ecm chapter 5

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CHAPTER 5CHAPTER 5PRACTICALPRACTICAL

COMMUNICATION SYSTEMSCOMMUNICATION SYSTEMS



Fiber Optic CommunicationFiber Optic CommunicationSystemSystem

IntroductionIntroduction

Fiber optic system : aFiber optic system : a communication systemcommunication system wherewherethethe informationinformation is put on ais put on a light beamlight beam andand transmittedtransmitted through athrough a guided cableguided cable ..

Light frequencies used in fiber optic systems areLight frequencies used in fiber optic systems arebetween 4.3x10between 4.3x10 1414 and .!x10and .!x10 1414 "#."#.

$hus$hus the higher the carrier frequencythe higher the carrier frequency % the% the wider thewider thebandwidthbandwidth % and consequently% the% and consequently% the greater thegreater theinformation&carrying capacityinformation&carrying capacity ..

'loc( diagram of a fiber optic communication lin(% is'loc( diagram of a fiber optic communication lin(% is

illustrated in Figure !.1.illustrated in Figure !.1.



IVC - Current-to-Voltage converter

Input

signal

Driving

circuit Electrical

LightCoupler

Light source

Transmitter

Repeater

CouplerLightElectrical

Light detector

IVC

VIC

Output

signal

Receiver

Fiber

cable

VIC - Voltage-to-Current converter

Figure !.1 'asic elements of a fiber optic communication systemFigure !.1 'asic elements of a fiber optic communication system

Electrical

LightCoupler

)epeater



The main elements in an opticalThe main elements in an opticalfi er communication lin! arefi er communication lin! are :&:&

"#"# $ri%in& circuitr'($ri%in& circuitr'( *ri+ing circuitry*ri+ing circuitry ser+esser+es as anas an electrical interface between theelectrical interface between the

input circuitry and the light sourceinput circuitry and the light source . ,t. ,t con+erts +oltagecon+erts +oltage signalsignaltoto currentcurrent signal -+oltage to current con+erter to dri+e thesignal -+oltage to current con+erter to dri+e thelight source.light source.

)#)# Li&ht SourceLi&ht Source ::Light source can be either a light&emitting diode -L/* orLight source can be either a light&emitting diode -L/* orLaser -Light mplification by timulated /mission ofLaser -Light mplification by timulated /mission of)adiation . Light source is to)adiation . Light source is to con+ert electrical energycon+ert electrical energy totooptical energyoptical energy % where% where the amount of light emitted isthe amount of light emitted is

proportional to the amount of dri+e currentproportional to the amount of dri+e current . nother words%. nother words%the light intensity depends on the amplitude +ariations of thethe light intensity depends on the amplitude +ariations of theinput signal.input signal.

*#*# Li&ht Source+to+fi er couplerLi&ht Source+to+fi er coupler ::$his is an$his is an interface to couple the lightinterface to couple the light emitted by the sourceemitted by the sourceinto the optical fiber cableinto the optical fiber cable ..



,#,# -i er Optics Ca le-i er Optics Ca le :: ,t is a long thin strand of glass or plastic fiber used to,t is a long thin strand of glass or plastic fiber used to

transfer signal in a form of light from a point to anothertransfer signal in a form of light from a point to anotherpoint. 2ost fiber cables ha+e a circular cross section with apoint. 2ost fiber cables ha+e a circular cross section with adiameter of only a fraction of an inch -,ts si#e is almost thediameter of only a fraction of an inch -,ts si#e is almost thesame as the si#e of human hair .same as the si#e of human hair .

$he characteristics of light transmission through a glass fiber$he characteristics of light transmission through a glass fiberdepend on many factors% for examples:&depend on many factors% for examples:&

$he composition of the fiber.$he composition of the fiber.$he amount type of light introduced into the fiber.$he amount type of light introduced into the fiber.$he diameter and length of the fiber.$he diameter and length of the fiber.



$he fiber optic consists of three parts:&$he fiber optic consists of three parts:&

$he core% where the light is passing through.$he core% where the light is passing through.

$he cladding% which surrounds the core with a lower$he cladding% which surrounds the core with a lowerrefracti+e index. ,t is to ensure that the light wa+esrefracti+e index. ,t is to ensure that the light wa+esremain within the core% to protect the fiber core fromremain within the core% to protect the fiber core fromscratches and to strengthen the fiber core.scratches and to strengthen the fiber core.

rotecti+e 5ac(et6coating. $his is the outer coating% maderotecti+e 5ac(et6coating. $his is the outer coating% madeof specially formulated plastic coating that pro+ides a firstof specially formulated plastic coating that pro+ides a first

le+el shoc( and resistance to damage and moisture% forle+el shoc( and resistance to damage and moisture% forthe fiber. $ypically it is a clear protecti+e coating or athe fiber. $ypically it is a clear protecti+e coating or amaterial made of stranded steel or a special yarn (nownmaterial made of stranded steel or a special yarn (nownas 7e+lar. 7e+lar is strong and preferred o+er steel as it isas 7e+lar. 7e+lar is strong and preferred o+er steel as it isan insulator. 7e+lar may forms a protecti+e slee+e oran insulator. 7e+lar may forms a protecti+e slee+e or

5ac(et o+er the cladding. 5ac(et o+er the cladding.

Fiber optic cable are also a+ailable in a flat ribbon form%Fiber optic cable are also a+ailable in a flat ribbon form%which are easier to use and more space&efficient%which are easier to use and more space&efficient%especially for multiple fibers.especially for multiple fibers.



.#.# -i er+to+detector coupler-i er+to+detector coupler ::$his is an interface between fiber and light&detector to$his is an interface between fiber and light&detector tocouple as much light as possible from the fiber cable intocouple as much light as possible from the fiber cable intothe light detector.the light detector.

/#/# Li&ht detectorLi&ht detector ::$he commonly used light detector or photo sensor is$he commonly used light detector or photo sensor iseither a ,8 -p&type&intrinsic&n&type diode or an *either a ,8 -p&type&intrinsic&n&type diode or an *-a+alanche photodiode . 'oth the * and ,8 diode-a+alanche photodiode . 'oth the * and ,8 diodecon+ert light energy to electrical energy or current.con+ert light energy to electrical energy or current.9onsequently% a current&to&+oltage con+erter -, 9 is9onsequently% a current&to&+oltage con+erter -, 9 isrequired% which transforms +ariations of detector currentrequired% which transforms +ariations of detector currentto output signal +oltage +ariations.to output signal +oltage +ariations.

