Telcos Move Closer To Video Over ADSL9/05/1999 8:00 PM Eastern
Internet-based technical innovations coming this fall
promise to bring entertainment services closer to reality for telcos and other entities
deploying ADSL links.
Examples can be found in the service territories of NBTel
in the Canadian province of New Brunswick and Kingston Communications Group in the East
Yorkshire region of England. Those companies have begun commercial offerings of digital-TV
services over asymmetrical-digital-subscriber lines in preparations for full-scale
rollouts in the weeks ahead.
In both cases, the companies are deploying
"headend-in-a-box" hardware from PixStream Inc., in conjunction with the
digital-TV operating system developed by iMagicTV Inc., to offer customers a full slate of
TV services delivered in MPEG-2 format via Internet-protocol-multicasting technology.
At the same time, in unrelated developments that represent
further advances in Web-based entertainment, Internet content providers are turning to two
suppliers of a new type of distribution service that could overcome Internet bottlenecks
that impede video delivery.
Akamai Technologies Inc. and Sandpiper Networks Inc. are
offering Web-site owners services that deliver content to Internet-service providers'
points of presence using proprietary technology that greatly enhances caching and other
Such developments were once of little concern to major
telephone companies. But the threat of bundled full-service competition from AT&T
Corp. and other MSOs made incumbent carriers realize the danger of not having TV services
to go with high-speed-data and voice services, PixStream vice president of marketing David
"Besides the deals with NBTel and Kingston, we have
trials under way with five carriers, including one large incumbent in the United States
and one in Canada," he added.
While ADSL doesn't represent the ultimate answer to
meeting the cable-TV threat, it is proving to be a more viable bridge to digital TV than
many had thought -- thanks partly to capabilities represented by the PixStream/iMagicTV
NBTel, for instance, is offering the full slate of
government-approved TV services -- representing 76 channels, along with 30 digital-audio
channels -- over full-rate ADSL links. That capacity could expand to hundreds of channels
if services were available, said Marcel LeBrun, president and CEO of iMagicTV, which is
owned in part by NBTel parent Aliant Inc.
"The data rates on their ADSL lines range from a
minimum of 4 megabits per second to 8 mbps, so there's enough capacity to serve
multiple TV sets in the home," LeBrun noted.
PixStream and iMagicTV use IP multicasting between the
headend and the DSLAMs (DSL-access multiplexers) that typically reside in
central-office-switch enclosures. The PixStream headend takes in analog or digital video
from any source, converts it to MPEG-2 and encapsulates the MPEG frames into IP packets.
The IP-multicast protocol allows all of the channels to be
streamed to all of the DSLAMs, and it offers a means of channel tuning that is key to
keeping costs down and keeping the process simple, Caputo noted.
"By employing very dense, integrated processing
technology, we're able to do in a single module what it takes 10 to 20 seven-foot
racks to do in an analog cable headend," Caputo said. "So telcos only have to
spend $1 million to $2 million for our gear, compared to the $20 million or more
they'd have to spend on traditional headends."
The downside for telcos is that full-rate ADSL can't
be delivered on a ubiquitous basis without major upgrades. That is why most carriers are
offering a much lower-rate ADSL service as the basic-level high-speed-data service --
typically in the 384-kilobit-per-second to 768-kbps range.
Even at these rates, current coverage is limited to about
60 percent of the total lines. That percentage is about to go up, though, as new equipment
is designed to work with lines that are connected to remote terminals served by
But the full-rate ADSL option offers a low-cost transition
into the video business for telcos, insofar as the ADSL systems they deploy can be
operated at full-rate, LeBrun noted.
For example, telcos that can't deliver a 5-mbps or
better line rate to some customers could begin deploying fiber deeper and using the
variation on DSL known as "VDSL" (very high-rate DSL), which uses shorter
copper-line distances to deliver data at 26 mbps to 52 mbps.
Telcos and ISPs are also exploring ways to tap enhanced
content from Web sites, which can be delivered to TVs using the types of set-tops being
supplied by Pace Micro Technology plc and other vendors.
To do so, telcos need to deliver streamed media efficiently
across the Internet and related long-haul lines -- which is where the Akamai and Sandpiper
technologies come into play.
"Akamai's core specialty is the ability to get
content out to points of presence that are close to end-users so that just a few users are
impinging on the servers at any one time," Cisco Systems Inc. vice president of
marketing Larry Lang said. Cisco is working with Akamai on a Web-streaming demonstration.
Akamai's system uses distributed servers to instantly
deliver the initial outline of each Web page in HTML (HyperText Markup Language) format to
the end-user from the closest POP, and then to tap other locations for cached content to
fill out the page shells.
A similar capability is being offered by Sandpiper, which
recently contracted with RealNetworks Inc. to equip its servers with RNI's
"G2" streaming technology.
"There's a lot of attention on the last-mile
problem, but there's also a first-mile issue, and that's what we're
focusing on," Sandpiper president and CEO Leo Spiegel said.