AJAL.A.J Assistant Professor –Dept of ECE,  Federal Institute of Science And Technology (FISAT)  TM     MAIL: ec2reach@gma...
Astronautics
Reference Book <ul><li>Title:  The Satellite Communication Applications Handbook  </li></ul><ul><li>Author:  Bruce R. Elbe...
Reference Books <ul><li>Title:  Satellite Communications </li></ul><ul><li>Author:  Dennis Roddy </li></ul><ul><li>ISBN:  ...
Reference Books <ul><li>Title:  Satellite Communication Engineering </li></ul><ul><li>Author:  Michael O. Kolawole </li></...
Pioneers in Satellite Communication <ul><li>Konstantin Tsiolkovsky (1857 - 1935) Russian visionary of space flight First d...
Satellite History Calendar <ul><li>1957  </li></ul><ul><ul><li>October 4, 1957: - First satellite - the Russian Sputnik 01...
Satellite History Calendar <ul><li>1965 </li></ul><ul><ul><li>Intelsat 1 becomes first commercial comsat: Early Bird </li>...
Satellite History Calendar <ul><li>1980  </li></ul><ul><ul><li>INTELSAT V launched - 3 axis stabilized satellite built by ...
Satellite History Calendar <ul><li>1996  </li></ul><ul><ul><li>INMARSAT III launched - first of the multibeam mobile satel...
What is a Satellite  ? <ul><li>A satellite is basically any object that revolves around a planet in a circular or elliptic...
How Is a Satellite Launched into an Orbit? <ul><li>All satellites today get into orbit by riding on a  rocket .  </li></ul>
  Orbital velocity <ul><li>  Orbital velocity  is the velocity needed to achieve balance between gravity's pull on the sat...
 
How Much Do Satellites Cost? <ul><li>a satellite launch can cost anywhere between $50 million and $400 million .  </li></u...
  Satellite   Natural Satellite   Artificial Satellite
 
Whose Satellite Was the First to Orbit Earth? <ul><li>The Soviet  Sputnik satellite  was the first to orbit Earth, launche...
Sputnik 2  - Mission <ul><li>Some scientists believed humans would be unable to survive the launch or the conditions of ou...
Manned spacecraft <ul><li>On 12 April 1961, aboard the Vostok 1,  Yuri Gagarin   became both the first human to travel int...
<ul><li>He founded the  </li></ul><ul><li>Indian Space Research Organisation (ISRO).   </li></ul>After Sarabhai died in 19...
INDIAN SATELLITE
IN July 18, 1980,  India launched the satellite Rohini 1 on an Satellite Launch Vehicle (SLV) rocket from the Sriharikota ...
Space station <ul><li>A space station (or orbital station) is a spacecraft capable of supporting a crew which is designed ...
NB: Terms <ul><li>The path a satellite follows is an  orbit . </li></ul><ul><li>In the orbit, the farthest point from Eart...
Satellite categories
<ul><li>Orbits: </li></ul><ul><li>LEO: Low Earth Orbit. </li></ul><ul><li>MEO: Medium Earth Orbit </li></ul><ul><li>GEO: G...
Satellite orbit altitudes
Satellite frequency bands
<ul><li>At the  Geostationary orbit  the satellite covers 42.2% of the earth’s surface. </li></ul><ul><li>Theoretically 3 ...
Geostationary Communication Satellites in Orbit Today
Satellites in geostationary orbit
Satellite orbits
Geostationary Orbit
Geostationary orbits <ul><li>Geostationary orbits </li></ul>
Polar Orbit
What is the period of the Moon, according to Kepler’s law? Example 16.1 Here C is a constant approximately equal to 1/100....
According to Kepler’s law, what is the period of a satellite that is located at an orbit approximately 35,786 km above the...
Classical satellite systems base station or gateway Inter Satellite Link  (ISL) Mobile User Link (MUL) Gateway Link (GWL) ...
