Low Earth Orbit Satellite Technology

1. Low Earth Orbit Satellite Technology

2. 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

3. Iridium, Thuraya and Garuda Satellites

5. Phone Terminals

6. 48 satellite Globalstar Constellation

7. MEO Antenna Array

8. SkyBridge An Example of an LEO Satelite system By Chris Crabtree

9. 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.

10. 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.

11. 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.

12. 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 :

14. 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.

16. When will SkyBridge beoperational? • 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.