CN114337933B - SCMA-based high-speed visible light communication system and adaptive codec method - Google Patents

SCMA-based high-speed visible light communication system and adaptive codec method Download PDF

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CN114337933B
CN114337933B CN202210254982.1A CN202210254982A CN114337933B CN 114337933 B CN114337933 B CN 114337933B CN 202210254982 A CN202210254982 A CN 202210254982A CN 114337933 B CN114337933 B CN 114337933B
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codebook
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CN114337933A (en
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余礼苏
刘超良
王玉皞
王正海
陈俊源
菅杰
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Nanchang University
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Abstract

The invention provides a high-speed visible light communication system based on SCMA and a self-adaptive coding and decoding method, which relate to the technical field of wireless communication, and the communication system comprises: the system comprises a signal sending end, a signal receiving end and a signal processing end, wherein the signal sending end is used for mapping bit signal streams of a plurality of users through a codebook and superposing the bit signal streams to synthesize a four-dimensional complex signal stream, and superposing and transmitting the complex signal stream; a visible light channel for transmitting the complex signal stream; and the signal receiving end is used for receiving the complex signal stream transmitted by the visible light channel and decoding the complex signal stream to obtain an original bit signal stream. The invention aims to reduce the complexity of the original MPA decoding algorithm to the maximum extent on the premise of ensuring the decoding accuracy.

Description

基于SCMA的高速可见光通信系统及自适应编解码方法SCMA-based high-speed visible light communication system and adaptive codec method

技术领域technical field

本发明涉及无线通信技术领域，特别涉及一种基于SCMA的高速可见光通信系统及自适应编解码方法。The present invention relates to the technical field of wireless communication, in particular to a high-speed visible light communication system based on SCMA and an adaptive coding and decoding method.

背景技术Background technique

继5G技术研发出来之后，人们又将研究目光聚焦到下一代移动通信技术即6G技术上，下一代移动通信技术有望用到可见光通信、非正交多址技术。可见光通信技术的优势在于其安全性高、保密性好、抗电磁干扰能力强，集通信与照明功能于一体，无电磁污染。而SCMA(Sparse Code Multiple Access，SCMA，稀疏码多址接入)技术就是一种多个用户共享频谱资源的非正交的多址接入技术，它将低密度签名(Low Density Signature, LDS)技术和码分多址(Code Division Multiple Access, CDMA)技术结合在一起，用来解决系统过载问题。传统SCMA解码技术采用消息传递算法(Message Passing Algorithm, MPA)，结合先验概率，利用因子图在用户节点和资源节点之间迭代更新后验概率消息，以尽可能准确地解码出原来各个用户发送的码字。相比于最大似然算法(Maximum Likelihood，ML)检测方法，MPA解码器的算法复杂度虽有所降低，但其复杂度随用户数量增加成指数级增长，从而导致解码效率低，不能满足未来6G系统的部署需求。另外针对非正交多址的多用户检测，也可以采用一种叫串行干扰消除(Successive interference cancellation, SIC)的技术,SIC解码技术相对于MPA解码技术可以大大降低其解码复杂度，SIC解码技术的一大缺点就是其解码性能不如MPA，特别是在高信噪比的情况下。Following the development of 5G technology, people have focused their research on the next-generation mobile communication technology, namely 6G technology. The next-generation mobile communication technology is expected to use visible light communication and non-orthogonal multiple access technology. The advantages of visible light communication technology lie in its high security, good confidentiality, strong anti-electromagnetic interference ability, integration of communication and lighting functions, and no electromagnetic pollution. The SCMA (Sparse Code Multiple Access, SCMA, sparse code multiple access) technology is a non-orthogonal multiple access technology in which multiple users share spectrum resources. Technology and Code Division Multiple Access (Code Division Multiple Access, CDMA) technology are combined to solve the problem of system overload. The traditional SCMA decoding technology adopts the Message Passing Algorithm (MPA), combined with the prior probability, and uses the factor graph to iteratively update the posterior probability message between the user node and the resource node, so as to decode the original message sent by each user as accurately as possible. codeword. Compared with the maximum likelihood algorithm (Maximum Likelihood, ML) detection method, the algorithm complexity of MPA decoder is reduced, but its complexity increases exponentially with the increase of the number of users, resulting in low decoding efficiency, which cannot meet the future requirements. Deployment requirements for 6G systems. In addition, for the multi-user detection of non-orthogonal multiple access, a technology called serial interference cancellation (SIC) can also be used. Compared with the MPA decoding technology, the SIC decoding technology can greatly reduce the decoding complexity. A big disadvantage of the technology is that its decoding performance is not as good as MPA, especially at high signal-to-noise ratios.

针对现在采用MPA解码算法带来的高复杂度的问题，人们又提出了许多改进的MPA算法，比如有基于对数域的MPA算法、基于串行方式的MPA解码算法、基于部分码字的MPA解码算法等等降低MPA解码复杂度的算法，可以发现这些算法只是在原有的MPA解码算法的基础上作改进，并没有提出另外一种有别与MPA的解码策略，这些改进的算法在降低原来MPA解码算法的复杂度的同时也使接收机的性能有一定的降低，说明这些改进方法是在牺牲解码准确性来换取算法的低复杂度。In view of the high complexity caused by the MPA decoding algorithm, many improved MPA algorithms have been proposed, such as the logarithmic domain-based MPA algorithm, the serial-based MPA decoding algorithm, and the partial codeword-based MPA algorithm. Decoding algorithms and other algorithms to reduce the complexity of MPA decoding, it can be found that these algorithms are only improved on the basis of the original MPA decoding algorithm, and there is no other decoding strategy different from MPA. The complexity of the MPA decoding algorithm also reduces the performance of the receiver to a certain extent, indicating that these improved methods sacrifice the decoding accuracy in exchange for the low complexity of the algorithm.

发明内容SUMMARY OF THE INVENTION

基于以上解码方式的不足，本发明的目的是提供一种基于SCMA的高速可见光通信系统及自适应编解码方法，旨在保证解码准确性的前提下如何最大可能降低原来MPA解码算法的复杂度。Based on the deficiencies of the above decoding methods, the purpose of the present invention is to provide a high-speed visible light communication system based on SCMA and an adaptive encoding and decoding method, aiming at how to reduce the complexity of the original MPA decoding algorithm to the greatest extent possible under the premise of ensuring the decoding accuracy.

本发明的第一方面在于提供一种基于SCMA的高速可见光通信系统，所述通信系统包括：A first aspect of the present invention is to provide a high-speed visible light communication system based on SCMA, the communication system comprising:

信号发送端，用于将若干用户的比特信号流经过码本映射以及叠加合成四维的复信号流，并将所述复信号流叠加传输；A signal sending end, used for synthesizing a four-dimensional complex signal stream through codebook mapping and superposition of the bit signal streams of several users, and superimposing and transmitting the complex signal stream;

可见光信道，用于传输所述复信号流；a visible light channel for transmitting the complex signal stream;

信号接收端，用于接收经所述可见光信道传输的所述复信号流，并对所述复信号流解码处理，以得到原始的比特信号流。The signal receiving end is configured to receive the complex signal stream transmitted through the visible light channel, and decode the complex signal stream to obtain the original bit signal stream.

根据上述技术方案的一方面，所述复信号流的表达式为：

Figure 566465DEST_PATH_IMAGE001
；According to an aspect of the above technical solution, the expression of the complex signal flow is:
Figure 566465DEST_PATH_IMAGE001
;

其中，J表示共J个用户，

Figure 467425DEST_PATH_IMAGE002
表示为第i个用户分配的功率；
Figure 92441DEST_PATH_IMAGE003
表示第i个用户发送的复信号流，x表示各个用户叠加的复信号流。Among them, J represents a total of J users,
Figure 467425DEST_PATH_IMAGE002
represents the power allocated for the i -th user;
Figure 92441DEST_PATH_IMAGE003
represents the complex signal stream sent by the i -th user, and x represents the complex signal stream superimposed by each user.

根据上述技术方案的一方面，对所述复信号流进行解码处理后的表达式为：According to an aspect of the above technical solution, the expression after decoding the complex signal stream is:

Figure 686234DEST_PATH_IMAGE004
；
Figure 686234DEST_PATH_IMAGE004
;

其中，

Figure 295070DEST_PATH_IMAGE005
表示接收端接收信号，
Figure 202983DEST_PATH_IMAGE006
表示用户i的信道增益，
Figure 10402DEST_PATH_IMAGE007
表示第i个用户发送的复信号流，
Figure 712779DEST_PATH_IMAGE008
表示为第i个用户分配的功率，n表示接收到的总的加性高斯白噪声
Figure 605648DEST_PATH_IMAGE009
。in,
Figure 295070DEST_PATH_IMAGE005
Indicates that the receiver receives the signal,
Figure 202983DEST_PATH_IMAGE006
is the channel gain of user i ,
Figure 10402DEST_PATH_IMAGE007
represents the complex signal stream sent by the i -th user,
Figure 712779DEST_PATH_IMAGE008
is the power allocated to the ith user, and n is the total received white Gaussian noise
Figure 605648DEST_PATH_IMAGE009
.

