Filtered multitone modulation for VDSL

Abstract

We present a filter-bank modulation technique called filtered multitone (FMT) and describe its application to data transmission for very-high-speed digital subscriber line (VDSL) technology. The proposed scheme leads to significantly lower spectral overlapping between adjacent subchannels than for known multicarrier techniques such as discrete multitone (DMT) or discrete wavelet multitone. This allows mitigating interference due to echo and near-end crosstalk signals, increasing system throughput and reach, and simplifying system operations for VDSL transmission. In the receiver of an FMT system, signal equalization is accomplished in the form of per-subchannel symbol-spaced or fractionally-spaced linear or decision-feedback equalization. We study by simulation the performance that can be achieved by FMT modulation for VDSL systems where upstream and downstream signals are separated by frequency-division duplexing. We also provide comparisons with DMT modulation for a typical transmission scenario.