Using fft and ifft for carrier modulation/demodulation In practice, such parallel data modulation and coherent demodulation can be simply done by using inverse fast Fourier transfer(IFft) and fast Fourier transfer (FFt) The basic orthogonal function is 2丌 g(k)=expl j k=0, 1,N-1,n=0,1,N-1 2 2 丌 >expl j pn expl -j kn=N,k=p N 2丌 2丌 exp pn expl-j3Mn=0,k≠p =0Using FFT and IFFT for carrier modulation/demodulation In practice, such parallel data modulation and coherent demodulation can be simply done by using inverse fast Fourier transfer (IFFT) and fast Fourier transfer (FFT) The basic orthogonal function is , 0,1,... 1, 0,1,... 1 2 ( ) exp  = − = −      = k n k N n N N g k j          =        −       = =       −        − = − = 1 0 1 0 0, 2 exp 2 exp , 2 exp 2 exp N n N n k n k p N pn j N j k n N k p N pn j N j    