each bit in the X-polarization generated 4D signal, the Y-polarization generated 4D signal, the log likelihood ratio of each bit is calculated according to the following formula:
Wherein, the Representing the log-likelihood ratio of the kth bit,Representing a standard constellation point with a k-th bit of 1,Represents a standard constellation point with a k-th bit of 0,Representing conditional probabilities.
In some embodiments of the present invention, in the step of calculating the log likelihood ratio of each bit in the X-polarization generated 4D signal and the Y-polarization generated 4D signal, the kth bit information in the received symbol is respectively calculated with a standard constellation point with the kth bit being 0) Comparing the Euclidean distance between them to obtain minimum value, and at the same time making them and standard constellation point whose k-th bit is 1#) Comparing the Euclidean distance between the two points, taking the minimum value, and calculating to obtainIn a gaussian channel, the formula for calculating the log-likelihood ratio is expressed as:
;
where y represents the received 4D signal, x represents the standard constellation point, Representing the log-likelihood ratio of the kth bit,Representing a standard constellation point with a k-th bit of 1,Represents a standard constellation point with a k-th bit of 0,Representing the variance characteristics of the gaussian channel itself,Representing the calculated total number of dimensions.
In some embodiments of the invention, the sub-family constraints are met due to the need to meet;
;
Wherein, the The sub-family constraint is represented by a sub-family constraint,Representing the dimensions j, y in the subfamily constraint, representing the received 4D signal, x representing the standard constellation point,Representation ofStandard constellation points with k-th bit i in each dimension,Representation ofStandard constellation points with k-th bit i satisfying the sub-family constraint in each dimension,Representation ofThe kth bit in the dimension that satisfies the j-th dimension subfamily constraint is the standard constellation point of i,Representing the sub-family, the subset to which the kth Bit belongs is referred to as the Bit-dependent dimension (Bit-RelatedDimension, BRD), m represents the dimension of the non-Bit-dependent dimension,Representing the calculated number of total dimensions,A 4D signal representing a non-bit dependent dimension,Standard constellation points representing non-bit dependent dimensions,A set of dimensions representing non-bit dependent dimensions,Representing the minimum euclidean distance in the bit dependent dimension.
In some embodiments of the present invention, the minimum Euclidean distance in the bit-dependent dimension is calculated according to the following formula:
When the dimension is the non-translated dimension or the case of tag bit=0 in the translated dimension, then:
When the dimension is the translation dimension and the sign bit=1, i.e. the symbol has amplitude translation, determining whether the bit is changed by using the gray coding rule determined by the transmitting end, if so, the data bit of the bit is opposite to the constellation point mapping bit, and consideration is needed at this timeAnd,Taking outAnd (3) withIs the minimum value of (2):
Wherein, the Is thatNot including
DerivingAfter that, in the same way,Can be expressed as:
Wherein the method comprises the steps of The set is:
Wherein, the Representing the minimum euclidean distance between the received signal and the standard constellation point for which the kth bit is i in the bit correlation dimension,Representing the minimum euclidean distance between the received signal and the standard constellation point for which k is 1-i in the bit correlation dimension,A set of dimensions representing bit-related dimensions in the SFC,A 4D signal representing the received bit-dependent dimension,Representing standard constellation points in the bit-dependent dimension.
The second aspect of the present invention also provides a hybrid codec device based on a sub-constellation space, the device comprising a computer apparatus comprising a processor and a memory, the memory having stored therein computer instructions for executing the computer instructions stored in the memory, the device implementing the steps of the method as described above when the computer instructions are executed by the processor.
The third aspect of the present invention also provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps performed by the aforementioned hybrid coding method under sub-constellation space.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
It will be appreciated by those skilled in the art that the objects and advantages that can be achieved with the present invention are not limited to the above-described specific ones, and that the above and other objects that can be achieved with the present invention will be more clearly understood from the following detailed description.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate and together with the description serve to explain the application.
Fig. 1 is a schematic diagram of an embodiment of a hybrid coding method based on a sub-constellation space according to the present invention;
FIG. 2 is a schematic diagram of a fixed bit puncturing Polar code structure;
FIG. 3 is a schematic diagram of signal constellation subset partitioning in each polarization;
FIG. 4 is a schematic diagram of signal generation;
fig. 5 is a schematic diagram of signal reception and demodulation.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments and the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. The exemplary embodiments of the present invention and the descriptions thereof are used herein to explain the present invention, but are not intended to limit the invention.
It should be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, while other details not greatly related to the present invention are omitted.
In order to solve the above problems, as shown in fig. 1, the present invention proposes a hybrid coding and decoding method based on a sub-constellation space, and the steps of the method include step S100 signal generation and step S200 signal reception demodulation:
the step of generating the signal in the step S100 includes:
As shown in fig. 4, step S110 generates bit information, and the bit information is separated into two paths of signals by using a bit distributor;
the bit distributor takes odd bits of bit information as one path of signal and even bits as one path of signal.
