This presentation gives an overview of the networking and conceptualize the terms of the Satellite networking systems, and also provide a glance of the typical functionality of the satellite system in establishing the worldwide mobile communication system, as well as the broadcasting system. With the support and encouragement of my faculty and friends developed this presentation... Thank you

2. Satellite Systems
Mobile Computing
• What is a Satellite?
• Types of Satellites
• History
• Basics
• Applications
• Routing
• Localization
• Handover

3. SATELLITE

4. What is a Satellite?
A satellite is an object in space that orbits or
circles around a bigger object.
Example: Earth is a satellite because it orbits around the sun.
Moon and ISS are a satellites because they orbits
earth. Note: Earth and Moon are called “natural satellites”

5. What satellite do?

6. SATELLITE
TYPES

7. TYPES
 Natural Satellites
– Moon
 Artificial Satellites
– International Space Station

8. HISTORY
OF
SATELLITES

9. History
 1945 – Arthur C. Clarke published his essay on ‘Extra Terrestrial Relays’.
 1957 – The first satellite SPUTNIK launched by Soviet Union.
 1960 – the first reflecting communication satellite ECHO was launched by
the America.
 1963 – The first geostationary satellite SYNCOM.
 1965 – The first commercial geostationary communication satellite
INTELSAT 1 (Early Bird).
INTELSAT2(1967) and INTELSAT3(1969)
 1976 – Three MARISAT satellites offering worldwide maritime
communication.
 1982 – The first mobile satellite telephone system, INMARSAT-A.
 1988 – INMARSAT-C, the first satellite to offer mobile and data services.
 1993 – INMARSAT-M helped in digitalizing the satellite telephone systems.
 1998 – The global satellite systems were introduced for small mobile
phones

10. BASICS:
ORBIT TYPES

11. BASICS: ORBIT TYPES
LEO = Low Earth Orbit (100 – 1,500
km)
MEO = Medium Earth Orbit (5,000 –
10,000 km)
GEO = Geostationary Earth Orbit
(36,000 km)
HEO = Highly Elliptical Orbit

12. BASICS: ORBIT TYPES
TYPE LEO MEO GEO
Description Low Earth Orbit Medium Earth Orbit Geostationary Earth Orbit
Height 100 – 300 miles 6,000 – 12,000 miles 22,300 miles
Time in LOS 15 min 2 – 4 Hours 24 Hours
Merits
1. Lower launch costs
2. Very short round trip
delays
3. Small path loss
1. Moderate launch cost
2. Small round trip delays
1. Covers 42.2% of the earth’s surface
2. Constant View
3. No problems due to Doppler
Demerits
1. Short Life
2. Encounters Radiation
belts
3. Short LOS
1. Round trip delays
2. Greater path loss
1. Larger round trip delays
2. Expensive equipment due to weak
signal

13. BASICS
OF
SATELLITES

14. BASICS
A Satellite orbit the Earth in one of the two
basic types of orbit.
 Circular satellite orbit:
• For a circular orbit, the distance from the Earth remains same at all
times.
 Elliptical satellite orbit:
• The elliptical orbit changes the distance to the Earth.

15. BASICS
 Circular orbit of the Satellite:
gravitational force
 centrifugal force
m is the mass of the satellite.
R is the radius of earth (i.e., 6370Km)
r is the distance of the satellite to the centre of the earth.
g is the acceleration of the gravity with g=9.81 m/s2
ω is the angular velocity with ω = 2 ∙∏∙f, where f is the frequency of the rotation.
Fg = m g (R/r)2
Fc = m ∙ r ∙ ω2

16. BASICS
 To keep the satellite in a stable orbit
the following equation
 , both forces must be equal.
 The distance r = (g·R2/(2·π·f)2)1/3
Fg =
Fc

17. DEPENDENCY OF SATELLITE PERIOD AND DISTANCE TO THE EARTH
Satellite
period [h]
velocity [x1000 km/h]
Synchronous distance
35,786 km
radius

18. INCLINATION ANGLE
 The inclination angle δ is defined as the angle
between the equatorial plane and the
plane described by the satellite orbit.
 Perigee, the closest point to the earth(not
circular).

