Open Access

Efficient Channel Shortening Equalizer Design

  • Richard K. Martin1Email author,
  • Ming Ding2,
  • Brian L. Evans2 and
  • C. Richard JohnsonJr.1
EURASIP Journal on Advances in Signal Processing20032003:906491

DOI: 10.1155/S1110865703307024

Received: 6 February 2003

Published: 24 December 2003

Abstract

Time-domain equalization is crucial in reducing channel state dimension in maximum likelihood sequence estimation and intercarrier and intersymbol 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 square 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.

Keywords

multicarrier modulation channel shortening time-domain equalization efficient computation symmetry

Authors’ Affiliations

(1)
School of Electrical and Computer Engineering, Cornell University
(2)
Department of Electrical and Computer Engineering, The University of Texas at Austin

Copyright

© Copyright © 2003 Hindawi Publishing Corporation 2003