scale.m

MIMO and VBLAST( please see the documentation)

function gain = scale(md,symb_energy)

%SCALE Constellation expansion factor.
%   GAIN = SCALE(MD,SYMB_ENERGY) simply computes an expansion
%   constellation factor which corresponds to set the modulated
%   signal power. SYMB_ENERGY is assumed to be SYMB_TIME * SIG_PWR
%   what corresponds to the symbol time duration and transmitted
%   signal power respectively. There are different formulas in the
%   SCALE function depending on MD. When MD equals to 4 or 8 the
%   formula for PSK "ring" contellation is used while for instance
%   of MD = 16 the gain for QAM "square" contellation is computed.
%
%   See also MODUL.

%   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>

switch md
case 16 % 16QAM
  md_qam = log2(md);
  gain = sqrt(6 * symb_energy / (md_qam ^ 2 + md_qam ^ 2 - 2));
otherwise % 4PSK, 8PSK
  gain = sqrt(2 * symb_energy);
end