DMT gets go-ahead for VDSL standard process

The votes have been counted, and barring a surprise appearance by Katherine Harris, discrete multi-tone (DMT) line coding will be the approved standard for VDSL in North America. In voting that concluded late last night, DMT was selected as the preferred line coding and will be the only line code specified as part of the American National Standard’s VDSL standard, according to the Alliance for Telecommunications Industry Solutions.

However, quadrature amplitude modulation (QAM) line coding, which faced off with DMT in the recently completed “VDSL Olympics” at Telcordia and BT, will become a specified Technical Requirement under Committee T1.

DMT, which has been gaining vocal support from vendors over the past few months, can support data at up to 50 Mb/s. One of the biggest pluses on the DMT side is its proven use in ADSL-based services.

QAM backers, however, point to their preferred line-coding use in early VDSL deployments. In particular, they point to the Asian market where VDSL has become one of the fastest growing technologies.