Proc. IEEE Int. Global Communications Conf., Nov. 29-Dec. 3, 2004, pp. 2297-2301, Dallas, TX USA.

An Achievable Performance Upper Bound for Discrete Multitone Equalization

Ming Ding, Zukang Shen, and Brian L. Evans

Embedded Signal Processing Laboratory, Wireless Networking and Communications Group, The University of Texas at Austin, Austin, TX 78712 USA - -


ADSL Research at UT Austin


Channel equalization plays a key role in enabling multicarrier wireline communication systems to achieve high bit rates. Some VDSL systems and all standard ADSL systems employ both time domain equalization (TEQ) and frequency domain equalization (FEQ). TEQ shortens channel memory, and FEQ inverts the shortened channel. A per tone equalizer (PTEQ) and a TEQ filter bank (TEQFB) tailor equalization on a per subchannel basis and achieve high bit rates. PTEQ jointly performs TEQ and FEQ by linearly combining subchannel fast Fourier transform (FFT) coefficients. TEQFB applies a real-valued finite impulse response filter per subchannel and a separate FEQ. In this paper, we present a complex-tap TEQFB to perform TEQ and FEQ jointly in the time domain. We optimize the additional parameter set of transmission delays for each subchannel with respect to bit rate. We present an iterative training method to design the complex TEQFB coefficients based on the second-order statistics of the input and output sequences, which removes the need for channel estimation. In simulation, the complex-tap TEQFB has a slight advantage in bit rate over existing methods due to the optimization of the subchannel transmission delays. PTEQ provides a better bit rate vs. complexity tradeoff.

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Last Updated 10/25/03.