IETE KSrinivasan Mem Presentation

8/14/2019 IETE KSrinivasan Mem Presentation

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ADVANCED

SATELLITE COMMUNICATION

TECHNOLOGY

Dr. S. PAL*

ISRO Satellite Centre,

BANGALORE - 560 017

10 July , 2003

* Author is Outstanding Scientist & Deputy Director, DCA


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For mankind to survive three things are essential:

LOVE

ENERGY COMMUNICATION

The last one becomes more important for present

days.


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When it come to communication, now-a-

days there are two buzz words:

Communication

Information Technology


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There is another word `information' which is also

closely related to communications means "contents" o

message. Claude Shannon defined "information" as"Reduction of Uncertainty". Information is also

described as "any difference that makes a difference".

Information is a notch on the spectrum with raw data

on low end and knowledge/wisdom on the high end. Itsuggests that the raw data when processed becomes

information. Information minus noise is intelligence or

understanding. Intelligence plus experience is

knowledge; and knowledge when further processed,

looked through scholastic eyes, gets philosophized andso becomes wisdom which is adored over ages. The

present day society is often referred as information

society.


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In the past few decades, persons and institutions

have been progressively unsettled by the rapid pace

of social and technological changes brought about

by Communications (telephony, TV etc.). In earlier

times the world around us seemed more stable andmajor changes in values, institutions and technology

evolved more slowly. It took centuries for the

Middle Ages to become the Renaissance, yet many

of us have experienced major technologicalrevolution in one life time in the last century.


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Many technological reversals have been seen like

the telephone which should have been on thewired network has become wireless, while the TV

which was wireless now works on cable. Many

individual spheres of working have become

almost universal, like education has come to thedrawing room from school and colleges, sectors

like banking, medicines, hospitals etc which were

location specific are available on net. There is

tremendous convergence and fusion o

communications, computers and associated

technology in the present era.


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We are presently getting on the crest of thethird wave which is INFORMATION &

COMMUNICATION REVOLUTION more

appropriately termed as `IT' -Information

Technology, the first being agriculture & thesecond being ``Industrial Revolution'. As we

become increasingly networked, our worlds will

grow smaller and bigger simultaneously.


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The conventional communication tools are:

Telegraphy using copper wire line

Telephony using copper wire line

Television

New papers, books, etc.

Means of Transport

All these have undergone a tremendous changes. A few new names

for the present day communication techniques are:

Electronic/Voice MailSpace Communications

Private Data Service using VAST

Auto Text Service

Video text service (Fascimile)Radio trunking/paging

Cellular Mobile Telephone (PCS)

Wireless in local loops

Local National & International information exchange

intelligent Networks & Integrated Services Networks


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New ones are:Mobile Satellite Telephone - Personal Communication

Systems INFOSAT (information satellite)

A major shift from analogue to digital domain

An increase in the value of software as opposed to

hardware content

Extension of optical technology towards the local loop

coupled with increasing use of optical switches and optical

processing

Use of wireless in access technology - New access &

Modulation codes

Ultra broad band services

Extensive use of spread spectrum and code division

multiple access techniques.


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Services planned / in existence are:

Virtual Private Networks. / PCS - PersonalCommunication Services

Call Collect Services / Desk top Video conferencing

Card Phone Services/ Tele-education/Telehealth/

TeleshoppingVideo Telephone / Interactive Video & Video on

demand

Multimedia transmission / reception /e-mail/e-

Governance/e-commerceGlobal positioning/timing system along with SATNAV

Digital TV, Direct TV to Home

MOST IMPORTANT - THE INTERNET & WORLD

WIDE WEB


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All these need either terrestrial or satellite channels to

serve the user. The present day scenario looks like:

Cable TV

Television

DVD

VideoCameraPrinter

PDA

Desktop PC

Cellular

Telephone

Fax

Pager

Internet

Cellular

Internet TV

Video on

Demand

Home Banking

Internet

Telephony

Network

Computing

Video

conferencing

Smart Card

Space

World

Wide

Web

Terrestrial

Credit Card

A FUTURE COMMUNICATION SCENARIO

AUDIO SYSTEM


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The situation changed considerably in eighties and the

communications requirements became really nerve-

racking. Imagine the transmission reception of signals

to satellites from:A ship pitching and rolling on the high seas

An aeroplane flying at a speed of >800 kms per

hour

An orbiting space vehicle/satellite with speeds >7to 8 kms per second

An aeroplane or a ship in distress

A mountaineer/A trekker/A forest guard/An

elephant/A tiger/A bird/A turtle/a dolphin

A man always on move / A motor vehicle.

