Bandwidth efficient wireless OFDM

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

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