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ECE 5233 Satellite Communications

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Presentation on theme: "ECE 5233 Satellite Communications"— Presentation transcript:

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

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