Satellite Networking Introductory Lecture

Satellite Networking

Introductory Lecture

http://web.uettaxila.edu.pk/CMS/SP2015/teSNms/http://web.uettaxila.edu.pk/CMS/SP2015/teSNms/

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.

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.

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.

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.

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.

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.

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.

Text Book

Title: The Satellite Communication Applications Handbook

Author: Bruce R. Elbert ISBN: 1580534902 EAN: 9781580534901 Publisher:

Artech House Publishers

Reference Books

Title: Satellite Communications Author: Dennis Roddy ISBN: 0071371761 EAN: 9780071371766 Publisher:

McGraw-Hill Professional

Reference Books

Title: Satellite Communication Engineering Author: Michael O. Kolawole ISBN: 082470777X EAN: 9780071371766 Publisher:

Marcel Dekker, Inc.

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)

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


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


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)


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


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?


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.

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.

Intelsat Structure

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

Eutelsat Structure

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.

Motivation to use Satellites

Satellite Missions

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

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

Satellite System Elements

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

Ground Segment Collection of facilities, Users and Applications

Earth Station = Satellite Communication Station (Fixed or Mobile)

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.

Satellite Uplink and Downlink

Satellite Communication

Source: Cryptome [Cryptome.org]

When using a satellite for long When using a satellite for long distance communications, the distance communications, the satellite acts as a repeater.satellite acts as a repeater.

An earth station transmits the An earth station transmits the signal up to the satellite signal up to the satellite (uplink), which in turn (uplink), which in turn retransmits it to the receiving retransmits it to the receiving earth station (downlink).earth station (downlink).

Different frequencies are used Different frequencies are used for uplink/downlink.for uplink/downlink.

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

Direct to User Services

One way Service (Broadcasting)One way Service (Broadcasting) Two way Service (Communication)Two way Service (Communication)

Satellite Signals

Used to transmit signals and data over long distances

Weather forecasting

Television broadcasting

Internet communication

Global Positioning Systems

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

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

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

Satellite Orbits

Source: Federation of American Scientists [www.fas.org]

Geosynchronous Orbit (GEO): Geosynchronous Orbit (GEO): 36,000 km above Earth, 36,000 km above Earth, includes commercial and includes commercial and military communications military communications satellites, satellites providing satellites, satellites providing early warning of ballistic early warning of ballistic missile launch.missile launch.

Medium Earth Orbit (MEO): Medium Earth Orbit (MEO): from 5000 to 15000 km, they from 5000 to 15000 km, they include navigation satellites include navigation satellites (GPS, Galileo, Glonass).(GPS, Galileo, Glonass).

Low Earth Orbit (LEO): from Low Earth Orbit (LEO): from 500 to 1000 km above Earth, 500 to 1000 km above Earth, includes military intelligence includes military intelligence satellites, weather satellites.satellites, weather satellites.

Satellite Orbits

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)

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

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

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)

Satellite Orbits

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

Why Satellites remain in Orbits?

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

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

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

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

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.

Earth’s atmosphere

Source: All about GPS [www.kowoma.de]

Q&A

????

Satellite Networking Introductory Lecture

Documents

Transcript of Satellite Networking Introductory Lecture