本发明的第二方面在于提供一种自适应编码方法，所述自适应编码方法应用于上述技术方案当中所述的基于SCMA的高速可见光通信系统，所述方法包括：A second aspect of the present invention is to provide an adaptive coding method, which is applied to the SCMA-based high-speed visible light communication system described in the above technical solution, and the method includes:

当信道状况

Figure 51673DEST_PATH_IMAGE010
时，
Figure 713599DEST_PATH_IMAGE011
表示信道状况的门限值，选择SIC解码方式的码本
Figure 586877DEST_PATH_IMAGE012
对用户的比特信号进行映射编码，具体包括：When the channel condition
Figure 51673DEST_PATH_IMAGE010
hour,
Figure 713599DEST_PATH_IMAGE011
Indicates the threshold value of the channel condition, selects the codebook of the SIC decoding method
Figure 586877DEST_PATH_IMAGE012
Mapping and encoding the user's bit signal, including:

根据预设的编码原理，设待编码的信号为X，X为

Figure 967043DEST_PATH_IMAGE013
矩阵；其中，V代表用户数，N代表每个用户发送的M进制信号个数；并且设每个用户发送的符号数均为N，用户j对应的码本为
Figure 951179DEST_PATH_IMAGE014
，其中
Figure 733190DEST_PATH_IMAGE015
表示一个
Figure 777370DEST_PATH_IMAGE016
三维数组,其中
Figure 644831DEST_PATH_IMAGE017
为SCMA中总的资源块数量，
Figure 432659DEST_PATH_IMAGE018
表示一个
Figure 69177DEST_PATH_IMAGE019
二维数组；According to the preset coding principle, set the signal to be coded as X , and X is
Figure 967043DEST_PATH_IMAGE013
matrix; among them, V represents the number of users, N represents the number of M -ary signals sent by each user; and the number of symbols sent by each user is N , and the codebook corresponding to user j is
Figure 951179DEST_PATH_IMAGE014
,in
Figure 733190DEST_PATH_IMAGE015
means a
Figure 777370DEST_PATH_IMAGE016
three-dimensional array, where
Figure 644831DEST_PATH_IMAGE017
is the total number of resource blocks in SCMA,
Figure 432659DEST_PATH_IMAGE018
means a
Figure 69177DEST_PATH_IMAGE019
Two-dimensional array;

用户通过码本映射叠加得出的码字为：The codeword obtained by the user through codebook mapping and superposition is:

Figure 284257DEST_PATH_IMAGE020
；
Figure 284257DEST_PATH_IMAGE020
;

其中

Figure 373436DEST_PATH_IMAGE022
表示叠加的合成码字。in
Figure 373436DEST_PATH_IMAGE022
Represents a superimposed composite codeword.

本发明的第三方面在于提供一种自适应编码方法，所述自适应编码方法应用于上述技术方案当中所述的基于SCMA的高速可见光通信系统，所述方法包括：A third aspect of the present invention is to provide an adaptive coding method, the adaptive coding method is applied to the SCMA-based high-speed visible light communication system described in the above technical solutions, and the method includes:

当信道状况

Figure 964954DEST_PATH_IMAGE023
时，选择MPA解码方式的码本
Figure 455979DEST_PATH_IMAGE024
对用户的比特信号进行映射编码，具体包括：When the channel condition
Figure 964954DEST_PATH_IMAGE023
When , select the codebook of MPA decoding mode
Figure 455979DEST_PATH_IMAGE024
Mapping and encoding the user's bit signal, including:

根据预设的编码原理，设待编码的信号为X，X为

Figure 841961DEST_PATH_IMAGE025
矩阵；其中，V代表用户数，N代表每个用户发送的M进制信号个数；并且设每个用户发送的符号数均为N，用户j对应的码本为
Figure 684015DEST_PATH_IMAGE026
，其中
Figure 813645DEST_PATH_IMAGE027
表示一个
Figure 362438DEST_PATH_IMAGE028
三维数组,其中
Figure 247217DEST_PATH_IMAGE029
为SCMA中总的资源块数量，
Figure 248671DEST_PATH_IMAGE030
表示一个
Figure 244309DEST_PATH_IMAGE031
二维数组；According to the preset coding principle, set the signal to be coded as X , and X is
Figure 841961DEST_PATH_IMAGE025
matrix; among them, V represents the number of users, N represents the number of M -ary signals sent by each user; and the number of symbols sent by each user is N , and the codebook corresponding to user j is
Figure 684015DEST_PATH_IMAGE026
,in
Figure 813645DEST_PATH_IMAGE027
means a
Figure 362438DEST_PATH_IMAGE028
three-dimensional array, where
Figure 247217DEST_PATH_IMAGE029
is the total number of resource blocks in SCMA,
Figure 248671DEST_PATH_IMAGE030
means a
Figure 244309DEST_PATH_IMAGE031
Two-dimensional array;

用户通过码本映射叠加得出的码字为：The codeword obtained by the user through codebook mapping and superposition is:

Figure 382029DEST_PATH_IMAGE032
。
Figure 382029DEST_PATH_IMAGE032
.

本发明的第四方面在于提供一种自适应解码方法，所述自适应解码方法应用于上述技术方案当中所述的基于SCMA的高速可见光通信系统，所述方法包括：A fourth aspect of the present invention is to provide an adaptive decoding method, which is applied to the SCMA-based high-speed visible light communication system described in the above technical solutions, and the method includes:

当信道状况

Figure 437710DEST_PATH_IMAGE033
时，选择SIC解码方式，具体包括：When the channel condition
Figure 437710DEST_PATH_IMAGE033
, select the SIC decoding method, including:

计算每个用户的码本功率，对所有用户的码本功率进行降序排序，并记录所有用户的码本功率的排列顺序；Calculate the codebook power of each user, sort the codebook powers of all users in descending order, and record the order of the codebook powers of all users;

按照所有用户的码本功率的排列顺序，依次对所述码本功率进行解码；According to the arrangement order of the codebook powers of all users, the codebook powers are sequentially decoded;

通过因子图

Figure 926460DEST_PATH_IMAGE034
查询此时解码用户所占资源块的位置，具体包括：Via factor graph
Figure 926460DEST_PATH_IMAGE034
Query the position of the resource block occupied by the decoding user at this time, including:

Figure 460210DEST_PATH_IMAGE035
，其中，k表示用户占用资源块的位置，
Figure 718016DEST_PATH_IMAGE036
表示第
Figure 944598DEST_PATH_IMAGE037
个用户，以上式子表示的是将第
Figure 655065DEST_PATH_IMAGE037
个用户在所述因子图
Figure 992505DEST_PATH_IMAGE038
中所占资源块的位置存到k中，find表示matlab软件中的find查询函数，用于查询每个用户所占用资源块的位置；
Figure 460210DEST_PATH_IMAGE035
, where k represents the location of the resource block occupied by the user,
Figure 718016DEST_PATH_IMAGE036
means the first
Figure 944598DEST_PATH_IMAGE037
users, the above formula represents the number of users
Figure 655065DEST_PATH_IMAGE037
users in the factor graph
Figure 992505DEST_PATH_IMAGE038
The position of the resource block occupied in the tk is stored in k , and find represents the find query function in the matlab software, which is used to query the position of the resource block occupied by each user;

解码第

Figure 370397DEST_PATH_IMAGE037
个用户发送的信号，具体包括：decode the first
Figure 370397DEST_PATH_IMAGE037
Signals sent by each user, including:

Figure 502301DEST_PATH_IMAGE039
；其中，m表示第n个符号对应的解码值，norm表示matlab软件中的norm取范数函数，min表示matlab软件中的min取最小值函数，
Figure 965643DEST_PATH_IMAGE041
表示接收端接收的信号，
Figure 841195DEST_PATH_IMAGE042
表示解码恢复信号，n表示第n个信号，
Figure 339173DEST_PATH_IMAGE043
表示解码出第j个用户发送的第n个信号；
Figure 502301DEST_PATH_IMAGE039
; where m represents the decoded value corresponding to the nth symbol, norm represents the norm function in matlab software, min represents the min value function in matlab software,
Figure 965643DEST_PATH_IMAGE041
represents the signal received by the receiver,
Figure 841195DEST_PATH_IMAGE042
represents the decoded recovered signal, n represents the nth signal,
Figure 339173DEST_PATH_IMAGE043
Indicates that the nth signal sent by the jth user is decoded;

每解码出一个用户的信号后，将次接收信号从总接收信号中剔除，具体包括：After each user's signal is decoded, the secondary received signal is removed from the total received signal, including:

Figure 579661DEST_PATH_IMAGE044
；
Figure 579661DEST_PATH_IMAGE044
;

其中，

Figure 592617DEST_PATH_IMAGE045
表示接收端接收信号，k表示表示用户占用资源块的位置，n表示第n个信号。in,
Figure 592617DEST_PATH_IMAGE045
Indicates that the receiver receives the signal, k represents the position of the resource block occupied by the user, and n represents the nth signal.