Figure !.; $ypical layers in a fiber optic cableFigure !.; $ypical layers in a fiber optic cable

PlasticOuterJacket

KevlarSleeve

Protective

Coating

Cladding Core



T'pes of fi er optic ca leT'pes of fi er optic ca le

$here are three commonly types of fiber optic cable:$here are three commonly types of fiber optic cable:

"#"# Sin&le mode fi er(Sin&le mode fi er(

$he single mode or mono&mode has a +ery small core$he single mode or mono&mode has a +ery small corediameter% typical core si#es are ; <m to 1! <m diameter.diameter% typical core si#es are ; <m to 1! <m diameter.

o% only a single path that light may ta(e as it propagateso% only a single path that light may ta(e as it propagatesdown the cable.down the cable.

ll light rays follow approximately the same path down thell light rays follow approximately the same path down thecable and ta(e approximately the same amount of time tocable and ta(e approximately the same amount of time totra+el the length of the cable.tra+el the length of the cable.

"ere% modal dispersion is #ero."ere% modal dispersion is #ero.

2odal dispersion is where the pulse at the end of the cable2odal dispersion is where the pulse at the end of the cableis lower in amplitude due to the attenuation of the light inis lower in amplitude due to the attenuation of the light inthe cable and increase in duration due to the different arri+althe cable and increase in duration due to the different arri+altimes of light rays.times of light rays.



Single mode fberSingle mode fber



)#)# Multimode step inde0 fi eMultimode step inde0 fi e r:r:

$he centre core is larger of about from !0 <m to$he centre core is larger of about from !0 <m to100 <m diameter.100 <m diameter.

,t has a large light&to&fiber aperture and allows,t has a large light&to&fiber aperture and allowsmore light to enter the cable.more light to enter the cable.

$he light rays are propagated down the cable in$he light rays are propagated down the cable ina #ig&#ag pattern% continuously reflecting off thea #ig&#ag pattern% continuously reflecting off theinterface boundary% resulting many paths.interface boundary% resulting many paths.

s a result% all light rays do not follow the sames a result% all light rays do not follow the samepath% with different propagation time.path% with different propagation time.

2odal dispersion exists.2odal dispersion exists.



Multimode step indexMultimode step index

fberfber



*#*# Multimode &raded inde0 fi erMultimode &raded inde0 fi er ::

$he centre core is about from !0 <m to 100 <m diameter.$he centre core is about from !0 <m to 100 <m diameter.

2ultimode graded&index fiber is characteri#ed by a central core2ultimode graded&index fiber is characteri#ed by a central corethat has a refracti+e index that is non&uniform= it is maximum atthat has a refracti+e index that is non&uniform= it is maximum atthe centre and decreases gradually toward the side of the cable.the centre and decreases gradually toward the side of the cable.

Light is propagated down the fiber by refraction% which results inLight is propagated down the fiber by refraction% which results ina continuous bending of the light rays% at many different angles.a continuous bending of the light rays% at many different angles.

s they propagate down the fiber% the light rays that tra+el in thes they propagate down the fiber% the light rays that tra+el in theoutermost area tra+el a greater distance% but with a higheroutermost area tra+el a greater distance% but with a higher+elocity% than the rays tra+eling near the centre -because+elocity% than the rays tra+eling near the centre -because+elocity is in+ersely proportional to the refracti+e index .+elocity is in+ersely proportional to the refracti+e index .

Finally% all the light rays arri+e at the end point at almost theFinally% all the light rays arri+e at the end point at almost thesame time% resulting less modal dispersion.same time% resulting less modal dispersion.



Multimode graded indexMultimode graded index

fberfber



d%anta&es fi er optic ca lesd%anta&es fi er optic ca leso%er con%entional electricalo%er con%entional electrical

ca lesca les

"#"# >ider bandwidth: Fiber optic cables ha+e>ider bandwidth: Fiber optic cables ha+ehigher information&carry capability.higher information&carry capability.

;; Lower loss6attenuation: >ith fiber&optic cables%Lower loss6attenuation: >ith fiber&optic cables%there is less signal attenuation o+er longthere is less signal attenuation o+er longdistances. $he loss is low as 0.; d'6(m% anddistances. $he loss is low as 0.; d'6(m% and

the repeater spacing?s are longer% thusthe repeater spacing?s are longer% thusreducing both system cost and complexity.reducing both system cost and complexity.

3.3. Light weight: @lass or plastic cables are muchLight weight: @lass or plastic cables are muchlighter than copper cables and offer benefits inlighter than copper cables and offer benefits in

those areas where low weight is critical.those areas where low weight is critical.



Advantages – cnt’d Advantages – cnt’d

4.4. mall si#e: ractically% fiber&optic cables aremall si#e: ractically% fiber&optic cables aremuch smaller in diameter than electricalmuch smaller in diameter than electricalcable. $herefore% more can be contained in acable. $herefore% more can be contained in a

smaller space.smaller space.

!.!. trength: Fiber&optic cables are strongertrength: Fiber&optic cables are strongerthan electrical cable and can support morethan electrical cable and can support moreweight. $hey are manufactured with +eryweight. $hey are manufactured with +ery

high tensile strengths% can be bent or twistedhigh tensile strengths% can be bent or twistedwithout damage. o% they are superior inwithout damage. o% they are superior interms of storage% transportation% handlingsterms of storage% transportation% handlingsand installation than corresponding copperand installation than corresponding coppercables.cables.



A.A. ecurity: Fiber&optic cables cannot be BtappedC asecurity: Fiber&optic cables cannot be BtappedC aseasily as electrical cables% and they do not radiateeasily as electrical cables% and they do not radiatesignals that can be pic(ed up for ea+esdroppingsignals that can be pic(ed up for ea+esdroppingpurposes. $here is less need for complex andpurposes. $here is less need for complex andexpensi+e encryption techniques.expensi+e encryption techniques.