Inclination inclination    satellite orbit perigee plane of satellite orbit equatorial plane
Elevation Elevation: angle    between center of satellite beam  and surface  minimal elevation: elevation needed at leas...
Link budget of satellites <ul><li>Parameters like attenuation or received power determined by four parameters: </li></ul><...
Atmospheric attenuation Example: satellite systems at 4-6 GHz elevation of the satellite 5° 10° 20° 30° 40° 50° Attenuatio...
<ul><li>Four different types of satellite orbits can be identified depending on the shape and diameter of the orbit: </li>...
Orbits II earth km 35768 10000 1000 LEO  (Globalstar, Irdium) HEO inner and outer Van Allen belts MEO (ICO) GEO (Inmarsat)...
Geostationary satellites <ul><li>Orbit 35,786 km distance to earth surface, orbit in equatorial plane (inclination 0°) </l...
LEO systems <ul><li>Orbit ca. 500 - 1500 km above earth surface </li></ul><ul><li>visibility of a satellite ca. 10 - 40 mi...
MEO systems <ul><li>Orbit ca. 5000 - 12000 km above earth surface </li></ul><ul><li>comparison with LEO systems: </li></ul...
Handover in satellite systems <ul><li>Several additional situations for handover in satellite systems compared to cellular...
What’s on a satellite? Communications Power Sensors/Instruments “ Bus”
How Satellites Work <ul><li>A Earth Station sends message in GHz range. (Uplink)  </li></ul><ul><li>Satellite Receive and ...
 
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SATELLITE COMMUNICATION

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  • EIRP: Equivalent isotropically radiated power or Effective isotropic radiated power is the amount of power that a theoretical isotropic antenna (that evenly distributes power in all directions) would emit to produce the peak power density observed in the direction of maximum antenna gain. EIRP can take into account the losses in transmission line and connectors and includes the gain of the antenna. The EIRP is often stated in terms of decibels over a reference power emitted by an isotropic radiator with an equivalent signal strength.
  • My slides on satellite

    1. 1. AJAL.A.J Assistant Professor –Dept of ECE, Federal Institute of Science And Technology (FISAT) TM   MAIL: ec2reach@gmail.com
    2. 2. Astronautics
    3. 3. Reference Book <ul><li>Title: The Satellite Communication Applications Handbook </li></ul><ul><li>Author: Bruce R. Elbert </li></ul><ul><li>ISBN: 1580534902 </li></ul><ul><li>EAN: 9781580534901 </li></ul><ul><li>Publisher: </li></ul><ul><li>Artech House Publishers </li></ul>
    4. 4. Reference Books <ul><li>Title: Satellite Communications </li></ul><ul><li>Author: Dennis Roddy </li></ul><ul><li>ISBN: 0071371761 </li></ul><ul><li>EAN: 9780071371766 </li></ul><ul><li>Publisher: </li></ul><ul><li>McGraw-Hill Professional </li></ul>
    5. 5. Reference Books <ul><li>Title: Satellite Communication Engineering </li></ul><ul><li>Author: Michael O. Kolawole </li></ul><ul><li>ISBN: 082470777X </li></ul><ul><li>EAN: 9780071371766 </li></ul><ul><li>Publisher: </li></ul><ul><li>Marcel Dekker, Inc. </li></ul>
    6. 6. Pioneers in Satellite Communication <ul><li>Konstantin Tsiolkovsky (1857 - 1935) Russian visionary of space flight First described the multi-stage rocket as means of achieving orbit. </li></ul><ul><ul><li>  </li></ul></ul><ul><li>Hermann Noordung (1892 - 1929) Postulated the geostationary orbit. </li></ul><ul><li>Arthur C. Clarke (1917 – 19 March 2008) Postulated the entire concept of international satellite telecommunications from geostationary satellite orbit including   coverage, power, services, solar eclipse. </li></ul><ul><ul><li>&quot;Wireless World&quot; (1945) </li></ul></ul>