本发明的第五方面在于提供一种自适应解码方法，其特征在于，所述自适应解码方法应用于上述技术方案当中所述的基于SCMA的高速可见光通信系统，所述方法包括：A fifth aspect of the present invention is to provide an adaptive decoding method, wherein the adaptive decoding method is applied to the SCMA-based high-speed visible light communication system described in the above technical solution, and the method includes:

当信道状况

Figure 6280DEST_PATH_IMAGE023
时，选择MPA解码方式，具体包括：When the channel condition
Figure 6280DEST_PATH_IMAGE023
, select the MPA decoding method, including:

初始化功能节点

Figure 93185DEST_PATH_IMAGE046
到用户节点
Figure 35733DEST_PATH_IMAGE047
概率值，具体实现如下所示：Initialize the function node
Figure 93185DEST_PATH_IMAGE046
to user node
Figure 35733DEST_PATH_IMAGE047
The probability value, the specific implementation is as follows:

Figure 270406DEST_PATH_IMAGE048
，其中，
Figure 425443DEST_PATH_IMAGE049
，其中，
Figure 694751DEST_PATH_IMAGE050
表示功能节点
Figure 277042DEST_PATH_IMAGE046
到用户节点
Figure 999010DEST_PATH_IMAGE047
传递消息的初始概率，k表示共有K个资源块，j表示共有J个用户，
Figure 957739DEST_PATH_IMAGE052
表示初始概率，
Figure 81553DEST_PATH_IMAGE047
表示第
Figure 100324DEST_PATH_IMAGE054
个用户节点，
Figure 309589DEST_PATH_IMAGE046
表示第
Figure 806429DEST_PATH_IMAGE056
个功能节点，
Figure 784749DEST_PATH_IMAGE057
表示用户待解码信号；
Figure 270406DEST_PATH_IMAGE048
,in,
Figure 425443DEST_PATH_IMAGE049
,in,
Figure 694751DEST_PATH_IMAGE050
Represents a function node
Figure 277042DEST_PATH_IMAGE046
to user node
Figure 999010DEST_PATH_IMAGE047
The initial probability of delivering a message, k represents a total of K resource blocks, j represents a total of J users,
Figure 957739DEST_PATH_IMAGE052
represents the initial probability,
Figure 81553DEST_PATH_IMAGE047
means the first
Figure 100324DEST_PATH_IMAGE054
user nodes,
Figure 309589DEST_PATH_IMAGE046
means the first
Figure 806429DEST_PATH_IMAGE056
function node,
Figure 784749DEST_PATH_IMAGE057
Indicates the signal to be decoded by the user;

功能节点更新，具体实现如下所示：Function node update, the specific implementation is as follows:

Figure 974422DEST_PATH_IMAGE058
Figure 670983DEST_PATH_IMAGE059
；
Figure 974422DEST_PATH_IMAGE058
Figure 670983DEST_PATH_IMAGE059
;

其中，

Figure 237093DEST_PATH_IMAGE060
表示用户节点
Figure 7603DEST_PATH_IMAGE047
到功能节点
Figure 430494DEST_PATH_IMAGE046
传递消息的更新概率，
Figure 552034DEST_PATH_IMAGE061
表示在因子图
Figure 452994DEST_PATH_IMAGE062
中第k行中非零元素的位置，
Figure 343590DEST_PATH_IMAGE063
表示第
Figure 937382DEST_PATH_IMAGE054
个用户的估计信号，
Figure 280639DEST_PATH_IMAGE064
表示噪声方差，
Figure 250869DEST_PATH_IMAGE065
表示信道增益，t表示迭代次数，
Figure 995971DEST_PATH_IMAGE066
表示接收端的接收信号；in,
Figure 237093DEST_PATH_IMAGE060
Represents a user node
Figure 7603DEST_PATH_IMAGE047
to function node
Figure 430494DEST_PATH_IMAGE046
the update probability of delivering the message,
Figure 552034DEST_PATH_IMAGE061
represented in a factor graph
Figure 452994DEST_PATH_IMAGE062
the position of the non-zero element in the kth row of ,
Figure 343590DEST_PATH_IMAGE063
means the first
Figure 937382DEST_PATH_IMAGE054
the estimated signal of each user,
Figure 280639DEST_PATH_IMAGE064
represents the noise variance,
Figure 250869DEST_PATH_IMAGE065
represents the channel gain, t represents the number of iterations,
Figure 995971DEST_PATH_IMAGE066
Represents the received signal at the receiving end;

判断是否达到最大迭代次数

Figure 760665DEST_PATH_IMAGE067
，若达到了最大迭代次数则进入下一步骤，若未达到最大迭代次数，则继续更新资源节点和用户节点；Determine whether the maximum number of iterations has been reached
Figure 760665DEST_PATH_IMAGE067
, if the maximum number of iterations is reached, go to the next step; if the maximum number of iterations is not reached, continue to update resource nodes and user nodes;

解码出每个用户发送的信号，具体实现如下所示：The signal sent by each user is decoded, and the specific implementation is as follows:

Figure 591217DEST_PATH_IMAGE068
；
Figure 591217DEST_PATH_IMAGE068
;

Figure 833980DEST_PATH_IMAGE069
；
Figure 833980DEST_PATH_IMAGE069
;

Figure 699168DEST_PATH_IMAGE070
；
Figure 699168DEST_PATH_IMAGE070
;

其中

Figure 634763DEST_PATH_IMAGE071
表示最后通过判决解码的比特信号，
Figure 952612DEST_PATH_IMAGE072
表示在因子图
Figure 999065DEST_PATH_IMAGE073
中第j列中非零元素的位置，
Figure 718759DEST_PATH_IMAGE074
表示最大迭代次数，
Figure 825256DEST_PATH_IMAGE075
表示待判决信号，判决规则为当表达式
Figure 630400DEST_PATH_IMAGE076
Figure 480545DEST_PATH_IMAGE077
为真时，此时判决的比特信号为1，反之判决为0，最后将判决得到的信号存入变量
Figure 320325DEST_PATH_IMAGE078
中。in
Figure 634763DEST_PATH_IMAGE071
represents the bit signal finally decoded by the decision,
Figure 952612DEST_PATH_IMAGE072
represented in a factor graph
Figure 999065DEST_PATH_IMAGE073
the position of the nonzero element in the jth column of ,
Figure 718759DEST_PATH_IMAGE074
represents the maximum number of iterations,
Figure 825256DEST_PATH_IMAGE075
Represents the signal to be decided, and the decision rule is when the expression
Figure 630400DEST_PATH_IMAGE076
Figure 480545DEST_PATH_IMAGE077
When it is true, the judged bit signal is 1 at this time, otherwise it is judged as 0, and finally the judged signal is stored in the variable
Figure 320325DEST_PATH_IMAGE078
middle.

与现有技术相比，采用本发明所示的基于SCMA的高速可见光通信系统及自适应编解码方法，有益效果在于：Compared with the prior art, by adopting the SCMA-based high-speed visible light communication system and the adaptive coding and decoding method shown in the present invention, the beneficial effects are:

1）针对SCMA辅助的高速可见光通信系统提出了一种新的基于信道状况的自适应编解码策略；1) A new adaptive coding and decoding strategy based on channel conditions is proposed for SCMA-assisted high-speed visible light communication systems;

2）在很大程度上可以明显降低系统解码复杂度，同时能够适当地降低系统的误码率，从而能够在整体上提升系统性能。2) The decoding complexity of the system can be significantly reduced to a large extent, and the bit error rate of the system can be appropriately reduced, thereby improving the system performance as a whole.

本发明的附加方面与优点将在下面的描述中部分给出，部分将从下面的描述中变得明显，或通过本发明的实践了解到。Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

附图说明Description of drawings

图1为本发明一实施例中基于SCMA的高速可见光通信系统的模型图；1 is a model diagram of a high-speed visible light communication system based on SCMA in an embodiment of the present invention;

图2为本发明一实施例中基于SCMA的高速可见光通信系统的自适应编、解码的系统模型图；FIG. 2 is a system model diagram of adaptive encoding and decoding of a SCMA-based high-speed visible light communication system according to an embodiment of the present invention;

图3为本发明一实施例中基于SCMA的高速可见光通信系统中其中一种自适应编码方法的流程图；3 is a flowchart of an adaptive coding method in an SCMA-based high-speed visible light communication system according to an embodiment of the present invention;

图4为本发明一实施例中基于SCMA的高速可见光通信系统中另一种自适应解码方法的流程图；4 is a flowchart of another adaptive decoding method in an SCMA-based high-speed visible light communication system according to an embodiment of the present invention;

图5为本发明一实施例中基于SCMA的高速可见光通信系统的自适应编、解码系统的性能仿真结果图；5 is a performance simulation result diagram of an adaptive encoding and decoding system of an SCMA-based high-speed visible light communication system according to an embodiment of the present invention;

图6为本发明一实施例中基于SCMA的高速可见光通信系统的自适应编、解码系统的性能仿真结果局部放大图；6 is a partial enlarged view of the performance simulation result of the adaptive encoding and decoding system of the SCMA-based high-speed visible light communication system in an embodiment of the present invention;

以下具体实施方式将结合上述附图进一步说明本发明。The following specific embodiments will further illustrate the present invention in conjunction with the above drawings.

具体实施方式Detailed ways

为使本发明的目的、特征与优点能够更加明显易懂，下面结合附图对本发明的具体实施方式做详细的说明。附图中给出了本发明的若干实施例。但是，本发明可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本发明的公开内容更加透彻全面。In order to make the objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the invention are presented in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

实施例一Example 1

请参阅图1-2，本发明的第一实施例提供了一种基于SCMA的高速可见光通信系统，该系统至少包括三部分，包括编码信号发送端、可见光信道、接收解码端。1-2, the first embodiment of the present invention provides a SCMA-based high-speed visible light communication system, the system includes at least three parts, including a coded signal sending end, a visible light channel, and a receiving and decoding end.