.. ,nterference immunity: Fiber&optic cables do not,nterference immunity: Fiber&optic cables do notradiate signals as some electrical cables and causeradiate signals as some electrical cables and causeinterference to other cables. $hey are also immuneinterference to other cables. $hey are also immuneto pic(up of interference from other sources. s theyto pic(up of interference from other sources. s theyare dielectric wa+eguides% they are free fromare dielectric wa+eguides% they are free fromelectromagnetic interference -/2, % radio frequencyelectromagnetic interference -/2, % radio frequencyinterference -)F, or switching transients gi+inginterference -)F, or switching transients gi+ingelectromagnetic pulses -/2 . $hey ha+e no opticalelectromagnetic pulses -/2 . $hey ha+e no opticalinterference between them and no crosstal(.interference between them and no crosstal(.

D.D. @reater safety: Fiber &optic cables do not carry@reater safety: Fiber &optic cables do not carryelectricity. $herefore% there is no shoc( ha#ard% noelectricity. $herefore% there is no shoc( ha#ard% noarching% no spar(s and no short circuits. $hey arearching% no spar(s and no short circuits. $hey arealso insulators so are not susceptible to lightningalso insulators so are not susceptible to lightningstri(es as electrical cables.stri(es as electrical cables.



E.E. ystem reliability and easy maintenance: $heystem reliability and easy maintenance: $helifetime is about ;0&30 years% it yields goodlifetime is about ;0&30 years% it yields goodreliability% reduces maintenance time% manpowerreliability% reduces maintenance time% manpowerand maintenance costs.and maintenance costs.

10. otential low cost as the total costs are10. otential low cost as the total costs arecontinuing to decline.continuing to decline.

11. 8o problems of corrosions.11. 8o problems of corrosions.



Attenuation1losses in fi er opticsAttenuation1losses in fi er optics

Ca le attenuationCa le attenuation

Ca le attenuation of a fi er optic ca le is e0pressed inCa le attenuation of a fi er optic ca le is e0pressed ind2 per unit len&th3 d21!m#d2 per unit len&th3 d21!m#

The total ca le attenuation depends on the ca leThe total ca le attenuation depends on the ca lelen&th#len&th#

-or a fi er optic ca le of a len&th3 L 4in !m53 the ca le-or a fi er optic ca le of a len&th3 L 4in !m53 the ca leattenuation is3attenuation is3

6"7 lo&6"7 lo& "7"7 4P4P oo 1P1P ii 581L 3 in d21!m#581L 3 in d21!m#

9here P9here P oo is the output po9er and Pis the output po9er and P ii is the input po9er#is the input po9er#



The possi le causes of ca le attenuationThe possi le causes of ca le attenuationare(are(

"#"# Scatterin& lossesScatterin& losses ::i.e. the radiation of propagated light due to the microscopici.e. the radiation of propagated light due to the microscopicimperfection of the fiber. >hen light rays that areimperfection of the fiber. >hen light rays that arepropagating stri(e these impurities% they are diffracted.propagating stri(e these impurities% they are diffracted.*iffraction causes the light to disperse or spread out in*iffraction causes the light to disperse or spread out inmany directions% which represent a loss in light power.many directions% which represent a loss in light power.

cattering also refers to the light loss because of lightcattering also refers to the light loss because of lightwa+es entering at the wrong incident angle and being lostwa+es entering at the wrong incident angle and being lostin the cladding due to refraction. $his is calledin the cladding due to refraction. $his is called Ra'lei&hRa'lei&hscatterin& loss#scatterin& loss#

)#)# A sorption lossesA sorption losses ::bsorption refers to how the light wa+es are actuallybsorption refers to how the light wa+es are actually

Bsoa(ed&upC in the fiber core due to the impurity of the Bsoa(ed&upC in the fiber core due to the impurity of theglass or plastic or due to any imperfections.glass or plastic or due to any imperfections.



2endin& losses(2endin& losses( occur because the light rays on the outside ofoccur because the light rays on the outside ofa sharp bend cannot tra+el fast enough to (eep up with thea sharp bend cannot tra+el fast enough to (eep up with theother rays and are lost.other rays and are lost.



$able !.1 shows losses in a typical in a typical multimode fiber$able !.1 shows losses in a typical in a typical multimode fiberas a function of wa+elength with )ayleigh and absorptionas a function of wa+elength with )ayleigh and absorptioncomponents shown for comparison% showing three windows.components shown for comparison% showing three windows.

>indow is a short range of wa+elength where the attenuation>indow is a short range of wa+elength where the attenuationis at minimum.is at minimum.

$able !.1 Loss spectrum of typical optical fiber$able !.1 Loss spectrum of typical optical fiber



Optical si&nal attenuation(Optical si&nal attenuation(

ptical signal attenuationptical signal attenuation is expressed in d'%is expressed in d'% ttenuation -d' G 10 logttenuation -d' G 10 log "7"7 -- oo 6 6 ii

where where oo is the output power and is the output power and ii is the input power.is the input power.

$he possible causes of cable attenuation are:$he possible causes of cable attenuation are:

"#"# Splicin& lossSplicin& loss ::plicing is a permanent 5ointing of two fibers.plicing is a permanent 5ointing of two fibers.

)#)# Couplin& lossesCouplin& losses ::$hese represent a large source of loss in commercial fiber$hese represent a large source of loss in commercial fiberoptic system. $hey occur at either= light source&to&fiberoptic system. $hey occur at either= light source&to&fiberconnections% fiber&to&fiber% or% fiber&to&photo detectorconnections% fiber&to&fiber% or% fiber&to&photo detectorconnections% mainly due to misalignments.connections% mainly due to misalignments.



Applications of -i er+Optic Ca leApplications of -i er+Optic Ca le ::Long&haul% bac(bone public and pri+ate networ(sLong&haul% bac(bone public and pri+ate networ(sLocal loop networ(sLocal loop networ(sFiber bac(bone networ(s -L 8 connecti+ityFiber bac(bone networ(s -L 8 connecti+ity"igh&resolution image and digital +ideo"igh&resolution image and digital +ideo$ studio&to& transmitter interconnection% elimination$ studio&to& transmitter interconnection% eliminationmicrowa+e radio lin(.microwa+e radio lin(.9losed&circuit $ systems used in building for security.9losed&circuit $ systems used in building for security.

ecure communications systems at military bases.ecure communications systems at military bases.9omputer networ(s% wide area and local area.9omputer networ(s% wide area and local area.

hipboard communications.hipboard communications.ircraft communications and controls.ircraft communications and controls.

