Transmit Spectra Adaptive to Noise and Interference at Activation for HDSL2

We present several methods for implementing optimal HDSL2 transmit spectra that, at activation, adapt to the surrounding interference and noise. The methods are based around either a set of xed transmit lters or a single adaptive transmit lter that uses the optimal transmit spectrum. Designing optimal spectra with minimum required power can further increase the spectral compatibility of the system. Transmit spectrum can be adapted on-line to changes in interference characteristics either by reshaping the spectrum optimally or by adjusting the power in step increments until the desired margin is reached (power control). Adaptation of transmit spectra to interference and noise could be made an option in the HDSL2 standard. NOTICE This contribution has been prepared to assist standards Committee T1-Telecommunications. This document is o ered to the Committee as a basis for discussion and is not a binding proposal on Rice University or on any company. The contents are subject to change in form or content after further study. Rice University speci cally reserves the right to add to, amend, or withdraw the statements contained herein. 1 Transmit Spectra Adaptive to Noise and Interference at Activation T1E1.4/98-258