Faced with fierce competition from cable operators, telephone companies are
now aggressively investing in digital subscriber line technology with the
objective of providing an economic broadband access alternative. However, h
igh-bitrate transmissions over the metallic access network is far from triv
ial. The subscriber loop predominantly consists of interconnection of twist
ed pair copper sections. This causes severe attenuation of the high-frequen
cy components of the transmitted signal. Equalization refers to the signal
processing in the transceiver to combat the effects of the dispersive chann
el on the transmitted signal. This article overviews equalization methods f
or discrete multitone modulation (DMT). The interference structure created
by a non-ideally equalized channel is analyzed. Time modulation as well as
frequency domain equalization methods are addressed.