satellite networks

1. Satellite Networking
Introductory Lecture
http://web.uettaxila.edu.pk/CMS/SP2015/teSNms/

2. Overview
 Satellite technology has progressed tremendously over
the last 50 years since Arthur C. Clarke first proposed
its idea in 1945 in his article in Wireless World.
 Today, satellite systems can provide a variety of
services including broadband communications,
audio/video distribution networks, maritime
navigation, worldwide customer service and support as
well as military command and control.
 Satellite systems are also expected to play an
important role in the emerging 4G global infrastructure
providing the wide area coverage necessary for the
realization of the “Optimally Connected Anywhere,
Anytime” vision that drives the growth of modern
telecom industry.

3. Course Objectives
This course aims to:
 Provide a broad overview of the status of digital
satellite communications.
 Discuss main physical, architectural and networking
issues of satellite systems.
 Provide in-depth understanding of modern modulation,
coding and multiple access schemes.
 Review the state of the art in open research areas such
as satellite networking, internet over satellite and
satellite personal communications.
 Highlight trends and future directions of satellite
communication.

4. Section 1: The SATCOM Industry –
System Design Issues /
Basics of Satellite Communication
 An Overview of Satellite Communications
 Examples of current military and commercial systems.
 Satellite orbits and transponder characteristics (LEO, MEO, GEO)
 Traffic Connectivity: Mesh, Hub-Spoke, Point-to-Point, Broadcast
 Basic satellite transmission theory
 Impairments of the Satellite Channel: Weather and Doppler effects,
Channel models.
 Communications Link Calculations: Definition of EIRP, Noise
temperature etc. Transponder gain and SFD. Link Budget Calculations.
Down-link requirements. Design of satellite links to achieve a
specified performance.
 Earth Station Antenna types: Pointing/Tracking. Small antennas at Ku
band. FCC-Intelsat-ITU antenna requirements and EIRP density
limitations.
 Brief introduction to implementation issues: LNA, Up/down converters
etc.

5. Section 2: Elements of
Transponder Design – The
Baseband / Fixed Satellite System
 Physical Layer of the Transponder – The Baseband System
 Introduction to the theory of Digital Communications:
Modulation, Equalization and FEC
 Digital Modulation Techniques: BPSK, QPSK, Nyquist signal shaping.
 Overview of Bandwidth Efficient Modulation (BEM) Techniques: M-
ary PSK, Trellis Coded 8PSK, QAM.
 PSK Receiver Implementation issues: Carrier recovery, phase slips,
differential coding.
 Overview of Forward Error Correction (FEC): Standard FEC
types (Block and Convolution Coding schemes, Viterbi
Decoding), Coding Gain, Concatenated coding, Turbo
coding.

6. Section 3: Multiple Access
Issues / Satellite
Communication Services
 Spread Spectrum Techniques: Military and
commercial use of spread-spectrum. Direct-
Sequence, Frequency-Hop and CDMA systems.
 Principles of Multiple Access Communications
 Multiplexing & Multiple Access FDD/TDD, FDMA, TDMA
 Concepts of Random Access: ALOHA, CSMA
 Multiple Access Techniques: FDMA, TDMA, CDMA.
Demand Assigned Multiple Access (DAMA) and
Bandwidth-on-Demand (BoD).
 TDMA Networks: Time Slots, Preambles, Suitability
for DAMA and BoD.

7. Section 4: SATCOM Networks
and Services / Foundation in
Space Marketing
 Satellite Communication Systems &
Networks
 Characteristics of IP and TCP/UDP over
satellite: Unicast and Multicast. Need for
Performance
 Performance Enhancing Proxy (PEP)
techniques.
 VSAT Networks and their system
characteristics.
 DVB standards and MultiFreq-TDMA
 The Future of SATCOM
 SATCOM’s role in the emerging 4G
Information and Communications (ICT)
infrastructure.

8. Section 5: Space Remote Sensing
/ Space Remote Sensing Systems
 A survey of historical and current remote sensing
systems will be presented, covering all major
governmental and private systems.
 The business of remote sensing, including system
development, launch, and operational costs will be
presented, along with remote sensing market trends
and user communities.

9. Text Book
 Title: The Satellite Communication
Applications Handbook
 Author: Bruce R. Elbert
 ISBN: 1580534902
 EAN: 9781580534901
 Publisher:
Artech House Publishers

10. Reference Books
 Title: Satellite Communications
 Author: Dennis Roddy
 ISBN: 0071371761
 EAN: 9780071371766
 Publisher:
McGraw-Hill Professional

11. Reference Books
 Title: Satellite Communication Engineering
 Author: Michael O. Kolawole
 ISBN: 082470777X
 EAN: 9780071371766
 Publisher:
Marcel Dekker, Inc.

