IEEE Transactions on Signal Processing, vol. 49, no. 12, pp. 3123-3135, Dec. 2001.

Equalization For Discrete Multitone Transceivers To Maximize Bit Rate

Guner Arslan (1), Brian L. Evans (2), and Sayfe Kiaei (3)

(1) Cicada Semiconductor, 811 Barton Springs Road, Suite 550, Austin, TX 78704 USA, garslan@cicada-semi.com

(2) Department of Electrical and Computer Engineering, Engineering Science Building, The University of Texas at Austin, Austin, TX 78712-1084 USA
bevans@ece.utexas.edu

(3) Department of Electrical Engineering, Arizona State University, P. O. Box 875706, Tempe, AZ 85287-5706 USA
Sayfe.Kaiei@asu.edu

Draft of Final Paper

ADSL TEQ Design Matlab toolbox, DSP source code, papers, and presentations

Abstract

In a discrete multitone receiver, a time-domain equalizer (TEQ) reduces intersymbol interference (ISI) by shortening the effective duration of the channel impulse response. Current TEQ design methods such as minimum mean-squared error (MMSE), maximum shortening SNR (MSSNR), and maximum geometric SNR (MGSNR) do not directly maximize bit rate. In this paper, we develop two TEQ design methods to maximize bit rate. First, we partition an equalized multicarrier channel into its equivalent signal, noise, and ISI paths to develop a new subchannel SNR definition. Then, we derive a nonlinear function of TEQ taps that measures bit rate, which the proposed maximum bit rate (MBR) method optimizes. We also propose a minimum-ISI method that generalizes the MSSNR method by weighting the ISI in the frequency domain to obtain higher performance. The minimum-ISI method is amenable to real-time implementation on a fixed-point digital signal processor. Based on simulations using eight different carrier-serving-area loop channels,

the proposed methods yield higher bit rates than MMSE, MGSNR, and MSSNR methods;
the proposed methods give three-tap TEQs with higher bit rates than 17-tap MMSE, MGSNR, and MSSNR TEQs;
the proposed MBR method achieves channel capacity with a five-tap TEQ; and
the proposed minimum-ISI method achieves the bit rate of the optimal MBR method.

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Last Updated 01/30/03.