Step S120, respectively encoding the two paths of signals and performing polarization multiplexing processing to obtain X polarization and Y polarization, namely respectively encoding the two paths of signals, namely adopting LDPC encoding to bit data to be formed into X polarization signals, adopting Polar encoding to bit data to be formed into Y polarization signals so as to compensate the situation that the effect of the Y polarization signals in subsequent processing is slightly worse than that of the X polarization signals, and performing polarization multiplexing processing to obtain X polarization and Y polarization;
step S130, constellation subset segmentation is carried out based on X polarized and Y polarized signals;
as shown in fig. 3, in an implementation, the constellation points of the signal in each polarization are divided into a plurality of subsets, including A, B, C and D four subsets.
And determining the sub-sets to which the signals of the X polarization and the Y polarization belong to complete constellation segmentation, and combining the four sub-sets of the X polarization and the Y polarization according to the determined sub-family constraint conditions to form a 4D sub-family.
Step S140, determining whether to carry out amplitude translation on Y polarization based on constellation segmentation results of X polarization and Y polarization, generating a four-phase shift keying signal based on the amplitude translation results of Y polarization, and outputting the signal;
in some embodiments of the present invention, in the step of determining whether to perform amplitude translation on the Y polarization based on the constellation segmentation result of the X polarization and the Y polarization, whether the sub-group formed by the subset of the X polarization and the Y polarization belongs to a combination corresponding to a preset sub-group constraint condition corresponding to the subset of the X polarization is determined based on the subset to which the X polarization belongs, if so, amplitude translation is not required, and if not, amplitude translation is performed on the Y polarization to a sub-group corresponding to the subset of the X polarization.
In a specific implementation process, the sub-families corresponding to the preset sub-family constraint conditions comprise A-D, B-C, C-B and D-A, wherein the first term corresponds to the subset of X polarization and the second term corresponds to the subset of Y polarization. If the sub-groups to which the actual X polarization and the Y polarization belong are A U C, amplitude translation is needed for the Y polarization, and the Y polarization is translated into the sub-group A U D corresponding to the sub-group constraint condition preset by the subset of the X polarization.
The step S200 of signal receiving demodulation includes:
As shown in fig. 5, step S210, separates the signal into three parts of a 4D signal generated by X polarization, a 4D signal generated by Y polarization, and a quadrature phase shift keying signal;
In a specific implementation process, the output signal includes a quadrature phase shift keying signal, the Y polarization includes an in-phase component and a quadrature component (for an adopted 64QAM signal, each symbol carries 6 bits of information altogether, wherein the first 3 bits are in-phase component information and the last 3 bits are quadrature component information), in the step of outputting the output signal, if amplitude translation is not required, the bit information carried by the quadrature phase shift keying signal is 00, if amplitude translation is required and the in-phase component of the Y polarization is translated, the bit information carried by the quadrature phase shift keying signal is 10, if amplitude translation is required and the quadrature component of the Y polarization is translated, the bit information carried by the quadrature phase shift keying signal is 10, and if amplitude translation is required and the in-phase component and the quadrature component of the Y polarization are translated, the bit information carried by the quadrature phase shift keying signal is 11.
Step S220, hard decision is carried out on the four-phase shift keying signal to obtain bit information of a mark bit;
Step S230, calculating the log likelihood ratio of each bit in the 4D signal generated by the X polarization and the 4D signal generated by the Y polarization;
And step S240, determining the data of each bit based on the log-likelihood ratio to obtain X polarization and Y polarization with amplitude translation, and restoring the amplitude translation of the Y polarization based on the bit data of the quadrature phase shift keying signal to obtain Y polarization, further demodulating and decoding the X polarization and the Y polarization, and outputting bit information.
By adopting the scheme, at a receiving end, the invention provides a multi-dimensional soft decision algorithm aiming at amplitude translation set segmentation, which is used for respectively carrying out bitwise decoding on data on X polarization and Y polarization. In the X polarization, the Euclidean distance can be directly calculated with a subset where a received symbol is located, namely constellation points in bit correlation dimension BRD, so as to obtain a log-likelihood ratio for decoding, in the Y polarization, each bit in two directions is decoded bit by bit according to the received sign bits in two directions of an in-phase component and a quadrature component, if the sign bit is 0, the decoding is carried out according to the log-likelihood ratio in the bit correlation dimension, and if the sign bit is 1, which bit is required to be changed according to Gray code mapping rules determined by a transmitting end, and the bit is reversed, so that the received signal point is translated back to the original position and then decoded in the bit correlation dimension. The algorithm has lower complexity, and has superior error rate performance due to the combination of probability amplitude shaping PAS and an integrated segmentation technology, and can be suitable for effectively decoding the translated encoded signal.
In some embodiments of the present invention, in the step of encoding two signals separately and performing polarization multiplexing processing to obtain X polarization and Y polarization, LDPC encoding and Polar encoding are respectively applied to the two signals.
