mimo_midamble.m

This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

% This matlab script simulates the MIMO channel estimation
% Based on the paper by Jaiganesh, Markus, Harish
% titled 'optimal Channel training for multiple antenna systems
% The matrix required on the receiver is developed here and dumped as txt
% file

clear all
seq =  [0,1,1,0,0,1,-1,0,-1,0,0,-1,-1,0,0,-1, ...  %MC CDMA midamble sequence
  0,-1,1,0,0,-1,-1,0,-1,0,0,1,-1,0,0,-1,...
  0,1,1,0,0,1,1,0,1,0,0,-1,-1,0,0,1,...
  0,1,-1,0,0,1,-1,0,-1,0,0,-1,1,0,0,-1,...
  0,-1,-1,0,0,1,-1,0,-1,0,0,-1,-1,0,0,-1,...
  0,-1,-1,0,0,-1,-1,0,-1,0,0,1,1,0,0,-1,...
  0,1,-1,0,0,1,1,0,1,0,0,-1,1,0,0,1,...
  0,1,1,0,0,-1,-1,0,-1,0,0,-1,1,0,0,-1,...
  0,1,1,0,0,-1,1,0,1,0,0,1,-1,0,0,1,...
  0,-1,1,0,0,-1,1,0,1,0,0,1,-1,0,0,-1,...
  0,1,1,0,0,-1,1,0,1,0,0,-1,-1,0,0,1,...
  0,-1,-1,0,0,1,-1,0,-1,0,0,-1,-1,0,0,1,...
  0,-1,1,0,0,1,-1,0,-1,0,0,-1,1,0,0,1,...
  0,-1,-1,0,0,1,-1,0,-1,0,0,-1,-1,0,0,-1,...
  0,1,-1,0,0,-1,-1,0,-1,0,0,1,1,0,0,1,...
  0,1,-1,0,0,-1,-1,0,-1,0,0,-1,-1,0,0,-1]';

cseq = complex( seq(1:2:end), seq(2:2:end));

Nt   = length(cseq); %Length of the midambles
L    = 16; %Length of the taps
M    = 4; %Number of Antennas

user = zeros( length(cseq), M );

for i=1:M
user(:,i) = circshift( cseq, 16*(i-1));
end

% S is of dimension (Nt - L + 1 x ML)
   
S = zeros( Nt - L + 1, M*L);
j = 0;
k = 0;
 for i = 1:M*L 
      if ( mod(i,L) == 1)
          k = k + 1;
          j = 0;
      end
  S(:,i) = user(end - j:-1:end - (Nt - L) - j,k); 
       j = j + 1; 
 end
 
 cpar = inv(S'*S)*S';
  
  
 isir1 = filter([0.8,0.6],1,user(:,1));
 isir2 = filter([0.6,0.8],1,user(:,2));
 isir  = isir1 + isir2;
 r   = 2000 * isir(end:-1:end-(Nt - L),1);
 
 h   = cpar*r;
 
 rpar = real(cpar);
 ipar = imag(cpar);
 
 
 rparl = reshape( rpar', size(rpar,1) * size( rpar,2 ), 1 ); 
 iparl = reshape( ipar', size(ipar,1) * size( ipar,2 ), 1 );
 
 
 par = zeros( length(rparl) * 2 , 1 );
 par(1:2:end) = rparl;
 par(2:2:end) = iparl;
 
 return;

 fp = fopen( '~selvan/Work/Matlab/mccdma_par.txt','w');
  
 col  = 8;
 for i = 1: length(par) / col
    for j = 1:col
     fprintf(fp, '%f,',par( (i-1) *col + j));
    end
    fprintf(fp,'\n');
end