,nterconnection of measuring and monitoring,nterconnection of measuring and monitoring

instruments in plants and laboratories.instruments in plants and laboratories.*ata acquisition and control signal communications in*ata acquisition and control signal communications inindustrial process control systems.industrial process control systems.



Pub ic S!itc"ing Te ep"onePub ic S!itc"ing Te ep"one#et!or$s %PST#&#et!or$s %PST#&


$he public telephone networ( accommodates two types of$he public telephone networ( accommodates two types ofsubscribers:subscribers:

1.1. ri+ate&line circuits or dedicated circuits H the customersri+ate&line circuits or dedicated circuits H the customerslease the equipments% transmission media6facilities andlease the equipments% transmission media6facilities andser+ices from the telephone companies or ser+iceser+ices from the telephone companies or ser+icepro+iders% on a permanent basis% eg large ban(s.pro+iders% on a permanent basis% eg large ban(s.

;.;. ublic subscribers H the customers share the equipmentsublic subscribers H the customers share the equipmentsand facilities that are a+ailable to all the publicand facilities that are a+ailable to all the publicsubscribers to the networ(% includes transmission facilitiessubscribers to the networ(% includes transmission facilitiesand telephone switches. ince subscribers to the publicand telephone switches. ince subscribers to the publicnetwor( are interconnected only temporarily throughnetwor( are interconnected only temporarily throughswitches% the networ( is called ublic witched $elephoneswitches% the networ( is called ublic witched $elephone8etwor( - $8 .8etwor( - $8 .



PSTN:s primar' characteristicsPSTN:s primar' characteristics

$hey include:$hey include:

i.i. nalog access% 300 to 3%400 ("#nalog access% 300 to 3%400 ("#

ii.ii. 9ircuits&switched duplex connection9ircuits&switched duplex connectioniii.iii. witched bandwidth A4 (bps% or 0.3 H 3.4 ("# forwitched bandwidth A4 (bps% or 0.3 H 3.4 ("# foranalog exchangesanalog exchanges

i+.i+. ,mmobility or +ery limited mobility,mmobility or +ery limited mobility+.+. 2any functions in common with another bearer2any functions in common with another bearer

networ(.networ(.



PSTN Teleser%icesPSTN Teleser%ices

$he terminals that can be connected to $8 are as shown in$he terminals that can be connected to $8 are as shown in

FigureFigure!.3.!.3.

Figure !.3 $erminals that can be connected to $8Figure !.3 $erminals that can be connected to $8



-i0ed telephone(-i0ed telephone(For fixed telephone% the generated information -+oice isFor fixed telephone% the generated information -+oice isanalog.analog.

-a0 ser%ice-a0 ser%ice ::For fax ser+ice% the generated information is digital% butFor fax ser+ice% the generated information is digital% buthas a built&in modem pro+iding an analog signal. ,t is ahas a built&in modem pro+iding an analog signal. ,t is adistributi+e ser+ice in+ol+es unidirectional communicationdistributi+e ser+ice in+ol+es unidirectional communicationto one recipient or broadcast to many recipients.to one recipient or broadcast to many recipients.

$ata communication$ata communication ::For data communication% computer generates digitalFor data communication% computer generates digitalsignal and connected to $8 through a modem% i.e. datasignal and connected to $8 through a modem% i.e. datacommunication +ia modem.communication +ia modem.

;ideo3 multimedia and tele9or!in&;ideo3 multimedia and tele9or!in& ::$he limited bandwidth of the $8 is the bottlenec( for$he limited bandwidth of the $8 is the bottlenec( forthe +ideo and multimedia ser+ices into $8% eg +ideothe +ideo and multimedia ser+ices into $8% eg +ideotelephony ser+ice. $he most tcommonly used telewor(ingtelephony ser+ice. $he most tcommonly used telewor(ingis a telephone% a fax and a computer with a modem H allis a telephone% a fax and a computer with a modem H allare connected to the $8.are connected to the $8.



Cordless telephoneCordless telephone ::9ordless telephone has an analog to digital9ordless telephone has an analog to digitalcon+erter *9 in the terminal.con+erter *9 in the terminal.

ince the $8 interface is analog% fax and data trafficince the $8 interface is analog% fax and data trafficmust be con+erted to analog signals in the frequencymust be con+erted to analog signals in the frequencyband 0.3 to 3.4 ("# with the help of built&in modem orband 0.3 to 3.4 ("# with the help of built&in modem orstand&alone modem. $he modem adapts the signal tostand&alone modem. $he modem adapts the signal tothe $8 by con+erting information from digital form tothe $8 by con+erting information from digital form toanalog form and +ice +ersa.analog form and +ice +ersa.



'ntegrated Services (igita'ntegrated Services (igita#et!or$ %'S(#&#et!or$ %'S(#&


, *8 is to support a wide range of +oice, *8 is to support a wide range of +oice

-telephone and non&+oice -digital data applications-telephone and non&+oice -digital data applicationsin the same networ( using a limited number ofin the same networ( using a limited number ofstandardi#ed facilities includes both switched and non&standardi#ed facilities includes both switched and non&switched connections. er+ices introduced into answitched connections. er+ices introduced into an, *8 should be compatible with A4&(bps switched, *8 should be compatible with A4&(bps switcheddigital connections% which is the basic building bloc( ofdigital connections% which is the basic building bloc( of, *8. , *8 pro+ides ser+ice features% maintenance, *8. , *8 pro+ides ser+ice features% maintenanceand networ( management function.and networ( management function.