In a specific application process, a convolutional code is generally adopted in a coding part of the TCM technology, the realization is simpler, the coding and decoding technology is mature, but the gain brought by the convolutional code is limited, so that a more efficient coding mode is cascaded before the TCM module, and the more efficient coding mode is an effective mode for obtaining higher coding gain. In the current advanced forward error correction coding (FEC), polar codes and LDPC codes have better bit error rate performance in the scenarios of short codes and long codes, and the decoding speed and decoding complexity of the Polar codes and the LDPC codes have great advantages, so that the Polar codes and the LDPC codes are used as coding modes adopted by control channels and data channels respectively in 5G scenarios. Therefore, combining Polar codes, LDPC codes with TCM can further improve the performance of the system.
By adopting the scheme, the binary bit stream input by the transmitting end is firstly distributed into two parts, and is respectively processed and then transmitted on two polarizations. One path of data is subjected to QC-LDPC coding and then transmitted on X polarization, the other path of data is subjected to Polar coding and then transmitted on Y polarization;
For the first path of data, the nature of LDPC coding is linear block codes, except that the check matrix is a sparse matrix, the code is indistinguishable from any other block codes, so that a construction mode of a common block code is directly adopted, firstly, a proper check matrix H is designed, then a generation matrix G is obtained according to dual, and then a complete code word is obtained by multiplying an information source code group and the generation matrix. Wherein the check matrix H can be obtained by a random construction method.
For Polar code coding adopted by the other path of data, the channel polarization phenomenon is mainly utilized, new sub-channel positions generated after the channel is combined and split are rearranged, information bits are placed in a perfect channel with the capacity close to 1, frozen bits are placed in a pure noise channel with the capacity close to 0, so that the Shannon limit is approximated, and the transmission rate as large as possible is achieved under the condition of minimizing the error rate. Due to the limitation of the encoder structure, the encoded code length is fixed asThe code length and the code rate have certain limitations, and the limitation can be solved by using a bit puncturing method. For the system Polar code, puncture positions are determined in the frozen bits according to the descending order of channel capacity after coding, namely, the position with higher channel level is selected as a known bit for puncture, data to be transmitted are put into the data bits and the puncture bits, and the rest frozen bits are input with 0. The known bit is deleted at the transmitting end, and then the known bit is inserted at the receiving end for decoding, so that the limitation of the code length can be solved, the transmission efficiency is improved, and the inserted known bit can be used for assisting in decoding at the receiving end, so that the error rate cannot be reduced.
In the implementation process, after the Polar codes are recombined and split, the binary memory-free channels are polarized, and two types of extreme channels are obtained under the condition that the sum capacity is kept unchanged, namely a good channel with the channel capacity approaching 1 and a bad channel with the channel capacity approaching 0, and the proportion of the good channel is approaching the capacity of the original channel more and more along with the increase of the code length N.
In the specific implementation process, in the step of performing Polar coding, bit puncturing is performed to obtain codeword lengthFor example, the process is as shown in fig. 2:
1. frozen bits and information bit positions are selected by using Ethernet density evolution or Gaussian approximation Information bits。
2. Calculating the channel capacity of the frozen bit by using the channel polarization, selecting the frozen bit with larger channel capacity as a fixed bit, and fixing the fixed bit asThe other two freeze bits input 0.
3. After unified coding of the system Polar codes, the channels are output。
4. Puncturing known bitsTransmitting the remaining signals。
5. Known bits are to be received at the receiving endInserted into the received data, and decoded.
In practical application, the performances of error rate, complexity and the like are comprehensively considered, and the corresponding known bits are increased when the middle-short code with the code length of hundreds of bits is selected. After coding and puncturing according to the method, the output data is subjected to probability amplitude shaping and signal set segmentation.
Two paths of codes enter a TCM module respectively, in the part, check bits are generated by adopting a convolution code or an exclusive OR mode, but firstly probability amplitude shaping is carried out, the check bits are not generated by information bits through exclusive OR, but are divided by constellation sets, the generated non-uniform 1D constellation amplitude sets are divided into two 1D subsets in an equally-spaced mode, at the moment, the minimum Euclidean distance of constellation points in each subset is twice as much as the original distance, then the set of each 1-dimensional component (i.e. in-phase and quadrature components) of a 2D constellation is formed into A, B, C, D2D subsets according to the 1D subsets, so that a ' subset constraint condition ' (SSC) ' of 2D signals in two polarization states is formed, the minimum Euclidean distance of constellation points in each 2D subset is 2 times that of the original 2D constellation, and finally the 1D subsets are combined into 4D subsets (A-U D, B-U C, C-U B, D-A), so that the ' subset constraint condition (SFC) ' where 4D signals are located is formed, and the minimum Euclidean distance of the 4D constellation points in each 2D subset is ensured. The division of the 64QAM signal constellation subset at each polarization is shown in fig. 3.
