demapper.m

是自己自创的好程序

% This function demap the complex data to soft information;
function Msgout=DeMapper(Sigequ,Bitpersym)
[M,N]=size(Sigequ);
for k=1:1:M
for i=1:1:N
    Msgout(k,(i-1)*Bitpersym+1:i*Bitpersym)=demapper_con(Sigequ(k,i),Bitpersym);
end
end
Msgout=(1-sign(Msgout))/2;

%define the subfunction demapper_con;
function msg=demapper_con(rc,Bitpersym)
switch Bitpersym
    case 1
        msg=real(rc);
    case 2
        rc=rc*sqrt(2);
        msg(1)=imag(rc);
        msg(2)=real(rc);
    case 4
        rc=rc*sqrt(10);
        msg(4)=real(rc);
        msg(2)=imag(rc);
        msg(3)=2-abs(real(rc));
        msg(1)=2-abs(imag(rc));
    case 6
        rc=rc*sqrt(42);
        msg(6)=real(rc);
        msg(3)=imag(rc);
        msg(5)=4-abs(real(rc));
        msg(2)=4-abs(imag(rc));
        if abs(real(rc))>4
            msg(4)=6-abs(real(rc));
        else
            msg(4)=abs(real(rc))-2;
        end
        
        if abs(imag(rc))>4
            msg(1)=6-abs(imag(rc));
        else
            msg(1)=abs(imag(rc))-2;
        end
end