Using modulated filter banks for ISI/ICI-corrupted multicarrier transmission

For Discrete Multitone (DMT) modulation orthogonality of the subchannels can only be guaranteed if the guard interval between consecutive symbols is at least as long as the channel impulse response. On the other hand, in order to minimize the delay of data running through a DMT system while maintaining a useful transceiver efficiency, the guard interval has to be as small as possible. In case of an insufficient guard interval DMT suffers from Intersymbol (ISI) and Intercarrier Interference (ICI) caused by poor frequency selectivity of the Discrete Fourier Transform (DFT) basis filters. In this paper we propose an algorithm using symbol-overlapping, redundant transforms for both, transmitter and receiver. We show that a combination of a low-delay cosine-modulated filter bank at the transmitter and an optimized filter bank at the receiver performs as good as the DMT solution, but with much smaller latency time. For channel equalization Zero-Forcing and MMSE methods are used. Different methods of redundancy insertion used for a better channel equalization are discussed. Due to better stopband attenuation of the basis filters modulated filter banks show less sensitivity to ISI/ICI and narrowband interferers.