alamouti_space_time_coding.m

space time coding-alamouti scheme

clc;
clear all;
close all;


N=1000;

s00=randsrc(1,N/2);  %% BPSK modulation %%
s11=randsrc(1,N/2);  %% BPSK modulation %%


i=1;

for k=1:length(s00)
    
    s0(i)=s00(k);
    s0(i+1)=-conj(s11(k));
    
    s1(i)=s11(k);
    s1(i+1)=conj(s00(k));
    
    i=i+2;
    
end


for snr=1:1:30
    
    for monte=1:1:100
       
        
        for a=1:4
            
            X1=randn(1,N);
            Y1=randn(1,N);

            ch(a,:)=channel(X1,Y1,N);                        
            
        end
        
            h0=ch(1,:);
            h1=ch(2,:);
            h2=ch(3,:);            
            h3=ch(4,:);
            
        
 %%----------------------------------------------------------------------%%
                          %% MRRC scheme %%
 %%----------------------------------------------------------------------%%  
    
%         r(1,:)=(h0.*s0);       %% antenna zero %%
%         
%         r(2,:)=(h1.*s0);       %% antenna one %%
%         
%         r(3,:)=(h2.*s0);       %% antenna two %%
%         
%         r(4,:)=(h3.*s0);       %% antenna three %%
%         
%         
%         for a=1:4
%             
%             p=(r(a,:)*r(a,:)')/length(r(a,:));
%             
%             n0(a,:)=noise(p,snr,N);
%             
%         end
%         
%         
%             r0=r(1,:)+n0(1,:);
%             r1=r(2,:)+n0(2,:);
%             r2=r(3,:)+n0(3,:);
%             r3=r(4,:)+n0(4,:);                               
%         
%         sest1=(conj(h0).*r0)+(conj(h1).*r1);     %% Two branch MRRC (ONE TX AND TWO RX) %%
%         sest2=(conj(h0).*r0)+(conj(h1).*r1)+(conj(h2).*r2)+(conj(h3).*r3);   %% Two branch MRRC (ONE TX AND FOUR RX) %%
%       
 %%----------------------------------------------------------------------%%
                          %% ALAMOUTI scheme (SPACE TIME ENCODING) %%
 %%----------------------------------------------------------------------%% 
                          
                        %% TWO TX AND ONE RX %%
                            
        rr(1,:)=((h0.*s0))+((h1.*s1));
        rr(2,:)=((((-1)*h0).*conj(s1)))+((h1.*conj(s0)));
        
        p=0;
        
        for a=1:2
            
            p=(rr(a,:)*rr(a,:)')/length(rr(a,:));
            
            n1(a,:)=noise(p,snr,N);
        end
            
        r00=rr(1,:)+n1(1,:);        
        r01=rr(2,:)+n1(1,:);
        
        sest3=(conj(h0).*r00)+(h1.*conj(r01));
        sest4=(conj(h1).*r00)-(h0.*conj(r01)); 
        
%                          %% TWO TX AND TWO RX %%
%         
%         rrr(1,:)=(sqrt(1/2)*(h0.*s0))+(sqrt(1/2)*(h1.*s1));
%         rrr(2,:)=(sqrt(1/2)*(((-1)*h0).*conj(s1)))+(sqrt(1/2)*(h1.*conj(s0)));
%         rrr(3,:)=(sqrt(1/2)*(h2.*s0))+(sqrt(1/2)*(h3.*s1));
%         rrr(4,:)=(sqrt(1/2)*(((-1)*h2).*conj(s1)))+(sqrt(1/2)*(h3.*conj(s0)));
%         
%         p=0;
%         
%         for a=1:4
%             
%             p=(rrr(a,:)*rrr(a,:)')/length(rrr(a,:));
%             
%             n2(a,:)=noise(p,snr,N);
%         end
%         
%         r10=rrr(1,:)+n2(1,:);
%         
%         r11=rrr(2,:)+n2(2,:);
%         
%         r12=rrr(3,:)+n2(3,:);
%         
%         r13=rrr(4,:)+n2(4,:);
%         
%         sest5=(conj(h0).*r10)+(h1.*conj(r11))+(conj(h2).*r12)+(h3.*conj(r13));
%         sest6=(conj(h1).*r10)-(h0.*conj(r11))+(conj(h3).*r12)-(h2.*conj(r13));  
        
