Proc. IEEE Int. Global
Nov. 29-Dec. 3, 2004, pp. 2297-2301, Dallas, TX USA.
An Achievable Performance Upper Bound for
Discrete Multitone Equalization
Zukang Shen, and
Brian L. Evans
Wireless Networking and
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
PTEQ provides a better bit rate vs. complexity tradeoff.
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Last Updated 10/25/03.