(Very-high speed DSL) will eventually emerge as a primary
"last-mile" broadband solution for both the home and business. The
value proposition for VDSL in both marketplaces is very attractive.
VDSL enables Telcos to offer broadband services that provide a
quantum leap in terms of access speed and applications available to
the end user. VDSL provides Telcos the technology to compete in the
residential market for bundled voice, data and video services using
copper infrastructure without having to install fiber-to-the-home.
Likewise, VDSL will provide a very low cost data transfer technology
enabling high-speed data networking, high quality video conferencing
and multiple voice lines for businesses over the existing copper
infrastructure. Although the capabilities of VDSL are revolutionary,
the industry has to overcome distance limitations and standards
issues before the technology will be viable as a mass-market
VDSL is one
of the most promising technologies to emerge in the current
telecommunications market. Like other xDSL technologies (ADSL, SDSL
and G.lite), VDSL utilizes a single twisted copper pair to provide
high speed access. While other xDSL services are capable of up to 8
Mbps download speed, VDSL facilitates transfer rates of up to 52
Mbps, which is 1,000 times the capacity of today's dial-up lines.
VDSL soon will be cost competitive with other xDSL technologies.
transfer speeds enables Telco's to cost-effectively provide many
services that cannot be supported by other lower speed DSL
solutions. ADSL, SDSL and G.lite are limited to providing data
access and a single video channel for the residential market and
primarily data access and limited data networking for the small
business market. Asymmetrical VDSL allows Telco's to penetrate the
residential market with multiple video services, bundled with data
access and telephony. Symmetrical VDSL provides bundled data
networking, video conferencing and voice service for the business
VDSL provides more bandwidth than is required for most applications
today, its potential value as a broadband solution will not be
realized for several years. The growth of VDSL is dependent upon
applications that are still in their infancy. Many of these new
value-added service offerings for businesses will significantly
drive the need for VDSL's increased bandwidth. Voice-over-DSL/IP,
Virtual Private Networks, firewalls and other IP-based applications
will be attractive to business customers since they replace the
functionality of more traditional technologies, but at lower cost
and more simple ease of use. Similarly, developments in
high-bandwidth video will make videoconferencing and other video
applications more accessible for businesses.
example that will drive VDSL acceptance is voice-over-DSL/IP, which
is already gaining small and medium sized business customers.
Instead of purchasing a costly T-1 connection, which includes 24
individual voice channels, businesses can use VDSL to install
voice-over-DSL, which will support hundreds of voice lines simultaneously on a single copper pair (compared to 24 for
other xDSL offerings) while providing dedicated bandwidth for data
services. This type of capacity will be attractive to companies that
will expand call centers, set up informal call centers or just
reduce corporate telecom costs. Given the high prices for substitute
products, such as SDSL and T-1 lines, the potential margins for VDSL
in this application could initially be quite large.
Voice-over-DSL/IP is expected to gain traction in the market by
technology also will provide bandwidth to enable Telcos to leverage
the existing copper infrastructure to provide residential video
services. As the cable industry moves into bundling telephone and
data services with broadcast television, Telcos require a technology
to enable them to remain competitive in the residential market. VDSL
is the only DSL technology with enough bandwidth to support bundled
digital broadcast TV for multiple TVs, data services and POTS on a
single copper line to the home. VDSL also can allow Telcos to
provide value-added video services over VDSL, including
video-on-demand, interactive TV and T-commerce.
VDSL offers the key to competing with cable offerings in the
residential market. Cable companies are beginning to focus on
bundling video, data and voice services over coaxial, thus
completely bypassing the Telco's infrastructure. To maintain a
competitive position, ILECs must enter into the video delivery
business, countering with video-over-VDSL. VDSL, with its high
transmit speeds, is the only DSL technology that allows ILECs to
provide video services to multiple televisions, while also offering
telephony and data access services. Although the margins on each
line are not large (estimated annual revenue per line of roughly
$400), the potential market base is immense, with nearly 100 million
potential residences. By 2002, Cahner's in-Stat predicts that over
500,000 homes will use video-over-VDSL services growing to over 7
million by 2005.
the potential VDSL currently exhibits, the technology must overcome
three major potential obstacles to adoption: the establishment of
standards; "last-mile" distance limitations; and provisioning.
- Currently there are two camps within the VDSL industry
advocating two different standards, QAM and DMT. Until standards
are established, it is unlikely that carriers will invest
significantly on large-scale VDSL deployments.
- Distance limitation is another major obstacle for VDSL, as the
technology is only effective over 4,000 feet of copper wire from
the CO (other DSL solutions can function at up to 18,000 feet).
Updated infrastructure projects that extend fiber to the
neighborhood, curb, or basement of a building, reduce the
distances required to deliver VDSL to the end-user. However, it
remains to be seen how far carriers are willing to expand
expensive fiber networks. VDSL will not be a large-scale
commercial solution, especially for the residential market, until
fiber is deployed further into the telecommunications
- The final obstacle is the most straightforward but most
essential to overcome -- provisioning. Current DSL offerings are
being hindered by inefficiencies in provisioning and deployment,
providing added momentum to competing and substitute technologies
such as cable. Provisioning problems are tarnishing the image DSL
as a communications solution, similarly to the way provisioning
contributed to the failure of ISDN.
still in its developmental stages. So far, few carriers in the US
have chosen to deploy VDSL. US West has deployed to approximately
50,000 homes in the Phoenix area, and GTE has preformed trials in
Tampa. However, both companies have shelved their projects
indefinitely due to their respective mergers. Most recently, Bell
Canada announced its VDSL deployment to several multi-dwelling units
in Canada and overseas, France Telecom and Singapore Telecom
recently announced VDSL deployments.
discuss or for more information regarding this article, please
contact Rob Fisher (301-664-7777)