Figure !.4 'asic , *8 conceptsFigure !.4 'asic , *8 concepts



Ser%ices in IS$NSer%ices in IS$N

Telephon'Telephon'Telefa0 4-A<5Telefa0 4-A<5;ideoconferencin& and %ideo+telephon';ideoconferencin& and %ideo+telephon'=i&h >ualit' sound=i&h >ualit' sound$ata communication includin& internet access$ata communication includin& internet accessCom inations of teleser%icesCom inations of teleser%ices



)obi e and Ce u ar)obi e and Ce u arCommunicationCommunication

Introduction to Cellular TelephoneIntroduction to Cellular Telephone

$he (ey principle of 9ellular $elephone or 9ellular )adio is$he (ey principle of 9ellular $elephone or 9ellular )adio isdetermined by sub&di+iding a relati+ely large geographicdetermined by sub&di+iding a relati+ely large geographic

mar(et area -called co+erage #one into small sectionsmar(et area -called co+erage #one into small sections-called cells .-called cells .

,t uses the concept of frequency re&use to increase the,t uses the concept of frequency re&use to increase thecapacity of a mobile telephone channelcapacity of a mobile telephone channel

9ellular telephone system allows a large number of users to9ellular telephone system allows a large number of users toshare the limited number of common usage of radioshare the limited number of common usage of radiochannelschannels



-undamental Concept of Cellular-undamental Concept of CellularTelephoneTelephone

/ach co+erage #one is further sub&di+ided into hexagonal&/ach co+erage #one is further sub&di+ided into hexagonal&shaped cells that fit together to form a honey&combshaped cells that fit together to form a honey&combpattern% as shown in Figure !.!. /ach geographical area ispattern% as shown in Figure !.!. /ach geographical area isallocated a fixed number of cellular +oice channels.allocated a fixed number of cellular +oice channels.

Figure !.! "exagonal honey&comb patternsFigure !.! "exagonal honey&comb patterns

*

+,

5

-

.

/ ce



The concept of a cellular are(The conc ept of a cellular are(1.1. cellular system allows frequency reused in the same area cellular system allows frequency reused in the same area

by splitting the entire region into many smaller cells.by splitting the entire region into many smaller cells.

;.;. /ach cell has a base station./ach cell has a base station.

3.3. 'ecause of low power of base station% the same frequency'ecause of low power of base station% the same frequencycan be used for another cell% which is not ad5acent -i.e.can be used for another cell% which is not ad5acent -i.e.ad5acent cells ha+e different frequency groups .ad5acent cells ha+e different frequency groups .

4.4. /ach mobile user is initially assigned a frequency and/ach mobile user is initially assigned a frequency andcommunicates with the closest base stations.communicates with the closest base stations.

!.!. >hen the mobile user crosses to some other cell% it is gi+en a>hen the mobile user crosses to some other cell% it is gi+en anew base station -)' % i.e. the cellular phone changes fromnew base station -)' % i.e. the cellular phone changes fromone channel to another as it crosses cell boundaries% e+enone channel to another as it crosses cell boundaries% e+enwhile the con+ersation is in progress.while the con+ersation is in progress.

A.A. $he )' s are lin(ed together so that a con+ersation can pass$he )' s are lin(ed together so that a con+ersation can passfrom one cell to another. $his will lin( the users in any twofrom one cell to another. $his will lin( the users in any twocells regardless of their channel assignments.cells regardless of their channel assignments.



Ph'sical si?e of a cell %aries3 depends onP h'sical si?e of a cell %aries3 depends onuser densit' and callin& pattern(user densit ' and callin& pattern(

1.1. Large 9ell & 2acrocells:Large 9ell & 2acrocells:)adius: 'etween 1.D (m & ;D (m)adius: 'etween 1.D (m & ;D (m'ase station transmit power:1 > & A >'ase station transmit power:1 > & A >

;.;. mall 9ells & 2icrocells:mall 9ells & 2icrocells:

)adius:Less than 4!0 m)adius:Less than 4!0 m'ase station transmit power:0.1 > & 1 >'ase station transmit power:0.1 > & 1 >pplications:"igh density areas eg large cities and insidepplications:"igh density areas eg large cities and inside

buildings.buildings.LimitationsLimitations :Low effecti+e wor(ing areas% reflections and:Low effecti+e wor(ing areas% reflections andsignal delayssignal delays

3.3. ery small cells & icocells:ery small cells & icocells:$o pro+ide reliable communication indoors% well&shielded$o pro+ide reliable communication indoors% well&shieldedareas or ares with high le+el of interference% eg undergroundareas or ares with high le+el of interference% eg undergroundmalls.malls.

d+antage: 9an use the same frequency as regular cells ind+antage: 9an use the same frequency as regular cells inthe same area.the same area.



SMART ANTENNA



Figure !.A illustrates the base station location in aFigure !.A illustrates the base station location in ahexagonal&shaped cells.hexagonal&shaped cells.

Figure !.A: Locations of base stationsFigure !.A: Locations of base stations

Centre0e1cited ce Edge0e1cited ce Corner0e1cited ce

%omni0directionaantenna&

%sectored

(irectionaantenna&

%sectored

(irectiona antenna&



-re>uenc' Reuse-re>uenc' Reuse

Frequency reuse is the process in which the same set ofFrequency reuse is the process in which the same set offrequencies or channels can be allocated to more than onefrequencies or channels can be allocated to more than onecell% pro+ided that the cells are separated by sufficientcell% pro+ided that the cells are separated by sufficientdistance.distance./ach cellular base station is allocated a group of channel/ach cellular base station is allocated a group of channelfrequencies that are different from those of neighboring cells%frequencies that are different from those of neighboring cells%and base station antennas are chosen to achie+e a desiredand base station antennas are chosen to achie+e a desiredco+erage pattern within a cell.co+erage pattern within a cell.

$he main ob5ecti+es of frequency re&use are$he main ob 5ecti+es of frequency re&use are ::-i-i $o (eep the transmitted power from each base station to a$o (eep the transmitted power from each base station to a

minimum.minimum.

-ii $o (eep the position of the antenna of the base station 5ust-ii $o (eep the position of the antenna of the base station 5usthigh enough to pro+ide for the area co+erage of thehigh enough to pro+ide for the area co+erage of therespecti+e cells.respecti+e cells.



