Standards project : T 1 E 1 . 4 : VDSL Title : Pulse Shaping with Zipper – Spectral Compatibility and Asynchrony Source : Telia Research AB Contact :

We have investigated what the effects of adding pulse shaping and windowing to a ZipperVDSL system would be. By adding short, pulse-shaped wings to the DMT symbol and accepting the, say, 3 % efficiency loss, the spectral sidelobes of the DMT-symbol are reduced. This provides several attractive features including the following: • The pulse shaping in the transmitter reduces the out of band power of the DMT-signal. • The spectral compatibility with other systems such as ADSL and CAP-VDSL is enhanced. • It becomes feasible to use Zipper-VDSL in a time-asynchronous mode, where a VTU-R only synchronizes itself to its VTU-O, while the VTU-R / VTU-O pair may be asynchronous to all other transceiver pairs. • The pulse shaping gives some increase in the depth of spectral notches, for HAM-bands etc. The windowing is a part of a powerful RFI-ingress suppressing method as proposed by Wiese and Bingham. This contribution has been prepared to assist ANSI Standards Subcommittee T1E1.4. This document (T1E1.4/98-041) is offered as a basis for discussions and is not a binding proposal of Telia Research AB and SGS-Thomson. Telia Research AB and SGS-Thomson specifically reserves the right to add to, amend or withdraw the statements contained herein. 2(6) Austin, Texas March 2-6, 1998 T1E1.4/98-041