In the diversity mode, the 2D signals on the X polarization are kept unchanged, meanwhile, the subset corresponding to the 2D signals on the Y polarization is selected according to the 4D sub-family under the constraint of SFC completed in combination to judge, and the 2D signals are decomposed into 1D signals to analyze when judging. When one 1D signal on Y polarization does not meet the current SFC subgroup constraint condition, the 1D signal is shifted to the adjacent signal point of the whole 2D constellation (the shifting direction is consistent in the same system), namely, the 1D signal is shifted to the complementary 1D subset, and a binary marking bit 1 is generated and recorded asIf the 1D signal on Y polarization meets the SFC condition of 4D subfamily, binary mark bit 0 is generated. Each 4D signal produces two flag bits. In this module, the final 4D signal is split into two 2D signals for transmission on the X-polarization and the Y-polarization, formed by polarization multiplexing. It is understood that the in-phase component and the quadrature component, which are present in the two polarization directions respectively, together constitute a four-dimensional signal. The 4D-PS signal generated according to the above method can realize set division at the time of transmission. During signal generation, one 4D symbol generates two binary flag bits, and the bits of the part of flag bits can be directly mapped into a modulation format that is easier to demodulate, such as Quadrature Phase Shift Keying (QPSK), but is not limited to QPSK.
After the above mixed coding, polarization multiplexing, probability shaping and constellation set segmentation, the mixed FEC-4D-PS-64QAM signal is finally obtained, and the complete generation process is shown in figure 4. Loading the laser on the laser, and putting the laser into a fiber channel for transmission.
At the receiving end, the received signals are subjected to dispersion compensation, polarization equalization and the like, then polarization demultiplexing is carried out, judgment is carried out by combining two polarization states, whether the corresponding component on Y polarization needs to make reverse translation or not is determined according to whether the mark bit is 1, and then probability amplitude shaping is carried out for demodulation. The decoding algorithm is optimized, and a multi-dimensional soft decision algorithm aiming at amplitude translation set segmentation is provided.
After obtaining the bit data, performing corresponding LDPC decoding and Polar decoding. For decoding of LDPC, BP algorithm is generally used. For Polar codes, known bits obtained by puncturing during encoding are required to be inserted into data demodulated by a TCM, then corresponding Polar code decoding is carried out, a Serial Cancellation List (SCL) algorithm is adopted, likelihood ratio (LLR) information of a bit channel is calculated through iteration, a concept of Path Metric (PM) is introduced, iterative decoding is carried out through multiple paths, and finally the one with the largest transition probability is selected and output, namely a final decoding result is compared with original bit data, and the bit error rate is obtained.
In some embodiments of the present invention, in the steps of calculating the log-likelihood ratio of each bit in the 4D signal generated by the X-polarization and the 4D signal generated by the Y-polarization, determining data of each bit based on the log-likelihood ratio to obtain the Y-polarization of the X-polarization and the amplitude shift, and recovering the amplitude shift of the Y-polarization based on the bit data of the quadrature phase shift keying signal to obtain the Y-polarization, and demodulating and decoding the X-polarization and the Y-polarization further:
directly decoding to obtain bit information of a marker bit by adopting a hard decision mode when the quadrature phase shift keying signal is demodulated;
In the 4D signal generated by the X polarization, the Euclidean distance is directly calculated with the subset to obtain the log-likelihood ratio for decoding;
In the 4D signal generated by Y polarization, each bit in two directions is decoded bit by bit according to the received mark bits in two directions of the in-phase component and the quadrature component, namely the two mark bits carried by the four-phase shift keying signal, if the mark bit is 0, the decoding is carried out according to the log likelihood ratio in the bit correlation dimension, if the mark bit is 1, the bit which is changed in the symbol is determined according to the Gray code mapping rule determined by the transmitting end, the bit is reversed, and the signal is reversely translated back to the original position and then decoded.
In a specific implementation process, an original calculation formula of the log-likelihood ratio is as follows:
It can be approximated as:
Wherein, the Representing the log-likelihood ratio of the kth signal bit,Representing a standard constellation point with a k-th bit of 1,Represents a standard constellation point with a k-th bit of 0,Representing conditional probabilities.
In Gaussian channel, log-likelihood ratio can be further expressed as following formula, namely, the k bit information in the received symbol is respectively mixed with standard constellation point with k bit being 0) Comparing the Euclidean distance between them to obtain minimum value, and at the same time making them and standard constellation point whose k-th bit is 1#) Comparing the Euclidean distance between the two points, taking the minimum value, and calculating to obtain。
Where y represents the received 4D signal, x represents the standard constellation point,Representing the log-likelihood ratio of the kth bit,Representing a standard constellation point with a k-th bit of 1,Represents a standard constellation point with a k-th bit of 0,Representing the variance characteristics of the gaussian channel itself,Representing the calculated total number of dimensions.
In the case of N dimensions, the kth bit information in the received symbol needs to be respectively combined with the standard constellation point with the kth bit of 0 in the N dimensions) Comparing the Euclidean distance between them, taking minimum value, and also making them and standard constellation point whose k-th bit is 1 #) Comparing the Euclidean distance between the two points, taking the minimum value, and calculating to obtainCan be expressed as:
Since it has been determined, at the transmitting end, what number of 4D subsets each Bit belongs to in the constellation diversity, and the 4D subset to which the kth Bit belongs is called a Bit correlation dimension (Bit-RelatedDimension, BRD), it can be calculated in two parts, namely non-BRD and BRD:
after simplification, it can be seen that the log-likelihood ratio of the kth bit is related to BRD only, so that only the euclidean distance from each constellation point in BRD is calculated in the algorithm.
