mconvencoder.m

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function [Out,BlkSize] = mConvEncoder(In,BlkSize,mode)
% Convolutional Encoder for the FEC Encoder for OFDMA 
% of IEEE 802.16-2004 (WiMAX) 
%
%     [Out,BlkSize] = mConvEncoder(In,BlkSize,mode)
%
% In     : binary input column vector or matrix (values 0 or 1)
%          one column per code block
% BlkSize: row vector, length = number of code blocks
%          number of data bits for each code block
% mode   : specifies the decoding mode
%          0 = CC    (tail-biting)
%          3 = ZT-CC (zero-tailing)
%
% Out    : binary output column vector or matrix (values 0 or 1)
%          one column per code block
%
% This convolutional encoder is a 1/2 rate encoder only.
% The other rates are realized by puncturing.
%
% This convolutional encoder is implemented as tail-biting encoder.
% The last six input bits initialize the state of the shift register.
% The output block size is twice the input block size.
%
% Matlab 7 Release 14 SP2
% The communication toolbox is required.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%  Property of Freescale
%  Freescale Confidential Proprietary
%  Freescale Copyright (C) 2005 All rights reserved
%  ----------------------------------------------------------------------------
%  $RCSfile: mConvEncoder.m.rca $
%  $Revision: 1.5 $
%  $Date: Tue Aug  8 11:40:17 2006 $
%  Target: Matlab
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[m,n]=size(In);

%check dimensions
[x,y]=size(BlkSize);
if ((x~=1)|(y~=n))
   error('Error: BlkSize must be row vector with the same number of columns as In.');
end

%define constant
trellis = poly2trellis(7,[171 133]);

%allocate output blocks
if islogical(In)
   %work-around since convenc does not allow logical input
   Out=logical(zeros(m*2,n));
else
   Out=zeros(m*2,n,class(In));
end

switch mode,
    case 0  %tail-biting
      for b=1:n, %loop over all blocks 
         initstate = [1 2 4 8 16 32]*logical(In(BlkSize(b)-5:BlkSize(b),b));
         Out(1:2*BlkSize(b),b) = convenc(double(In(1:BlkSize(b),b)),trellis,initstate);
      end
    case 3  %zero-tailing
      for b=1:n, %loop over all blocks 
         In(BlkSize(b)-7:BlkSize(b),b)=0; % set last byte to zero
         Out(1:2*BlkSize(b),b) = convenc(double(In(1:BlkSize(b),b)),trellis);
      end
    otherwise
      error('Error: Viterbi decoder mode unknown.');
end

BlkSize = BlkSize*2;