clc;
clear all;
        % AWGN noise deviation
     load H;
        [m,n]=size(H);
        r=1-m/n;
 sgm= sigma(r);
 sgm=sgm(1:13);
  uu=length(sgm);
biterr=[];
         ber=[]; 
  for j=1:uu     %for different sigma values(i.e SNR values) of AWGN
            error=0;
           disp(j);
        for i=1:1000  %for 1000 blocks of data transmitted to get an average number of errors
   disp(i);
        x=zeros(1,n);         %as symmetric channel all zero codeword would do 
        y=x;                     
        z = -2*y+1;                  % BPSK modulation
        z=z + sgm(j)*randn(1,n);     % AWGN transmission
        f1=1./(1+exp(2*z/sgm(j)^2));        % likelihoods
        f1 = (f1(:))';                      % make it a row vector
        f0=1-f1;
        [z_hat, success, k] = ldpc_decode(z,f0,f1,H);
error=error+size(find(z_hat),1);
end
disp(error);
biterr=[biterr,error];
ber=[ber, error/n/1000];
end
save errH biterr;
save berH ber;