Restoring the amplitude-shifted signal, and providing a multi-dimensional soft decision algorithm aiming at amplitude shift set segmentation:
In some embodiments of the invention, the sub-family constraints are met due to the need to meet ;
;
Wherein, the The sub-family constraint is represented by a sub-family constraint,Representing the dimensions j, y in the subfamily constraint, representing the received 4D signal, x representing the standard constellation point,Representation ofStandard constellation points with k-th bit i in each dimension,Representation ofStandard constellation points with k-th bit i satisfying the sub-family constraint in each dimension,Representation ofThe kth bit in the dimension that satisfies the j-th dimension subfamily constraint is the standard constellation point of i,Representing the sub-family, the subset to which the kth bit belongs is referred to as the bit-dependent dimension, m represents the dimension of the non-bit-dependent dimension,Representing the calculated number of total dimensions,A 4D signal representing a dimension other than the bit-dependent dimension,Standard constellation points representing non-bit dependent dimensions,A set of dimensions representing non-bit dependent dimensions,Representing the minimum euclidean distance in the bit dependent dimension.
In some embodiments of the invention, when the dimension is the non-translated dimension or the dimension is the translated dimension but the flag bit = 0, thenAt this time:
When the dimension is the translation dimension and the sign bit=1, i.e. the symbol has amplitude translation, determining whether the bit is changed by using the gray coding rule determined by the transmitting end, if the bit is changed, the data bit of the bit is opposite to the constellation point mapping bit, and then consideration is needed AndIn both cases the number of the cases,Taking outAnd (3) withIs the minimum value of (2):
Wherein, the Is thatNot including
DerivingAfter that, in the same way,Can be expressed as:
Wherein the method comprises the steps of The set is:
Wherein, the Representing the minimum euclidean distance of the received signal and the standard constellation point for bit i in the bit correlation dimension,Representing the minimum euclidean distance between the received signal and the standard constellation point for which the kth bit is 1-i in the bit correlation dimension,Representing the bit-related dimensions in the SFC,A 4D signal representing the received bit-dependent dimension,Representing standard constellation points in the bit-dependent dimension.
Summarizing the above deductions, in any caseUnder S-dimensional SFC constraints, this can be expressed as:
in the specific implementation process, judging according to the obtained log-likelihood ratio, and demodulating PAS probability amplitude shaping;
LDPC decoding is carried out on the bit data in the X polarization direction obtained by demodulation, BP algorithm is adopted, polar decoding is carried out on the bit data in the Y polarization direction, and SCL algorithm is adopted. Note that before Polar decoding, the known bits of the digits punctured by the transmitting end are inserted into the multi-dimensional soft decision output bits on the Y polarization, and then decoding is performed;
and (5) after decoding, calculating the error rate.
The beneficial effects of the invention include:
1. The invention adopts the parallel coding of Polar codes and LDPC codes and combines the modes of Polarization Multiplexing (PM) technology, set Segmentation (SP) theory, probability Amplitude Shaping (PAS) technology and the like with TCM technology, realizes the mixed coding modulation of four-dimensional high-order signals under the space of sub-constellations, and optimizes the decoding algorithm;
When the PAS technology and the set segmentation technology adopted in the TCM are simultaneously applied to optical fiber communication, the problem that the PAS is not compatible occurs, namely, if PAS shaping is firstly carried out and then set segmentation is carried out, the shaped symbol distribution is disordered, and if the PAS shaping is firstly carried out and then set segmentation is carried out, the decoding of a receiving end is not facilitated. Therefore, the invention adopts an amplitude translation method, translates the amplitude of signals after PAS on Y polarization according to constraint conditions while segmenting the set, so as to obtain the mark bit (0 or 1) for auxiliary decoding, and solve the problem that the two signals cannot be compatible.
3. At a receiving end, the invention provides a multi-dimensional soft decision algorithm aiming at amplitude translation set segmentation, which respectively carries out bitwise decoding on data on X polarization and Y polarization. In the X polarization, the Euclidean distance can be directly calculated with constellation points in a subset (namely bit related dimension BRD) where a received symbol is located to obtain a log-likelihood ratio for decoding, in the Y polarization, each bit in two directions is decoded bit by bit according to the received sign bits in two directions of an in-phase component and a quadrature component respectively, if the sign bit is 0, the decoding is carried out in the BRD according to the log-likelihood ratio, if the sign bit is 1, which bit is required to be changed according to a Gray code mapping rule determined by a transmitting end, and the bit is reversed, so that the received signal point is translated back to the original position and then decoded in the BRD. The algorithm has lower complexity, and has superior bit error rate performance because PAS and the integrated segmentation technology can be combined.
The embodiment of the invention also provides a mixed coding and decoding device based on the sub-constellation space, which comprises a computer device, wherein the computer device comprises a processor and a memory, the memory is stored with computer instructions, the processor is used for executing the computer instructions stored in the memory, and the device realizes the steps realized by the method when the computer instructions are executed by the processor.