12. Pioneers in Satellite
Communication
 Konstantin Tsiolkovsky (1857 - 1935)
Russian visionary of space flight First described the
multi-stage rocket as means of achieving orbit.
 Link: The life of Konstantin Eduardovitch Tsiolkovsky
 Hermann Noordung (1892 - 1929)
Postulated the geostationary orbit.
 Link: The Problem of Space Travel: The Rocket Motor
 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.
 Link: "Wireless World" (1945)

13. Satellite History Calendar
 1957
 October 4, 1957: - First satellite - the Russian Sputnik 01
 First living creature in space: Sputnik 02
 1958
 First American satellite: Explorer 01
 First telecommunication satellite: This satellite broadcast a taped message: Score
 1959
 First meteorology satellite: Explorer 07
 1960
 First successful passive satellite: Echo 1
 First successful active satellite: Courier 1B
 First NASA satellite: Explorer 08
 April 12, 1961: - First man in space
 1962
 First telephone communication & TV broadcast via satellite: Echo 1
 First telecommunication satellite, first real-time active, AT&T: Telstar 1
 First Canadian satellite: Alouette 1
 On 7th 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.
 Rehbar-II followed a successful launch on 9th June 1962

14. Satellite History Calendar
 1963
 Real-time active: Telstar 2
 1964
 Creation of Intelsat
 First geostationary satellite, second satellite in stationary orbit: Syncom 3
 First Italian satellite: San Marco 1
 1965
 Intelsat 1 becomes first commercial comsat: Early Bird
 First real-time active for USSR: Molniya 1A
 1967
 First geostationary meteorology payload: ATS 3
 1968
 First European satellite: ESRO 2B
 July 21, 1969: - First man on the moon

15. Satellite History Calendar
 1970
 First Japanese satellite: Ohsumi
 First Chinese satellite: Dong Fang Hong 01
 1971
 First UK launched satellite: Prospero
 ITU-WARC for Space Telecommunications
 INTELSAT IV Launched
 INTERSPUTNIK - Soviet Union equivalent of INTELSAT formed
 1974
 First direct broadcasting satellite: ATS 6
 1976
 MARISAT - First civil maritime communications satellite service started
 1977
 EUTELSAT - European regional satellite
 ITU-WARC for Space Telecommunications in the Satellite Service
 1979
 Creation of Inmarsat (International Marine Satellite)

16. Satellite History Calendar
 1980
 INTELSAT V launched - 3 axis stabilized satellite built by Ford Aerospace
 1983
 ECS (EUTELSAT 1) launched - built by European consortium supervised by ESA
 1984
 UK's UNISAT TV DBS satellite project abandoned
 First satellite repaired in orbit by the shuttle: SMM
 1985
 First Brazilian satellite: Brazilsat A1
 First Mexican satellite: Morelos 1
 1988
 First Luxemburg satellite: Astra 1A
 1989
 INTELSAT VI - one of the last big "spinners" built by Hughes
 Creation of Panamsat - Begins Service
 1990
 IRIDIUM, TRITIUM, ODYSSEY and GLOBALSTAR S-PCN projects proposed - CDMA designs more popular
 EUTELSAT II
 On 16 July 1990, Pakistan launched its first experimental satellite, BADR-I from China

17. Satellite History Calendar
 1992
 OLYMPUS finally launched - large European development satellite with Ka-band, DBTV and Ku-band
SS/TDMA payloads - fails within 3 years
 1993
 INMARSAT II - 39 dBW EIRP global beam mobile satellite - built by Hughes/British Aerospace
 1994
 INTELSAT VIII launched - first INTELSAT satellite built to a contractor's design
 Hughes describe SPACEWAY design
 DirecTV begins Direct Broadcast to Home
 1995
 Panamsat - First private company to provide global satellite services.
 1996
 INMARSAT III launched - first of the multibeam mobile satellites (built by GE/Marconi)
 Echostar begins Diresct Broadcast Service
 1997
 IRIDIUM launches first test satellites
 ITU-WRC'97
 1999
 AceS launch first of the L-band MSS Super-GSOs - built by Lockheed Martin
 Iridium Bankruptcy - the first major failure?

18. Satellite History Calendar
 2000
 Globalstar begins service
 Thuraya launch L-band MSS Super-GSO
 2001
 XM Satellite Radio begins service
 Pakistan’s 2nd Satellite, BADR-B was launched on 10 Dec 2001 at 9:15a from Baikonour Cosmodrome,
Kazakistan
 2002
 Sirius Satellite Radio begins service
 Paksat-1, was deployed at 38 degrees E orbital slot in December 2002
 2004
 Teledesic network planned to start operation
 2005
 Intelsat and Panamsat Merge
 VUSat OSCAR-52 (HAMSAT) Launched
 2006
 CubeSat-OSCAR 56 (Cute-1.7) Launched
 K7RR-Sat launched by California Politechnic University
 2007
 Prism was launched by University of Tokyo
 2008
 COMPASS-1; a project of Aachen University was launched from Satish Dawan Space Center, India. It failed
to achieve orbit.

