A new receiver structure for improving the performance of conventional Discrete Multitone (DMT) based Digital Subscriber Line (DSL) transceivers is described. In this method, the conventional demodulator consisting of a FFT followed by a scalar frequency-domain equalizer is augmented by an additional data-path utilizing windowing. Time-limited receiver windowing is done independently for each symbol over the orthogonality interval while the transmitter is unchanged. Windowing can be carried out efficiently in the time or frequency domain. A decision feedback equalizer is used to cancel the resulting inter-bin-interference. Computer simulation results are presented for ADSL with realistic interference conditions which show that this method is most effective against narrowband interference and other impairments which lead to diminished inter-bin orthogonality. The overall technique is also applicable to other multicarrier modems such as VDSL and wireless OFDM.

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In this paper are presented methods for persubchannel equalization and echo cancellation in the OQAMbased parallel data transmission, which exploit the inherent T/2 AM signaling structure of the orthogonally frequencydivision multiplexed T/2-offset quadrature subchannel signals. The method of equalization on itself represents an alternative approach to the previously known one, whereas the method of echo cancellation gives potentially the only valid solution of this problem at the time being. The computationally efficient realization of echo cancellation is based on the conventional combination of poly-phase (PP) filtering and discrete Fourier transforms in realizing filter banks. The LMS algorithm convergence behavior has been analyzed by computer simulation, along with those of a two-step strategy to speed-up adaptation of the corresponding FIR adaptive structures.

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