Low Earth Orbit Satellite Technology

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Low Earth Orbit Satellite Technology
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Mobile Phone Technologies

• Supply Dialup Telephones and data
• Switch from terrestrial to satellite
• Satellite not able to penetrate buildings
• GEO illuminate 1/3 of earths surface at 35,800km,
  400ms delay
• MEO 5000-12,000km, 10 satellites, 100ms
• LEO 500-1500km, 40-70 satellites, 10ms

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Iridium, Thuraya and Garuda Satellites
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Phone Terminals
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48 satellite Globalstar Constellation
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MEO Antenna Array
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SkyBridge

• An Example of an
• LEO Satelite system
• By
• Chris Crabtree

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What is SkyBridge?

• SkyBridge is a satellite-based system
  designed to provide global access to interactive,
  multimedia communications. Built around a
  constellation of 80 low earth orbit satellites,
  SkyBridge provides the communications
  infrastructure for a full range of broadband
  services, including Internet access and high
  speed data communications. SkyBridge can also
  provide narrowband services and infrastructure
  links.

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SkyBridge Advantages

• High-reliability through simple architecture -
  All traffic management and routing is handled on
  the ground there is no need for direct links
  between satellites.
• High local content - The gateway handles
  interconnections with local servers and with
  terrestrial telecommunications networks. Each
  gateway controls and manages all SkyBridge
  traffic within its respective coverage area.

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Advantages Continued..

• Full compatibility with existing applications
  -Because it uses low earth orbit satellites,
  SkyBridge propagation times are akin to those for
  landline broadband transmission systems, i.e. 20
  milliseconds (compared to 500 milliseconds for
  geo stationary satellites). This means that
  applications currently used or in development for
  existing broadband networks can be seamlessly
  transmitted via SkyBridge.
• Huge, incremental capacity - SkyBridge will
  provide worldwide coverage starting with around
  40 satellites. As new satellite links are
  progressively rolled out, the total system
  capacity increases, attaining over 20 million
  simultaneously connected end-users with 80
  satellites in place.
• Low cost - Capital cost per end-user is
  equivalent to investment cost for terrestrial
  broadband infrastructure in dense areas.

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How it works
The system is based on a constellation of 80 LEO
satellites which link professional and
residential users equipped with low-cost
terminals to terrestrial gateways. User terminals
are not specific to the system and the
architecture of the receiving sites may be
adapted to the following configurations
individual reception, community reception (a
SkyBridge terminal is shared between several
subscribers) and professional configuration where
the SkyBridge terminal is connected to a LAN or a
PBX
For Example
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About the Satellites
Each satellite is in a circular orbit at an
altitude of 1457 km above the Earth. The
constellation is divided into two symmetrical
Walker sub-constellations of 40 satellites each.
A satellite has a 3000 km radius coverage
divided into fixed spot beams of 350 km radius.
Each user is attached to one and only one
SkyBridge gateway. The traffic to and from any of
the SkyBridge users will always be concentrated
on the gateway where the user is registered.
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When will SkyBridge be operational?

• The SkyBridge project is designed for rapid
  implementation, with service to be rolled out by
  the end of 2001.
• The lifetime of the first-generation satellite
  constellation is projected out to 2009.