Bandwidth efficient OFDM communication system

Abstract

Due to ever-increasing bandwidth demands in future wireless service, the radio frequency band becomes more and more invaluable. In conventional OFDM there is a lot of wastage of bandwidth in the Guard Interval. We aim to reduce or eliminate the Guard Interval completely to increase bandwidth efficiency. This was suggested by Yi Sun in an IEEE journal paper titled, ‘Bandwidth Efficient Wireless OFDM’. We consider the OFDM that achieves high efficiency of bandwidth usage, allows ISI and ICI to exist, and uses sufficient statistics insymbol demodulation. A one-tap decision feedback equalizer (DFE) is proposed for equalization of the bandwidth-efficient OFDM system Though occupying a narrowerbandwidth, the one-tap DFE-based bandwidth-efficient OFDM system achieves lower symbolerror rate and higher mutual information than the conventional DFT-based OFDM system. The proposed OFDM system presents a monotonically increasing symbol error rate. Orthogonal Frequency Division Multiplexing (OFDM) an efficient modulation scheme for frequency selective channels, e.g. how Intersymbol Interference (ISI) can be avoided using orthogonal subcarriers. In order to transfer data over the channel, data is compressed in frames of desired length. At the receiver the signal is sampled. A key issue is to synchronize the system in order to distinguish what frame the samples belong to. Another issue is to avoid interference, which may deteriorate the performance of the modem.