VDSL a choice for bundled services.
Electronic Buyers' News, March 20, 2000 p40
By Schenck, Martin
The flourishing deployment of technologies like digital subscriber line demonstrates how local exchange carriers are moving toward new and advanced broadband services.
Now, LECs face a challenge from cable providers that promise to bundle voice, video, and data using cable-modem technology. In response to the challenge, DSL-chip vendors continue to develop higher-bandwidth technologies such as Very High Bit-Rate DSL (VDSL).
Targeted at residential and business markets, VDSL is a high-end DSL technology that provides broadband transmission at speeds of up to 26 Mbits/s downstream and up to 13 Mbits/s upstream.
As a result of these speeds, the deployment of VDSL technology enables LECs to provide bundled services like voice, data, and video simultaneously. VDSL technology is also programmable, enabling both symmetric and asymmetric DSL services. Using VDSL, LECs can compete for bundled services without the need to deploy fiber-to-the-home.
While only in its infancy, the VDSL chipset market is projected to grow from 80,000 units in 1998 to 1.76 million units in 2003, a compound annual growth rate of 86% in the next five years, according to Dataquest Inc., San Jose.
Before VDSL can be deployed on a mass scale, however, the standards question must be resolved. The three major standards bodies-ANSI, the ITU, and ETSI-started working on VDSL in 1996. Good progress has been made in these bodies, including the choice of FDD (frequency-division duplexing) as the standard duplexing scheme. But there are still some issues in terms of line code.
ETSI has agreed on two competing line-code technologies, QAM and DMT. A draft ETSI standard is expected in the first half of this year. ANSI initially decided to defer line-code selection to the ITU to concentrate on other specifications. More recently, ANSI has adopted a dual-line-code standard-DMT and QAM-at least for the time being. In the ITU, however, the line-code issue remains further from resolution, which has contributed to tying up prog- ress on VDSL.
Adoption of a single line-code standard is desirable, but it has been impossible up to now to select one over the other. However, with ETSI providing a standard framework this year and ANSI heading in the same direction, system vendors can now begin to address the LECs' demand for competitive solutions capable of bundling voice, video, and data.
LECs also recently expressed interest in transmission-rate standards, providing asymmetric-based VDSL services at speeds up to 22 Mbits/s downstream and 3 Mbits/s upstream. For symmetric-based VDSL services, there is a push to support downstream and upstream transmission rates of 13 Mbits/s.
But to compete with cable providers, the most important issue is early deployment of VDSL systems, which involves solving the standards issue.
A second criterion is the availability of field-proven VDSL chipsets.
Although the dual-line-code situation in ETSI and ANSI still requires system vendors and LECs to choose one line code over the other, the immediate need to compete with cable will reduce the selection criteria to issues such as availability of FDD-based solutions, complexity, power consumption, and maturity of technology.
With all the chipsets available today-and with support from the industry-QAM is poised to become the de facto standard, ultimately resolving the dual-line-code situation and opening the floodgates for VDSL.
-Martin Schenck is ADSL product marketing manager at Infineon Technologies Inc., San Jose.
ebnonline.com |
