www.pudn.com > MPSK_MFSK.rar > mpsk.m

M=8; 
 %  signal noisy ratio 
 esnodb=1:10; 
 esno=10.^(esnodb/10); 
 es=1; 
 no=10.^(-esnodb/10); 
 sigma=sqrt(no/2); 
  
 for m=1:length(esnodb); 
     error(m)=0; 
     s_data(m)=0; 
while error(m)<=1000 
        %input data 
        da=ceil(rand(1,10000)*M); 
       % QPSK modulation. 
        iin=sqrt(es)*cos((2*pi/M)*(da-1)); 
        qin=sqrt(es)*sin((2*pi/M)*(da-1)); 
       %AWGN channel 
        AWGNi=randn(1,length(da))*sigma(m); 
        AWGNq=randn(1,length(da))*sigma(m);        
      % data transmitted throng AWGN channel 
        ich=iin+AWGNi; 
        qch=qin+AWGNq; 
     %distance counter 
      for i=1:M 
         d(i,:)=(ich-cos((2*pi/M)*(i-1))).^2+(qch-sin((2*pi/M)*(i-1))).^2; 
     end 
    %judge the nearest piont 
      for j=1:length(qch) 
          dd(j)=find(d(:,j)==min(d(:,j))); 
          if dd(j)~=da(j) 
              error(m)=error(m)+1; 
          end 
      end 
      s_data(m)=s_data(m)+10000; 
  end 
end 
% bit error ratio counter 
pe=error./s_data; 
 
%display the result 
% the result of theory 
ps=erfc(sqrt(esno)*sin(pi/M)); 
 
semilogy(esnodb,pe,'b * -');hold on; 
semilogy(esnodb,ps,'rd-'); 
 
xlabel('Es/N0(dB)');ylabel('BER'); 
legend('the result of simulation','the result of theory');