brmet.m

MIMO and VBLAST( please see the documentation)

function metric = brmet(sig,q_test,ch_coefs);

%BRMET A user defined branch metric.
%   METRIC = BRMET(SIG,Q_TEST,CH_COEFS) evaluates branch metric and
%   returns the result as a column vector for all testing channel
%   symbols Q_TEST. In fact entries of METRIC variable correspond to
%   the squared distance of received signal SIG and testing channel
%   symbols Q_TEST in Eucledian space. CH_COEFS simply contains a
%   complex path fadings in  MIMO channel.
%
%   See also DETECT, CHANNEL.

%   Copyright 2001-2002 Kamil Anis, [e-mail]
%   Dept. of Radioelectronics, 
%   Faculty of Electrical Engineering
%   Czech Technical University in Pragu
%   $Revision: 2.0 $  $Date: 2002/10/23 17:33:28 $
%   --
%   <additional stuff should go here>

[m,n] = size(ch_coefs);
[q_dim,foo] = size(q_test);
sig = repmat(sig,q_dim,1);
outsum = 0;

for j=1:m % outer sum
  insum = 0;
  
	for i=1:n % inner sum
      insum1 = ch_coefs(i,j) .* q_test(:,i);
      insum = insum + insum1;
	end
  
  outsum1 = abs(sig(:,j) - insum) .^ 2;
  outsum = outsum + outsum1;
end
  
metric = outsum;