%  baseband OFDM_DFT  %
close all; clear all;
T = 1000;    % symbol period
f = 1/T;   % frequency
N = 8;        % data No.
k = 0:N-1;
t = k./N/f;


data = floor(rand(1,2*N)*2);   % data 0&1
qp = [1+i -1+i 1-i -1-i];    
              
for n = 1:N
sums = 2*data(2*n-1)+data(2*n); 
d(n) = qp(sums+1);
end 

a = real(d);
b = imag(d);

u = ifft(d);
sB = real(u);


df=fft(u); 


a1=real(df);
b1=imag(df);




  figure(1)
  plot(t,sB);
  title('OFDM signal');
    
  figure(2)
  subplot(12,1,1:2);stem(0:2*N-1,data);
  
  subplot(12,1,4:5);stem(k,a);
  subplot(12,1,6:7);stem(k,b);
  
  subplot(12,1,9:10);stem(k,a1);
  subplot(12,1,11:12);stem(k,b1);
  title('transmitted/received signal');