其中，在信号发送端，J个用户共用K个资源块，为了更好地说明本发明的实现原理，以下所说的系统模型当中都是6个用户共用4个资源块，发送信号的构成表达式如下所示：Among them, at the signal transmitting end, J users share K resource blocks. In order to better illustrate the implementation principle of the present invention, in the system model described below, 6 users share 4 resource blocks, and the composition of the transmitted signal is expressed as The formula is as follows:

Figure 535406DEST_PATH_IMAGE079
Figure 535406DEST_PATH_IMAGE079

具体而言，这里6个用户的信号经过码本映射后经过叠加合成了4维的复信号流，将各个用户的复信号流进行叠加传输。然而，由于可见光通信只能采用强度调制/直接检测(IM/DD)的方法进行信号传输与转换，必须将编码得到的复数信号流转换为正实值的信号流，常用的方法是采用厄米特对称变换。而在本实施例中，为了实现高速可见光通信，采用了ACO-OFDM技术。这里在进行ACO-OFDM调制之前必须对产生的4维并行的复信号进行并串转换，经ACO-OFDM调制之后的信号变成了串行信号，并且对已调制的信号再进行变换，使它的维度和开始时经过码本映射后的信号的维度是一样的，将转换的4维并行信号驱动4基色LED灯进行信号的传输，至此，实现了J个用户共用4个频谱资源块进行信号的发送。Specifically, the signals of the six users here are mapped by the codebook and then superimposed to synthesize a 4-dimensional complex signal stream, and the complex signal streams of each user are superimposed and transmitted. However, since visible light communication can only use the intensity modulation/direct detection (IM/DD) method for signal transmission and conversion, the encoded complex signal stream must be converted into a positive real-valued signal stream. The commonly used method is to use Hermitian Special symmetry transformation. However, in this embodiment, in order to realize high-speed visible light communication, ACO-OFDM technology is adopted. Here, the generated 4-dimensional parallel complex signal must be converted to serial before ACO-OFDM modulation is performed. The signal modulated by ACO-OFDM becomes a serial signal, and the modulated signal is transformed to make it The dimension of the signal is the same as that of the signal after the codebook mapping at the beginning. The converted 4-dimensional parallel signal drives the 4-primary LED lights for signal transmission. So far, it is realized that J users share 4 spectrum resource blocks for signal transmission. of sending.

在上述实施例中，为了便于分析，假定各个用户都是在相同的可见光信道下进行信号传输的，所以它们的信道状况是相同的，并且它们都经过了信道均衡。In the above embodiment, for the convenience of analysis, it is assumed that each user transmits signals under the same visible light channel, so their channel conditions are the same, and they have all undergone channel equalization.

进一步地，在信号接收端，发送信号经过可见光信道进行传输之后，再通过滤光片滤波和ACO-OFDM解调之后混合噪声的信号表示是如下所示：Further, at the signal receiving end, after the transmitted signal is transmitted through the visible light channel, the signal representation of mixed noise after filter filtering and ACO-OFDM demodulation is as follows:

Figure 624584DEST_PATH_IMAGE080
Figure 624584DEST_PATH_IMAGE080

式中，

Figure 216103DEST_PATH_IMAGE081
表示用户i的信道增益，n表示接收到的总的加性高斯白噪声
Figure 707127DEST_PATH_IMAGE082
。In the formula,
Figure 216103DEST_PATH_IMAGE081
is the channel gain of user i , and n is the total received white Gaussian noise
Figure 707127DEST_PATH_IMAGE082
.

实施例二Embodiment 2

请参阅图3，本发明的第二实施例提供了一种自适应编码方法，该自适应的编码方法表示的是待发送信号在SCMA编码映射的时候根据信道的状况来自适应地选择一种合适的码本来进行编码映射。Referring to FIG. 3 , the second embodiment of the present invention provides an adaptive coding method. The adaptive coding method indicates that a signal to be transmitted adaptively selects an appropriate coding method according to the channel conditions during SCMA coding and mapping. codebook for encoding mapping.

其中，信道状况采用了一个量化指标信噪比

Figure 93109DEST_PATH_IMAGE083
来衡量，通过理论分析和仿真验证可以发现，采用一种适宜以SIC解码的码本在SIC解码方式下得到的信噪比-误码率曲线图和采用适宜以MPA解码的码本在MPA解码方式下得到的信噪比-误码率曲线图有一个相交的交点。可以从理论分析上得到这个交点所对应的信噪比，将接收到的噪声功率与接收到的噪声比值来量化信道状况，用
Figure 935163DEST_PATH_IMAGE083
表示，把得出来的这个信噪比的值设为区分信道状况的阈值条件，用
Figure 64793DEST_PATH_IMAGE084
表示Among them, the channel condition adopts a quantitative indicator SNR
Figure 93109DEST_PATH_IMAGE083
To measure, through theoretical analysis and simulation verification, it can be found that the signal-to-noise ratio-bit error rate curve obtained by using a codebook suitable for SIC decoding in SIC decoding mode and using a codebook suitable for MPA decoding in MPA decoding mode The signal-to-noise ratio-bit error rate curve obtained in this way has an intersecting point of intersection. The signal-to-noise ratio corresponding to this intersection can be obtained theoretically, and the received noise power and the received noise ratio can be used to quantify the channel condition, using
Figure 935163DEST_PATH_IMAGE083
means that the value of the obtained signal-to-noise ratio is set as the threshold condition for distinguishing the channel condition, and the
Figure 64793DEST_PATH_IMAGE084
express

在本实施例当中，当信道状况

Figure 410324DEST_PATH_IMAGE085
时，选择SIC解码方式的码本
Figure 232786DEST_PATH_IMAGE086
对用户的比特信号进行映射编码，具体包括：In this embodiment, when the channel condition
Figure 410324DEST_PATH_IMAGE085
When the codebook of the SIC decoding method is selected
Figure 232786DEST_PATH_IMAGE086
Mapping and encoding the user's bit signal, including:

根据预设的编码原理，设待编码的信号为X，X为

Figure 296557DEST_PATH_IMAGE087
矩阵；其中，V代表用户数，N代表每个用户发送的M进制信号个数；并且设每个用户发送的符号数均为N，用户j对应的码本为
Figure 964299DEST_PATH_IMAGE088
，其中
Figure 429915DEST_PATH_IMAGE089
表示一个
Figure 423279DEST_PATH_IMAGE028
三维数组,其中
Figure 708767DEST_PATH_IMAGE029
为SCMA中总的资源块数量，
Figure 711358DEST_PATH_IMAGE090
表示一个
Figure 969164DEST_PATH_IMAGE031
二维数组；According to the preset coding principle, set the signal to be coded as X , and X is
Figure 296557DEST_PATH_IMAGE087
matrix; among them, V represents the number of users, N represents the number of M -ary signals sent by each user; and the number of symbols sent by each user is N , and the codebook corresponding to user j is
Figure 964299DEST_PATH_IMAGE088
,in
Figure 429915DEST_PATH_IMAGE089
means a
Figure 423279DEST_PATH_IMAGE028
three-dimensional array, where
Figure 708767DEST_PATH_IMAGE029
is the total number of resource blocks in SCMA,
Figure 711358DEST_PATH_IMAGE090
means a
Figure 969164DEST_PATH_IMAGE031
Two-dimensional array;

用户通过码本映射叠加得出的码字为：The codeword obtained by the user through codebook mapping and superposition is:

Figure 930167DEST_PATH_IMAGE091
；
Figure 930167DEST_PATH_IMAGE091
;

其中

Figure 906213DEST_PATH_IMAGE022
表示叠加的合成码字。in
Figure 906213DEST_PATH_IMAGE022
Represents a superimposed composite codeword.

具体而言，本实施例所示的自适应编码方法包括：Specifically, the adaptive coding method shown in this embodiment includes:

步骤S1，当信道状况

Figure 243653DEST_PATH_IMAGE085
时，通过SIC解码方式的码本
Figure 355966DEST_PATH_IMAGE092
对用户的比特信号进行映射编码;Step S1, when the channel condition
Figure 243653DEST_PATH_IMAGE085
, through the codebook of SIC decoding method
Figure 355966DEST_PATH_IMAGE092
Mapping and encoding the user's bit signal;

具体而言，步骤S1包括步骤S11-S12：Specifically, step S1 includes steps S11-S12:

步骤S11，根据SCMA的编码原理，不失一般性，假设待编码的信号为X，X是一个

Figure 753449DEST_PATH_IMAGE087
矩阵，其中V代表有多少个用户，N代表每个用户发送的M进制信号个数，假定每个用户发送的符号数都是N，用户j对应的码本为
Figure 951212DEST_PATH_IMAGE088
；Step S11, according to the coding principle of SCMA, without loss of generality, it is assumed that the signal to be coded is X , and X is a
Figure 753449DEST_PATH_IMAGE087
matrix, where V represents how many users there are, and N represents the number of M -ary signals sent by each user. Assuming that the number of symbols sent by each user is N , the codebook corresponding to user j is
Figure 951212DEST_PATH_IMAGE088
;

步骤S12，用户通过码本映射叠加得出的码字为：Step S12, the codeword obtained by the user through the codebook mapping and superposition is:

Figure 92344DEST_PATH_IMAGE093
。
Figure 92344DEST_PATH_IMAGE093
.

