DMT line code for VDSL

Eleven Digital Subscriber Line semiconductor and system vendors have announced their support of Discrete Multi-Tone modulation as the line code for standard-compliant very-high-bit-rate digital subscriber lines.

Eleven Digital Subscriber Line (DSL) semiconductor and system vendors have announced their support of Discrete Multi-Tone (DMT) modulation as the line code for standard-compliant very-high-bit-rate digital subscriber lines (VDSL).

The vendor group, who together supply the dominant share of ADSL ports shipped world-wide, includes Alcatel, Analog Devices, Broadcom Corporation, Ericsson, Ikanos Communications, Intel, LSI Logic, Nokia, STMicroelectronics, Texas Instruments and Thomson Multimedia.

‘DMT line coding for VDSL has been promoted for many years,’ said Matt Davis, Director of Broadband Access Technologies for The Yankee Group. ‘With 11 of the leading DSL silicon and systems providers supporting DMT, which represents the majority of the DSL market, it is clear that DMT is on track to become the favoured modulation for standardised VDSL deployments world-wide.’

DMT is the most widely deployed DSL line code, with more than 36 million ADSL lines deployed world-wide at the end of 2002, according to a study by Point Topic. Extending DMT capabilities from ADSL to VDSL sets the stage for a multi-DSL infrastructure capable of providing a range of services from Internet access and packet telephony to high-quality digital video.

‘Consolidating ADSL/VDSL into a single line code is key to streamline networks allowing lower operational costs,’ said Ragnar Erkander, Vice President of Broadband Access Portfolio Management at Ericsson AB. ‘Creating a common line code for ADSL and VDSL will also lay the foundation for software-configured DSL ports, which is crucial to reaching high network utilisation rates.’

Three standards bodies, the Committee T1 Working Group T1E1.4, the IEEE 802.3ah Ethernet in the First Mile Task Force and the ITU-T Study Group 15, have stated their intention to select a VDSL line code for standardisation within the next two months.