sq32qam_gray_demap.m

一些关于调指和解调的小程序

function out=sq32QAM_Gray_demap(input)

K=length(input);
d=1/sqrt(24);                         %%% The minimum distance between constellations is 2*d
x=d*[5,3,1,-1,-3,-5];        %%% coordinate matrix
y=d*[5,3,1,-1,-3,-5];


for i=1:K
    temp(i,:)=[real(input(i)),imag(input(i))]; %%% 复数矩阵变成实数矩阵，便于处理
end

max=d*[1,5                  %%% coordinate matrixbase code, 8-QAM
       1,3
       1,1
       3,1
       5,1
       5,3
       5,5
       3,5];
code=[0 0 0               %%% base code matrix, match with max
      0 0 1
      0 1 1
      1 1 1
      1 0 1
      1 0 0
      1 1 0
      0 1 0];
    
    
for i=1:K
%%%--------Minimun Euclidean distance demodulation--------------------
    if temp(i,1)>=0 & temp(i,2)>=0          %%% first field
        max1=max;                           %%% coordinate matrix of first field 
        for k=1:8
            dis(k)=(temp(i,1)-max1(k,1))^2+(temp(i,2)-max1(k,2))^2;
        end
        
        [di,num]=min(dis);  
        tb=code(num,:);
        t_out(i,:)=[0 0 tb];
    end
    
    if temp(i,1)<0 & temp(i,2)>=0          %%% second field
        max2=[-max(:,1),max(:,2)];         %%% coordinate matrix of second field
        for k=1:8
            dis(k)=(temp(i,1)-max2(k,1))^2+(temp(i,2)-max2(k,2))^2;
        end
        
        [di,num]=min(dis);  
        tb=code(num,:);
        t_out(i,:)=[0 1 tb];
    end
        
    if temp(i,1)<0 & temp(i,2)<0           %%% third field
        max3=(-1)*max;                     %%% coordinate matrix of third field 
        for k=1:8
            dis(k)=(temp(i,1)-max3(k,1))^2+(temp(i,2)-max3(k,2))^2;
        end
                
        [di,num]=min(dis);  
        tb=code(num,:);
        t_out(i,:)=[1 1 tb];
    end
    
    if temp(i,1)>0 & temp(i,2)<=0          %%% forth field
        max4=[max(:,1),-max(:,2)];         %%% coordinate matrix of forth field 
        for k=1:8
            dis(k)=(temp(i,1)-max4(k,1))^2+(temp(i,2)-max4(k,2))^2;
        end
        
        [di,num]=min(dis);  
        tb=code(num,:);
        t_out(i,:)=[1 0 tb];
    end
end
 
for i=1:K
    for m=1:5
        out(5*(i-1)+m)=t_out(i,m);     %%% P/S transform, the out is a serial binary sequence
    end
end


clear K x y max code temp t_out tb