raised-cosine-error-rate-.zip_raised cosine_升余弦

global dt t f df N T close all clear Eb_N0 Pe N=2^15; %采样点数 L=4; %每码元的采样点数 M=N/L; %码元数 Rb=2; %码速率是2Mb/s Ts=1/Rb; %码元间隔 dt=Ts/L; %时域采样间隔 df=1/(N*dt); %频域采样间隔 T=N*dt; %截短时间 Bs=N*df/2; %系统带宽 alpha=0.5 %滚降系数０.5 t=linspace(-T/2,T/2,N); %时域横坐标 f=linspace(-Bs,Bs,N)+eps; %频域横坐标 hr1=sin(pi*t/Ts)./(pi*t/Ts); hr2=cos(alpha*pi*t/Ts)./(1-(2*alpha*t/Ts).^2); hr=hr1.*hr2; %升余弦脉冲波形 HR=abs(t2f(hr)); %升余弦脉冲的傅式，变换取模是为了忽略时延 GT=sqrt(HR); %最佳系统的发送接收滤波器的傅式变 GR=GT; for loop1=1:10; Eb_N0(loop1)=(loop1-1); %Eb/N0 in dB eb_n0(loop1)=10^(Eb_N0(loop1)/10); Eb=1; n0=Eb/eb_n0(loop1); %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 for loop2=1:3; b=sqrt(rand^2+rand^2); tao=rand*Ts; %设置延迟时间 phi=rand*2*pi; [b,tao,phi] C=1-b*exp(-j*(2*pi*f*tao+phi)); %多径信道 aC=10*log10(abs(C)); a=sign(randn(1,M)); imp=zeros(1,N); %产生冲激序 imp(L/2:L:N)=a/dt; IMP=t2f(imp); IMP_1=IMP.*HR.*C; %信道的傅式变换 c=f2t(IMP_1); c=real(c); %不加噪声的输出 n_ch=sqrt(sita)*randn(size(t)); %信道噪声 nr=real(f2t(t2f(n_ch).*GR)); %输出噪声 sr=real(f2t(IMP.*HR))+nr; %接收信号 y=sr(L/2:L:N); %取样延迟 aa=sign(y); %判决 n_err=n_err+length(find(aa~=a)) %错误累计 end Pe(loop1)=n_err/(M*loop2); semilogy(Eb_N0,Pe,'g'); %Pe~Eb/N0曲线画图 xlabel('Eb/N0');ylabel('Pe');title('多径信道 Pe~Eb/N0曲线'); eb_n0=10.^(Eb_N0/10); hold on semilogy(Eb_N0,0.5*erfc(sqrt(eb_n0))); axis([0,8,1e-3,1]) xlabel('Eb/N0') ylabel('Pe') legend('实际','理论') end