Optimal Transmit Spectra for Communication on
Digital Subscriber Lines
Rohit Gaikwad
(rohitg@rice.edu)
Electrical and Computer Engineering, Rice University
Richard Baraniuk (richb@rice.edu)
Electrical and Computer Engineering, Rice University
This paper presents a general framework for designing optimal transmit spectra
for symmetric bit-rate communication services dominated by crosstalk,
in particular Digital Subscriber Line (DSL) services such as the proposed
HDSL2. Using the channel, noise, and interference transfer
functions, we set up and solve an optimization problem to maximize
the joint capacity of neighboring lines. Joint signaling techniques
and optimal power distribution yield significant gains in bit rates
(or performance margins) over current schemes. Furthermore, by design,
the spectra are spectrally compatible with existing neighboring
services. The framework is quite general --- it does not depend on
the exact choice of modulation scheme, for example. It is also
extremely simple and of low computational complexity.