DMT systems, DWMT systems and digital filter banks

Abstract

A multicarrier modulation system called discrete multitone (DMT) was chosen by the American National Standards Institute (ANSI) as a working standard for asymmetric digital subscriber line (ADSL) signaling. The DMT system uses the inverse and forward discrete Fourier transform (DFT) for modulation and demodulation. An alternative to the classic DMT system is to substitute a discrete wavelet transform in place of the DFT as the modulating transform. This new method is called discrete wavelet multitone (DWMT) signaling, and has been shown to be superior to the DMT system in certain channel environments. This paper illustrates that the DMT system and the DWMT system are both based on the theory of M-band wavelet filter banks. In particular, DMT and DWMT are linked formally through a discussion of digital multirate filter hanks and digital transmultiplexer. In addition the advantages of wavelet transform-based transmultiplexers over DFT-based transmultiplexers are discussed. >