make_interleaver.m

用Matlab仿真turbocode的算法

%******************************************************************************
%*                                                                            *
%* make_interleaver.m                                                         *
%* Zufalls- und Blockinterleaver                                              *
%*                                                                            *
%******************************************************************************
%* Author(s)    : Andreas Dittrich                                            *
%* Project start: 23.11.2000                                                  *
%* Completed    : 23.11.2000                                                  *
%* Last change  : 23.04.2001                                                  *
%* Time         : 14:45                                                       *
%******************************************************************************
%* Changes      : |                                                           *
%******************************************************************************
%******************************************************************************
%* Last change: 23.04.2001                                                    *
%* Time       : 14:45                                                         *
%* By         : Andreas Dittrich                                              *
%* Description: semirandom and block added.                                   *
%******************************************************************************
%******************************************************************************
%*                                                                            *
%* function [IL,IL_inv] = make_interleaver( N, IL_method );                   *
%*                                                                            *
%******************************************************************************
%* make_interleaver erzeugt ein Interleaver-/Deinterleavervektor              *
%* Bsp.: x_interleaved = x(IL), x = x_interleaved(IL_inv)                     *
%*                                                                            *
%* N = Anzahl der Elemente                                                    *
%* IL_method = Interleavermethode: {'random','block','semirandom'}            *
%******************************************************************************

function [IL,IL_inv] = make_interleaver( N, IL_method );
if (nargin==1),
   [IL,IL_inv] = make_interleaver_random( N );
else if (nargin==2),
      switch lower(IL_method)
      case 'random', [IL,IL_inv] = make_interleaver_random( N );
      case 'block', [IL,IL_inv] = make_interleaver_block( N );
      case 'semirandom', [IL,IL_inv] = make_interleaver_semirandom( N );
      case 'ttcmrandom', [IL,IL_inv] = make_interleaver_ttcmrandom( N );
      otherwise, error('unknown Iterleaver Method');
      end
   end
end


%************** Random Interleaver ****************
function [IL,IL_inv] = make_interleaver_random( N );
IL = zeros(1,N);
IL_inv = zeros(1,N);
[tmp, IL] = sort(rand(1,N)); 
IL_inv(IL)= [1:N];
% Alternative Methode (langsamer)
%Topf = [1:N];
%for i = [N:-1:2],
%   x = ceil( i*rand );
%   IL(i)=Topf(x);
%   IL_inv(IL(i))=i;
%   Topf(x) = Topf(i);
%end;
%IL(1) = Topf(1);
%IL_inv(IL(1))=1;

%************** Block Interleaver ****************
function [IL,IL_inv] = make_interleaver_block( N );
IL = zeros(1,N);
IL_inv = zeros(1,N);
N_sqr = floor( sqrt(N) );
block = zeros(N_sqr,N_sqr);
block(1:N_sqr*N_sqr) = [1:N_sqr*N_sqr];
IL = [reshape(block',1,N_sqr*N_sqr),[(N_sqr*N_sqr+1):N]];
IL_inv(IL) = [1:N];

%************** Semirandom (Block+Random) Interleaver ****************
function [IL,IL_inv] = make_interleaver_semirandom( N );
[IL,IL_inv] = make_interleaver_block( N );
N_sqrh = floor( sqrt(N)/2 );
N_subblocks = floor( N/N_sqrh );
for i=1:N_subblocks,
   [tmp, IL2] = sort(rand(1,N_sqrh));
   IL((i-1)*N_sqrh+[1:N_sqrh]) = IL( IL2 + (i-1)*N_sqrh );
end,
[tmp, IL2] = sort(rand(1,(N-N_subblocks*N_sqrh)));
IL( (N_subblocks*N_sqrh+1):N ) = IL( N_subblocks*N_sqrh + IL2 );
IL_inv(IL) = [1:N];

%************** TTCM Random Interleaver ****************
function [IL,IL_inv] = make_interleaver_ttcmrandom( N );
IL = zeros(1,N);
IL_inv = zeros(1,N);
[tmp, tmp1] = sort(rand(1,ceil(N/2)));
[tmp, tmp2] = sort(rand(1,floor(N/2)));
IL (1:2:end)=2*tmp1-1;
IL (2:2:end)=2*tmp2;
IL_inv(IL)= [1:N];
% Alternative Methode (langsamer)
%Topf = [1:N];
%for i = [N:-1:2],
%   x = ceil( i*rand );
%   IL(i)=Topf(x);
%   IL_inv(IL(i))=i;
%   Topf(x) = Topf(i);
%end;
%IL(1) = Topf(1);
%IL_inv(IL(1))=1;