cm_sm32.m

QPSK在加性高斯白噪声环境下

function[pb,ps]=cm_sm32(snr_in_dB)
N=10000;
E=1;
snr=10^(snr_in_dB/10);
sgma=sqrt(E/snr)/2;
s00=[1 0];
s01=[0 1];
s11=[-1 0];
s10=[0 -1];
for i=1:N,
    temp=rand;
    if(temp<0.25),
        dsource1(i)=0;
        dsource2(i)=0;
    elseif(temp<0.5),
        dsource1(i)=0;
        dsource2(i)=1;
        elseif(temp<0.75),
        dsource1(i)=1;
        dsource2(i)=0;
        else
        dsource1(i)=1;
        dsource2(i)=1;
    end;
end;
numofsymbolerror=0;
numofbiterror=0;
for i=1:N,
    n(1)=gngauss(sgma);
      n(2)=gngauss(sgma);
      if((dsource1(i)==0)&(dsource2(i)==0)),
          r=s00+n;
      elseif((dsource1(i)==0)&(dsource2(i)==1)),
          r=s01+n;
       elseif((dsource1(i)==1)&(dsource2(i)==0)),
             r=s10+n;
      else
        r=s11+n;  
      end;
      c00=dot(r,s00);
       c01=dot(r,s01);
        c10=dot(r,s10);
         c11=dot(r,s11);
         c_max=max([c00 c01 c10 c11]);
         if(c00==c_max),
             decis1=0;decis2=0;
         elseif(c01==c_max),
             decis1=0;decis2=1;
         elseif(c10==c_max),
             decis1=1;decis2=0;
         else 
            decis1=1;decis2=1; 
         end;
         symbolerror=0;
         if(decis1~=dsource1(i)),
             numofbiterror=numofbiterror+1;
             symbolerror=1;
         end;
         if(decis2~=dsource2(i)),
             numofbiterror=numofbiterror+1;
             symbolerror=1;
         end;
         if(symbolerror==1),
             numofsymbolerror=numofsymbolerror+1;
         end;
end;
ps=numofsymbolerror/N;
pb=numofbiterror/(2*N);