    7. 7. Satellite History Calendar <ul><li>1957 </li></ul><ul><ul><li>October 4, 1957: - First satellite - the Russian Sputnik 01 </li></ul></ul><ul><ul><li>First living creature in space: Sputnik 02 </li></ul></ul><ul><li>1958 </li></ul><ul><ul><li>First American satellite: Explorer 01 </li></ul></ul><ul><ul><li>First telecommunication satellite: This satellite broadcast a taped message: Score </li></ul></ul><ul><li>1959 </li></ul><ul><ul><li>First meteorology satellite: Explorer 07 </li></ul></ul><ul><li>1960 </li></ul><ul><ul><li>First successful passive satellite: Echo 1 </li></ul></ul><ul><ul><li>First successful active satellite: Courier 1B </li></ul></ul><ul><ul><li>First NASA satellite: Explorer 08 </li></ul></ul><ul><li>April 12, 1961: - First man in space </li></ul><ul><li>1962 </li></ul><ul><ul><li>First telephone communication & TV broadcast via satellite: Echo 1 </li></ul></ul><ul><ul><li>First telecommunication satellite, first real-time active, AT&T: Telstar 1 </li></ul></ul><ul><ul><li>First Canadian satellite: Alouette 1 </li></ul></ul><ul><ul><li>On 7 th June 1962 at 7:53p the two-stage rocket; Rehbar-I was successfully launched from Sonmiani Rocket Range. It carried a payload of 80 pounds of sodium and soared to about 130 km into the atmosphere. With the launching of Rehbar-I, Pakistan had the honour of becoming the third country in Asia and the tenth in the world to conduct such a launching after USA, USSR, UK, France, Sweden, Italy, Canada, Japan and Israel. </li></ul></ul><ul><ul><li>Rehbar-II followed a successful launch on 9 th June 1962 </li></ul></ul><ul><li>1963 </li></ul><ul><ul><li>Real-time active: Telstar 2 </li></ul></ul><ul><li>1964 </li></ul><ul><ul><li>Creation of Intelsat </li></ul></ul><ul><ul><li>First geostationary satellite, second satellite in stationary orbit: Syncom 3 </li></ul></ul><ul><ul><li>First Italian satellite: San Marco 1 </li></ul></ul>
    8. 8. Satellite History Calendar <ul><li>1965 </li></ul><ul><ul><li>Intelsat 1 becomes first commercial comsat: Early Bird </li></ul></ul><ul><ul><li>First real-time active for USSR: Molniya 1A </li></ul></ul><ul><li>1967 </li></ul><ul><ul><li>First geostationary meteorology payload: ATS 3 </li></ul></ul><ul><li>1968 </li></ul><ul><ul><li>First European satellite: ESRO 2B </li></ul></ul><ul><li>July 21, 1969: - First man on the moon </li></ul><ul><li>1970 </li></ul><ul><ul><li>First Japanese satellite: Ohsumi </li></ul></ul><ul><ul><li>First Chinese satellite: Dong Fang Hong 01 </li></ul></ul><ul><li>1971 </li></ul><ul><ul><li>First UK launched satellite: Prospero </li></ul></ul><ul><ul><li>ITU-WARC for Space Telecommunications </li></ul></ul><ul><ul><li>INTELSAT IV Launched </li></ul></ul><ul><ul><li>INTERSPUTNIK - Soviet Union equivalent of INTELSAT formed </li></ul></ul><ul><li>1974 </li></ul><ul><ul><li>First direct broadcasting satellite: ATS 6 </li></ul></ul><ul><li>1976  </li></ul><ul><ul><li>MARISAT - First civil maritime communications satellite service started </li></ul></ul><ul><li>1977  </li></ul><ul><ul><li>EUTELSAT - European regional satellite </li></ul></ul><ul><ul><li>ITU-WARC for Space Telecommunications in the Satellite Service </li></ul></ul><ul><li>1979 </li></ul><ul><ul><li>Creation of Inmarsat </li></ul></ul>
