=[-Bs+df/2:df:Bs];%频域横坐标t=[-T/2+dt/2:dt:T/2];%时域横坐标g=sin(pi*t/Ts).*cos(pi*t*aa/Ts)./[pi*t/Ts.*(1-4*t.^2*aa^2/Ts^2)];%升余弦脉冲波形GG=t2f(g);GG=abs(GG);%升余弦脉冲的傅式变换GT=sqrt(GG);GR=GT;%最佳系统的发送接收滤波器的傅式变换forl1=1:20;Eb_N0(l1)=(l1-1);%Eb/N0indBeb_n0(l1)=10^(Eb_N0(l1)/10);Eb=1;n0=Eb/eb_n0(l1);%信道的噪声谱密度sita=n0*Bs;%信道中噪声功率n_err=0;%误码计数forl2=1:20;b=sign(randn(1,M));s=zeros(1,N);%产生冲激序列s(L/2:L:N)=b/dt;SS=t2f(s);S=SS.*GG;%信道的傅式变化a=f2t(S);a=real(a);%不加噪声的输出n_ch=sqrt(sita)*randn(size(t));%信道噪声N_CH=t2f(n_ch);nr=real(f2t(N_CH.*GR));%输出噪声sr=a+nr;%接收信号y=sr(L/2-L/4:L:N-L/4);%取样bb=sign(y);%判决n_err=n_err+length(find(bb~=b));%错误累计endPe(l1)=n_err/(M*l2);semilogy(Eb_N0,Pe,'g');%Pe~Eb/N0曲线画图xlabel('Eb/N0');ylabel('Pe');title('Pe~Eb/N0曲线');eb_n0=10.^(Eb_N0/10);holdonsemilogy(Eb_N0,0.5*erfc(sqrt(eb_n0)));axis([0,15,1e-4,1])
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