Journal of Signal Processing Systems,
Mar. 2012, vol. 66, no. 3, pp. 259-272.
(First online May 31, 2011.)
Design of Sparse Filters for Channel Shortening
Brian L. Evans
Department of Electrical
and Computer Engineering,
Engineering Science Building,
The University of Texas at Austin,
Austin, TX 78712 USA
ADSL Research at UT Austin
Channel shortening equalizers are used in acoustics to reduce
reverberation, in error control decoding to reduce complexity, and
in communication receivers to reduce inter-symbol interference.
The cascade of a channel and channel shortening equalizer ideally
produces an overall impulse response that has most of its energy
compacted into fewer adjacent samples.
Once designed, channel shortening equalizers filter the received
signal on a per-sample basis and need to be adapted or re-designed
if the channel impulse response changes significantly.
In this paper, we evaluate sparse filters as channel shortening
Unlike conventional dense filters, sparse filters have a small
number of non-contiguous non-zero coefficients.
Our contributions include
We apply the proposed equalizer design procedures to
- proposing optimal and sub-optimal low complexity algorithms
for sparse shortening filter design, and
- evaluating impulse response energy compaction vs. design and
implementation stage computational complexity tradeoffs for the
Our simulation results utilize measured channel impulse responses
and show that sparse filters are able to achieve the same channel
energy compaction with half as many coefficients as dense filters.
- asymmetric digital subscriber line channels and
- underwater acoustic communication channels.
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