    9. 9. Satellite History Calendar <ul><li>1980  </li></ul><ul><ul><li>INTELSAT V launched - 3 axis stabilized satellite built by Ford Aerospace </li></ul></ul><ul><li>1983  </li></ul><ul><ul><li>ECS (EUTELSAT 1) launched - built by European consortium supervised by ESA </li></ul></ul><ul><li>1984  </li></ul><ul><ul><li>UK's UNISAT TV DBS satellite project abandoned </li></ul></ul><ul><ul><li>First satellite repaired in orbit by the shuttle: SMM </li></ul></ul><ul><li>1985 </li></ul><ul><ul><li>First Brazilian satellite: Brazilsat A1 </li></ul></ul><ul><ul><li>First Mexican satellite: Morelos 1 </li></ul></ul><ul><li>1988 </li></ul><ul><ul><li>First Luxemburg satellite: Astra 1A </li></ul></ul><ul><li>1989   </li></ul><ul><ul><li>INTELSAT VI - one of the last big &quot;spinners&quot; built by Hughes </li></ul></ul><ul><ul><li>Creation of Panamsat - Begins Service </li></ul></ul><ul><ul><li>On 16 July 1990, Pakistan launched its first experimental satellite, BADR-I from China </li></ul></ul><ul><li>1990  </li></ul><ul><ul><li>IRIDIUM, TRITIUM, ODYSSEY and GLOBALSTAR S-PCN projects proposed - CDMA designs more popular </li></ul></ul><ul><ul><li>EUTELSAT II </li></ul></ul><ul><li>1992  </li></ul><ul><ul><li>OLYMPUS finally launched - large European development satellite with Ka-band, DBTV and Ku-band SS/TDMA payloads - fails within 3 years </li></ul></ul><ul><li>1993  </li></ul><ul><ul><li>INMARSAT II - 39 dBW EIRP global beam mobile satellite - built by Hughes/British Aerospace </li></ul></ul><ul><li>1994  </li></ul><ul><ul><li>INTELSAT VIII launched - first INTELSAT satellite built to a contractor's design </li></ul></ul><ul><ul><li>Hughes describe SPACEWAY design </li></ul></ul><ul><ul><li>DirecTV begins Direct Broadcast to Home </li></ul></ul><ul><li>1995 </li></ul><ul><ul><li>Panamsat - First private company to provide global satellite services. </li></ul></ul>
    10. 10. Satellite History Calendar <ul><li>1996  </li></ul><ul><ul><li>INMARSAT III launched - first of the multibeam mobile satellites (built by GE/Marconi) </li></ul></ul><ul><ul><li>Echostar begins Diresct Broadcast Service </li></ul></ul><ul><li>1997  </li></ul><ul><ul><li>IRIDIUM launches first test satellites </li></ul></ul><ul><ul><li>ITU-WRC'97 </li></ul></ul><ul><li>1999  </li></ul><ul><ul><li>AceS launch first of the L-band MSS Super-GSOs - built by Lockheed Martin </li></ul></ul><ul><ul><li>Iridium Bankruptcy - the first major failure? </li></ul></ul><ul><li>2000  </li></ul><ul><ul><li>Globalstar begins service </li></ul></ul><ul><ul><li>Thuraya launch L-band MSS Super-GSO </li></ul></ul><ul><li>2001 </li></ul><ul><ul><li>XM Satellite Radio begins service </li></ul></ul><ul><ul><li>Pakistan’s 2 nd Satellite, BADR-B was launched on 10 Dec 2001 at 9:15a from Baikonour Cosmodrome, Kazakistan </li></ul></ul><ul><li>2002 </li></ul><ul><ul><li>Sirius Satellite Radio begins service </li></ul></ul><ul><ul><li>Paksat-1, was deployed at 38 degrees E orbital slot in December 2002, Paksat-1, was deployed at 38 degrees E orbital slot in December 2002 </li></ul></ul><ul><li>2004  </li></ul><ul><ul><li>Teledesic network planned to start operation </li></ul></ul><ul><li>2005  </li></ul><ul><ul><li>Intelsat and Panamsat Merge </li></ul></ul><ul><ul><li>VUSat OSCAR-52 (HAMSAT) Launched </li></ul></ul><ul><li>2006 </li></ul><ul><ul><li>CubeSat-OSCAR 56 (Cute-1.7) Launched </li></ul></ul><ul><ul><li>K7RR-Sat launched by California Politechnic University </li></ul></ul><ul><li>2007 </li></ul><ul><ul><li>Prism was launched by University of Tokyo </li></ul></ul><ul><li>2008 </li></ul><ul><ul><li>COMPASS-1; a project of Aachen University was launched from Satish Dawan Space Center, India. It failed to achieve orbit. </li></ul></ul>