19. Intelsat
 INTELSAT is the original "International
Telecommunications Satellite Organization". It once
owned and operated most of the World's satellites used
for international communications, and still maintains a
substantial fleet of satellites.
 INTELSAT is moving towards "privatization", with
increasing competition from commercial operators
 (e.g. Panamsat, Loral Skynet, etc.).
 INTELSAT Timeline:
 Interim organization formed in 1964 by 11 countries
 Permanent structure formed in 1973
 Commercial "spin-off", New Skies Satellites in 1998
 Full "privatization" by April 2001
 INTELSAT has 143 members and signatories listed here.

20. Intelsat Structure

21. Eutelsat
 Permanent General Secretariat opened September 1978
 Intergovernmental Conference adopted definitive statutes with 26
members on 14 May 1982
 Definitive organization entered into force on 1 September 1985
 General Secretariat -> Executive Organ
 Executive Council -> EUTELSAT Board of Signatories
 Secretary General -> Director General
 Current DG is Michel de Rosen
 Currently almost 50 members
 Moving towards "privatization"
 Limited company owning and controlling of all assets and activities
 Also a "residual" intergovernmental organization which will ensure that
basic principles of pan-European coverage, universal service, non-
discrimination and fair competition are observed by the company

22. Eutelsat Structure

23. Communication Satellites
 A Communication Satellite can be looked upon as a
large microwave repeater
 It contains several transponders which listens to some
portion of spectrum, amplifies the incoming signal and
broadcasts it in another frequency to avoid interference
with incoming signals.

24. Motivation to use Satellites

25. Satellite Missions
Source: Union of Concerned Scientists [www.ucsusa.org]

26. Satellite Microwave
Transmission
 Satellites can relay signals over a long distance
 Geostationary Satellites
 Remain above the equator at a height of about 22300
miles (geosynchronous orbits)
 Travel around the earth in exactly the same time, the
earth takes to rotate

27. Satellite System Elements

28. Space Segment
 Satellite Launching Phase
 Transfer Orbit Phase
 Deployment
 Operation
 TT&C - Tracking Telemetry and Command Station
 SSC - Satellite Control Center, a.k.a.:
 OCC - Operations Control Center
 SCF - Satellite Control Facility
 Retirement Phase

29. Ground Segment
 Collection of facilities, Users and Applications
 Earth Station = Satellite Communication Station
(Fixed or Mobile)

30. Satellite Uplink and Downlink
 Downlink
 The link from a satellite down to one or more
ground stations or receivers
 Uplink
 The link from a ground station up to a
satellite.
 Some companies sell uplink and downlink
services to
 television stations, corporations, and to other
telecommunication carriers.
 A company can specialize in providing uplinks,
downlinks, or both.

31. Satellite Uplink and Downlink

32. Satellite Communication
Source: Cryptome [Cryptome.org]
 When using a satellite for long
distance communications, the
satellite acts as a repeater.
 An earth station transmits the
signal up to the satellite
(uplink), which in turn
retransmits it to the receiving
earth station (downlink).
 Different frequencies are used
for uplink/downlink.

33. Satellite Transmission Links
 Earth stations Communicate by sending signals to the
satellite on an uplink
 The satellite then repeats those signals on a downlink
 The broadcast nature of downlink makes it attractive for
services such as the distribution of TV programs

34. Direct to User Services
One way Service (Broadcasting) Two way Service (Communication)

35. Satellite Signals
 Used to transmit signals and data over long distances
 Weather forecasting
 Television broadcasting
 Internet communication
 Global Positioning Systems

36. Satellite Transmission Bands
Frequency Band Downlink Uplink
C 3,700-4,200 MHz 5,925-6,425 MHz
Ku 11.7-12.2 GHz 14.0-14.5 GHz
Ka 17.7-21.2 GHz 27.5-31.0 GHz
The C band is the most frequently used. The Ka and Ku bands are reserved
exclusively for satellite communication but are subject to rain attenuation

37. Types of Satellite Orbits
 Based on the inclination, i, over the equatorial
plane:
 Equatorial Orbits above Earth’s equator (i=0°)
 Polar Orbits pass over both poles (i=90°)
 Other orbits called inclined orbits (0°<i<90°)
 Based on Eccentricity
 Circular with centre at the earth’s centre
 Elliptical with one foci at earth’s centre

