turbo_sys_demo.m

[LDPC码]是LDPC码相关论文 [WuYuFei]中是WuYuFei的论文 [WuYufei_matlab]是WuYufei做Turbo码的Matlab程序 程序实现在固定信噪比和卷积长度的

clc;
clear all;

% Write display messages to a text file
diary 帧长4096信噪比-10迭代20次.txt

% Choose decoding algorithm 
dec_alg = 0;

% Frame size
L_total = 4096;	 % infomation bits plus tail bits

% Code generator
g = [ 1 1 1;
      1 0 1 ];

[n,K] = size(g); 
m = K - 1;
nstates = 2^m; 
puncture = 0;


% Code rate
rate = 1/(2+puncture);   

% Fading amplitude; a=1 in AWGN channel
a = 1; 

% Number of iterations
   niter = 20;

   EbN0db = [-10];

   nEN = 1;
   en = 10^(EbN0db(nEN)/10);    % convert Eb/N0 from unit db to normal numbers
   L_c = 4*a*en*rate;       	% reliability value of the channel
   sigma = 1/sqrt(2*rate*en); 	% standard deviation of AWGN noise

      x = round(rand(1, L_total-m));                  % info. bits
      [temp, alpha] = sort(rand(1,L_total));          % random interleaver mapping
      en_output = encoderm( x, g, alpha, puncture ) ; % encoder output (+1/-1)
          
      r = en_output+sigma*randn(1,L_total*(2+puncture)); % received bits
      yk = demultiplex(r,alpha,puncture); % demultiplex to get input for decoder 1 and 2
      
% Scale the received bits      
      rec_s = 0.5*L_c*yk;

% Initialize extrinsic information      
      L_e1= zeros(niter,L_total);
      L_e2= zeros(niter,L_total);
      L_e=zeros(1,L_total);
      for iter = 1:niter
% Decoder one
         L_a(alpha) = L_e;  % a priori info. 
         if dec_alg == 0
            L_all = logmapo(rec_s(1,:), g, L_a, 1);  % complete info.
         else   
            L_all = sova0(rec_s(1,:), g, L_a, 1);  % complete info.
         end   
         L_e = L_all - 2*rec_s(1,1:2:2*L_total) - L_a;  % extrinsic info.
         L_e1(iter,:)=L_e(1,:);
% Decoder two         
         L_a = L_e(alpha);  % a priori info.
         if dec_alg == 0
            L_all = logmapo(rec_s(2,:), g, L_a, 2);  % complete info.  
         else
            L_all = sova0(rec_s(2,:), g, L_a, 2);  % complete info. 
         end
         L_e = L_all - 2*rec_s(2,1:2:2*L_total) - L_a;  % extrinsic info.
         L_e2(iter,:)=L_e(1,:);
      end	

      save turbo_sys_demo  L_e1 L_e2
      L_e1
      L_e2
  diary off