    11. 11. What is a Satellite ? <ul><li>A satellite is basically any object that revolves around a planet in a circular or elliptical path. </li></ul><ul><li>satellites were exotic, top-secret devices. They were used primarily in a military capacity , for activities such as navigation and espionage. </li></ul><ul><li>Now they are an essential part of our daily lives. We see and recognize their use in weather reports, television transmission by DIRECTV and the DISH Network, and everyday telephone calls </li></ul>
    12. 12. How Is a Satellite Launched into an Orbit? <ul><li>All satellites today get into orbit by riding on a  rocket . </li></ul>
    13. 13.   Orbital velocity <ul><li>  Orbital velocity  is the velocity needed to achieve balance between gravity's pull on the satellite and the  inertia  of the satellite's motion </li></ul><ul><li>-- the satellite's tendency to keep going. </li></ul>
    14. 15. How Much Do Satellites Cost? <ul><li>a satellite launch can cost anywhere between $50 million and $400 million . </li></ul><ul><li>hurricane-watch satellite   mission cost $290 million. </li></ul><ul><li>missile-warning satellite  cost $682 million. </li></ul>NOTE a shuttle mission could easily carry several satellites into orbit
    15. 16.   Satellite   Natural Satellite   Artificial Satellite
    16. 18. Whose Satellite Was the First to Orbit Earth? <ul><li>The Soviet  Sputnik satellite was the first to orbit Earth, launched on Oct. 4, 1957. </li></ul>Sputnik 1, the first satellite, shown with four whip antennas
    17. 19. Sputnik 2 - Mission <ul><li>Some scientists believed humans would be unable to survive the launch or the conditions of outer space, so engineers viewed flights by non-human animals as a necessary precursor to human missions. </li></ul>Laika was a Soviet space dog that became the first animal to orbit the Earth – as well as the first animal to die in orbit.
    18. 20. Manned spacecraft <ul><li>On 12 April 1961, aboard the Vostok 1, Yuri Gagarin became both the first human to travel into space, and the first to orbit the earth.  </li></ul>
    19. 21. <ul><li>He founded the </li></ul><ul><li>Indian Space Research Organisation (ISRO).  </li></ul>After Sarabhai died in 1971, the Vikram Sarabhai Space Center (VSSC) in Tiruvananthapuram is named for him.  മല്ലിക സാരാഭായ് <ul><li>The  Padma Bhushan  is the third highest civilian award in the Republic of India, after the Bharat Ratna and the Padma Vibhushan, but comes before the Padma Shri. It is awarded by the Government of India. </li></ul>
    20. 22. INDIAN SATELLITE
    21. 23. IN July 18, 1980, India launched the satellite Rohini 1 on an Satellite Launch Vehicle (SLV) rocket from the Sriharikota Island launch site
    22. 24. Space station <ul><li>A space station (or orbital station) is a spacecraft capable of supporting a crew which is designed to remain in space (most commonly in low Earth orbit) for an extended period of time, and to which other spacecraft can dock. </li></ul>Habitability These stations have various issues that limit their long-term habitability, such as very low recycling rates, relatively high radiation levels and a lack of gravity. Some of these problems cause discomfort and long-term health effects . 