Concept of fre>uenc' reuseConce pt of fre>uenc' reuse ((

Figure !. 9ellular frequency reuse conceptFigure !. 9ellular frequency reuse concept

A2

C

(

F

A

2

(E

F3

A2

C

(

E

F3

A coverage

area C uster /

C uster *C uster +

E

3

C



ClusterCluster is a group of cells.is a group of cells.From Figure !. abo+e:From Figure !. abo+e:

$he co+erage area consists of 3 clusters.$he co+erage area consists of 3 clusters./ach cluster has cells/ach cluster has cells/ach cell is assigned the same number of full&duplex/ach cell is assigned the same number of full&duplextelephone channelstelephone channels9ell with the same letter use the same set of channel9ell with the same letter use the same set of channelfrequenciesfrequencies

$ l b f h l l



$otal number of channels in a cluster$otal number of channels in a cluster ::

F =G N ( F =G N ( channels6clusterchannels6cluster

wherewhere GG G 8umber of channels in a cellG 8umber of channels in a cellN =N = 8umber of cells in a cluster8umber of cells in a cluster

-$ypical +alues:-$ypical +alues: N N G 3% % 1;G 3% % 1;

>hen a cluster is duplicated>hen a cluster is duplicated mm times within a gi+en ser+ice area% thetimes within a gi+en ser+ice area% the

total number of full&duplex channel in a ser+ice area becomes%total number of full&duplex channel in a ser+ice area becomes%

C = m G N C = m G N -channels6ser+ice area -channels6ser+ice area = m F = m F

wherewhere C =C = 8umber of full&duplex channels in an area8umber of full&duplex channels in an area

m G number of clusters in a ser+ice aream G number of clusters in a ser+ice area-clusters6ser+ice area -clusters6ser+ice areaGG G 8umber of full&duplex channels in a cell G 8umber of full&duplex channels in a cellN =N = 8umber of cells in a cluster8umber of cells in a clusteri.e Ci.e C α α mm



Cellular S'stem Topolo&'Cellular S'stem Topolo&')adio 8etwor( is defined by a set of radio&frequency)adio 8etwor( is defined by a set of radio&frequencytranscei+ers -base stations located within each of the cells.transcei+ers -base stations located within each of the cells.

Figure !.D illustrates a simplified cellular telephone system thatFigure !.D illustrates a simplified cellular telephone system thatincludes the basic components: 2obile unit% 'ase station andincludes the basic components: 2obile unit% 'ase station and2obile $elephone witching ffice -2$ .2obile $elephone witching ffice -2$ .

Figure !.D implified cellular telephone system topologyFigure !.D implified cellular telephone system topology



Mo ile UnitMo ile Unit ::

2obile Init communicates directly with the base stations2obile Init communicates directly with the base stations-o+er dedicated data lin(s & metallic non&metallic and the-o+er dedicated data lin(s & metallic non&metallic and thebase station communicates directly with a 2$ -o+er free&base station communicates directly with a 2$ -o+er free&space6airwa+es .space6airwa+es .

2ase Station2ase Station ::

1.1. er+es as central control for all users within a cell.er+es as central control for all users within a cell.

;.;. 9onsists of a low&power radio transcei+er% power amplifiers9onsists of a low&power radio transcei+er% power amplifiersand cell&site controllerand cell&site controller

3.3. ro+ides an interface between mobile telephone sets andro+ides an interface between mobile telephone sets andthe 2$ .the 2$ .



Mo ile Telephone S9itchin& Office 4MTSO5Mo ile Telephone S9itchin& Office 4MTSO5

1. 9ontrols channel assignments% call processing% call setup1. 9ontrols channel assignments% call processing% call setupand call termination% includes signaling% switching%and call termination% includes signaling% switching%super+ision% and allocating radio&frequency channels.super+ision% and allocating radio&frequency channels.

;. ro+ides a centrali#ed administration and maintenance;. ro+ides a centrali#ed administration and maintenancepoint for the entire networ(point for the entire networ(

3. ,nterfaces with the public telephone networ( o+er wire line3. ,nterfaces with the public telephone networ( o+er wire line+oice trun(s for the con+entional wired telephones and+oice trun(s for the con+entional wired telephones andinterfaces with data lin(s.interfaces with data lin(s.

4. 2ost 2$ are connected to the signaling networ(%4. 2ost 2$ are connected to the signaling networ(%which allows cellular telephone to operate outside theirwhich allows cellular telephone to operate outside theirser+ice area.ser+ice area.



Sate ite CommunicationSate ite CommunicationSystemSystem

Introduction to SatelliteIntroduction to SatelliteCommunication S'stemCommunication S'stem

satellite system consists of: satellite system consists of:

-- i a transponder -a radio repeater in the s(y %i a transponder -a radio repeater in the s(y %-ii a ground&based station to control its operation-ii a ground&based station to control its operation-iii a user networ( of earth stations that pro+ide the facilities for-iii a user networ( of earth stations that pro+ide the facilities for

transmission and reception of communication traffics throughtransmission and reception of communication traffics throughthe satellite system.the satellite system.



atellites recei+ed a signal from the ground station% do theatellites recei+ed a signal from the ground station% do theamplification and frequency translation% and broadcast it toamplification and frequency translation% and broadcast it toearth stations that are able to recei+e transmissions.earth stations that are able to recei+e transmissions.

satellite begins at a single earth station% passes through satellite begins at a single earth station% passes throughthe satellite% and ends at one or more earth stations.the satellite% and ends at one or more earth stations.

atellite communication systems utili#e microwa+e terminalsatellite communication systems utili#e microwa+e terminalsboth on satellites and in earth stations for high reliable andboth on satellites and in earth stations for high reliable andhigh&capacity system.high&capacity system.Figure !.E below shows the basic elements of aFigure !.E below shows the basic elements of a

communications satellite.communications satellite.Sate ite in geosync"ronous orbit

Transponder

4p in$(o!n in$(o!n in$

4p in$

Eart" station Eart" station



Satellite transponderSatellite transponderatellite transponder acts li(e a repeater% consists of aatellite transponder acts li(e a repeater% consists of a

recei+er and a transmitter. $he main functions of a satelliterecei+er and a transmitter. $he main functions of a satellite

transponder are:transponder are:-i-i to pic( up the transmitted signal from the transmitter onto pic( up the transmitted signal from the transmitter on

the earth%the earth%-ii to amplify the signal%-ii to amplify the signal%-iii-iii to translate the carrier frequency to another frequency to translate the carrier frequency to another frequency

-i+ to retransmit the amplified signal to the recei+er on the-i+ to retransmit the amplified signal to the recei+er on theearthearthFigure !.10 below shows a bloc( diagram of a satelliteFigure !.10 below shows a bloc( diagram of a satellitetransponder.transponder.

