The OFDM system and equalization algorithm based on the fractional Fourier transform

The performance of traditional OFDM system is greatly degraded in time-varying fading channel due to the inter-carrier interference (ICI). This paper proposes an OFDM system based on the fractional Fourier transform in which traditional Fourier transform is replaced by fractional Fourier transform to modulate and demodulate the symbols. The algorithm for selecting the optimal order of fractional Fourier transform is derived. Moreover, the multiplication filter in fractional Fourier domain is designed according to the minimum mean square error (MMSE) criterion to equalize the received signal. Theoretical analysis and numerical simulation results show that the proposed equalizer in optimal fractional Fourier domain can significantly improve the performance of OFDM compared with Fourier domain equalizer.