    23. 25. NB: Terms <ul><li>The path a satellite follows is an  orbit . </li></ul><ul><li>In the orbit, the farthest point from Earth is the  apogee , </li></ul><ul><li>and the nearest point is the  perigee </li></ul>
    24. 26. Satellite categories
    25. 27. <ul><li>Orbits: </li></ul><ul><li>LEO: Low Earth Orbit. </li></ul><ul><li>MEO: Medium Earth Orbit </li></ul><ul><li>GEO: Geostationary Earth Orbit </li></ul>
    26. 28. Satellite orbit altitudes
    27. 29. Satellite frequency bands
    28. 30. <ul><li>At the Geostationary orbit the satellite covers 42.2% of the earth’s surface. </li></ul><ul><li>Theoretically 3 geostaionary satellites provides 100% earth coverage </li></ul>
    29. 31. Geostationary Communication Satellites in Orbit Today
    30. 32. Satellites in geostationary orbit
    31. 33. Satellite orbits
    32. 34. Geostationary Orbit
    33. 35. Geostationary orbits <ul><li>Geostationary orbits </li></ul>
    34. 36. Polar Orbit
    35. 37. What is the period of the Moon, according to Kepler’s law? Example 16.1 Here C is a constant approximately equal to 1/100. The period is in seconds and the distance in kilometers.
    36. 38. According to Kepler’s law, what is the period of a satellite that is located at an orbit approximately 35,786 km above the Earth? Example 16.2 Solution Applying the formula, we get
    37. 39. Classical satellite systems base station or gateway Inter Satellite Link (ISL) Mobile User Link (MUL) Gateway Link (GWL) footprint small cells (spotbeams) User data PSTN ISDN GSM GWL MUL PSTN: Public Switched Telephone Network
    38. 40. Inclination inclination   satellite orbit perigee plane of satellite orbit equatorial plane
    39. 41. Elevation Elevation: angle  between center of satellite beam and surface  minimal elevation: elevation needed at least to communicate with the satellite footprint
    40. 42. Link budget of satellites <ul><li>Parameters like attenuation or received power determined by four parameters: </li></ul><ul><li>sending power </li></ul><ul><li>gain of sending antenna </li></ul><ul><li>distance between sender and receiver </li></ul><ul><li>gain of receiving antenna </li></ul><ul><li>Problems </li></ul><ul><li>varying strength of received signal due to multipath propagation </li></ul><ul><li>interruptions due to shadowing of signal (no LOS) </li></ul><ul><li>Possible solutions </li></ul><ul><li>Link Margin to eliminate variations in signal strength </li></ul><ul><li>satellite diversity (usage of several visible satellites at the same time) helps to use less sending power </li></ul>L: Loss f: carrier frequency r: distance c: speed of light
    41. 43. Atmospheric attenuation Example: satellite systems at 4-6 GHz elevation of the satellite 5° 10° 20° 30° 40° 50° Attenuation of the signal in % 10 20 30 40 50 rain absorption fog absorption atmospheric absorption 
    42. 44. <ul><li>Four different types of satellite orbits can be identified depending on the shape and diameter of the orbit: </li></ul><ul><li>GEO: geostationary orbit, ca. 36000 km above earth surface </li></ul><ul><li>LEO (Low Earth Orbit): ca. 500 - 1500 km </li></ul><ul><li>MEO (Medium Earth Orbit) or ICO (Intermediate Circular Orbit): ca. 6000 - 20000 km </li></ul><ul><li>HEO (Highly Elliptical Orbit) elliptical orbits </li></ul>Orbits I
    43. 45. Orbits II earth km 35768 10000 1000 LEO (Globalstar, Irdium) HEO inner and outer Van Allen belts MEO (ICO) GEO (Inmarsat) Van-Allen-Belts: ionized particles 2000 - 6000 km and 15000 - 30000 km above earth surface