38. Types of Satellite based
Networks
 Based on the Satellite Altitude
 GEO – Geostationary Orbits
 36000 Km = 22300 Miles, equatorial, High latency
 MEO – Medium Earth Orbits
 High bandwidth, High power, High latency
 LEO – Low Earth Orbits
 Low power, Low latency, More Satellites, Small Footprint
 VSAT
 Very Small Aperture Satellites
 Private WANs

39. Satellite Orbits
Source: Federation of American Scientists [www.fas.org]
 Geosynchronous Orbit
(GEO): 36,000 km above
Earth, includes commercial
and military communications
satellites, satellites providing
early warning of ballistic
missile launch.
 Medium Earth Orbit (MEO):
from 5000 to 15000 km,
they include navigation
satellites (GPS, Galileo,
Glonass).
 Low Earth Orbit (LEO): from
500 to 1000 km above Earth,
includes military intelligence
satellites, weather satellites.

40. Satellite Orbits

41. GEO - Geostationary Orbit
 In the equatorial plane
 Orbital Period = 23 h 56 m 4.091 s
= 1 sidereal day*
 Satellite appears to be stationary over any
point on equator:
 Earth Rotates at same speed as Satellite
 Radius of Orbit r = Orbital Height + Radius of
Earth
 Avg. Radius of Earth = 6378.14 Km
 3 Satellites can cover the earth (120° apart)

42. NGSO - Non Geostationary
Orbits
 Orbit should avoid Van
Allen radiation belts:
 Region of charged
particles that can cause
damage to satellite
 Occur at
 ~2000-4000 km and
 ~13000-25000 km

43. LEO - Low Earth Orbits
 Circular or inclined orbit with < 1400 km
altitude
 Satellite travels across sky from horizon to horizon in
5 - 15 minutes => needs handoff
 Earth stations must track satellite or have Omni
directional antennas
 Large constellation of satellites is needed for
continuous communication (66 satellites needed to
cover earth)
 Requires complex architecture
 Requires tracking at ground

44. HEO - Highly Elliptical Orbits
 HEOs (i = 63.4°) are suitable to
provide coverage at high latitudes
(including North Pole in the northern
hemisphere)
 Depending on selected orbit (e.g.
Molniya, Tundra, etc.) two or three
satellites are sufficient for continuous
time coverage of the service area.
 All traffic must be periodically
transferred from the “setting”
satellite to the “rising” satellite
(Satellite Handover)

45. Satellite Orbits
Source: Union of Concerned Scientists [www.ucsusa.org]

46. Why Satellites remain in
Orbits?

47. Advantages of Satellite
Communication
 Can reach over large geographical area
 Flexible (if transparent transponders)
 Easy to install new circuits
 Circuit costs independent of distance
 Broadcast possibilities
 Temporary applications (restoration)
 Niche applications
 Mobile applications (especially "fill-in")
 Terrestrial network "by-pass"
 Provision of service to remote or underdeveloped
areas
 User has control over own network
 1-for-N multipoint standby possibilities

48. Disadvantages of Satellite
Communication
 Large up front capital costs (space segment and launch)
 Terrestrial break even distance expanding (now approx.
size of Europe)
 Interference and propagation delay
 Congestion of frequencies and orbits

49. When to use Satellites
 When the unique features of satellite
communications make it attractive
 When the costs are lower than terrestrial routing
 When it is the only solution
 Examples:
 Communications to ships and aircraft (especially
safety communications)
 TV services - contribution links, direct to cable
head, direct to home
 Data services - private networks
 Overload traffic
 Delaying terrestrial investments
 1 for N diversity
 Special events

50. When to use Terrestrial
 PSTN - satellite is becoming increasingly
uneconomic for most trunk telephony
routes
 but, there are still good reasons to use
satellites for telephony such as: thin
routes, diversity, very long distance traffic
and remote locations.
 Land mobile/personal communications - in
urban areas of developed countries new
terrestrial infrastructure is likely to
dominate (e.g. GSM, etc.)
 but, satellite can provide fill-in as
terrestrial networks are implemented, also
provide similar services in rural areas and
underdeveloped countries

51. Frequency Bands Allocated
to the FSS
 Frequency bands are allocated to different services
at World Radio-communication Conferences (WRCs).
 Allocations are set out in Article S5 of the ITU Radio
Regulations.
 It is important to note that (with a few exceptions)
bands are generally allocated to more than one radio
services.
 CONSTRAINTS
 Bands have traditionally been divided into
“commercial" and "government/military" bands,
although this is not reflected in the Radio Regulations
and is becoming less clear-cut as "commercial"
operators move to utilize "government" bands.

52. Earth’s atmosphere
Source: All about GPS [www.kowoma.de]

53. Q&A
 ????