mobile satellite systems

Mobile Satellite Systems
• Like cellular systems, except that the base
stations (i.e., satellites) move as will as
mobile devices
• Satellite coverage attractive for areas of world
not well served by existing terrestial
infrastructure: ocean areas, developing
countries

• Interesting aspects of the satellite link:
– 270 ms propagation delay (geosync)
– Transmission cost independent of distance
– Very high bit rates are possible; can avoid bandwidth
limitations of terrestrial links
– An inherently broadcast medium
– Dynamic assignment of channels between geographically
dispersed users
– A transmitting station can receive its own transmission;
can be exploited for transmission control


• Assigned Frequencies
– P Band: 0.225-0.39 GHz
– J Band: 0.35-0.53 GHz
– L Band: 0.39-1.55 GHz
– S Band: 1.55-5.2 GHz
– C Band: 3.9-6.2 GHz
– X Band: 5.2-10.9 GHz
– K Band: 10.9-36.0 GHz
– Ku Band: 15.35-17.25 GHz
– Q Band: 36-46 GHz
– V Band: 46-56 GHz
– W Band: 56-100 GHz
• Antenna gain proportional to ƒ2, free space loss to 1/ƒ2
• Counterbalanced by noise and absorption issues
Earlier satellites, interference
with terrestrial microwave links
(4/6 GHz)
Newer generation satellite
systems (14/16 GHz)
Also interest in 20/30 GHz
systems (Ka Band, NASA ACTS)