SkyBridge Makes Plans For The Launching Pad
(not sure if posted before...)
zdnet.com
By Ken Freed,
Special To Inter@ctive Week
January 11, 1999 11:33 AM ET
SkyBridge is ready to start putting its planned
low-earth-orbit satellite broadband network into place
in coming weeks, as it begins launching its planned
80-satellite constellation into orbit. If it meets its
current schedule, SkyBridge will have all 80 birds in
place and operating in three years, at a cost of about
$4.2 billion.
As satellite operators like GlobalStar Communications
and Iridium have learned, satellite launch and
deployment plans have a way of straying off course.
But with market forecasts for broadband services
pegged at 400 million users by 2005, SkyBridge is
looking to give Microsoft's Teledesic satellite network
and four other competitors a run for their money as
they look to sell capacity to telecom operators and
Internet service providers (ISPs).
Like Teledesic, SkyBridge has some deep-pocketed
backers, led by network equipment giant Alcatel,
which formed the SkyBridge consortium in 1993.
SkyBridge initially expected to have 60 satellites in its
network, but it announced in June 1998 that it is
adding 20 more satellites to its constellation.
"Our market forecasts and conclusions drawn from
meetings we've had with telecom operators from
around the world convinced us that the demand for
bandwidth will be far higher than we had originally
anticipated," said Pascale Sourisse, president and
chief executive officer of SkyBridge, when the
expansion was announced.
SkyBridge expects to start delivering voice, data and
multimedia traffic through 200 terrestrial gateways
worldwide by the end of 2001. Rather than deal
directly with end users, SkyBridge plans to sell
carriage services to national and regional
telecommunications operators and ISPs, which can
then put their own brands on the service.
Frugal Birds
SkyBridge satellites, which will be positioned about
900 miles above the earth's surface, will avoid
interfering with transmissions from direct broadcast
satellite (DBS) and other systems operating at higher
orbits through the "frequency reuse" adopted by the
International Telecommunication Union at the 1997
World Radiocommunication Conference. Under that
agreement, SkyBridge can share the 10-gigahertz to
18-GHz frequencies in the Ku-band and the 18-GHz to
30-GHz frequencies in the Ka-band within certain
power restrictions.
When a SkyBridge satellite moves into the conus, or
transmission field, of a higher orbiting bird, it will stop
transmitting until it passes through that zone. Traffic
will be redirected to another SkyBridge satellite that is
within transmission range of the intended ground
station.
"With 80 satellites circling the globe in a deterministic
manner, we'll know exactly where each one will be at
any given second," says Laurent Combarel, system
design manager at SkyBridge. "Since the exclusion
zones can be preprogrammed into our control
systems, we will be able to provide uninterrupted
services to each of our 200 local gateways
worldwide."
Combarel adds that traffic management will take place
on the ground and that SkyBridge won't route signals
between satellites. That makes SkyBridge's approach
different from that of other operators, including
Teledesic, which plans to relay signals between
satellites.
SkyBridge demonstrated its technology at an August
1998 meeting of the ITU in Geneva. DBS programming
signals from two service providers were received with
an "absence of any perceptible impact" on their
signals, according to SkyBridge.
Data transfer rates on the asymmetrical SkyBridge
system will range from the base speed of 16 kilobits
per second to 20 megabits per second for downlink
traffic from the satellite to residential subscribers.
Uplink speeds will range up to 2 Mbps.
Star Search
In addition to Alcatel, SkyBridge backers include Loral
Space & Communications and Japanese technology
companies Mitsubishi, Sharp and Toshiba, among
others. Alcatel and Loral are involved in other satellite
projects, while Mitsubishi and Toshiba are Alcatel
technology partners in some nonsatellite businesses.
SkyBridge's chief competitor among prospective
low-earth-orbit satellite operators is Teledesic, which
is backed by Microsoft, cellular pioneer Craig McCaw
and technology partners, including Boeing and
Motorola. The Teledesic network will comprise 288
Ka-band satellites that will operate roughly 430 miles
above the earth.
Motorola is the main force behind Celestri, a third
competitor in this market. Celestri will include both
low-earth-orbit and higher-orbit geostationary
satellites, with 63 satellites operating at 875 miles
above the earth and nine geostationary birds operating
at 22,000 miles above the planet.
Three more systems are being put together to deliver
broadband satellite service from higher-orbit satellites.
These include the Cyberstar system from Loral, with
three Ka-band satellites and a still unspecified number
of Ku-band satellites, the Astrolink system from
Lockheed Martin, with nine Ka-band satellites, and
the Spaceway system from Hughes Network
Systems, with eight Ka-band satellites.
SkyBridge will be able to deliver two-way satellite
service through the use of transceiver terminals. That
will give the service an advantage over today's DBS
services, which offer only one-way connectivity.
"The biggest problem with all broadband systems is
the last mile to the customer premises," says David
Finkelstein, senior vice president of marketing and
business development at SkyBridge. "SkyBridge will
be solving this problem by providing connectivity from
the local gateways to the end users. What makes
satellite networks a unique proposition is that no other
single technology can provide global access to
customers anywhere in the world." |
