Low-complexity ICI suppression for OFDM over time- and frequency-selective Rayleigh fading channels

While rapid variations of the fading channel cause intercarrier interference (ICI) in OFDM, thereby degrading its performance considerably, they also introduce temporal diversity, which can be exploited to improve the performance. We first derive a matched filter bound (MFB) for OFDM transmissions over doubly-selective Rayleigh fading channels, which benchmarks the best possible performance if ICI is completely cancelled without noise enhancement. We then develop low-complexity MMSE and DFE receivers for ICI suppression. Simulations show that the DFE receiver can collect significant gains of ICI-impaired OFDM with affordable complexity.