QPSK，16PSK与QAM信号的误码率

clear; Fd=1; Fs=3*Fd; M=4; for SNR_db=0:10:20 Eb_N0=10^(SNR_db/10); sgma=sqrt(1/(8*Eb_N0)); x=randint(10,1,M); y=dmodce(x,Fd,Fs,'psk',M); ynoise=y+sqrt(Fs/Fd)*sgma*(randn(length(y),1)+j*randn(length(y),1)); z=ddemodce(ynoise,Fd,Fs,'psk',M); [numbers,pm(SNR_db/10+1)]=symerr(x,z); figure(SNR_db+1); hold on; for i=0:M-1 plot(cos(2*pi*i/M),sin(2*pi*i/M),'.','MarkerSize',20); end plot(ynoise,'+'); hold off; end; SNR_db=0:20; SNR1_db=0:20; for n=1:length(SNR_db) Eb_N0=10^(SNR_db(n)/10); sgma=sqrt(1/(8*Eb_N0)); x=randint(10000,1,M); y=dmodce(x,Fd,Fs,'psk',M); ynoise=y+sqrt(Fs/Fd)*sgma*(randn(length(y),1)+j*randn(length(y),1)); z=ddemodce(ynoise,Fd,Fs,'psk',M); [numbers,pm(n)]=symerr(x,z); end; for m=1:length(SNR1_db) Eb_N0=10^(SNR1_db(m)/10); pm_theory(m)=2*Qfunct(sqrt(2*Eb_N0))*(1-1/2*Qfunct(sqrt(2*Eb_N0))); pe_theory(m)=pm_theory(m)/log2(M); end semilogy(SNR_db,pm,'*',SNR1_db,pm_theory); xlabel('信噪比(dB)'); ylabel('误符号率'); legend('仿真得到的误符号率','理论符号误码曲线');