The embodiment of the invention also provides a computer readable storage medium, on which a computer program is stored, which when being executed by a processor, is configured to implement the steps implemented by the aforementioned hybrid coding and decoding method based on the sub-constellation space. The computer readable storage medium may be a tangible storage medium such as Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, floppy disks, hard disk, a removable memory disk, a CD-ROM, or any other form of storage medium known in the art.
Those of ordinary skill in the art will appreciate that the various illustrative components, systems, and methods described in connection with the embodiments disclosed herein can be implemented as hardware, software, or a combination of both. The particular implementation is hardware or software dependent on the specific application of the solution and the design constraints. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, a plug-in, a function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine readable medium or transmitted over transmission media or communication links by a data signal carried in a carrier wave.
It should be understood that the invention is not limited to the particular arrangements and instrumentality described above and shown in the drawings. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and shown as examples. The method processes of the present invention are not limited to the specific steps described and shown, but various changes, modifications and additions, or the order between steps may be made by those skilled in the art after appreciating the spirit of the present invention.
In this disclosure, features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations can be made to the embodiments of the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1.一种基于子星座空间下的混合编译码方法，其特征在于，所述方法的步骤包括信号生成和信号接收解调：1. A hybrid coding method based on a sub-constellation space, characterized in that the method comprises the steps of signal generation and signal reception and demodulation: 所述信号生成的步骤包括：The signal generation step comprises: 生成比特信息，采用比特分配器将比特信息分离为两路信号；对两路信号分别编码并进行偏振复用处理得到X偏振和Y偏振；基于X偏振和Y偏振的信号进行星座子集分割；基于X偏振和Y偏振的星座分割结果确定是否对Y偏振进行幅度平移，基于Y偏振的幅度平移结果生成四相相移键控信号，输出信号；generating bit information, separating the bit information into two signals using a bit distributor; encoding the two signals respectively and performing polarization multiplexing processing to obtain X polarization and Y polarization; performing constellation subset segmentation based on the X polarization and Y polarization signals; determining whether to perform amplitude shift on the Y polarization based on the constellation segmentation results of the X polarization and the Y polarization, generating a four-phase phase shift keying signal based on the amplitude shift result of the Y polarization, and outputting the signal; 所述信号接收解调的步骤包括：The steps of receiving and demodulating the signal include: 将信号分离为X偏振产生的4D信号、Y偏振产生的4D信号和四相相移键控信号三部分；对四相相移键控信号进行硬判决得出标记位的比特信息；计算所述X偏振产生的4D信号、Y偏振产生的4D信号中每个比特的对数似然比；基于对数似然比确定每个比特的数据，得到X偏振和幅度平移的Y偏振；并基于四相相移键控信号的比特数据对Y偏振的幅度平移进行还原，得到Y偏振，进一步对X偏振和Y偏振进行解调和译码，输出比特信息。The signal is separated into three parts: a 4D signal generated by X polarization, a 4D signal generated by Y polarization, and a quaternary phase shift keying (QPSK) signal; a hard decision is performed on the QPSK signal to obtain bit information of a marker bit; a log likelihood ratio of each bit in the 4D signal generated by X polarization and the 4D signal generated by Y polarization is calculated; data of each bit is determined based on the log likelihood ratio to obtain the X polarization and the amplitude-shifted Y polarization; the amplitude shift of the Y polarization is restored based on the bit data of the QPSK signal to obtain the Y polarization; the X polarization and the Y polarization are further demodulated and decoded to output the bit information. 2.根据权利要求1所述的基于子星座空间下的混合编译码方法，其特征在于，在对两路信号分别编码并进行偏振复用处理得到X偏振和Y偏振的步骤中，分别对两路信号采用LDPC编码和Polar编码。2. The hybrid coding method based on the sub-constellation space according to claim 1 is characterized in that, in the step of respectively encoding the two signals and performing polarization multiplexing processing to obtain X polarization and Y polarization, LDPC coding and Polar coding are respectively used for the two signals. 3.根据权利要求1所述的基于子星座空间下的混合编译码方法，其特征在于，在基于X偏振和Y偏振的星座分割结果确定是否对Y偏振进行幅度平移的步骤中，基于所述X偏振所属的子集判断所述X偏振和Y偏振的子集所组成的子族是否属于所述X偏振的子集对应预设的子族约束条件对应的组合，若属于，则不需要进行幅度平移；若不属于，则对Y偏振进行幅度平移，平移至所述X偏振的子集对应的子族。