在本实施例中，当信道状况

Figure 324742DEST_PATH_IMAGE094
时，选择MPA解码方式的码本
Figure 627547DEST_PATH_IMAGE024
对用户的比特信号进行映射编码，具体包括：In this embodiment, when the channel condition
Figure 324742DEST_PATH_IMAGE094
When , select the codebook of MPA decoding mode
Figure 627547DEST_PATH_IMAGE024
Mapping and encoding the user's bit signal, including:

根据预设的编码原理，设待编码的信号为X，X是一个

Figure 578186DEST_PATH_IMAGE087
矩阵，其中V代表有多少个用户，N代表每个用户发送的M进制信号个数，假定每个用户发送的符号数都是N，用户j对应的码本为
Figure 257429DEST_PATH_IMAGE095
；According to the preset coding principle, let the signal to be coded be X , X is a
Figure 578186DEST_PATH_IMAGE087
matrix, where V represents how many users there are, and N represents the number of M -ary signals sent by each user. Assuming that the number of symbols sent by each user is N , the codebook corresponding to user j is
Figure 257429DEST_PATH_IMAGE095
;

用户通过码本映射叠加得出的码字为

Figure 344333DEST_PATH_IMAGE096
。The codeword obtained by the user through the codebook mapping superposition is
Figure 344333DEST_PATH_IMAGE096
.

具体而言，本实施例所示的自适应编码方法包括：Specifically, the adaptive coding method shown in this embodiment includes:

步骤S2：当信道状况

Figure 818040DEST_PATH_IMAGE094
时，通过MPA解码方式的码本
Figure 990395DEST_PATH_IMAGE024
对用户的比特信号进行映射编码；Step S2: When the channel condition
Figure 818040DEST_PATH_IMAGE094
, the codebook of MPA decoding method
Figure 990395DEST_PATH_IMAGE024
Mapping and coding the user's bit signal;

具体而言，步骤S2包括步骤S21-S22：Specifically, step S2 includes steps S21-S22:

步骤S21，根据SCMA的编码原理，不失一般性，假设待编码的信号为X，X是一个

Figure 473329DEST_PATH_IMAGE087
矩阵，其中V代表有多少个用户，N代表每个用户发送的M进制信号个数，假定每个用户发送的符号数都是N，用户j对应的码本为
Figure 414741DEST_PATH_IMAGE097
；Step S21, according to the coding principle of SCMA, without loss of generality, it is assumed that the signal to be coded is X , and X is a
Figure 473329DEST_PATH_IMAGE087
matrix, where V represents how many users there are, and N represents the number of M -ary signals sent by each user. Assuming that the number of symbols sent by each user is N , the codebook corresponding to user j is
Figure 414741DEST_PATH_IMAGE097
;

步骤S22，用户通过码本映射叠加得出的码字为

Figure 324928DEST_PATH_IMAGE098
。Step S22, the codeword obtained by the user through codebook mapping and superposition is:
Figure 324928DEST_PATH_IMAGE098
.

实施例三Embodiment 3

请参阅图4，本发明的第三实施例提供了一种自适应解码方法，用于采取合适的解码算法对信号进行解码，恢复出原始比特信号流。Referring to FIG. 4 , a third embodiment of the present invention provides an adaptive decoding method, which is used to decode a signal by adopting an appropriate decoding algorithm to recover an original bit signal stream.

在本实施例中，当信道状况

Figure 984579DEST_PATH_IMAGE099
时，选择SIC解码方式，具体包括：In this embodiment, when the channel condition
Figure 984579DEST_PATH_IMAGE099
, select the SIC decoding method, including:

计算每个用户的码本功率，对所有用户的码本功率进行降序排序，并记录所有用户的码本功率的排列顺序；Calculate the codebook power of each user, sort the codebook powers of all users in descending order, and record the order of the codebook powers of all users;

按照所有用户的码本功率的排列顺序，依次对所述码本功率进行解码；According to the arrangement order of the codebook powers of all users, the codebook powers are sequentially decoded;

通过因子图

Figure 208887DEST_PATH_IMAGE034
查询此时解码用户所占资源块的位置，具体包括：Via factor graph
Figure 208887DEST_PATH_IMAGE034
Query the position of the resource block occupied by the decoding user at this time, including:

Figure 332701DEST_PATH_IMAGE035
，其中，
Figure 351472DEST_PATH_IMAGE100
表示第
Figure 295158DEST_PATH_IMAGE101
个用户，并将第
Figure 57577DEST_PATH_IMAGE036
个用户在所述因子图
Figure 35898DEST_PATH_IMAGE034
中所占资源块的位置存到k中；
Figure 332701DEST_PATH_IMAGE035
,in,
Figure 351472DEST_PATH_IMAGE100
means the first
Figure 295158DEST_PATH_IMAGE101
users, and put the first
Figure 57577DEST_PATH_IMAGE036
users in the factor graph
Figure 35898DEST_PATH_IMAGE034
The position of the resource block occupied in the t is stored in k ;

解码第

Figure 225571DEST_PATH_IMAGE102
个用户发送的信号，具体包括：decode the first
Figure 225571DEST_PATH_IMAGE102
Signals sent by each user, including:

Figure 945569DEST_PATH_IMAGE039
；
Figure 945569DEST_PATH_IMAGE039
;

每解码出一个用户的信号后，将次接收信号从总接收信号中剔除，具体包括：After each user's signal is decoded, the secondary received signal is removed from the total received signal, including:

Figure 246100DEST_PATH_IMAGE044
。
Figure 246100DEST_PATH_IMAGE044
.

具体而言，本实施例所示的自适应解码方法包括：Specifically, the adaptive decoding method shown in this embodiment includes:

步骤S1：当信道状况

Figure 78927DEST_PATH_IMAGE103
时，这里我们选择SIC解码方式;Step S1: When the channel condition
Figure 78927DEST_PATH_IMAGE103
, here we choose the SIC decoding method;

具体而言，步骤S1包括步骤S11-S16：Specifically, step S1 includes steps S11-S16:

步骤S11，求出每个用户的码本功率；Step S11, find out the codebook power of each user;

步骤S12，对用户的码本功率进行降序排序，并记录它们的排列顺序；Step S12, sort the codebook powers of the users in descending order, and record their arrangement order;

步骤S13，按码本功率排列顺序依次进行解码；Step S13, decode sequentially according to the order of the codebook power;

步骤S14，通过因子图

Figure 439501DEST_PATH_IMAGE034
找到此时解码用户所占资源块的位置，实现方法如下所示：Step S14, pass the factor graph
Figure 439501DEST_PATH_IMAGE034
Find the location of the resource block occupied by the decoding user at this time. The implementation method is as follows:

Figure 357778DEST_PATH_IMAGE035
，这里
Figure 462001DEST_PATH_IMAGE037
表示第
Figure 414913DEST_PATH_IMAGE037
个用户，这里将第
Figure 946389DEST_PATH_IMAGE037
个用户在因子图
Figure 351962DEST_PATH_IMAGE034
中所占资源块的位置存到了k中；
Figure 357778DEST_PATH_IMAGE035
,here
Figure 462001DEST_PATH_IMAGE037
means the first
Figure 414913DEST_PATH_IMAGE037
users, here will be the first
Figure 946389DEST_PATH_IMAGE037
users in the factor graph
Figure 351962DEST_PATH_IMAGE034
The position of the resource block occupied in the t is stored in k ;

步骤S15，解码出第

Figure 994296DEST_PATH_IMAGE037
个用户发送的信号，具体实现如下所示：Step S15, decode the first
Figure 994296DEST_PATH_IMAGE037
The signal sent by each user is implemented as follows:

Figure 4977DEST_PATH_IMAGE039
；
Figure 4977DEST_PATH_IMAGE039
;

步骤S16，每次解码出一个用户的信号之后，都要将次接收信号从总的接收信号中剔除，以减少对接下来要检测用户的干扰，具体实现如下：In step S16, after decoding a user's signal each time, the secondary received signal must be removed from the total received signal to reduce interference to the next user to be detected. The specific implementation is as follows:

Figure 769671DEST_PATH_IMAGE044
，这里需要把每个用户的信号都检测出来之后才能进入下一轮信号的检测，也就是说检测时按顺序来的，不能跳跃检测。
Figure 769671DEST_PATH_IMAGE044
, here it is necessary to detect the signal of each user before entering the next round of signal detection, that is to say, the detection comes in sequence and cannot be skipped.

