Channel equalization for wireless OFDM systems with ICI and ISI

In an OFDM system for wireless communications, a guard interval longer than the channel delay is used to avoid interchannel interference (ICI) and intersymbol interference (ISI), so the multiplexed subchannels can be decoupled by the discrete Fourier transform (DFT). However, this ICI- and ISI-free OFDM system reduces the efficiency of bandwidth usage and prevents the use of sufficient statistics in channel equalization. We consider an OFDM system that achieves one hundred percent efficiency of bandwidth usage and uses sufficient statistic. A one-tap decision feedback equalizer (DFE) is proposed. It is demonstrated that though occupying a narrower bandwidth, the one-tap DFE based, ICI and ISI OFDM system achieves a lower symbol error rate and higher mutual information between the input of the decision device and transmitted symbols