ofdm_signal.rar_GI-ZP OFDM_The Signal_guard interval_ofdm_ofdm s

% Faculty of Engineering, University of Fukui. 2003/11/11 % coded by Sokthai Chan ([email protected]) % OFDM signal and its spectrum ( Guard Interval insertion ) clear all; Fd=1; % symbol rate (1Hz) Fs=1*Fd; % number of sample per symbol M=4; % kind(range) of symbol (0,1,2,3) Ndata=1024; % all transmitted data symbol Sdata=64; % 64 data symbol per frame to ifft Slen=128; % 128 length symbol for IFFT Nsym=Ndata/Sdata; % number of frame -> Nsym frame GIlen=144; % symbol with GI insertion GI=16; % guard interval length % vector initialization X=zeros(Ndata,1); Y1=zeros(Ndata,1); Y2=zeros(Ndata,1); Y3=zeros(Slen,1); z0=zeros(Slen,1); z1=zeros(Ndata/Sdata*Slen,1); g=zeros(GIlen,1); z2=zeros(GIlen*Nsym,1); z3=zeros(GIlen*Nsym,1); % random integer generation by M kinds X = randint(Ndata, 1, M); % digital symbol mapped as analog symbol Y1 = modmap(X, Fd, Fs, 'qask', M); % covert to complex number Y2=amodce(Y1,1,'qam'); for j=1:Nsym; for i=1:Sdata; Y3(i+Slen/2-Sdata/2,1)=Y2(i+(j-1)*Sdata,1); end z0=ifft(Y3); for i=1:Slen; z1(((j-1)*Slen)+i)=z0(i,1); end % for i=1:Slen; g(i+16)=z0(i,1); end for i=1:GI; g(i)=z0(i+Slen-GI,1); end for i=1:GIlen; z2(((j-1)*GIlen)+i)=g(i,1); end end % graph on time domain figure(1); f = linspace(-Sdata,Sdata,length(z1)); plot(f,abs(z1)); Y4 = fft(z1); % if Y4 is under 0.01 Y4=0.001 for j=1:Ndata/Sdata*Slen; if abs(Y4(j)) < 0.01 Y4(j)=0.01; end end Y4 = 10*log10(abs(Y4)); % graph on frequency domain figure(2); f = linspace(-Sdata,Sdata,length(Y4)); plot(f,Y4); axis([-Slen/2 Slen/2 -20 20]);