alamouti.m

这个程序主要是实现空时编码的matlab编解码仿真。

function [s_antenna1, s_antenna2]=alamouti(symbol_block,set)

%   [s_antenna1, s_antenna2]=alamouti(symbol_block,set)
%
%	Output:
%	s_antenna1	    - Symbolstream to be put on antenna 1. (symbol-vector)
%	s_antenna2	    - Symbolstream to be put on antenna 2. (symbol-vector)
%   
%   Input:
%   symbol_block    - block of symbols to be alamouti-coded (REAL VALUED SYMBOLS!) (symbol-vector)
%   set             - if set to 0, no alamouti coding is performed. (int 0,1)
%                     if set to 1, alamouti coding is performed.
%
%   Short Theoretical Background for the Function:
%
%   Space-Time coding for two antennas, using the alamouti algorithm.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
%%% Function part of simulation for Space-Time
%%% coding project, group Grey-2001.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%   Author: Stefan Uppg錼d
%   Date: 2001-03-19
%   Version: 1.1
%   Revision (Name & Date): FH 2001-03-28 see line 40
%   2.0 FH 2001-04-01   clever vector implementation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% set = 0, put all data in antenna nr.1

if(set==0)
    s_antenna1 = symbol_block;
    s_antenna2 = zeros(1,length(symbol_block));
elseif(set==1)
    
    a = ones(1,length(symbol_block));
    a(2:2:end) = -1*a(2:2:end);
    %s_antenna1 = (diag(symbol_block)*a')';  % [s0 -s1 s2 -s3 ...]
    s_antenna1 = a.*symbol_block;           % should be the same as with diag
    s_antenna2 = [];     
    
    odd = zeros(1,length(symbol_block));
    even = odd;
    odd(1:2:end) = symbol_block(2:2:end);
    even(2:2:end) = symbol_block(1:2:end);
    s_antenna2 = odd + even;
     
else
    s_antenna1 = symbol_block;
    s_antenna2 = [];
end