在本实施例中，当信道状况

Figure 396962DEST_PATH_IMAGE094
时，选择MPA解码方式，具体包括：In this embodiment, when the channel condition
Figure 396962DEST_PATH_IMAGE094
, select the MPA decoding method, including:

初始化功能节点到用户节点概率值，具体实现如下所示：Initialize the function node to the user node probability value, the specific implementation is as follows:

Figure 842986DEST_PATH_IMAGE048
，其中，
Figure 770491DEST_PATH_IMAGE049
，其中，k表示共有K个资源块，j表示共有J个用户；
Figure 842986DEST_PATH_IMAGE048
,in,
Figure 770491DEST_PATH_IMAGE049
, where k represents a total of K resource blocks, and j represents a total of J users;

功能节点更新，具体实现如下所示：Function node update, the specific implementation is as follows:

Figure 909348DEST_PATH_IMAGE104
Figure 961618DEST_PATH_IMAGE059
，其中，
Figure 273651DEST_PATH_IMAGE105
表示在因子图
Figure 993345DEST_PATH_IMAGE106
中第k行中非零元素的位置；
Figure 909348DEST_PATH_IMAGE104
Figure 961618DEST_PATH_IMAGE059
,in,
Figure 273651DEST_PATH_IMAGE105
represented in a factor graph
Figure 993345DEST_PATH_IMAGE106
the position of the non-zero element in the kth row of ;

判断是否达到最大迭代次数

Figure 99841DEST_PATH_IMAGE067
，若达到了最大迭代次数则进入下一步骤，若未达到最大迭代次数，则继续更新资源节点和用户节点；Determine whether the maximum number of iterations has been reached
Figure 99841DEST_PATH_IMAGE067
, if the maximum number of iterations is reached, go to the next step; if the maximum number of iterations is not reached, continue to update resource nodes and user nodes;

解码出每个用户发送的信号，具体实现如下所示：The signal sent by each user is decoded, and the specific implementation is as follows:

Figure 639407DEST_PATH_IMAGE068
；
Figure 639407DEST_PATH_IMAGE068
;

Figure 489551DEST_PATH_IMAGE107
；
Figure 489551DEST_PATH_IMAGE107
;

Figure 63752DEST_PATH_IMAGE070
；
Figure 63752DEST_PATH_IMAGE070
;

具体而言，本实施例所示的自适应解码方法包括：Specifically, the adaptive decoding method shown in this embodiment includes:

步骤S2，当信道状况

Figure 341150DEST_PATH_IMAGE108
时，这里我们选择MPA解码方式;Step S2, when the channel condition
Figure 341150DEST_PATH_IMAGE108
, here we choose MPA decoding method;

具体而言，步骤S2包括步骤S21-S25：Specifically, step S2 includes steps S21-S25:

步骤S21，初始化功能节点

Figure 633591DEST_PATH_IMAGE046
到用户节点
Figure 21847DEST_PATH_IMAGE047
概率值，具体实现如下所示：Step S21, initialize the function node
Figure 633591DEST_PATH_IMAGE046
to user node
Figure 21847DEST_PATH_IMAGE047
The probability value, the specific implementation is as follows:

Figure 716133DEST_PATH_IMAGE048
，这里
Figure 164432DEST_PATH_IMAGE049
，其中，
Figure 678590DEST_PATH_IMAGE050
表示功能节点
Figure 870537DEST_PATH_IMAGE046
到用户节点
Figure 419330DEST_PATH_IMAGE047
传递消息的初始概率，k表示共有K个资源块，j表示共有J个用户，
Figure 38530DEST_PATH_IMAGE052
表示初始概率，
Figure 305564DEST_PATH_IMAGE047
表示第
Figure 238884DEST_PATH_IMAGE054
个用户节点，
Figure 438922DEST_PATH_IMAGE046
表示第
Figure 229023DEST_PATH_IMAGE056
个功能节点，
Figure 983352DEST_PATH_IMAGE057
表示用户待解码信号；
Figure 716133DEST_PATH_IMAGE048
,here
Figure 164432DEST_PATH_IMAGE049
,in,
Figure 678590DEST_PATH_IMAGE050
Represents a function node
Figure 870537DEST_PATH_IMAGE046
to user node
Figure 419330DEST_PATH_IMAGE047
The initial probability of delivering a message, k represents a total of K resource blocks, j represents a total of J users,
Figure 38530DEST_PATH_IMAGE052
represents the initial probability,
Figure 305564DEST_PATH_IMAGE047
means the first
Figure 238884DEST_PATH_IMAGE054
user nodes,
Figure 438922DEST_PATH_IMAGE046
means the first
Figure 229023DEST_PATH_IMAGE056
function node,
Figure 983352DEST_PATH_IMAGE057
Indicates the signal to be decoded by the user;

步骤S22，功能节点更新，具体实现如下所示：Step S22, the function node is updated, and the specific implementation is as follows:

Figure 720364DEST_PATH_IMAGE058
Figure 40487DEST_PATH_IMAGE059
；
Figure 720364DEST_PATH_IMAGE058
Figure 40487DEST_PATH_IMAGE059
;

其中，

Figure 939173DEST_PATH_IMAGE060
表示用户节点
Figure 977536DEST_PATH_IMAGE047
到功能节点
Figure 252660DEST_PATH_IMAGE046
传递消息的更新概率，
Figure 427289DEST_PATH_IMAGE061
表示在因子图
Figure 762456DEST_PATH_IMAGE062
中第k行中非零元素的位置，
Figure 22536DEST_PATH_IMAGE063
表示第
Figure 101350DEST_PATH_IMAGE054
个用户的估计信号，
Figure 130486DEST_PATH_IMAGE064
表示噪声方差，
Figure 636554DEST_PATH_IMAGE065
表示信道增益，t表示迭代次数，
Figure 383930DEST_PATH_IMAGE066
表示接收端的接收信号；in,
Figure 939173DEST_PATH_IMAGE060
Represents a user node
Figure 977536DEST_PATH_IMAGE047
to function node
Figure 252660DEST_PATH_IMAGE046
the update probability of delivering the message,
Figure 427289DEST_PATH_IMAGE061
represented in a factor graph
Figure 762456DEST_PATH_IMAGE062
the position of the non-zero element in the kth row of ,
Figure 22536DEST_PATH_IMAGE063
means the first
Figure 101350DEST_PATH_IMAGE054
the estimated signal of each user,
Figure 130486DEST_PATH_IMAGE064
represents the noise variance,
Figure 636554DEST_PATH_IMAGE065
represents the channel gain, t represents the number of iterations,
Figure 383930DEST_PATH_IMAGE066
Represents the received signal at the receiving end;

步骤S23，用户节点更新，具体实现如下所示：Step S23, the user node is updated, and the specific implementation is as follows:

Figure 856DEST_PATH_IMAGE109
，这里
Figure 150078DEST_PATH_IMAGE110
表示在因子图
Figure 827047DEST_PATH_IMAGE073
中第
Figure 61719DEST_PATH_IMAGE112
列中非零元素的位置；
Figure 856DEST_PATH_IMAGE109
,here
Figure 150078DEST_PATH_IMAGE110
represented in a factor graph
Figure 827047DEST_PATH_IMAGE073
B
Figure 61719DEST_PATH_IMAGE112
the position of the non-zero element in the column;

步骤S24，判断是否达到最大迭代次数

Figure 482336DEST_PATH_IMAGE067
，如果达到了最大迭代次数则进入下一步骤，如果还未达到最大迭代次数，则继续更新资源节点和用户节点；Step S24, determine whether the maximum number of iterations is reached
Figure 482336DEST_PATH_IMAGE067
, if the maximum number of iterations is reached, go to the next step, and if the maximum number of iterations has not been reached, continue to update resource nodes and user nodes;

步骤S25，解码出每个用户发送的信号，具体实现如下所示：In step S25, the signal sent by each user is decoded, and the specific implementation is as follows:

Figure 689326DEST_PATH_IMAGE068
；
Figure 689326DEST_PATH_IMAGE068
;

Figure 333934DEST_PATH_IMAGE069
；
Figure 333934DEST_PATH_IMAGE069
;

Figure 55903DEST_PATH_IMAGE070
。
Figure 55903DEST_PATH_IMAGE070
.

综上，采用本发明中的自适应编解码方法，针对6个用户共用4个频谱资源块的基于SCMA的高速可见光通信系统，可以生成两套不同的码本组合，其中，采用SIC解码所优化的编码码本，用

Figure 14631DEST_PATH_IMAGE113
表示，采用MPA解码所优化的编码码本，用
Figure 138445DEST_PATH_IMAGE114
表示。图5和图6表示采用所构造的两套码本组合
Figure 157217DEST_PATH_IMAGE115
和
Figure 304164DEST_PATH_IMAGE116
所构造的码本组合
Figure 128901DEST_PATH_IMAGE086
与
Figure 44904DEST_PATH_IMAGE114
进行自适应编解码得出的性能曲线图，从图5和图6得到的仿真结果可以看出，在
Figure 296894DEST_PATH_IMAGE117
时，采用SIC解码算法的性能确实优于采用MPA解码算法，而在
Figure 665558DEST_PATH_IMAGE108
时，采用MPA解码算法的性能确实优于采用SIC解码算法；因此，从仿真结果层面可以看出本发明提出的自适应编解码方法是合理且能够实现的，根据信道状况自适应编码和自适应解码，既降低了系统解码的误码率同时也降低了系统的解码复杂度。To sum up, using the adaptive coding and decoding method in the present invention, for the SCMA-based high-speed visible light communication system in which 6 users share 4 spectrum resource blocks, two sets of different codebook combinations can be generated. The codebook of , using
Figure 14631DEST_PATH_IMAGE113
Represents that, using the encoding codebook optimized by MPA decoding, use
Figure 138445DEST_PATH_IMAGE114
express. Figures 5 and 6 show two sets of codebook combinations constructed using
Figure 157217DEST_PATH_IMAGE115
and
Figure 304164DEST_PATH_IMAGE116
The constructed codebook combination
Figure 128901DEST_PATH_IMAGE086
and
Figure 44904DEST_PATH_IMAGE114
The performance curve obtained by adaptive encoding and decoding can be seen from the simulation results obtained in Figure 5 and Figure 6.
Figure 296894DEST_PATH_IMAGE117
, the performance of the SIC decoding algorithm is indeed better than that of the MPA decoding algorithm.
Figure 665558DEST_PATH_IMAGE108
When the MPA decoding algorithm is used, the performance of the MPA decoding algorithm is indeed better than that of the SIC decoding algorithm; therefore, it can be seen from the simulation results that the adaptive coding and decoding method proposed by the present invention is reasonable and achievable. Decoding not only reduces the bit error rate of system decoding, but also reduces the decoding complexity of the system.