3. The hybrid coding method based on a sub-constellation space according to claim 1, characterized in that, in the step of determining whether to perform amplitude shifting on the Y polarization based on the constellation segmentation results of the X polarization and the Y polarization, a determination is made based on the subset to which the X polarization belongs whether the subfamily consisting of the subsets of the X polarization and the Y polarization belongs to a combination corresponding to a preset subfamily constraint condition corresponding to the subset of the X polarization. If so, no amplitude shifting is required; if not, the Y polarization is amplitude shifted to the subfamily corresponding to the subset of the X polarization. 4.根据权利要求3所述的基于子星座空间下的混合编译码方法，其特征在于，所述输出信号中包括四相相移键控信号，所述Y偏振包括同相分量和正交分量，在所述输出信号的步骤中，若不需要进行幅度平移，则所述四相相移键控信号所携带的比特信息为00；若需要进行幅度平移，且平移Y偏振的同相分量，则所述四相相移键控信号所携带的比特信息为10；若需要进行幅度平移，且平移Y偏振的正交分量，则所述四相相移键控信号所携带的比特信息为01；若需要进行幅度平移，且平移Y偏振的同相分量和正交分量，则所述四相相移键控信号所携带的比特信息为11。4. The hybrid coding method based on the sub-constellation space according to claim 3 is characterized in that the output signal includes a quaternary phase shift keying signal, the Y polarization includes an in-phase component and a quadrature component, and in the step of outputting the signal, if amplitude shifting is not required, the bit information carried by the quaternary phase shift keying signal is 00; if amplitude shifting is required, and the in-phase component of the Y polarization is shifted, the bit information carried by the quaternary phase shift keying signal is 10; if amplitude shifting is required, and the quadrature component of the Y polarization is shifted, the bit information carried by the quaternary phase shift keying signal is 01; if amplitude shifting is required, and the in-phase component and the quadrature component of the Y polarization are shifted, the bit information carried by the quaternary phase shift keying signal is 11. 5.根据权利要求1所述的基于子星座空间下的混合编译码方法，其特征在于，在计算所述X偏振产生的4D信号、Y偏振产生的4D信号中每个比特的对数似然比；基于对数似然比确定每个比特的数据，得到X偏振和幅度平移的Y偏振；并基于四相相移键控信号的比特数据对Y偏振的幅度平移进行还原，得到Y偏振，进一步对X偏振和Y偏振进行解调和译码的步骤中；5. The hybrid coding method based on sub-constellation space according to claim 1, characterized in that, in the steps of calculating the log-likelihood ratio of each bit in the 4D signal generated by the X polarization and the 4D signal generated by the Y polarization; determining the data of each bit based on the log-likelihood ratio to obtain the X polarization and the amplitude-shifted Y polarization; and restoring the amplitude shift of the Y polarization based on the bit data of the quadrature phase shift keying signal to obtain the Y polarization, and further demodulating and decoding the X polarization and the Y polarization; 在四相相移键控信号解调时采用硬判决的的方式直接进行译码得出标记位的比特信息；When demodulating the quaternary phase shift keying signal, a hard decision method is used to directly decode the bit information of the mark bit; 在X偏振产生的4D信号中，直接与所在的子集进行欧式距离的计算，得出对数似然比进行译码；In the 4D signal generated by X polarization, the Euclidean distance is directly calculated with the subset in which it is located, and the log-likelihood ratio is obtained for decoding; 在Y偏振产生的4D信号中，根据接收到的同相分量、正交分量两个方向的标记位，即四相相移键控信号的两个标记位，分别对两个方向上的每个比特进行逐位译码；若标记位为0，在比特相关维度中根据对数似然比进行译码，若标记位为1，则需要根据发送端确定的格雷码映射规则，确定符号中发生改变的比特，并将其反转，再进行译码。In the 4D signal generated by Y polarization, each bit in the two directions is decoded bit by bit based on the marker bits of the received in-phase component and orthogonal component, that is, the two marker bits of the quadrature phase shift keying signal. If the marker bit is 0, decoding is performed based on the log-likelihood ratio in the bit-related dimension. If the marker bit is 1, it is necessary to determine the changed bit in the symbol according to the Gray code mapping rules determined by the transmitter, invert it, and then decode it. 6.根据权利要求1所述的基于子星座空间下的混合编译码方法，其特征在于，在计算所述X偏振产生的4D信号、Y偏振产生的4D信号中每个比特的对数似然比的步骤中，根据如下公式计算每个比特的对数似然比：6. The hybrid coding method based on a sub-constellation space according to claim 1, wherein in the step of calculating the log-likelihood ratio of each bit in the 4D signal generated by the X polarization and the 4D signal generated by the Y polarization, the log-likelihood ratio of each bit is calculated according to the following formula: 其中，表示第k个比特位的对数似然比，表示第k位为1的标准星座点，表示第k位为0的标准星座点，表示条件概率。in, represents the log-likelihood ratio of the k-th bit, represents the standard constellation point where the kth bit is 1, represents the standard constellation point where the kth bit is 0, represents the conditional probability. 7.