Band passfilter BP!"

#o$%noisea&plifier #NA"

Mi'er BP!

#ocaloscillator

#o$%po$er a&plifier

!re(uenc) converter

!ro&eart* station To eart*station

$he ' F limits the total noise$he ' F limits the total noise.



$he F limits the total noise.$he F limits the total noise.$he L8 amplifies the recei+ed signal and fed it to the frequency$he L8 amplifies the recei+ed signal and fed it to the frequencycon+erter which con+erts the high&band uplin( frequency to the low&con+erter which con+erts the high&band uplin( frequency to the low&band downlin( frequency.band downlin( frequency.$his is an )F&to&)F repeater.$his is an )F&to&)F repeater.

/ach )F satellite channel requires a separate transponder./ach )F satellite channel requires a separate transponder.

Satellite s'stem lin!sSatellite s'stem lin!s1.1. Up lin!Up lin! : ,t is the path of the satellite signal from the earth: ,t is the path of the satellite signal from the earth

transmitter to the recei+er of the satellite. $he frequency signaltransmitter to the recei+er of the satellite. $he frequency signalbeing transmitted from the earth station to the satellite is called thebeing transmitted from the earth station to the satellite is called theuplin( frequency. For example: the uplin( frequency for a 9&band isuplin( frequency. For example: the uplin( frequency for a 9&band isA @"#.A @"#.

;.;. $o9n lin!($o9n lin!( ,t is the path of the satellite signal from the satellite,t is the path of the satellite signal from the satellitetransmitter to the recei+er on the earth. $he retransmitted signaltransmitter to the recei+er on the earth. $he retransmitted signalfrom the satellite to the recei+ing stations is called the down&lin(.from the satellite to the recei+ing stations is called the down&lin(.For example: the downlin( frequency for a 9&band is 4 @"#.For example: the downlin( frequency for a 9&band is 4 @"#.

NoteNote :: $he uplin( and downlin( use different carrier frequencies to$he uplin( and downlin( use different carrier frequencies toa+oid interference% and the frequency con+ersion is done in thea+oid interference% and the frequency con+ersion is done in thetransponder.transponder.



Earth stationsEarth stations

Figure !.11 shows an earth station transmitter.Figure !.11 shows an earth station transmitter.

From Figure !.11% the intermediate frequency -,FFrom Figure !.11% the intermediate frequency -,Fmodulator con+erts the input baseband signals to an F2%modulator con+erts the input baseband signals to an F2%a 7% or a J 2 modulated intermediate frequency.a 7% or a J 2 modulated intermediate frequency.

$he up& con+erter -mixer and bandpass filter con+erts$he up& con+erter -mixer and bandpass filter con+ertsthe ,F to an appropriate )F carrier frequency.the ,F to an appropriate )F carrier frequency.

$he high power amplifier -" pro+ides adequate input$he high power amplifier -" pro+ides adequate inputsensiti+ity and output power to propagate the signal tosensiti+ity and output power to propagate the signal to

the satellite transponder.the satellite transponder.



Figure !.11 n earth station transmitterFigure !.11 n earth station transmitter

+ataBase,and in

!+M or PCM-T+M

Modulator

!M. PSKor /AM"

Mi'er BP!

0ig* Po$er

A&plifier

r1enerator

2p%Converter

Tel

3ideo

0ig* po$erA&plifier

0PA"

To satellite

Figure ! 1; shows an earth station recei+erFigure !.1; shows an earth station recei+er.



Figure !.1; shows an earth station recei+er.Figure !.1; shows an earth station recei er.From Figure !.1;% L8 which is a highly sensiti+e and low&From Figure !.1;% L8 which is a highly sensiti+e and low&noise de+ice amplifies the recei+ed signal.noise de+ice amplifies the recei+ed signal.$he )F&to&,F down&con+erter is a mixer and bandpass filter$he )F&to&,F down&con+erter is a mixer and bandpass filtercombination% which con+erts the recei+ed )F signal to ancombination% which con+erts the recei+ed )F signal to anintermediate frequency -,F .intermediate frequency -,F .

Figure !.1; n earth station recei+erFigure !.1; n earth station recei+er

!ro&satellite

#o$ noiseA&plifier

#NA"

Mi'erBP!

1enerator

+e&odulator

!M. PSKor /AM"

Base,and out

( !+M or PCM-T+M )

Tel

+ata

+o$n%converter

video



Cross+Lin!sCross+Lin!s

-i&ure .#"* Intersatellite-i&ure .#"* Intersatellitelin!lin!

Eart"

4p in$5(o!n in$ 4p in$5(o!n in$

Cross0 in$sat/ sat*

station/ station*

'ntersate ite in$



-re>uenc' allocations-re>uenc' allocations

$able !.1 shows the frequency bands for the$able !.1 shows the frequency bands for thesatellite frequency range.satellite frequency range.

$he most common carrier frequencies used for$he most common carrier frequencies used forsatellite communications are the A64 @"# -9&bandsatellite communications are the A64 @"# -9&bandand 1461; @"# -7u&band bands% especially forand 1461; @"# -7u&band bands% especially for+oice and data telecommunications.+oice and data telecommunications.

t these bands% the signal attenuation is minimum.t these bands% the signal attenuation is minimum.

$he first number is the uplin( frequency% and the$he first number is the uplin( frequency% and thesecond number is the downlin( frequency% that is Asecond number is the downlin( frequency% that is A@"# is the uplin( frequency and 4 @"# is the@"# is the uplin( frequency and 4 @"# is thedownlin( frequency for a 9&band.downlin( frequency for a 9&band.



$able !.1 atellite frequency bands$able !.1 atellite frequency bands



Satellite Or itSatellite Or it

$hree basic types of orbits are:$hree basic types of orbits are:

1.1. Polar Or itPolar Or it : ,t is a north&south orbit% normally used for na+igation%: ,t is a north&south orbit% normally used for na+igation%weather satellites% meteorological and land resource satelliteweather satellites% meteorological and land resource satellitesystems. ,t is not used for telecommunication purposes.systems. ,t is not used for telecommunication purposes.

