modul.m

MIMO and VBLAST( please see the documentation)

function sig_modul = modul(data,md,pulse,samples,gain,varargin)

%MODUL Multidimensional digital modulator.
%   SIG_MOD = MODUL(DATA,MD,PULSE,SAMPLES,GAIN) performs linear
%   memoryless digital modulation of input DATA. The output signal 
%   sampled SAMPLES-times per symbol period is assumed to be 
%   a complex envelope of real bandpass signal.MD corresponds to the
%   number of constellation signals. Possible values for MD are 4|8|16.
%   This corresponds to the 4PSK, 8PSK and 16QAM signal constellations
%   respectively.The order of the 16QAM constellation signals is
%   defined via external file qam16.txt and may be arbitrarily modified.
%   The samples of appropriate modulation impulse must be provided to
%   the modulator via PULSE variable. GAIN is the value of
%   constellation expansion factor which may be obtained from SCALE
%   function.
%
%   SIG_MOD = MODUL(...,'EchoOn') toggles internal function echo
%   on.
%
%   See also MAKEPULSE, SCALE.

%   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>

% 16QAM definition
load qam16.txt;
[frame_length,space_dim,frames]=size(data);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% BODY BEGIN %%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for k = 1:frames
	switch md
	case 16         % 16QAM
		for l = 1:space_dim
		k1(:,l) = qam16(data(:,l,k) + 1,1);
		k2(:,l) = qam16(data(:,l,k) + 1,2);
		end
		
		q(:,:,k) = (2 * k1 - md - 1) - i * (2 * k2 - md - 1);
		
	otherwise
		expr = 2 * pi * i / md;
		q(:,:,k) = exp(expr * data(:,:,k));
	end
	
	sig_up(:,:,k) = upsample(q(:,:,k),samples);
	
	% to compute convolution signals must be vectors -> for loop
	for j = 1:space_dim
		sig_modul(:,j,k) = gain * conv(pulse,sig_up(:,j,k));
	end
end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% BODY END %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if (isempty(varargin) == 0) & (varargin{end} == 'EchoOn')
	[indent,gap,name] = iprompt('MODUL:');

	if (md == 4) | (md == 8)
        str1 = 'PSK';
	else
        str1 = 'QAM';
	end
	
	[m,foo1,foo2] = size(sig_modul);
	
	str2 = num2str(frame_length);
	str3 = num2str(frames);
	str4 = num2str(m);
	str5 = num2str(md);
	
	disp(' ');
	disp([name,gap,'Modulation ',str5,str1,' performed; ',str2,' symbols,',...
    str3,' frame(s).']);
	disp([indent,'Total signal length: ',str4,' samples.']);
	disp(' ');
end