19. INCLINATION ANGLE OF A SATELLITE

20. ELEVATION ANGLE
 The elevation angle ε is defined as the angle
between the center of the satellite beam
and the plane tangential to the earth’s
surface.
 Also called as Footprint
Footprint

21. ELEVATION ANGLE OF A SATELLITE
ε
Elevation:
angle ε between center of satellite
beam and surface
Minimal elevation:
elevation needed at least
to communicate with the satellite

22. APPLICATIONS

23. APPLICATIONS
 Weather forecasting
– Monitoring the geographic movements of the
earth and forward the surveillance in the form of
pictures using infra red or visible light.
 Radio and TV broadcast
– Broadcasting of the programs with the help of
satellite dishes comprising of 30-40 cm of
diameter

24. APPLICATIONS
Military satellites
– Used for the carrying out espionage
– Safe from attack by enemies
 Satellites for navigation
– GPS (Geo Positioning System)
– This system allows precision localization worldwide
 Global mobile communications
– The latest trend for satellites is the support of global
mobile data communication

25. ROUTING

26. ROUTING
Gateways and fixed terrestrial networks
User sends data up to a satellite.
Data forwarded across multiple gateways to reach the
receiver.
Routing takes place in fixed networks.
Limitations:
This requires two uplinks and two downlinks

27. ROUTING
Inter satellite links (ISL)
Traffic can be routed between the satellites.
Only one uplink and one downlink per direction needed
for the connection of two users.
Routing within the satellites reduces the number of
Gateways needed on earth.
Limitations:
More complex focusing of antennas between satellites
High system complexity due to moving routers.

28. footprint
ISDN PSTN GSM
User Data
Base Station
Or Gateway
Small cells
(Spot Beams)
Inter Satellite Link
[ISL]
Mobile User Link
(MUL)
Gateway Link
(GWL) GWL
MWL
TYPICAL SATELLITE SYSTEM FOR MOBILE
COMMUNICATIONS

29. LOCALIZATION

30. LOCALIZATION
Satellite localization:
Mechanism is similar to traditional cellular networks.
Satellites are termed as ‘Base Station’ (movable).
Gateways maintains several registers:
– Home Location Register (HLR)
• Stores the static information about the user’s current location
– Visitor Location Register (VLR)
• Stores the last known location of a mobile user.
– Satellite User Mapping Register (SUMR)
• Current position of satellites and a mapping of each user to the current
satellite

31. LOCALIZATION
Registration of Base Station:
 The mobile station initially sends a signal which one or several
satellites can receive.
 Satellites receiving such a signal report this event to a
gateway.
 The gateway can now determine the location of the user via
the location of the satellites.
 User data requested from his/her HLR, VLR and SUMR are
updated

32. LOCALIZATION
Calling a Mobile Station:
 Similar to GSM
 Call gets forwarded to Gateway
 Gateway localizes the mobile station using HLR and VLR.
 SUMR finds the appropriate satellite for communication and
the connection can be set up.

33. HANDOVER

34. HANDOVER
Def: “The process of transferring satellite control responsibility
from one earth station to another without loss or interruption of
service”
Each satellite represents a base station for a mobile
phone.
Compared to terrestrial networks, additional
instances of handover required due to the
movement of the satellites.

35. HANDOVER
• Intra – satellite handover
• Inter – satellite handover
• Gateway handover
• Inter – system handover
Examples:
Iridium (77 electrons)

36. HANDOVER
Intra – Satellite Handover:
– User move from one spot beam to another
– Special antennas of Satellites can create several spot
beams
– The same effect can be produced even in the
movement of the satellite.
Inter – Satellite Handover:
– leaving one footprint or satellite moves away
– Handover from one footprint to another footprint
– Can also takes place between satellites (ISL).

37. HANDOVER
Gateway Handover:
– Handover from one gateway to another
– Mobile station is still in the footprint of a satellite, but
gateway leaves the footprint
Inter-System Handover:
– Handover between satellite systems and terrestrial
cellular systems
– Mobile station can reach a terrestrial network again
which might be cheaper, has a low latency

38. footprint
ISDN PSTN GSM
User Data
Base Station
Or Gateway
Small cells
(Spot Beams)
Inter Satellite Link
[ISL]
Mobile User Link
(MUL)
Gateway Link
(GWL) GWL
MWL
Satellite System (Communication)

39.  Satellite systems are not aimed to replace the classical
terrestrial networking system but complimenting them.
 Satellites remain the best utilization for communications
based upon the speed and other advantages as
mentioned in this presentation.