DMT takes gold at VDSL Olympics

Discrete Multi-Tone line coding took a big step toward standardization with the announcement that it had outperformed Quadrature Amplitude Modulation at the recently completed VDSL Olympics.

The two line codes, which have been backed by vendors on both sides, are competing to become the standard technology that will be used in VDSL equipment. Committee T1 (T1E1.4) is expected to announce its choice by the end of this week and will use results from the Olympics in that decision, according Richard Sekar, vice president of marketing for Ikanos, which is among the most vocal vendors in the DMT camp.

“It is important that the standards body makes a single line code because it’s in the best interest of the consumer,” Sekar said. “The bickering between QAM and DMT slowed things down.”

The results from the tests, conducted in part by Telcordia, build on an announcement during Supercomm two weeks ago in which 11 semiconductor and system vendors threw their support behind DMT.

QAM, which has been in the market longer than DMT, is deployed in a number of important Asian carriers’ networks as well as in early commercial deployments at Bell Canada. However, there has been a marked shift over the last few months as more vendors and some carriers shift favor to DMT. The results of this week’s tests simply add another nail in the coffin of QAM, Sekar said.

“QAM guys once again are claiming they are the most mature,” he said. “If all they can show with the most mature technology is performance that is less than half of DMT, there isn’t much room for growth.”