                    %% SIGNAL ESTIMATION %%
                    
                for i=1:1:N
                    
%                     if ((dist(sest1(i),-1))<(dist(sest1(i),1)))
%                        decision1(i)=-1;
%                     else
%                        decision1(i)=1;                    
%                     end
%                     
%                     if ((dist(sest2(i),-1))<(dist(sest2(i),1)))
%                        decision2(i)=-1;
%                     else
%                        decision2(i)=1;                    
%                     end
                   

                    if ((dist(sest3(i),-1))<(dist(sest3(i),1)))
                       decision3(i)=-1;
                    else
                        decision3(i)=1;
                    end
                    
                    
                    if ((dist(sest4(i),-1))<(dist(sest4(i),1)))
                       decision4(i)=-1;
                    else
                       decision4(i)=1;                    
                    end
                    
%                     if ((dist(sest5(i),-1))<(dist(sest5(i),1)))
%                        decision5(i)=-1;
%                     else
%                        decision5(i)=1;                    
%                     end
%                     
%                     if ((dist(sest6(i),-1))<(dist(sest6(i),1)))
%                        decision6(i)=-1;
%                     else
%                        decision6(i)=1;                    
%                     end

                end
                
                    %% ERROR CALCULATION %%
        
        error1=0;
        error2=0;
        error3=0;
        error4=0;
        error5=0;
        error6=0;
        
                for i=1:1:N
                    
%                     if (decision1(i)~=s0(i))
%                        error1=error1+1;
%                     end
%                     
%                     if (decision2(i)~=s0(i))
%                        error2=error2+1;
%                     end
                    
                    if (decision3(i)~=s0(i))
                       error3=error3+1;
                    end

                    if (decision4(i)~=s1(i))
                       error4=error4+1;
                    end
                    
%                     if (decision5(i)~=s0(i))
%                        error5=error5+1;
%                     end
% 
%                     if (decision6(i)~=s1(i))
%                        error6=error6+1;
%                     end
                    
                end
                
                
%             ber1(monte)=(error1/N);
%             
%             ber2(monte)=(error2/N);
%             
            ber3(monte)=((error3+error4)/(2*N));
%             ber4(monte)=((error5+error6)/(2*N));
            
 %%-----------------------------------------------------------------------%%
                 %% Two branch MRRC (ONE TX AND TWO RX) %%
 %%-----------------------------------------------------------------------%%
            
    end
    
%     pb1(snr)=mean(ber1);
%     
%     pb2(snr)=mean(ber2);
    
    pb3(snr)=mean(ber3);
    
%     pb4(snr)=mean(ber4);
%     
    
end

snr=1:30;%     pb4(snr)=mean(ber4);
%     


% semilogy(snr,pb1,'-rd','LineWidth',2,...
%                        'MarkerEdgeColor','k',...
%                        'MarkerFaceColor','g',...
%                        'MarkerSize',5);
% hold on;

% semilogy(snr,pb2,'-gs','LineWidth',2,...
%                        'MarkerEdgeColor','k',...
%                        'MarkerFaceColor','c',...
%                        'MarkerSize',5);
% hold on;

semilogy(snr,pb3,'-bh','LineWidth',2,... 
                       'MarkerEdgeColor','k',...
                       'MarkerFaceColor','y',...
                       'MarkerSize',5);
hold on;  %     pb4(snr)=mean(ber4);
%     


% semilogy(snr,pb4,'^--','LineWidth',2,... 
%                       'MarkerEdgeColor','k',...
%                       'MarkerFaceColor','r',...
%                       'MarkerSize',5);
% hold on;
%                       


% semilogy(snr,pb1,'r*-');
% hold on;
% semilogy(snr,pb2,'g*-');
% hold on;
% semilogy(snr,pb3,'k^-');
% hold on;
% semilogy(snr,pb4,'ko-');

grid on;
hold on;

%symerr(x,y);