No=variance;
   % assume the codeword c, the parity check matrix H and No are already loaded into the MATLAB memory 
  tx_waveform=bpsk(u,1);  %amp= 1 
  rx_waveform=awgn(tx_waveform,No); 
  scale(1:length(u))=1;  %No fading. 
  vhat=decode_ldpc(rx_waveform,No,1,h,scale) %since amp=1; 
  % assume we have the rearranged_cols array output by the rearrange_cols( ) function already loaded into MATLAB memory 
  uhat = extract_mesg(vhat,rearranged_cols);