main_algorithm.m

LDPC码的编解码Matlab仿真 希望对大家有用

clear all;
close all;
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%%%%%%%%%%%%%%%%%%%%%%%%%% initialize the ldpc parameters %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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data_number=2000;
h=ldpc_generate(data_number,2*data_number,3,2,123);
[H,G]=ldpc_h2g(h,2);
[rows,cols] = size(H);
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% begin to test the algorithm %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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aver_num=20;

sn=1;

sep_err_data=0;
total_data=0;


for SNR=-0.4:0.2:1.4
    for avernum=1:aver_num;
          data_source=round(rand(1,size(G,1)));
          data_out_ldpc=ldpc_encode(data_source,G,2); 
          
          mod_data=2*data_out_ldpc-1;
        
     
   
%%%%%%%%%%%%%%%%%% pass the signal throuth the AWGN channel %%%%%%%%%%%%%%%%
          sig_power=1;
          alpha=sqrt(sig_power/(10^(SNR/10)));    
          
          channel_output=mod_data+alpha*randn(1,size(G,2));
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%%%%%%%%%%%%%%%% obtain the initial soft value of the filter %%%%%%%%%%%%%%%
          L_pri0(1:length(data_out_ldpc))=0.5;
          L_pri1=L_pri0;
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         f1=1./(1+exp(-2*channel_output/alpha^2));        % likelihoods
         f0=1-f1;
         [sep_est_data,success,k] = ldpc_decode(channel_output,f0,f1,H);
         sep_est_source=sep_est_data(size(G,2)+1-size(G,1):size(G,2));
         sep_errnum(avernum)=biterr(sep_est_source',data_source);
         sep_err_data=sep_err_data+sep_errnum(avernum);

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    end
    sep_err_snr(sn)=sep_err_data/(total_data*aver_num);
    sn=sn+1;
    
    sep_err_data=0;    
    total_data=0;
end

semilogy(SNR,sep_err_snr);
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haiyan=1;