If using satellites to communicate is a great marvel,

doing the same without stopping or even slowing down

is almost miracle.


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VARIOUS CONVENTIONAL SATELLITE

COMMUNICATION SERVICES:

Telephony/TV Broadcasting/Data reception anddistribution/Direct Television broadcasting/Disaster

warning/Continuous weather monitoring/Spacecraft

Vehicle Tracking and Commanding/ Intersatellite

links/ Mail /Internet/Data mining

Position (GPS) and time determination / Moving

motor vehicle tracking etc.

* The commercial communication satellite servicesare rapidly becoming a large & global business

increasing from $11 billion in 1992 to $20 billion in

1996 and $75 billion by year 2005. (Projections have

come down to $$66.5 billion due to iridium failureand overall slump in the market)


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Before one goes ahead with communication

satellites, it will be quite important & relevant

to talk about latest arrival on thecommunication technology scene : the

INTERNET & THE WEB. Internet the

new incarnation of mass

communication is becoming quitepopular. Internet the parasite which

has almost eaten away the host - the

telecom channels, is influencing our

every sphere of life.


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The next stage 3.0 has been denoted "The information

Super High Way". Internet 3.0 could provide

symmetrical, high bandwidth links that can

simultaneously carry telephone, video (Television) anddata. Ideally bandwidth could be at a maximum

capacity of the copper wire that link central offices &

homes at a minimum of 6-25 MBPS.

In assessing the societal implications of powerfulhistorical forces, it is essential to take the long view.

However, when events are developing as rapidly as they

are on the internet, it is meaningless to look out further

than 15 years.

The safest prediction is that by 2010 or 2015 the

Internet, as we know it, will no longer exist. There will

just be the Net a ubiquitous, broadband data dial-tone

provided by a cable telephone, wireless or satellite

operators.


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Teledesic, Skybridge, Cyber Star, Astrolink iPSTAR

etc., are planning to provide internet & multimedia

services through space. Clearly changes will have a big

impact on society.

How big according to The Economist, a conservative an

perceptive publication not normally known for

exaggeration, the impact is likely to be `ahead of thetelephone and television but behind the printing press

and the motorcar".

The point is that the Net is a phenomenon that cannot

be ignored. It is an agent of change in all sectors osociety.


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The changes won't occur in isolation, but they

will be going on simultaneously, resulting in

unpredictable, unanticipated synergy. In turn,

this will lead to truly profound changes in

society & the present technological paradigm.

To help all these & to spread the net at a faster

pace even to inaccessible & remote places

Satellite Communication plays a major role,

besides the conventional terrestrial links,

optical links etc., which cater to cities and

larger population bases owning to the

economics.


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Having talked about INTERNET let us come back to space

communications.

The most popular one is going to be :

MOBILE PERSONAL COMMUNICATIONS


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One may be forced to

say that the future

communication willbe dominated by theMOBILE PERSONAL

COMMUNICATION

SERVICES and the

overall system designwill be done around

the main dictating

factor: spacecraft

G/T independent o

orbital heights and

frequency.

Th d t ti hi h b i ll d


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The ground stations which are becoming smaller and

smaller day by day will be of pocket size calculator.

The size of the ground station & that of satellites have

gone a tremendous change over years.


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The satellites for mobile communication services could

be LEO/GEO/ICO. As of today the LEO (Low Earth

Orbiting) constellations have provided the services.

IRIDIUM SYSTEM


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Mobile Satellite Communications using LEO, MEO or Geo has

received a setback because of the commercial failure of Irridium

and Global Star. The failures were due to the fact that the

project was engineering led - rather than marketing led. Theastronomically high terminal & service cost as compared to

terrestrial based systems was another reason for its failures.

