ECE 5233 Satellite Communications

1. ECE 5233 Satellite Communications Prepared by: Dr. Ivica Kostanic Lecture 1: Introduction to Satellite Systems (Sections 1.1-1.4) 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 • Earthsegment • Serviceproviderhub (ground) • Userterminals • Space segment • 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 – 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 • 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 • Heavilydependent on the end application Globstar satellite phones Satellite on the move Marine satellite antennas Satellite TV equipment

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: 8-12GHz • Ku band: 12-18GHz • K band: 18-26.5GHz • Ka band: 26.5-40GHz • 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. Frequency management • 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 ITU Regions 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 (1945-1960) • Early days of extensive scientific research • “Dreaming” of what is possible • Innovation (1960-1970) • Establishment of governmental space exploration agencies and international satellite consortia • Development of communication and rocket technology • First launches • Commercialization (1970-1980) • Satellite communication becomes commercial technology • Applications: cross continental telephony and satellite TV • Liberalization (1980-1990) • 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 https://www.youtube.com/watch?v=eYUxkSFCKZQ