gusucode.com > 基于4PAM调制性能误码率仿真源码程序 > 基于4PAM调制性能误码率仿真源码程序/designFilter.m
clear all; clc; Nb = 40000; T = 1; % T: symbol period a = 0.25; % a: roll-off factor N = 4; % N: filter delay in symbol period T Fs = 4; % Fs: samples/symbol %EbN0dB = 30; %EbN0 = 10^(EbN0dB/10); EbN0dB=1:30; %Eb/N0 in dB EbN0 = 10.^(EbN0dB/10); Nerr=zeros(1,length(EbN0)); % initialize Nerr vector for k=1:length(EbN0) % 0 or 1 random input data b=rand(1,Nb)>0.5; b2 = reshape(b,2,[])'; %4PAM mapping for i = 1:length(b2) x(1,i) = (2*b2(i,1) -1) * (2*(b2(i,2)==0)+1); end %trasmit filter %xs = upsample(x,Fs); h = srrc_fir(a,N,Fs,T); s = rcosflt(x,1,Fs,'filter',h); %s = filter(h,1,xs); %r = awgn(s,EbN0dB(1,k),'measured'); Eb=1; % bit energy N0=Eb/EbN0(k); % noise PSD (W/Hz) varn=N0/2; % noise variance noise=sqrt(varn)*randn(length(s),1); % AWGN ~ N(0,varn) r=s+noise; % received signal %y = filter(h,1,r); y = rcosflt(r,1,Fs,'Fs/filter',h); z2 = downsample(y,Fs); % Downsample. z = [z2(2*N+1:end-2*N)]'; % Account for delay. %eyediagram(y(1:2000),Fs*2) %grid on; %plot(z,'.') %grid on; %4PAM demapping for i = 1:length(z) d2(1,i) = z(1,i)>0; d2(2,i) = abs(z(1,i)) < 2; end d = reshape(d2,1,[]); Nerr(k)=sum(b~=d); % the number of error bits end ber=Nerr/Nb; % bit error rate by simulation EbN0dB2=0:0.01:10; EbN02=10.^(EbN0dB2/10); ber2=Q(sqrt(2*EbN02)); % bit error rate by theory figure; semilogy(EbN0dB,ber,'s'); hold on; semilogy(EbN0dB2,ber2); xlabel('E_b/N_0'); ylabel('BER'); grid on; legend('Simulation', 'Theory');