Trade-off between SNR and ISI in
Multi-Channel Zero Forcing
Equalizers
Trade-off between SNR and ISI in
Multi-Channel Zero Forcing
Equalizers
T. Settle, M. D. Zoltowski and V. Balakrishnan
IEEE Signal Processing Workshop on Statistical Signal
and Array Processing
pages 96-99,
Portland, OR, September 1998
Abstract: Multi-channel linear equalizers are commonly
employed in digital communication systems to mitigate channel
distortions and thereby reduce inter-symbol interference
(ISI). Traditional multi-channel linear equalizer design for linear
time-invariant channels requires synthesis of equalizing filters such
that the frequency response of the overall system has unit magnitude
and linear phase. In this work, we investigate the efficacy of
deliberately allowing equalization errors, i.e., allowing deviations
from unit magnitude and linear phase of the overall frequency
response, with the goal of increasing the signal-to-noise ratio (SNR)
in the symbol decision statistics. Our approach relies on numerical
convex optimization based on linear matrix inequalities. Our
investigations reveal that as the allowable equalization error is
increased, the mean-square error (MSE) of the post-equalizer signal
constellation decreases despite the attendant increase in ISI. This
implies that the trade-off between SNR and ISI in the symbol decision
statistic weighs more heavily in favor of SNR improvement for a
surprisingly large range of allowable equalization error.
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