1. Satellite Communication
Introductory Lecture

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 speech and video coding, satellite networking, internet over satellite and satellite personal communications.
Highlight trends and future directions of satellite communication

4. Course Pre-requisites
Principles of digital communications
Telecom systems design

5. Section 1: The SATCOM Industry – System Design Issues
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 and G/T ratio, Eb/No. 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, oscillator phase noise.
SFD = Saturation Flux Density: the saturation flux density is a measure of the power density required at the input of the satellite (right before the receiving antenna) in order to deliver the maximum EIRP from the amplifier in the output, considering the backoffs set by the satellite operator. it can be specified independent of the position where you are in the coverage area, as it is transponder specific.

6. Section 2: Elements of Transponder Design – The Baseband
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.

7. Section 3: Multiple Access Issues
Spread Spectrum Techniques: Military and commercial use of spread-spectrum. Direct-Sequence PN, 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. DAMA and Bandwidth-on-Demand (BoD).
TDMA Networks: Time Slots, Preambles, Suitability for DAMA and BoD.

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

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

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

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

12. Pioneers in Satellite Communication
Konstantin Tsiolkovsky ( ) 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 ( ) 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
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

14. Satellite History Calendar
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
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

15. 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
On 16 July 1990, Pakistan launched its first experimental satellite, BADR-I from China
1990 
IRIDIUM, TRITIUM, ODYSSEY and GLOBALSTAR S-PCN projects proposed - CDMA designs more popular
EUTELSAT II
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.
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.

16. Satellite History Calendar
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?
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, 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.

17. Intelsat
INTELSAT is the original "Inter-governmental 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.

18. Intelsat Structure

19. 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 Giuliano Berretta
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

20. Eutelsat Structure

21. Communication Satellite
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.

22. Motivation to use Satellites

23. Satellite Missions
Source: Union of Concerned Scientists [

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

25. Satellite System Elements

26. 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

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

28. Satellite Uplink and 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.

29. Satellite Uplink and Downlink

30. Satellite Communication
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.
Source: Cryptome [Cryptome.org]

31. 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

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

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

34. Satellite Transmission Bands
Frequency Band
Downlink
Uplink C
3,700-4,200 MHz
5,925-6,425 MHz Ku
GHz
GHz Ka
GHz
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

35. 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

36. Types of Satellite based Networks
Based on the Satellite Altitude
GEO – Geostationary Orbits
36000 Km = 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

37. Satellite Orbits
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 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.
Source: Federation of American Scientists [

38. Satellite Orbits

39. GEO - Geostationary Orbit
In the equatorial plane
Orbital Period = 23 h 56 m 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 = Km
3 Satellites can cover the earth (120° apart)
*More detail in next lecture: A sidereal day is the time between consecutive crossings of any particular longitude on the earth with reference to
inertial space (or it’s own axis); I.e., in practice, with reference to any star other than the sun. This corresponds to a 360 degree rotation.

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

41. LEO - Low Earth Orbits
Circular or inclined orbit with < 1400 km altitude
Satellite travels across sky from horizon to horizon in 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

42. 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)

43. Satellite Orbits
Source: Union of Concerned Scientists [

44. Why Satellites remain in Orbits

45. 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
Transponders are microwave repeaters carried by communications satellites. Transparent transponders can handle any signal whose format can fit in the transponder bandwidth. No signal processing occurs other than that of heterodyning (frequency changing) the uplink frequency bands to those of the downlinks. Such a satellite communications system is referred to as a bent-pipe system. Connectivity among earth stations is reduced when multiple narrow beams are used. Hence, the evolution proceeded from the transparent transponder to transponders that can perform signal switching and format processing.

46. 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
Breakeven Distance: As the cost of Satellite Circuit is independent of distance on the Earth between the two ends, whilst the cost of a terrestrial circuit is approximately directly proportional to that distance, the concept of a "breakeven" distance where the costs are equal has been used to determine where services should be routed via satellite. This breakeven distance varies according to the size of the route, growth rate, and any special networking requirements.

