codeword.m

卷积码的编码及解码代码

function [c0, c1] = codeWord(nrSt, G)
% Create codewords when the input is '0' and '1'
% nrSt, number of state
% G, generator matrix
%
% c0, codeword when input is '0'
% c1, codeword when input is '1'

% Find the code rate denominator R and constraint lengths K
[R, K] = size(G);

% Code words matrices
c0 = [];  c1 = [];

for state = 0:nrSt - 1

   % Code words for '0'
   tmpBit = bitand( G, repmat( dec2bin( state, K) - 48, R, 1));
   c0 = [c0; mod( sum( tmpBit, 2), 2)'];
   
   % Code words for '1'
   tmpBit = bitand( G, repmat( dec2bin( state + nrSt, K) - 48, R, 1));
   c1 = [c1; mod( sum( tmpBit, 2), 2)'];   
end

% The output size must be R times nrSt (-1/1)
c0 = 2*c0' - 1;
c1 = 2*c1' - 1;