根据权利要求6所述的基于子星座空间下的混合编译码方法，其特征在于，在计算所述X偏振产生的4D信号、Y偏振产生的4D信号中每个比特的对数似然比的步骤中，分别将接收到的符号中的第k个比特信息分别与第k位为0的标准星座点（）间的欧式距离进行对比，取最小值；同时也将其与第k位为1的标准星座点（）间的欧式距离进行对比，取最小值，再计算得出，在高斯信道中，计算对数似然比的公式表示为：7. The hybrid coding method based on the sub-constellation space according to claim 6, characterized in that in the step of calculating the log-likelihood ratio of each bit in the 4D signal generated by the X polarization and the 4D signal generated by the Y polarization, the k-th bit information in the received symbol is respectively compared with the standard constellation point ( ) and take the minimum value; at the same time, it is also compared with the standard constellation point with the kth bit being 1 ( ) to compare the Euclidean distance between them, take the minimum value, and then calculate , in Gaussian channel, the formula for calculating log-likelihood ratio is expressed as: ； ; 其中，y表示接收到的4D信号，x表示标准星座点，表示第k个比特位的对数似然比，表示第k位为1的标准星座点，表示第k位为0的标准星座点，表示高斯信道自身的方差特征，表示计算的总维度数。Where y represents the received 4D signal, x represents the standard constellation point, represents the log-likelihood ratio of the k-th bit, represents the standard constellation point where the kth bit is 1, represents the standard constellation point where the kth bit is 0, Represents the variance characteristics of the Gaussian channel itself, Indicates the total number of dimensions to be calculated. 8.根据权利要求7所述的基于子星座空间下的混合编译码方法，其特征在于，由于需要满足子族约束条件，即；8. The hybrid coding method based on sub-constellation space according to claim 7 is characterized in that, due to the need to satisfy the sub-family constraint condition, ; ； ; 其中，表示子族约束条件，表示子族约束条件中的维度j，y表示接收到的4D信号，x表示标准星座点，表示个维度中第k位为i的标准星座点，表示个维度中满足子族约束条件的第k位为i的标准星座点，表示个维度中满足第j维子族约束条件的第k位为i的标准星座点，表示子族，第k比特所属于的子集称为比特相关维度，m表示非比特相关维度的维度，表示计算的总维度数，表示非比特相关维度的维度的4D信号，表示非比特相关维度的标准星座点，表示非比特相关维度的维度集合，表示比特相关维度中的最小欧式距离，表示比特相关维度。in, represents the subfamily constraint, represents the dimension j in the subfamily constraint, y represents the received 4D signal, and x represents the standard constellation point. express The kth position in the dimension is the standard constellation point i, express The kth standard constellation point in the dimension that satisfies the subfamily constraint is i, express The kth standard constellation point in the dimension that satisfies the jth subfamily constraint is i, represents a subfamily, the subset to which the kth bit belongs is called the bit-related dimension, and m represents the dimension of the non-bit-related dimension. Indicates the total number of dimensions calculated, A 4D signal representing the dimensions of the non-bit-related dimensions, represents the standard constellation points of non-bit-related dimensions, A set of dimensions representing non-bit-related dimensions, represents the minimum Euclidean distance in the bit-related dimension, Indicates bit-related dimensions. 9.根据权利要求8所述的基于子星座空间下的混合编译码方法，其特征在于，根据如下公式计算比特相关维度中的最小欧式距离：9. The hybrid coding method based on the sub-constellation space according to claim 8, characterized in that the minimum Euclidean distance in the bit correlation dimension is calculated according to the following formula : 当维度为未平移维度或维度为平移维度但标记位=0时，此时，此时：When the dimension is not shifted or the dimension is shifted but the flag bit is 0, ,at this time: 当维度为平移维度，且标记位=1即符号产生过幅度平移时，利用发射端确定的格雷编码规则判断该位是否改变，若改变，该位的数据比特与星座点映射比特相反，则需要考虑和两种情况，取与的最小值：When the dimension is a translation dimension and the mark bit = 1, that is, the symbol has undergone amplitude translation, the Gray coding rule determined by the transmitter is used to determine whether the bit has changed. If it has changed, the data bit of the bit is opposite to the constellation point mapping bit, then it is necessary to consider and Two situations, Pick and Minimum value of: 其中，是的一个子集，不包含 in, yes A subset of excluding 得出后，同理，可以表示为：Conclusion Later, similarly, It can be expressed as: 其中集合为：in The collection is: 其中，表示比特相关维度中接收信号和第k位为i的标准星座点的最小欧式距离，表示比特相关维度中接收信号和第k位为1-i的标准星座点间的最小欧式距离，表示SFC中的比特相关维度，表示接收到的比特相关维度的4D信号，表示比特相关维度中的标准星座点。in, represents the minimum Euclidean distance between the received signal and the k-th standard constellation point i in the bit-related dimension, represents the minimum Euclidean distance between the received signal and the k-th standard constellation point 1-i in the bit-related dimension, represents the bit-related dimension in SFC, represents the 4D signal of the received bit-dependent dimensions, represents a standard constellation point in the bit-dependent dimension. 10.一种基于子星座空间下的混合编译码装置，其特征在于，该装置包括计算机设备，所述计算机设备包括处理器和存储器，所述存储器中存储有计算机指令，所述处理器用于执行所述存储器中存储的计算机指令，当所述计算机指令被处理器执行时该装置实现如权利要求1-9任一项所述方法所实现的步骤。10. A hybrid encoding and decoding device based on a sub-constellation space, characterized in that the device includes a computer device, the computer device includes a processor and a memory, the memory stores computer instructions, the processor is used to execute the computer instructions stored in the memory, and when the computer instructions are executed by the processor, the device implements the steps implemented by the method according to any one of claims 1 to 9.
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