function [modulated_coded_symbols]=space_time_coding(modulated_symbols,code_name,rate,num_code,zero_padding)
%% Space_time_coding
%
%Encode an input stream into a specified space time block code.
%
%Input: - modulated_symbols: a vector of symbols (if the length does not match with the STBC
% structure you must use the zero_padding option)
% - code_name: A string corresponding to the code name
% ('SM','Alamouti','OSTBC3','STBC3','QOSTBC4','OSTBC4','STBC4','OSTBC5','OSTBC6','OSTBC7')
% - rate: a string with the code rate '1/2','3/4','1','N'
% - zero_padding (optionnal): if there is a 5th input and if the length does not
% match with the space time bloc coding structure, than the modulated symbols are padded with zero.
%
%Output: modulated_coded_symbols
%
%Example:
%>> C=space_time_coding([1+i,2+2*i],'Alamouti','1',1)
%C =
% 1.0000 + 1.0000i -2.0000 + 2.0000i
% 2.0000 + 2.0000i 1.0000 - 1.0000i
%
%Remarks:
%To obtain the code matrix, enter for example:
%>>space_time_coding([1:4]+i*[1:4],'OSTBC4','3/4',1)
%
%To obtain the code length and the number of transmitter used by a STBC,
%enter: size(space_time_coding(0,'OSTBC4','3/4',1,1))
%
%Reference:
%
%[1] S.M Alamouti " A simple transmitter diversity scheme for wireless
%communications" IEEE J.Select Areas Communication vol 16,
%October 1998
%[2] V.Tarokh "Space Time BLock Codes from Orthogonal Designs" IEEE
%Transactions on Information theory, vol 45, July 1999
%[3] G.Ganesan and P. Stoica "Space time Block Codes: A Maximum SNR
%approach", IEEE Transactions on Information Theory, vol 47, may 2001.
%[4] I. Jafarkhani: "A Quasi Orthogonal Space Time Block Code"
%IEEE Transactions Letters on Communications, Vol. 49,
%No.1, 2001
%
%
%Programmed by V. Choqueuse (vincent.choqueuse@gmail.com)
modulated_coded_symbols=[];
switch code_name
case 'SM'
%% Spatial Multiplexing %%
nb_emitters=str2num(rate);
if(mod(length(modulated_symbols),nb_emitters)~=0) && (nargin==5)
modulated_symbols(end+1:end+(nb_emitters-mod(length(modulated_symbols),nb_emitters)))=0;
end
if (mod(nb_emitters,1)==0)
modulated_coded_symbols=reshape(modulated_symbols,nb_emitters,prod(size(modulated_symbols))/nb_emitters);
else
fprintf('Error: Spatial Mulitplexing -> code rate must be an integer\n');
end
case 'Alamouti'
if (strcmp(rate,'1')==1)
%% Alamouti code %%
%[1] S.M Alamouti " A simple transmitter diversity scheme for wireless
%communications" IEEE J.Select Areas Communication vol 16, October 1998
if(mod(length(modulated_symbols),2)~=0) && (nargin==5)
modulated_symbols(end+1:end+(2-mod(length(modulated_symbols),2)))=0;
end
symboles_reshape=reshape(modulated_symbols,2,length(modulated_symbols)/2);
x1=[1 0];
x2=[0 1];
P1=[x1;x2];
P2=[-x2;x1];
P= [P1;conj(P2)];
modulated_coded_symbols=P*symboles_reshape;
modulated_coded_symbols(3:4,:)=conj(modulated_coded_symbols(3:4,:));
modulated_coded_symbols=reshape(modulated_coded_symbols,2,prod(size(modulated_coded_symbols))/2);
else
fprintf('Error: Alamouti coding -> code rate must be 1\n');
end
case 'OSTBC3'
switch rate
case '1/2'
%% Tarokh OSTBC
%[2] V.Tarokh "Space Time BLock Codes from Orthogonal Designs" IEEE
%Transactions on Information theory, vol 45, July 1999
if(mod(length(modulated_symbols),4)~=0) && (nargin==5)
modulated_symbols(end+1:end+(4-mod(length(modulated_symbols),4)))=0;
end
symboles_reshape=reshape(modulated_symbols,4,length(modulated_symbols)/4);
x1=[1 0 0 0];
x2=[0 1 0 0];
x3=[0 0 1 0];
x4=[0 0 0 1];
P1=[x1;x2; x3];
P2=[-x2;x1;-x4];
P3=[-x3;x4;x1];
P4=[-x4;-x3;x2];
P=[P1;P2;P3;P4];
modulated_coded_symbols=[P;P]*symboles_reshape;
modulated_coded_symbols(13:end,:)=conj(modulated_coded_symbols(13:end,:));
modulated_coded_symbols=reshape(modulated_coded_symbols,3,prod(size(modulated_coded_symbols))/3);
case '3/4'
switch num_code
case 1
%% Ganesan STBC
%[3] G.Ganesan and P. Stoica "Space time Block Codes: A Maximum SNR
%approach", IEEE Transactions on Information Theory, vol 47, may 2001.
if(mod(length(modulated_symbols),3)~=0) && (nargin==5)
modulated_symbols(end+1:end+(3-mod(length(modulated_symbols),3)))=0;
end
symboles_reshape=reshape(modulated_symbols,3,length(modulated_symbols)/3);
symboles_reshape_conj=conj(symboles_reshape);
x1=[1 0 0];
x2=[0 1 0];
x3=[0 0 1];
x0=[0 0 0];
P1=[x1;x0;x0];
P2=[x0;x1;-x3];
P3=[x2;x0;x0];
P4=[-x3;x0;x0];
P=[P1;P2;P3;P4];
P1_conj=[x0;x0;-x2];
P2_conj=[x0;x0;x0];
P3_conj=[x0;x3;x1];
P4_conj=[x0;x2;x0];
P_conj=[P1_conj;P2_conj;P3_conj;P4_conj];
modulated_coded_symbols=P*symboles_reshape+P_conj*symboles_reshape_conj;
modulated_coded_symbols=reshape(modulated_coded_symbols,3,prod(size(modulated_coded_symbols))/3);
case 2
%% Ganesan STBC
%[3] G.Ganesan and P. Stoica "Space time Block Codes: A Maximum SNR
%approach", IEEE Transactions on Information
%Theory, vol 47, may 2001.
if(mod(length(modulated_symbols),3)~=0) && (nargin==5)
modulated_symbols(end+1:end+(3-mod(length(modulated_symbols),3)))=0;
end
symboles_reshape=reshape(modulated_symbols,3,length(modulated_symbols)/3);
symboles_reshape_conj=conj(symboles_reshape);
x1=[1 0 0];
x2=[0 1 0];
x3=[0 0 1];
x0=[0 0 0];
P1=[x1;x2;x3];
P2=[x0;x0;x0];
P3=[x0;x0;x0];
P4=[x0;x0;x0];
P=[P1;P2;P3;P4];
P1_conj=[x0;x0;x0];
P2_conj=[-x2;x1;x0];
P3_conj=[x3;x0;-x1];
P4_conj=[x0;-x3;x2];
P_conj=[P1_conj;P2_conj;P3_conj;P4_conj];
modulated_coded_symbols=P*symboles_reshape+P_conj*symboles_reshape_conj;
modulated_coded_symbols=reshape(modul
