%Upconverter L = length(carriers);
chips = [ carriers.';zeros((2*q)-1,L)]; p=1/Rs:1/Rs:T/2; g=ones(length(p),1); dummy=conv(g,chips(:)); u=[dummy; zeros(46,1)]; [b,aa] = butter(13,1/20); uoft = filter(b,aa,u);
delay=64; %接收端重构滤波器延迟
s_tilde=(uoft(delay+(1:length(t))).').*exp(1i*2*pi*fc*t); s=real(s_tilde); %OFDM 接收 %Downconversion
r_tilde=exp(-1i*2*pi*fc*t).*s; %(F) figure(1); subplot(211); plot(t,real(r_tilde)); axis([0e-7 12e-7 -60 60]); grid on; figure(1); subplot(212); plot(t,imag(r_tilde)); axis([0e-7 12e-7 -100 150]); grid on; figure(2);
ff=(Rs)*(1:(q*FS))/(q*FS); subplot(211);
plot(ff,abs(fft(r_tilde,q*FS))/FS); grid on;
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基于MATLAB实现OFDM的仿真
figure(2); subplot(212);
pwelch(r_tilde,[],[],[],Rs); %载波抑制
[B,AA] = butter(3,1/2);
r_info=2*filter(B,AA,r_tilde); %基带信号持续时间(G) figure(3); subplot(211); plot(t,real(r_info)); axis([0 12e-7 -60 60]); grid on; figure(3); subplot(212); plot(t,imag(r_info)); axis([0 12e-7 -100 150]); grid on; figure(4);
f=(2/T)*(1:(FS))/(FS); subplot(211);
plot(ff,abs(fft(r_info,q*FS))/FS); grid on; subplot(212);
pwelch(r_info,[],[],[],Rs); %抽样
r_data=real(r_info(1:(2*q):length(t)))... %离散时间基带信号 +1i*imag(r_info(1:(2*q):length(t))); % (H) figure(5) figure(5); subplot(212);
stem(tt(1:20),(imag(r_data(1:20)))); axis([0 12e-7 -100 150]);
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grid on; figure(6);
f=(2/T)*(1:(FS))/(FS); subplot(211);
plot(f,abs(fft(r_data,FS))/FS); grid on; subplot(212);
pwelch(r_data,[],[],[],2/T); ?T
info_2N=(1/FS).*fft(r_data,FS); % (I)
info_h=[info_2N(1:A/2) info_2N((FS-((A/2)-1)):FS)]; %限幅 for k=1:N,
a_hat(k)=alphabet((info_h(k)-alphabet)==min(info_h(k)-alphabet)); %j end; figure(7)
plot(info_h((1:A)),'.k');
title('info-h Received Constellation') axis square; axis equal; figure(8)
plot(a_hat((1:A)),'or'); title('a_hat 4-QAM') axis square; axis equal; grid on;
axis([-1.5 1.5 -1.5 1.5]);; subplot(211);
stem(tt(1:20),(real(r_data(1:20)))); axis([0 12e-7 -60 60]);
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