FFT-based equalizer with Doppler compensation for OFDM systems in time-variant multipath channels

In Orthogonal Frequency Division Multiplexing (OFDM) mobile communication systems time-varying channels cause an inter-carrier interference (ICI) and degrade the performance due to the frequency orthogonality loss. Doppler shift compensation or equalization is very complex and often prohibitive in consumer receiver equipment. We propose a Doppler effect compensation / equalization technique for these kinds of scenarios. Using this technique we can compensate fast time-varying channels perfectly within an OFDM symbol with uniform Doppler shift and perfect channel knowledge. The computational complexity of the technique is the same as of FFT (N log(N)).