|DSL: There's Treasure In Them Thar' Copper
BY FRANK AKERS
As customer demand for higher-speed Internet access and additional phone lines
accelerates throughout the nation, network service providers are faced with a real
dilemma: How to deliver both broadband and multiple services without discarding their
single greatest asset the copper network.
Network service providers, particularly the incumbent local-exchange carriers (LECs),
have invested many millions of dollars to create networks that are essentially ubiquitous
throughout the United States. Dataquest estimates
service providers have installed more than 200 million copper lines in North America and
close to 900 million copper lines worldwide. The total number of copper lines could exceed
one billion by 2002, Dataquest estimates. Until recently, these networks have served both
business and residential customers well and generated roughly $100 billion annually for
Not only do customers need more telephone lines for Internet access, they also need
faster ones. To meet these demands, service providers have several options. Replacing the
copper network with fiber would deliver the increased bandwidth customers crave, but this
solution is costly and so time consuming that it would likely leave them at a serious
competitive disadvantage. To meet demand for additional phone lines, carriers could
install more copper lines, but they would face similar barriers in terms of cost and time.
Plus, adding copper to the network now, when most agree that the networks of the future
will be fiber-based, is not the best long-term solution.
MAKING USE OF EXISTING COPPER
New technologies exist that allow service providers to address the speed
challenges and gain better return from their installed copper plant, both for the short
and long term. The most promising is digital subscriber line (DSL), which enables a copper
cable pair carrying POTS (Plain Old Telephone Service) traffic today to carry digitized
voice and data traffic at speeds far surpassing analog delivery.
For the network access provider, the principal benefit of DSL is this ability to permit
the rapid flow of information using existing copper infrastructure. DSL service
implementations also allow baseband voice and data traffic to be separated at the point
where they enter the network. Consequently, data traffic can be routed around the
traditional telephony network to an alternate data communications network, freeing the
telephony network to carry only voice traffic. This allows service providers to meet the
growing need for high-speed data services without having to upgrade their traditional
But most DSL service equipment offerings available today, known as DSLAMs, have serious
distance limitations they are not designed to operate at distances greater than
18,000 feet, and due to cable impairments, they rarely reach that far. This means that
providers cannot offer DSL to approximately 50 percent of their customers. Exacerbating
the challenge service providers face is demand for DSL customers want it, and they
want it quickly. In fact, demand is far outpacing the LECs ability to deploy DSL.
But a proven method for overcoming the distance limitations inherent in DSL is now
available in the form of long-range DSL transmission systems. These systems enable service
providers to provision DSL services to virtually all subscribers on their network in a
timely and cost-effective fashion.
These new systems allow network access providers to turn standard copper lines into
high-speed digital conduits that are capable of supporting more than one DSL-based access
service over long distances. Traditional DSL service equipment does not allow a single
copper line to provide multiple digital services. These long-range DSL transmission
systems utilize the copper infrastructure to deliver eight digital access lines used for
voice, high-speed analog modem access, and CLASS services such as Caller ID on one copper
pair as far as 100,000 feet from the central office. In addition, they facilitate delivery
of three high-speed DSL access services, including 144 Kbps DSL service, or ISDN Digital
Subscriber Line (IDSL) on one copper pair to locations as far as 100,000 feet from the
central office. IDSL may operate at the lowest speed of the DSL services, but at 144 Kbps,
it is still four times faster than the 33 Kbps speed at which most V.90 modems actually
operate. As a Dataquest analyst said, IDSLs market success proves that the
question to answer at this market stage is not How fast is the service? but
rather How fast can I get it?
These systems are designed to interoperate with a carriers existing
infrastructure, and offer efficient and cost effective installation and maintenance,
outside plant durability, and deployment flexibility. Thus, these long-range DSL
transmission systems which can be installed in a matter of hours provide a
cost-effective and time-saving alternative to upgrading the network. This equipment can be
placed virtually anywhere in the copper network in part because it is designed to have
very low power requirements. The technology allows service providers to power their
systems from the central office for a full 100,000 feet, giving carriers the flexibility
to deploy elements of these long-range DSL transmission systems wherever they are needed
regardless of power availability at a particular location.
The network technology that supports these long-range DSL transmission systems is known
as high bit-rate digital subscriber line HDSL, or SDSL. These systems are very easy to
install and are much less expensive than adding fiber or additional copper lines, and they
meet Public Utilities Commissions (PUC) requirements for minimum modem connection speeds.
Network access providers can use long-range DSL transmission systems to rapidly increase
network capacity in rural and suburban areas. By installing long-range DSL transmission
systems in the network, providers can deliver up to eight telephone lines, or three IDSL
lines on a single twisted pair to businesses, apartment buildings, or neighborhoods up to
100,000 feet away. And because they enable individual lines to be dropped at multiple,
random locations along the single copper pair route, they provide a flexible ability to
respond to moves and changes that will occur. These devices can be installed either in the
central office, or co-located with an existing digital loop carrier, or DLC, which enables
carriers to extend the capacity and range of existing digital loop carriers.
Long-range DSL transmission systems are hardened against the outside environment and
are capable of testing individual subscriber drops, up to and including the telephone set,
and reporting the results to existing legacy test systems. This significantly reduces
network access providers needs to dispatch trucks and repair personnel to distant
points in the network.
Yet another specialized DSL transmission system is available that aggregates multiple
DSL service offerings and offers long-range transport along fiber optic rings at speeds of
40 Mbps. These systems distribute DS1, IDSL, and digital access lines to multiple
locations in service providers networks. Combining copper and fiber-based systems
allows network access providers to deliver services to virtually any location within a
7,000 square mile network serving area.
A BRIGHT FUTURE FOR xDSL
While copper-line communications may disappear some day, network access providers
cannot afford to abandon this tremendous resource for a long time to come. The pressure to
deliver high-bandwidth access to business and residential customers is growing stronger as
telecommuters, home-office users, business customers, and even recreational users demand
faster Internet connections. In addition to this customer demand, providers are under
pressure from competitors particularly cable providers who offer
high-bandwidth alternatives with their cable modems.
Products that help the carriers leverage their virtually ubiquitous copper plant are
helping carriers begin to close that gap, and over time, Dataquest predicts xDSL will
outpace cable-based service. In fact, despite a slower start, Dataquest predicts that
shipments of xDSL customer premises equipment (CPE) will skyrocket, and far outdistance
the installed base of cable modems. In 1997, about 71,000 units of xDSL CPE were shipped
nationwide, compared with 213,000 cable modems. But by 2003, the analysts predict 9.7
million units of xDSL CPE will ship, nearly twice the 5.3 million cable modems Dataquest
expects to be delivered.
The race to hang on to satisfied customers and expand the number of services they buy
is just getting started. The competition will become stiffer, but the LECs have a
remarkable resource in their extensive, high-quality networks. Predictions that copper is
dead as a transmission medium are very premature. New technologies that are simple and
inexpensive to add to the trusted copper network are already available and are
continuously being improved, and will enable it to carry multiple services and greater
quantities of higher bandwidth traffic well into the new millennium. c
Frank Akers is founder, chairman of the board, and chief development officer of
GoDigital Networks. GoDigital provides long-range DSL transmission systems that increase
the bandwidth and performance of copper lines at very long distances from the central
office. The companys GDSL systems enable network access providers to address the
demand for multiple voice and high-speed reliable Internet access and data services by
turning standard copper lines into high-speed digital conduits that support multiple
digital access services at long distances. For more information, visit GoDigitals
Web site at www.godigital.com.