modulation.m

传统的卷积码和Turbo码直到今天仍有广泛的应用

function [ModulateResult,index]=modulation(code,index)
%/// QPSK,16-QAM,64QAM modulations
I=0;
Q=0;
if index<4
    %QPSK modulations
    index=1;
    ModulateResult=zeros(1,length(code)/2);
    for k=1:length(ModulateResult)
        ModulateResult(k)=2*code(2*k-1)-1+(2*code(2*k)-1)*i;
    end
    ModulateResult=ModulateResult/sqrt(2);
elseif index==5|index==4
    %16-QAM modulations
    index=2;
    ModulateResult=zeros(1,length(code)/4);
    for k=1:length(ModulateResult)
        if code((k-1)*4+2)==0
            I=3*(2*code((k-1)*4+1)-1);
        else
            I=2*code((k-1)*4+1)-1;
        end
        if code(k*4)==0
            Q=3*(2*code((k-1)*4+3)-1);
        else
            Q=2*code((k-1)*4+3)-1;
        end
        ModulateResult(k)=I+i*Q;
    end
    ModulateResult=ModulateResult/sqrt(10);
else
    %64-QAM modulations
    index=3;
    ModulateResult=zeros(1,length(code)/6);
    for k=1:length(ModulateResult)
        if code((k-1)*6+5:k*6)==[0 0]
            Q=7*(2*code((k-1)*6+4)-1);
        elseif code((k-1)*6+5:k*6)==[0 1]
            Q=5*(2*code((k-1)*6+4)-1);
        elseif code((k-1)*6+5:k*6)==[1 1]
            Q=3*(2*code((k-1)*6+4)-1);
        else
            Q=2*code((k-1)*6+4)-1;
        end
        if code((k-1)*6+2:(k-1)*6+3)==[0 0]
            I=7*(2*code((k-1)*6+1)-1);
        elseif code((k-1)*6+2:(k-1)*6+3)==[0 1]
            I=5*(2*code((k-1)*6+1)-1);
        elseif code((k-1)*6+2:(k-1)*6+3)==[1 1]
            I=3*(2*code((k-1)*6+1)-1);
        else
            I=2*code((k-1)*6+1)-1;
        end
        ModulateResult(k)=I+i*Q;
    end
    ModulateResult=ModulateResult/sqrt(42);
end