在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不一定指的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任何的一个或多个实施例或示例中以合适的方式结合。In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

以上实施例仅表达了本发明的几种实施方式，其描述较为具体与详细，但并不能因此而理解为对本发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形与改进，这些都属于本发明的保护范围。因此，本发明专利的保护范围应以所附权利要求为准。The above examples only represent several embodiments of the present invention, and the descriptions thereof are more specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (5)

1.一种基于SCMA的高速可见光通信系统，其特征在于，所述通信系统包括：1. a high-speed visible light communication system based on SCMA, is characterized in that, described communication system comprises: 信号发送端，用于将若干用户的比特信号流经过码本映射以及叠加合成四维的复信号流，并将所述复信号流叠加传输；A signal sending end, used for synthesizing a four-dimensional complex signal stream through codebook mapping and superposition of the bit signal streams of several users, and superimposing and transmitting the complex signal stream; 可见光信道，用于传输所述复信号流；a visible light channel for transmitting the complex signal stream; 信号接收端，用于接收经所述可见光信道传输的所述复信号流，并对所述复信号流解码处理，以得到原始的比特信号流；a signal receiving end, configured to receive the complex signal stream transmitted through the visible light channel, and decode the complex signal stream to obtain the original bit signal stream; 所述信号发送端具体用于：The signal transmitter is specifically used for: 当信道状况
Figure 491982DEST_PATH_IMAGE001
时，
Figure 747514DEST_PATH_IMAGE002
表示信道状况的门限值，选择SIC解码方式的码本
Figure 262809DEST_PATH_IMAGE003
对用户的比特信号进行映射编码，具体包括：When the channel condition
Figure 491982DEST_PATH_IMAGE001
hour,
Figure 747514DEST_PATH_IMAGE002
Indicates the threshold value of the channel condition, selects the codebook of the SIC decoding method
Figure 262809DEST_PATH_IMAGE003
Mapping and encoding the user's bit signal, including: 根据预设的编码原理，设待编码的信号为X，X为
Figure 513662DEST_PATH_IMAGE004
矩阵；其中，V代表用户数，N代表每个用户发送的M进制信号个数；并且设每个用户发送的符号数均为N，用户j对应的码本为
Figure 980678DEST_PATH_IMAGE005
，其中
Figure 316981DEST_PATH_IMAGE006
表示一个
Figure 901546DEST_PATH_IMAGE007
三维数组,其中
Figure 882272DEST_PATH_IMAGE008
为SCMA中总的资源块数量，
Figure 628511DEST_PATH_IMAGE009
表示一个
Figure 452110DEST_PATH_IMAGE010
二维数组；According to the preset coding principle, set the signal to be coded as X , and X is
Figure 513662DEST_PATH_IMAGE004
matrix; among them, V represents the number of users, N represents the number of M -ary signals sent by each user; and the number of symbols sent by each user is N , and the codebook corresponding to user j is
Figure 980678DEST_PATH_IMAGE005
,in
Figure 316981DEST_PATH_IMAGE006
means a
Figure 901546DEST_PATH_IMAGE007
three-dimensional array, where
Figure 882272DEST_PATH_IMAGE008
is the total number of resource blocks in SCMA,
Figure 628511DEST_PATH_IMAGE009
means a
Figure 452110DEST_PATH_IMAGE010
Two-dimensional array; 用户通过码本映射叠加得出的码字为：The codeword obtained by the user through codebook mapping and superposition is:
Figure 699421DEST_PATH_IMAGE011
；
Figure 699421DEST_PATH_IMAGE011
; 其中，
Figure 659287DEST_PATH_IMAGE012
表示第j个用户发送的第i个M进制的数字信号；in,
Figure 659287DEST_PATH_IMAGE012
Represents the i -th M -ary digital signal sent by the j -th user; 或者，当信道状况
Figure 576427DEST_PATH_IMAGE013
时，选择MPA解码方式的码本
Figure 28268DEST_PATH_IMAGE014
对用户的比特信号进行映射编码，具体包括：Or, when channel conditions
Figure 576427DEST_PATH_IMAGE013
When , select the codebook of MPA decoding mode
Figure 28268DEST_PATH_IMAGE014
Mapping and encoding the user's bit signal, including: 根据预设的编码原理，设待编码的信号为X，X为
Figure 689057DEST_PATH_IMAGE015
矩阵；其中，V代表用户数，N代表每个用户发送的M进制信号个数；并且设每个用户发送的符号数均为N，用户j对应的码本为
Figure 503429DEST_PATH_IMAGE016
，其中
Figure 748728DEST_PATH_IMAGE017
表示一个
Figure 281340DEST_PATH_IMAGE007
三维数组,其中
Figure 745820DEST_PATH_IMAGE008
为SCMA中总的资源块数量，
Figure 414698DEST_PATH_IMAGE018
表示一个
Figure 80166DEST_PATH_IMAGE010
二维数组；According to the preset coding principle, set the signal to be coded as X , and X is
Figure 689057DEST_PATH_IMAGE015
matrix; among them, V represents the number of users, N represents the number of M -ary signals sent by each user; and the number of symbols sent by each user is N , and the codebook corresponding to user j is
Figure 503429DEST_PATH_IMAGE016
,in
Figure 748728DEST_PATH_IMAGE017
means a
Figure 281340DEST_PATH_IMAGE007
three-dimensional array, where
Figure 745820DEST_PATH_IMAGE008
is the total number of resource blocks in SCMA,
Figure 414698DEST_PATH_IMAGE018
means a
Figure 80166DEST_PATH_IMAGE010
Two-dimensional array; 用户通过码本映射叠加得出的码字为：The codeword obtained by the user through codebook mapping and superposition is:
Figure 100075DEST_PATH_IMAGE019
；
Figure 100075DEST_PATH_IMAGE019
; 其中，
Figure 102666DEST_PATH_IMAGE012
表示第j个用户发送的第i个M进制的数字信号。in,
Figure 102666DEST_PATH_IMAGE012
Indicates the i -th M -ary digital signal sent by the j -th user. 2.根据权利要求1所述的基于SCMA的高速可见光通信系统，其特征在于，所述复信号流的表达式为：
Figure 281843DEST_PATH_IMAGE020
；2. the high-speed visible light communication system based on SCMA according to claim 1, is characterized in that, the expression of described complex signal flow is:
Figure 281843DEST_PATH_IMAGE020
; 其中，J表示共J个用户，
Figure 977267DEST_PATH_IMAGE021
表示为第i个用户分配的功率；
Figure 218892DEST_PATH_IMAGE022
表示第i个用户发送的复信号流，x表示各个用户叠加的复信号流。Among them, J represents a total of J users,
Figure 977267DEST_PATH_IMAGE021
represents the power allocated for the i -th user;
Figure 218892DEST_PATH_IMAGE022
represents the complex signal stream sent by the i -th user, and x represents the complex signal stream superimposed by each user. 3.根据权利要求1所述的基于SCMA的高速可见光通信系统，其特征在于，对所述复信号流进行解码处理后的表达式为：3. the high-speed visible light communication system based on SCMA according to claim 1, is characterized in that, the expression after described complex signal stream is decoded and processed is:
Figure 166120DEST_PATH_IMAGE023
；
Figure 166120DEST_PATH_IMAGE023
; 其中，
Figure 340749DEST_PATH_IMAGE024
表示接收端接收信号，
Figure 579312DEST_PATH_IMAGE025
表示用户i的信道增益，
Figure 839392DEST_PATH_IMAGE026
表示第i个用户发送的复信号流，
Figure 183786DEST_PATH_IMAGE027
表示为第i个用户分配的功率，n表示接收到的总的加性高斯白噪声
Figure 822709DEST_PATH_IMAGE028
。in,
Figure 340749DEST_PATH_IMAGE024
Indicates that the receiver receives the signal,
Figure 579312DEST_PATH_IMAGE025
is the channel gain of user i ,
Figure 839392DEST_PATH_IMAGE026
represents the complex signal stream sent by the i -th user,
Figure 183786DEST_PATH_IMAGE027
is the power allocated for the ith user, and n is the total received white Gaussian noise
Figure 822709DEST_PATH_IMAGE028
. 4.一种自适应解码方法，其特征在于，所述自适应解码方法应用于权利要求1-3任一项所述的基于SCMA的高速可见光通信系统，所述方法包括：4. An adaptive decoding method, wherein the adaptive decoding method is applied to the SCMA-based high-speed visible light communication system according to any one of claims 1-3, and the method comprises: 当信道状况
Figure 859935DEST_PATH_IMAGE029
时，选择SIC解码方式，具体包括：When the channel condition
Figure 859935DEST_PATH_IMAGE029
, select the SIC decoding method, including: 计算每个用户的码本功率，对所有用户的码本功率进行降序排序，并记录所有用户的码本功率的排列顺序；Calculate the codebook power of each user, sort the codebook powers of all users in descending order, and record the order of the codebook powers of all users; 按照所有用户的码本功率的排列顺序，依次对所述码本功率进行解码；According to the arrangement order of the codebook powers of all users, the codebook powers are sequentially decoded; 通过因子图
Figure 341732DEST_PATH_IMAGE030
查询此时解码用户所占资源块的位置，具体包括：Via factor graph
