EURASIP Journal on
Applied Signal Processing,
vol. 2003, no. 13, pp. 1279-1290, Dec. 1, 2003.
Efficient Channel Shortening Equalizer Design
Rick K. Martin (1),
Ming Ding (2),
Brian L. Evans (2),
C. Rick Johnson, Jr.
(1) Department of Electrical and Computer Engineering,
Rhodes Hall, Cornell University,
Ithaca, NY 14853 USA
(2) Department of Electrical and Computer Engineering,
Engineering Science Building,
The University of Texas at Austin,
Austin, TX 78712-1084 USA
at Cornell -
at UT Austin
Time-domain equalization is crucial in reducing
channel state dimension in maximum likelihood sequence
estimation, and inter-carrier and inter-symbol interference
in multicarrier systems. A time-domain equalizer
(TEQ) placed in cascade with the channel produces an
effective impulse response that is shorter than the channel
impulse response. This paper analyzes two TEQ design
methods amenable to cost-effective real-time implementation:
minimum mean squared error (MMSE) and maximum
shortening SNR (MSSNR) methods. We reduce
the complexity of computing the matrices in the MSSNR
and MMSE designs by a factor of 140 and a factor of 16
(respectively) relative to existing approaches, without degrading
performance. We prove that an infinite length
MSSNR TEQ with unit norm TEQ constraint is symmetric.
A symmetric TEQ halves FIR implementation complexity,
enables parallel training of the frequency-domain
equalizer and TEQ, reduces TEQ training complexity by
a factor of 4 and doubles the length of the TEQ that can
be designed using fixed-point arithmetic, with only a small
loss in bit rate. Simulations are presented for designs with
a symmetric TEQ or target impulse response.
Last Updated 12/04/07.