During the10 years of realization of the project the CELL

handset cost, airtime &size reduced considerably while no such

effort was made for iridium (handset cost $3000, airtime $3-9,

total no. of customers 15000). On engineering account the two

projects cannot be considered as failures. In spite of cellular

telephone & other mobile services, the two systems along with

Thuraya have shown their usefulness over others in Afghanistanand Iraq operations and also communications to inaccessible

places. INMARSAT has touched its 200000th customer very

recently. These figures should not make one think that there is

no future for MSS.


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Before commenting on any technology or the market it

is advisable to look on the s-curve

New technologies and markets are generally

characterized by an S- Shaped growth curve

STAGE 2 ----> Rapid growth driven by mass

adoption

STAGE 3 ---> Failing off with the adoption by

the most conservative population

STAGE 1 -->Emerging having slow growth

spurred by early adopters


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In the foreseeable future new equipments and

techniques will be used in satellite technology which

will extend and improve the possibilities of satellite

communications beyond our present imaginations.Some of these we discuss today:

The size of Geo satellite will continue to

increase . Incremental improvements are

foreseen in intelligent bus design whichtakes care of the spacecraft control traffic

control and particularly the thermal

control to allow the use of prime power

beyond 10 to 15 KWS.

Small GEOs for smaller capacity routes

will also be used (one may seriously start

thinking about I-2000 and even Met Sat

bus for Indian conditions).


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Greater Transmit

power and more

complex antennas onthe satellites will

make operations

possible with a large

number of very small

Earth stations.

DBS/DTH services

with 300 - 500

channels.The servicemay broadcast

multimedia &

internet .


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Phased array - orbit

re-configurable

antennas with digital

beam forming capable

of dynamically sharing

RF power, controlling

EIRPs and generating

large number of spotbeams will be used

extensively. This may

call for large

deployable antennas (>25 meter in diameter),

complex feed systems.

The similar systems

may be even needed

for ground networks.


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Efficient signal processors and switching equipment

will enable signal processing to be performed

onboard right down to operations similar to

switching in exchanges which will provide bettermesh connectivity. ATM switches onboard space

crafts may be used. Onboard multiplexing of digital

TV transmission may be done.

Networking technology for the seamless integration

of high data rate communication satellites &

terrestrial facilities.

Direct connections between satellites (Inter satellite

links) will shorten the transmission routes. The ISLs

could be in millimeter waves or even in optical

domain.


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The use of higher frequency bands (Ka band and V

band) & frequency reuse by multiple beams will

enlarge the available bandwidths and thus the

transmission capacity. Future even space laser

communication technique may be employed to

increase the data rates to giga bits.

Miniaturization of electronics will enhance the

launch capabilities & reduce the cost.

High speed two way INTERNET - through VSAT.

This avoids the installation of broad band access

through terrestrial network. It can provide upto

40 MBPS links.


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It was expected that the space based high speed

internet service would hit the services over $600million in 2001, reflecting triple digit growth rate.

Howevernon-start of some of the planned satellites

has brought this figure to ~ $400 million.

As of today internet is the greatest thing to happen

in the satellite industry; since some genius decided

he could deliver TV on cable. For many space

segment operators INTERNET is the biggestearner. As of today internet is going towards zero

tolerance for failure. The goal is more & more

critical services to NET.


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The LEO internet provider in pipe line are:

Skybridge (80 S/c - 4 S/C for 20 planes) 1496KMS,

Ku-Band 20 MBPS down & 2.5 MBPS up. Global

coverage

Teledesic

New ICO.

The GEO systems : Astrolink, Cyberstar,

Spaceway.

Non- starter


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The technology issues are: Bandwidth

availability.

Use of Ka & V-bands and their weather

dependence has to be examined. It should

follow TCP/IP standards.

It should be possible to integrate with land

mobile system GSM (TDMA), CDMA, the 3Gbased on wide band CDMA (W-CDMA).


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We have talked / heard / read that internet/IP

offers opportunities of convergence of data,video and voice on the same network. Most IPrelated ventures however, were badly hit by the

infamous Internet bubble in 2001. One of themost disappointing developments leveraging onconvergence of various technologies through IPand the power of vast geographical coverage of

satellite in the satellite market in the last 2years, is clearly the satellite IP multicast andcontent distribution market.


