基于MATLAB的多进制LDPC译码算法的仿真

Posted 2022-03-18 fpga&matlab

1.仿真预览

2.部分核心代码

clc;
clear;
close all;
warning off;
addpath 'functions\\'

q         = 4;                      %定义伽罗达域,支持4,8,16
nbits     = log2(q);                %多进制符号值
EbNo      = [0  0.5  1  1.5 2];   %信噪比

%以下两个值设置小点，这样仿真可以快点,值较大的时候，仿真速度非常慢，但性能较好
M         = 24;              %校验数
N         = 32;             %矩阵长度
t         = 3;               %权值                 
h         = ldpc_generate(M,N,t,q,1); %产生矩阵H
[H,G]     = ldpc_h2g(h,q);                    %产生矩阵G

for kk=1:length(EbNo)
    kk
    totalNumErr = 0;
    count       = 0;
    SNR         = 10^(EbNo(kk)/10);
    sigma       = 1/(sqrt(SNR));    

    while (totalNumErr < 40)%仿真越长，效果越OK
        kk
        totalNumErr
        
        %产生一组随机数
        x  = floor(rand(1,size(G,1))*q); 
        
        %进行多进制准循环LDPC编码
        y  = func_Ldpc_enc(x,G,q);   
        
        %多进制信道处理
        yb = (fliplr(de2bi(y,nbits)))';      
        yb = yb(:);                          
        zb = 2*yb-1;                      
        zb = zb + sigma*randn(size(zb));      

        f1=1./(1+exp(-2*zb/sigma^2));        
        f1 = f1(:);                         
        f1 = reshape(f1,nbits,length(y));                    
        f0=1-f1;
        junk = ones(q,length(y));           
        [v0, v1, pp] = func_message_passing(f0,f1,junk);    
        
        [z_hat,success, k] = func_Ldpc_dec_log(pp,H,q);
        x_hat = z_hat(size(G,2)+1-size(G,1):size(G,2));
        x_hat = x_hat';    
        
        %统计误码率
        totalNumErr = totalNumErr+(sum (x_hat~=x'));
       
        count = count + 1;
    end
    
    BERs(kk)=totalNumErr/(count*length(x));
end

figure;
semilogy(EbNo,BERs,'r-o');
xlabel('EbN0');
ylabel('BER');
grid on;

if q == 4
   save ERR4_log.mat EbNo BERs
end
if q == 8
   save ERR8_log.mat EbNo BERs
end
if q == 16
   save ERR16_log.mat EbNo BERs
end

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