Figure 341732DEST_PATH_IMAGE030
Query the position of the resource block occupied by the decoding user at this time, including:
Figure 614450DEST_PATH_IMAGE031
，其中，k表示用户占用资源块的位置，
Figure 232513DEST_PATH_IMAGE032
表示第
Figure 440641DEST_PATH_IMAGE033
个用户，以上式子表示的是将第
Figure 285100DEST_PATH_IMAGE033
个用户在所述因子图
Figure 971296DEST_PATH_IMAGE034
中所占资源块的位置存到k中，find表示matlab软件中的find查询函数，用于查询每个用户所占用资源块的位置；
Figure 614450DEST_PATH_IMAGE031
, where k represents the location of the resource block occupied by the user,
Figure 232513DEST_PATH_IMAGE032
means the first
Figure 440641DEST_PATH_IMAGE033
users, the above formula represents the number of users
Figure 285100DEST_PATH_IMAGE033
users in the factor graph
Figure 971296DEST_PATH_IMAGE034
The position of the resource block occupied in the % is stored in k , and find represents the find query function in the matlab software, which is used to query the position of the resource block occupied by each user; 解码第
Figure 975024DEST_PATH_IMAGE033
个用户发送的信号，具体包括：decode the first
Figure 975024DEST_PATH_IMAGE033
Signals sent by each user, including:
Figure 714572DEST_PATH_IMAGE035
；其中，m表示第n个符号对应的解码值，norm表示matlab软件中的norm取范数函数，min表示matlab软件中的min取最小值函数，
Figure 905382DEST_PATH_IMAGE037
表示接收端接收的信号，
Figure 395269DEST_PATH_IMAGE038
表示解码恢复信号，n表示第n个信号，
Figure 128870DEST_PATH_IMAGE039
表示解码出第j个用户发送的第n个信号；
Figure 714572DEST_PATH_IMAGE035
; Among them, m represents the decoded value corresponding to the nth symbol, norm represents the norm function in matlab software, min represents the min value function in matlab software,
Figure 905382DEST_PATH_IMAGE037
represents the signal received by the receiver,
Figure 395269DEST_PATH_IMAGE038
represents the decoded recovered signal, n represents the nth signal,
Figure 128870DEST_PATH_IMAGE039
Indicates that the nth signal sent by the jth user is decoded; 每解码出一个用户的信号后，将次接收信号从总接收信号中剔除，具体包括：After each user's signal is decoded, the secondary received signal is removed from the total received signal, including:
Figure 678800DEST_PATH_IMAGE040
；
Figure 678800DEST_PATH_IMAGE040
; 其中，
Figure 622485DEST_PATH_IMAGE041
表示接收端接收信号，k表示表示用户占用资源块的位置，n表示第n个信号。in,
Figure 622485DEST_PATH_IMAGE041
Indicates that the receiver receives the signal, k represents the position of the resource block occupied by the user, and n represents the nth signal. 5.一种自适应解码方法，其特征在于，所述自适应解码方法应用于权利要求1-3任一项所述的基于SCMA的高速可见光通信系统，所述方法包括：5. An adaptive decoding method, wherein the adaptive decoding method is applied to the SCMA-based high-speed visible light communication system according to any one of claims 1-3, and the method comprises: 当信道状况
Figure 775118DEST_PATH_IMAGE042
时，选择MPA解码方式，具体包括：When the channel condition
Figure 775118DEST_PATH_IMAGE042
, select the MPA decoding method, including: 初始化功能节点
Figure 222280DEST_PATH_IMAGE043
到用户节点
Figure 208691DEST_PATH_IMAGE044
概率值，具体实现如下所示：Initialize the function node
Figure 222280DEST_PATH_IMAGE043
to user node
Figure 208691DEST_PATH_IMAGE044
The probability value, the specific implementation is as follows:
Figure 249459DEST_PATH_IMAGE045
，其中，
Figure 81149DEST_PATH_IMAGE046
，其中，
Figure 382817DEST_PATH_IMAGE047
表示功能节点
Figure 166227DEST_PATH_IMAGE043
到用户节点
Figure 818926DEST_PATH_IMAGE044
传递消息的初始概率，k表示共有K个资源块，j表示共有J个用户，
Figure 454306DEST_PATH_IMAGE049
表示初始概率，
Figure 751427DEST_PATH_IMAGE044
表示第
Figure 814061DEST_PATH_IMAGE051
个用户节点，
Figure 688476DEST_PATH_IMAGE043
表示第
Figure 127547DEST_PATH_IMAGE053
个功能节点，
Figure 794021DEST_PATH_IMAGE054
表示用户待解码信号；
Figure 249459DEST_PATH_IMAGE045
,in,
Figure 81149DEST_PATH_IMAGE046
,in,
Figure 382817DEST_PATH_IMAGE047
Represents a function node
Figure 166227DEST_PATH_IMAGE043
to user node
Figure 818926DEST_PATH_IMAGE044
The initial probability of delivering a message, k represents a total of K resource blocks, j represents a total of J users,
Figure 454306DEST_PATH_IMAGE049
represents the initial probability,
Figure 751427DEST_PATH_IMAGE044
means the first
Figure 814061DEST_PATH_IMAGE051
user nodes,
Figure 688476DEST_PATH_IMAGE043
means the first
Figure 127547DEST_PATH_IMAGE053
function node,
Figure 794021DEST_PATH_IMAGE054
Indicates the signal to be decoded by the user; 功能节点更新，具体实现如下所示：Function node update, the specific implementation is as follows:
Figure 27556DEST_PATH_IMAGE055
Figure 389267DEST_PATH_IMAGE056
；
Figure 27556DEST_PATH_IMAGE055
Figure 389267DEST_PATH_IMAGE056
; 其中，
Figure 241817DEST_PATH_IMAGE057
表示用户节点
Figure 638163DEST_PATH_IMAGE044
到功能节点
Figure 42600DEST_PATH_IMAGE043
传递消息的更新概率，
Figure 517706DEST_PATH_IMAGE058
表示在因子图
Figure 298580DEST_PATH_IMAGE059
中第k行中非零元素的位置，
Figure 549432DEST_PATH_IMAGE060
表示第
Figure 136DEST_PATH_IMAGE051
个用户的估计信号，
Figure 602019DEST_PATH_IMAGE061
表示噪声方差，
Figure 921005DEST_PATH_IMAGE062
表示信道增益，t表示迭代次数，
Figure 150998DEST_PATH_IMAGE063
表示接收端的接收信号；in,
Figure 241817DEST_PATH_IMAGE057
Represents a user node
Figure 638163DEST_PATH_IMAGE044
to function node
Figure 42600DEST_PATH_IMAGE043
the update probability of delivering the message,
Figure 517706DEST_PATH_IMAGE058
represented in a factor graph
Figure 298580DEST_PATH_IMAGE059
the position of the non-zero element in the kth row of ,
Figure 549432DEST_PATH_IMAGE060
means the first
Figure 136DEST_PATH_IMAGE051
the estimated signal of each user,
Figure 602019DEST_PATH_IMAGE061
represents the noise variance,
Figure 921005DEST_PATH_IMAGE062
represents the channel gain, t represents the number of iterations,
Figure 150998DEST_PATH_IMAGE063
Represents the received signal at the receiving end; 判断是否达到最大迭代次数
Figure 162816DEST_PATH_IMAGE064
，若达到了最大迭代次数则进入下一步骤，若未达到最大迭代次数，则继续更新资源节点和用户节点；Determine whether the maximum number of iterations has been reached
Figure 162816DEST_PATH_IMAGE064
, if the maximum number of iterations is reached, go to the next step; if the maximum number of iterations is not reached, continue to update resource nodes and user nodes; 解码出每个用户发送的信号，具体实现如下所示：The signal sent by each user is decoded, and the specific implementation is as follows:
Figure 720837DEST_PATH_IMAGE065
；
Figure 720837DEST_PATH_IMAGE065
;
Figure 718880DEST_PATH_IMAGE066
；
Figure 718880DEST_PATH_IMAGE066
;
Figure 678745DEST_PATH_IMAGE067
；
Figure 678745DEST_PATH_IMAGE067
; 其中
Figure 595886DEST_PATH_IMAGE068
表示最后通过判决解码的比特信号，
Figure 798459DEST_PATH_IMAGE069
表示在因子图
Figure 724827DEST_PATH_IMAGE070
中第j列中非零元素的位置，
Figure 539199DEST_PATH_IMAGE071
表示最大迭代次数，
Figure 768186DEST_PATH_IMAGE072
表示待判决信号，判决规则为当表达式
Figure 566378DEST_PATH_IMAGE073
Figure 765278DEST_PATH_IMAGE074
为真时，此时判决的比特信号为1，反之判决为0，最后将判决得到的信号存入变量
Figure 824370DEST_PATH_IMAGE075
中。in
Figure 595886DEST_PATH_IMAGE068
represents the bit signal finally decoded by the decision,
Figure 798459DEST_PATH_IMAGE069
represented in a factor graph
Figure 724827DEST_PATH_IMAGE070
the position of the nonzero element in the jth column of ,
Figure 539199DEST_PATH_IMAGE071
represents the maximum number of iterations,
Figure 768186DEST_PATH_IMAGE072
Represents the signal to be decided, and the decision rule is when the expression
Figure 566378DEST_PATH_IMAGE073
Figure 765278DEST_PATH_IMAGE074
When it is true, the judged bit signal is 1 at this time, otherwise it is judged as 0, and finally the judged signal is stored in the variable
Figure 824370DEST_PATH_IMAGE075
middle.
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