47. 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
1 for N Diversity: Where there is negligible likelihood of route failure, there is no need for route diversity protection and the type of protection used is known as "1 for N". In point to point radio systems it is (typically 7 : 1) throughout the world. If a worker section down a route fails, the traffic is switched to a stand-by section. After repair of the worker, traffic is returned to it after a suitable period of time. This period of time is that necessary for a stability test, to check that the fault has been genuinely cleared. Traffic loss due to section failure can typically be reduced by several hundred times by the use of "1-for-N" protection.

48. 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

49. 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.
FSS: Stands for Fixed Satellite Services. Satellite communications in the FSS frequency band were initially developed in order to provide transmission links between the public switched telephone networks (PSTNs) of different countries, first intercontinental and then regional (e.g. the Intelsat and Eutelsat systems respectively);

50. Earth’s atmosphere
Source: All about GPS [

51. Atmospheric Losses
Different types of atmospheric losses can disturb radio wave transmission in satellite systems:
Atmospheric absorption
Atmospheric attenuation
Traveling ionospheric disturbances

52. Atmospheric Absorption
Energy absorption by atmospheric gases, which varies with the frequency of the radio waves.
Two absorption peaks are observed (for 90º elevation angle):
22.3 GHz from resonance absorption in water vapour (H2O)
60 GHz from resonance absorption in oxygen (O2)
For other elevation angles:
[AA] = [AA]90 cosec 
Source: Satellite Communications, Dennis Roddy, McGraw-Hill

53. Atmospheric Attenuation
Rain is the main cause of atmospheric attenuation (hail, ice and snow have little effect on attenuation because of their low water content).
Total attenuation from rain can be determined by:
A = L [dB]
where  [dB/km] is called the specific attenuation, and can be calculated from specific attenuation coefficients in tabular form that can be found in a number of publications
where L [km] is the effective path length of the signal through the rain; note that this differs from the geometric path length due to fluctuations in the rain density.

54. Traveling Ionospheric Disturbances
Traveling ionospheric disturbances are clouds of electrons in the ionosphere that provoke radio signal fluctuations which can only be determined on a statistical basis.
The disturbances of major concern are:
Scintillation;
Polarisation rotation.
Scintillations are variations in the amplitude, phase, polarisation, or angle of arrival of radio waves, caused by irregularities in the ionosphere which change over time.
The main effect of scintillations is fading of the signal.

55. What is Polarisation?
Polarisation is the property of electromagnetic waves that describes the direction of the transverse electric field.
Since electromagnetic waves consist of an electric and a magnetic field vibrating at right angles to each other.
it is necessary to adopt a convention to determine the polarisation of the signal.
Conventionally, the magnetic field is ignored and the plane of the electric field is used.

56. Types of Polarisation Linear Polarisation (horizontal or vertical):
the two orthogonal components of the electric field are in phase;
The direction of the line in the plane depends on the relative amplitudes of the two components.
Circular Polarisation:
The two components are exactly 90º out of phase and have exactly the same amplitude.
Elliptical Polarisation:
All other cases.
Linear Polarisation
Circular Polarisation
Elliptical Polarisation

57. Satellite Communications
Alternating vertical and horizontal polarisation is widely used on satellite communications
This reduces interference between programs on the same frequency band transmitted from adjacent satellites (One uses vertical, the next horizontal, and so on)
Allows for reduced angular separation between the satellites.
Information Resources for Telecommunication Professionals [

58. Related Information

59. Q&A
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60. Assignment #1
Read the paper of Arthur C. Clark and summarize his suggestions to support Satellite for Communication purposes
Visit and visit JTrack-3D Link under Important Links section to complete the assignment
You need to find out the satellite name of PakSat-1 in JTrack-3D and send a snapshot of JTrack-3D with PakSat-1 in it