Two-Way Data Traffic Via Satellite Thrives5/30/1999 8:00 PM Eastern
Technical innovations are transforming the usefulness of
satellites for handling Internet-protocol traffic, including the media-rich components
that Internet-service providers need to provide digital-subscriber-line services to
consumers.While some of these developments will enhance the effectiveness of
direct-to-home delivery of Internet services, the primary impact will likely be in the
realm of low-cost backbone support for IP traffic, in direct competition with
high-capacity, long-haul fiber networks.
A new company, iBEAM Broadcasting Corp., is already using
such techniques to deliver streamed multimedia services to ISPs in the United States. And
more support systems for ISPs are taking shape here and abroad.
For example, Comsat Corp. is using an internally developed
means of delivering point-to-point bandwidth-on-demand support for its own Intranets and
extranets in preparation for commercial rollout of the technology next year.
As described by Prakash Chitre, vice president at Comsat
Laboratories, the new "Linkway" system uses small terminals at end-user sites,
linked to Comsat's operations center, to set up distribution and bandwidth configurations
suited to delivering data files in their native formats, including IP.
"It's a quantum jump from point-to-point to providing
a low-cost, meshed-network solution that can support bandwidth on demand for VPNs [virtual
private networks], Intranets, extranets, multimedia, video teleconferencing and other such
capabilities via satellite," Chitre said.
"We've been working on this set of solutions for over
five years, and now, we're ready to move to the product stage," Chitre added.
Comsat just won its first contract to use the system from
European satellite company EutelSat, which will carry multimedia IP and other data traffic
from the United States via its new Atlantic Gate bird at 12.5 degrees west longitude.
German-based Internet SkyWay is using the satellite to
deliver a new trans-Atlantic 45-megabit-per-second Internet-backbone service to ISPs that
also involves delivery of intra-European push and caching services from EutelSat's W2 at
16 degrees east longitude.
"We believe the demand for capacity to deliver TV
services will begin to level off, but the use of capacity for data is just beginning, and
it could become a significant contributor to our growth going forward," Paris-based
EutelSat spokeswoman Vanessa O'Connor said.
EutelSat operates 14 satellites, including five Ku-band
birds that orbit in the firm's 13 degrees east longitude "Hotbed" cluster.
Comsat's Linkway product uses a technique already in
commercial use that allows end-users to deliver packets in the TCP (Transport Control
Protocol) format -- the most commonly used transport format in IP communications.
"TCP spoofing" allocates more bandwidth to TCP
for the satellite transport link than is used on the ground, thereby overcoming
restrictions that have kept TCP/IP traffic from moving faster than 384 kilobits per second
via satellite, Chitre said.
"We can deliver TCP-based data at tens of megabits per
second," he said. In addition, he noted, the company has implemented Reed-Solomon
coding with interleaving to reduce bit-error rates so that a typical 10-3 BER
in an IP feed becomes 10-11.
U.S. ISPs are getting a taste of what's to come in
satellite-based backbone support for IP traffic through iBEAM, which began operations
about a year ago specifically to provide a means of delivering streamed media to ISPs.
The company now has 50 data-center modules installed at ISP
points of presence, vice president of marketing Tom Gillis said.
The company -- which signed distribution deals with
Internet portal Snap, Bloomberg Interactive Television and Simply TV -- provides a way for
ISPs to offer streamed media transparently to end-users, Gillis said.
"When the user requests a download from a site in the
usual way, our system intercepts the signal and brings in the site's media stream over the
satellite," he added.
Using a portion of a satellite transponder, iBEAM delivers
6 mbps in total payload in increments ranging from 28 kbps to 300 kbps, depending on
Rather than the IP-multicasting mode that some new
satellite-backbone services plan to implement, iBEAM delivers feeds in point-to-point
unicast mode, simplifying processing at data centers, Gillis said.
If users have DSL access or cable modems, they get the
signals at 300 kbps, Gillis added. He noted that the company is exploring the possibility
of moving to higher speeds and using more transponder bandwidth.
A major development launching satellite providers into the
IP-multimedia-transport business is the nearly universal implementation of IP-into-MPEG
(Motion Picture Expert Group) formatting as part of the processing architecture of MPEG
This has made delivery of IP multimedia in broadcast mode
an off-the-shelf reality that overcomes many issues attending delivery of services in
native IP format.
Those issues include the bit-error problem and the absence
of encryption capabilities, according to Burt Liebowitz, chief technology officer at Loral
Orion Network Systems, a unit of Loral Space & Communications Ltd.
"We're building an IP-multicast satellite network that
will deliver 58 [mbps] per transponder to ISP points of presence using a lot of the
technology that has been standardized for digital television," Liebowitz said.
By encapsulating IP streamed media into 188-byte packets of
MPEG, satellite operators exploit the forward-error correction and other signal-protection
and encryption capabilities of the TV standard.
"You can buy an entire receiver chip that will receive
a 58-mbps pipe and do very sophisticated forward-error correction on it -- decoding and a
whole bunch of other fancy satellite stuff -- for about $10," Liebowitz said.
"We used to spend about $30,000 for such boxes."
Such economies don't address the meshed-network needs for
the full slate of services that Comsat is preparing to support. But they are well-suited
for delivering multimedia on a point-to-multipoint basis, Liebowitz said.