codeh4.m

Adaptive Filter_Simon Haykin_Matlab_code STBC

function [err]=codeH4(index,snr,nsymb,Mary,modtype,nRx,err);
%Routine that preforms simulations based on QAM Mary modulation
%and using coding scheme H3.

nTx=4;
%Generate Data
%Possible Symbol Set
Set=[0:Mary-1]';  
Smap=dmodce(Set,1,1,'qask',Mary);
%Generate Symbols
symb=randsrc(nsymb,1,[0:Mary-1]);
%Encode with PSK
msg=dmodce(symb,1,1,'qask',Mary);
%Noise Stats
Eav=Smap'*Smap/Mary;
NF=10^(snr/10);
S=sqrt(nTx*Eav/(2*NF));
%Operate on a block by block itteration
for k=1:3:nsymb,
    Sv=msg(k:k+2);  %vector of next three bits
    %Make next block
    F1  =  Sv(3)/sqrt(2);
    F33 = (-Sv(1) - Sv(1)' + Sv(2) - Sv(2)')/2;
    F34 = (-Sv(2) - Sv(2)' + Sv(1) - Sv(1)')/2;
    F43 = (+Sv(2) + Sv(2)' + Sv(1) - Sv(1)')/2;
    F44 = -(+Sv(1) + Sv(1)' + Sv(2) - Sv(2)')/2;
   
    H4 = [+Sv(1)  Sv(2)  F1   F1;
          -Sv(2)' Sv(1)' F1  -F1;
           F1'    F1'    F33  F34;
           F1'   -F1'    F43  F44];
    
    noise=S*(randn(4,1) + i*randn(4,1));  %Dimension porportional to block size
    H=(randn(nTx,1) + i*randn(nTx,1))/sqrt(2);  %Channel Gain Matrix  
    rx= H4*H + noise;              
    
    %Demodulate
    S1 = + rx(1)*H(1)' + rx(2)'*H(2) ...
         + (rx(4) - rx(3)) * (H(3)' - H(4)') / 2 ...
         - (rx(3) + rx(4))' * (H(3) + H(4)) / 2;
    
    S2 = + rx(1)*H(2)' - rx(2)'*H(1) ...
         + (rx(4) + rx(3)) * (H(3)' - H(4)') / 2 ...
         + (-rx(3) + rx(4))' * (H(3) + H(4)) / 2;
     
    S3 = + (rx(1) + rx(2))*H(3)'/sqrt(2) + (rx(1) - rx(2))*H(4)'/sqrt(2) ...
         + rx(3)'*(H(1) + H(2))/sqrt(2) ...
         + rx(4)'*(H(1) - H(2))/sqrt(2);
     
    
    for L=1:Mary
        Con = (-1 + H'*H) * Smap(L) * Smap(L)';
        
        %For s1
        est_s1(L)= real( (S1 - Smap(L))*(S1 - Smap(L))' + Con);
        
        %For s2
        est_s2(L)= real( (S2 - Smap(L))*(S2 - Smap(L))' + Con);
        
        %For s3
        est_s3(L)= real( (S3 - Smap(L))*(S3 - Smap(L))' + Con);
    end
    %Choose symbols that minimize the est_* vectors
    %Decide in favour of min value 
    [A,B]=min(est_s1);
    shat(k)=B-1;      %-1 b/c index starts at 0 and not 1
    [A,B]=min(est_s2);
    shat(k+1)=B-1;    %-1 b/c index starts at 0 and not 1
    [A,B]=min(est_s3);
    shat(k+2)=B-1;      %-1 b/c index starts at 0 and not 1
end
%Compute symbol errors
err(index)=sum(shat~=symb');