A combined DMT/DWMT system for DSL application

Abstract

A drawback of discrete multitone transmission (DMT) using discrete Fourier transform (DFT) bases as carriers is its sensitivity to narrow band interference. With overlapped orthogonal wavelet bases as carriers, discrete wavelet multitone transmission (DWMT) possesses better spectral containment than the DFT-based DMT, and can achieve a high level of immunity to narrow band interference at the cost of higher system delay and complexity. In this paper, we propose the use of overlapped pseudo-orthogonal bases for DWMT, which can be easily implemented on current DMT system. The resulting combined system can adapt itself to different channel environments by selecting the better transmission mode from DMT and DWMT, thereby combating narrow band interference effectively.