Interference Suppression in DMT Receivers Using Windowing

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.