    44. 46. Geostationary satellites <ul><li>Orbit 35,786 km distance to earth surface, orbit in equatorial plane (inclination 0°) </li></ul><ul><li> complete rotation exactly one day, satellite is synchronous to earth rotation </li></ul><ul><li>fix antenna positions, no adjusting necessary </li></ul><ul><li>satellites typically have a large footprint (up to 34% of earth surface!), therefore difficult to reuse frequencies </li></ul><ul><li>bad elevations in areas with latitude above 60° due to fixed position above the equator </li></ul><ul><li>high transmit power needed </li></ul><ul><li>high latency due to long distance (ca. 275 ms) </li></ul><ul><li> not useful for global coverage for small mobile phones and data transmission, typically used for radio and TV transmission </li></ul>
    45. 47. LEO systems <ul><li>Orbit ca. 500 - 1500 km above earth surface </li></ul><ul><li>visibility of a satellite ca. 10 - 40 minutes </li></ul><ul><li>global radio coverage possible </li></ul><ul><li>latency comparable with terrestrial long distance connections, ca. 5 - 10 ms </li></ul><ul><li>smaller footprints, better frequency reuse </li></ul><ul><li>but now handover necessary from one satellite to another </li></ul><ul><li>many satellites necessary for global coverage </li></ul><ul><li>more complex systems due to moving satellites </li></ul><ul><li>Examples: </li></ul><ul><li>Iridium (start 1998, 66 satellites) </li></ul><ul><ul><li>Bankruptcy in 2000, deal with US DoD (free use, saving from “deorbiting”) </li></ul></ul><ul><li>Globalstar (start 1999, 48 satellites) </li></ul><ul><ul><li>Not many customers (2001: 44000), low stand-by times for mobiles </li></ul></ul>
    46. 48. MEO systems <ul><li>Orbit ca. 5000 - 12000 km above earth surface </li></ul><ul><li>comparison with LEO systems: </li></ul><ul><li>slower moving satellites </li></ul><ul><li>less satellites needed </li></ul><ul><li>simpler system design </li></ul><ul><li>for many connections no hand-over needed </li></ul><ul><li>higher latency, ca. 70 - 80 ms </li></ul><ul><li>higher sending power needed </li></ul><ul><li>special antennas for small footprints needed </li></ul><ul><li>Example: </li></ul><ul><li>ICO (Intermediate Circular Orbit, Inmarsat) start ca. 2000 </li></ul><ul><ul><li>Bankruptcy, planned joint ventures with Teledesic, Ellipso – cancelled again, start planned for 2003 </li></ul></ul>
    47. 49. Handover in satellite systems <ul><li>Several additional situations for handover in satellite systems compared to cellular terrestrial mobile phone networks caused by the movement of the satellites </li></ul><ul><ul><li>Intra satellite handover </li></ul></ul><ul><ul><ul><li>handover from one spot beam to another </li></ul></ul></ul><ul><ul><ul><li>mobile station still in the footprint of the satellite, but in another cell </li></ul></ul></ul><ul><ul><li>Inter satellite handover </li></ul></ul><ul><ul><ul><li>handover from one satellite to another satellite </li></ul></ul></ul><ul><ul><ul><li>mobile station leaves the footprint of one satellite </li></ul></ul></ul><ul><ul><li>Gateway handover </li></ul></ul><ul><ul><ul><li>Handover from one gateway to another </li></ul></ul></ul><ul><ul><ul><li>mobile station still in the footprint of a satellite, but gateway leaves the footprint </li></ul></ul></ul><ul><ul><li>Inter system handover </li></ul></ul><ul><ul><ul><li>Handover from the satellite network to a terrestrial cellular network </li></ul></ul></ul><ul><ul><ul><li>mobile station can reach a terrestrial network again which might be cheaper, has a lower latency etc. </li></ul></ul></ul>
    48. 50. What’s on a satellite? Communications Power Sensors/Instruments “ Bus”
    49. 51. How Satellites Work <ul><li>A Earth Station sends message in GHz range. (Uplink) </li></ul><ul><li>Satellite Receive and retransmit signals back. (Downlink) </li></ul><ul><li>Other Earth Stations receive message in useful strength area. (Footprint) </li></ul>
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