1. ECE 5233 Satellite Communications
Prepared by:
Dr. Ivica Kostanic
Lecture 1: Introduction to Satellite Systems
(Sections )
Spring 2014

2. Outline Class overview Configuration of a satellite systems
Elements of a satellite system
Types of satellite systems
Brief history of satellite communication

3. Satellite communication system
Satellite system consists of
Earth segment (traffic and control)
Space segment
Earth segment
Service provider hub (ground)
User terminals
Satellite (s)
Communication links to and from satellites
Data center of the sat-com provider
Central hub (receives data stream and sends it toward satellite)
Satellite (receives data stream, amplifies and sends it back towards ground)
End user antenna – critical part (small size, high performance)
Modem – receives data stream
User end network – usually IP network

4. Ground segment Consists of earth stations
Satellite network may have one or more earth stations
Earth station may be transmit-receive or receive only
Earth stations are connected to terrestrial networks (PSTN for CS traffic or Internet for PS)
Usually have very large antennas (up to 30m in diameter)
Earth stations have high quality and redundant links to terrestrial networks
Example of a Ku band earth station antenna
Functional block diagram of an earth station

5. Space segment Satellite consist of Payload Two types of satellites
Payload – used in communication
Platform – facilitates operation of payload
Payload
Receive antenna
Electronics for communication
Transmit antenna
Two types of satellites
“Bent pipes” (transparent)
Regenerative (base band processing)
Smallest assignable recourse
Satellite transponder
Satellite usually hosts multiple transponders
Satellite usually operates in single band (although there are some multiband satellites)
Transmit antenna may be
Single beam – one area of the Earth
Multi beam – multiple areas of the Earth
Basics of “bent pipe” architecture
Satellite with onboard processing

6. End user segment User stations User equipment may
Mobile stations (mobile terminals)
VSAT terminals
Gateways (connect space segment to terrestrial networks)
User equipment may
Connect to user stations
Example: Satellite TV
Integrate with user stations
Example: Satellite phone
Heavily dependent on the end application
Globstar satellite phones
Marine satellite antennas
Satellite TV equipment
Satellite on the move

7. Types of satellite orbits
Constellation of Globstar system
Orbit height
Low Earth Orbit (LEO)
Attitude 160-2,000km
Satellite speed ~ 8km/sec
Orbital period ~ 90 min
Example: Globstar, 48 satellites in six planes, 1413km
Medium Earth Orbit (MEO)
Altitude 2,000km -35,786km
Satellite speed 8km/sec to 3 km/sec
Orbital period 2 to 24h
Example: GPS, 24 satellites in 6 planes, 20,200km
Geosynchronous orbit (GSO)
Altitude 35,768km
Satellite speed ~ 3km/sec
Non zero inclination
Orbital period 24 hours
Geostationary orbit (GEO)
GSO satellite in zero inclination orbit
Constellation of GPS system

8. Satellite services Fixed satellite services (FSS)
PTP or PTMP delivery of signal across the Globe
Mobile satellite services (MSS)
Delivery of satellite signal to mobile platforms (either terrestrial, marine or aeronautical)
Broadcast satellite services (BSS)
Broadcast of satellite signal (TV, radio)
Navigation satellite services (NAV)
Earth exploration services (ESS)
Space research services (SRS)
Space operations services (SOS)
Radio determination satellite services (RSS)
Inter-satellite services (ISS)

9. Frequency bands used for sat-comm
Satellites operate in microwave frequency range
Two links
Uplink – ground to satellite
Downlink – satellite to ground
Each link uses its own band
Uplink operates on higher frequency
Microwave frequency bands
L band: 1-2GHz
S band: 2-4GHz
C band: 4-8GHz
X band: GHz
Ku band: GHz
K band: GHz
Ka band: GHz
Majority of existing systems operate in C and Ku
Higher frequencies
More available spectrum
Better antenna directivity
Higher propagation losses
More sophisticated technology
Frequency chart for communication satellite services

10. Example: VIASAT license in Ka band as of 2010
Frequency management
ITU Regions
Responsibility of International Telecommunication Union ITU
Insures:
Non-interference condition between different satellite systems
Fairness between nations in access to the satellite frequencies
Frequency allocation may be
exclusive for given service
shared between services
Service provisioning usually requires consent of all countries within coverage area of the satellite
Frequency is usually allocated in pairs
One frequency for UL
One frequency for DL
UL frequency is higher
Example: VIASAT license in Ka band as of 2010

11. Beginnings of satellite communication
Origins: Arthur Clarke’s article in Wireless World in 1945
WW-II stimulated development of two key technologies
Microwave communication
Missile technology
First satellite launched in 1957 by USSR
Sputnik, 83.6kg, LEO, atmospheric studies
Mission duration 3 months
First commercial communication satellite 1967
Intelsat I - EarlyBird, 34.5kg, GEO, communication satellite
Coverage between US and Europe
Operated 4 years (deactivated in 1969)
Launched from KSC
Could handle 240 voice and 1 TV channel
Owned by Intelsat (52 countries)
Sputnik 1
Intelsat- EarlyBird

12. Development of satellite communication
Imagination ( )
Early days of extensive scientific research
“Dreaming” of what is possible
Innovation ( )
Establishment of governmental space exploration agencies and international satellite consortia
Development of communication and rocket technology
First launches
Commercialization ( )
Satellite communication becomes commercial technology
Applications: cross continental telephony and satellite TV
Liberalization ( )
Transformation of international governmental consortia
Market led approach allowed private investments
Regulatory framework changes that allowed all of the transformations to take place
Privatization and private ventures (1990 – on)
Communication satellites become mainstream technology led by private business
Leading applications: broadcast TV, data backhaul, mobile communications in the air and on the sea, navigation, etc.
Future – integration of satellite technology with Internet
Satellite applications (values in B$)
History channel documentary: Satellites – how they work