OFDM.rar_doppler shift OFDM_ofdm多径时延_多径效应_多普勒频OFDM_多普勒频移OFDM

%% simulation of OFDM through multipath channel %% the time resolution is ts=1/Fs=0.078us %% GSM TU channel: six rays %% power dB----->value delay(us) %% -3.0 0£®1897 0 %% 0 0£®3785 0.2 %% -2.0 0£®2388 0.5 %% -6.0 0£®0951 1.6 %% -8.0 0£®0600 2.3 %% -10.0 0£®0379 5.0 clear error=zeros(1,100); frame_total=1; N=2048; %% number of subcarriers G=120; %% length of guard interval multipath=[sqrt(0.1897) 0 sqrt(0.3785) 0 0 sqrt(0.2388) 0 0 0 0 sqrt(0.0951) 0 0 0 0 sqrt(0.06) 0 0 0 0 0 0 sqrt(0.0379)]; %% power multipath_channel=zeros(1,length(multipath)); EN=[10]; r=zeros(1,length(EN)); for snr=1:length(EN) en = 10^((EN(snr))/10); sigma = 1/sqrt(2*en); for frame_temp=1:frame_total multipath_channel=multipath.*(randn(1,length(multipath_channel))+j*randn(1,length(multipath_channel)))*sqrt(0.5); %% rayleigh fading fdata=2*round(rand(1,N))-1; %% BPSK data tdata=ifft(fdata,N)*sqrt(N); %% OFDM modulation tdata_guard=[zeros(1,G) tdata];[tdata(N-G:N) tdata]; %% add guard interval,cyclic prefix tdata_chan=filter(multipath_channel,[1],tdata_guard);;%% passing through the multipath channel tdata_chan_dguard=tdata_chan(G+1:N+G); %% discard the guard interval fdata_rev_channel=fft(tdata_chan_dguard,N)/sqrt(N); %% OFDM channel estimation demodulate fchan_est=fdata_rev_channel./fdata; %% frequency channel fading facor h=[multipath_channel,zeros(1,N+G-length(multipath))]; fchan_est1=fft(h,N); %fchan_est1=fchan_1(:)+conj([fchan_1(G+1:N),zeros(1,G)]'); figure plot([1:2048],fchan_est,'r',[1:2048],fchan_est1,'b') le=length(tdata_chan); noise=sigma*(randn(1,le)+j*randn(1,le)); tdata_chan1=tdata_chan+noise; %% add the AWGN tdata_chan_dguard1=tdata_chan1(G+1:N+G); %% discard the guard interval fdata_rev=fft(tdata_chan_dguard1,N)/sqrt(N); fdata_rev1=fdata_rev.*conj(fchan_est);%% channel compensation error(snr)=error(snr)+sum(sign(real(fdata_rev1))~=fdata); end end ber=error(1:length(EN))/(N*frame_total) r= 10.^(EN/10); pb=0.5*(1-sqrt(r./(1+r))) figure semilogy(EN,ber,'b-*',EN,pb,'r-^')