Equalization Techniques for Multicarrier Modulation
Mr. Guner Arslan
UT Austin
Wednesday, August 11th, 3:30 PM, ENS 602
arslan@ece.utexas.edu
Abstract
The development of the Internet and multimedia applications has created a
demand for high-speed communication which requires broadband channels.
Inter-symbol interference (ISI) is a major problem with these channels. This
undesired effect is caused by spectral shaping of a channel. Two approaches to
combat ISI are full channel equalization and multi-carrier modulation (MCM)
which is currently one of the most promising techniques for high-speed digital
communications. It has been standardized for asymmetric digital subscriber
lines (ADSL) and digital audio/video broadcasting. With MCM, the problem of
fully equalizing a channel is converted into partitioning the channel into
small subchannels. However, this does not imply that equalization is not
required in an MCM system. A guard period longer than the channel impulse
response is required to separate subchannels at the receiver. Performance loss
due to this guard period can be reduced with an equalizer which shortens the
channel.
Starting with background information for multicarrier modulation, the
definition of the channel shortening problem is given. We present existing
solutions and their drawbacks before we derive a new objective function. This
objective function maximizes the geometric signal-to-noise ratio which is
currently one of the most popular performance measures in MCM equalizers. New
optimality criteria are discussed to overcome the drawbacks of existing ones.
A list of Telecommunications and Signal Processing Seminars is available at
from the ECE department Web pages under "Seminars".
The Web address for the Telecommunications and Signal Processing Seminars is
http://anchovy.ece.utexas.edu/seminars