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There is no shortage of failed ventures and

nonstarters. Despite IPs promise of

convergence and cost efficiencies, loading

video on to core IP infrastructure networksis still taboo because of the BW hungry

nature of video transmission. The satellite

ISP backbone market, however is suffering.

The biggest threat is fibre.In spite of all these, broad band IP satellite

based services are going to grow up.ip-

STAR(launch 2004) & EUTELSATs European

based satellite broad band projectare going

ahead with their plans and developments.

Satellite broad band IP services are going to

grow up in the next couple of years


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The new breed of satellites will be agile, flexible,

intelligent & powerful. They will have digital

bandwidth. This makes the services they carry an

easy fit in the present digital networks with a specific

provider ground equipment. They will:

Switch & route high data rates instantaneously among

thousands of users.

Continuously change the antenna beam patterns/eirp

as traffic demands

Buffer and multiplex data

Null interference, providing a strong, clear signal &use of adaptic arrays & processing.

Cross link to other satellites (ISL: Optical or V-band)

Use of Soft radio


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The future satellites will be :

Small Geo - co-located at a single point. Suitablefor small transponder demands even suitable for

DTH-Ka Band

Large Geo - Suitable for multiple established

services/Ku & Ka Band Mini/micro/mono & pico satellites.

The satellite driven broadband system become more

popular because it provides the last mile solution whichis a great boon for developing countries.


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Satellites have innate advantage that make them an attractive

alternative or complement to terrestrial broadband circuits.

First is speed they can be built , launched and put into service

in as little as 12 to 24 months providing the last mileconnection. It also provides bandwidth on demand. User pays

for the time which he utilizes.

Although broad band satellites are considered to be poor

cousins of OFC - No country requires more than what satellitecannot give. Europe requirement is 450 Mbits/s and US bound

capacity is 3.5 Gbits/S.

Many times one feels that for the over capacity of the fibre one

has to pay while for space based links you pay for the time you

use.


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In my opinion SPACE COMMUNICATION SCENARIO will be:

The future Telecommunication spacecraft will be developed

from transmission in to Information Satellites (INFOSAT).

They will be given many of the properties of terrestrial

telephone exchanges and signal processing equipments and it

will be possible to integrate them directly into future global

networks.

They will thus permit immediate applications of many existingand future services. Because of their inherent built up

flexibility, these satellites will be able to support and speed up

the initial experimental phase of many new services before their

trial on terrestrial networks. These type of satellites will enablenew services to be tried out over a large area before being put in

to the market and optimally adapted to suit the most

appropriate transmission medium.


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The satellite platform will have multiple reconfigurable

antennas/transmitters with dynamic power sharing /

Receivers in various frequency ranges / large

reconfigurable switching matrices at baseband and at

RF level / intersatellite links permitting signals to be

exchanged between satellites according to changing

requirements / complex and efficient analog / optical /digital signal processors / New modulation technique

and multiple access techniques.

It will be sufficiently broadband systems & may haveeven optical space communication components.


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The satellites besides their autonomous control andpower generation equipment may have sensors to

observe the earths atmosphere and pass the data to an

appropriate station after processing. This will help to

deal with the situation like Orissa Cyclone. Such asystem will obviously have Geo synchronous spacecraft

with some orbiting satellites to take care of North/South

pole regions.


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Presently man is in a shrinking globe and also in

expanding universe with lots of technological surprises

for the technological pandits. We are becoming

increasing networked thereby our world is growingsmaller & bigger simultaneously. Space

Communication in all its forms will complement the

terrestrial technologies. Vision is always of one of hope

for human betterment.

OBP, ISL,Phased ArrayGP


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CONFUSION

CONVERGENCE and FUSION of

various Communication Technologies

Broad Band Satellite Links

Video Conferencing

DBS - 300 Channels Mobile

BroadbandIn

ternet

LifeTimeMovie

Network

OFC

CableT

V

E-mail

Here

X A 0

GEO,MEO,LEOAda

ptiveA

rray

GPS

WAA

S,LAAS

SB

AS


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THANK YOU

IETE KSrinivasan Mem Presentation

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