;.;. Ellipticall' inclined or itEllipticall' inclined or it : ,t is used for )ussian domestic systems%: ,t is used for )ussian domestic systems%with inclination of A3 degrees and a 1;&hour orbit period% but +isiblewith inclination of A3 degrees and a 1;&hour orbit period% but +isiblefor D hours only. o% 3 satellites are needed for continuous co+erage.for D hours only. o% 3 satellites are needed for continuous co+erage.

3.3. Circular E>uatorial Or itCircular E>uatorial Or it : ,t is called: ,t is called &eos'nchronous or it&eos'nchronous or it . $his. $hissatellite in a geosynchronous orbit is at a height of about 3!%D00satellite in a geosynchronous orbit is at a height of about 3!%D00(m% has ;4&hour orbit period% and its angular speed is equal to the(m% has ;4&hour orbit period% and its angular speed is equal to therotational speed of the earth. o% it appears stationary or motionlessrotational speed of the earth. o% it appears stationary or motionless

o+er a fixed point on the earth?s surface. $he satellite is +isible fromo+er a fixed point on the earth?s surface. $he satellite is +isible from163 of the earth?s surface% so 3 satellites are needed for full co+erage163 of the earth?s surface% so 3 satellites are needed for full co+erageof the earth.of the earth.

$he abo+e basic orbits are as shown in Figure !.14.$he abo+e basic orbits are as shown in Figure !.14.



Figure !.14 $hree satellite orbitsFigure !.14 $hree satellite orbits



Ad%anta&es of &eos'nchronousAd%anta &es of &eos'nchronoussatellitessatellites ((

1.1. $he satellite remains almost stationary relati+e to the$he satellite remains almost stationary relati+e to theearth station% so% the computer&controlled trac(ing of theearth station% so% the computer&controlled trac(ing of thesatellite is minimi#ed.satellite is minimi#ed.

;.;. geosynchronous satellite is permanently in +iew% so% geosynchronous satellite is permanently in +iew% so%there are no brea(s in transmission. $here is no need tothere are no brea(s in transmission. $here is no need toswitch from one satellite to another.switch from one satellite to another.

3.3. *ue to high altitude% it can co+er a large area on earth*ue to high altitude% it can co+er a large area on earth-about 163 of the earth % and a large number of earth-about 163 of the earth % and a large number of earthstations may intercommunicate. $hree satellites can gi+estations may intercommunicate. $hree satellites can gi+eglobal co+erage except in the polar regions.global co+erage except in the polar regions.

4.4. $he effects of *oppler shift are negligible. *oppler shift is$he effects of *oppler shift are negligible. *oppler shift isthe change in the apparent frequency of the radiation tothe change in the apparent frequency of the radiation toand from the satellite caused by the motion of the satelliteand from the satellite caused by the motion of the satelliteto and from the earth station.to and from the earth station.



$isad%anta&es of &eos'nchronous$isad%anta &es of &eos'nchronoussatellites(satellites(

1.1. Latitudes greater than D1.;!0 8orth and outh are notLatitudes greater than D1.;!0 8orth and outh are notco+ered.co+ered.

;.;. *ue to the high latitudes of geosynchronous satellite% the*ue to the high latitudes of geosynchronous satellite% therecei+ed signal power% which is in+ersely proportional to therecei+ed signal power% which is in+ersely proportional to thesquare of the distance% is +ery wea(% and the signalsquare of the distance% is +ery wea(% and the signalpropagation delay is about 300 msec.propagation delay is about 300 msec.

S'stem performanceS'stem performance

Figure !.1! shows a simplified bloc( diagram of a satelliteFigure !.1! shows a simplified bloc( diagram of a satellitesystem which is showing the +arious gains and losses thatsystem which is showing the +arious gains and losses thatmay affect the system performance.may affect the system performance.>hen e+aluating the performance% the uplin( and downlin(>hen e+aluating the performance% the uplin( and downlin(parameters are considered separately% and then the o+erallparameters are considered separately% and then the o+erallperformance is determined by combining them in theperformance is determined by combining them in theappropriate manner.appropriate manner.

sate ite Pin%s&



Figure !.1! simplified satellite lin(sFigure !.1! simplified satellite lin(s

HPA

Pt

67b

3t1

PinPrad

6p%up&

3 Te%s&

3r1%s&

3t1%s&67b

Prad%s&

6p%do!n&

3r1%e&

3 Te%e&

67b

Pcap

Pcap

Transmitter Receiver

llS lli S' P



Satellite S'stem ParametersSatellite S'stem Parameters

"# Effecti%e Isotropic Radiated Po9er 4EIRP5("# Effecti%e Isotropic Radiated Po9er 4EIRP5(

/,) is defined as an equi+alent transmit power./,) is defined as an equi+alent transmit power.

EIRP EIRP = P = P inin x G x G tx tx

>here%>here% P P inin GG antenna input powerantenna input power

GG tx tx GG transmit antenna gaintransmit antenna gain

r%r%

EIRP EIRP 4d2@5 4d2@5 10 log10 log 1010 P P inin -d'>-d'> B B t0t0 -d'-d'



,n respect to the transmitter output:,n respect to the transmitter output:

Pi Pi nn = P = P t t - L - L bobo - L - L fbfb

-d'> -d' -d' -d'-d'> -d' -d' -d'

>here%>here% P P t t GG saturated output powersaturated output power LLbobo GG bac(&off lossbac(&off loss LLfbfb GG feeder branching lossfeeder branching loss

$herefore%$herefore%

EIRP =EIRP = P P t t - L - L bobo - L - L fbfb + G + G tx tx

-d'> -d'> -d'-d'> -d'> -d' -d'-d' -d' -d'



Example 1:Exam ple 1: satellite earth station transmitter operates with an satellite earth station transmitter operates with an

antenna inputantenna inputpower of 10 (>% a bac(&off loss of 3 d' and a total feederpower of 10 (>% a bac(&off loss of 3 d' and a total feeder

andandbranching loss of 4 d'. $he transmit antenna gain is 40 d'.branching loss of 4 d'. $he transmit antenna gain is 40 d'.*etermine the station /,) .*etermine the station /,) .

Solution:Solution:

EIRP EIRP = P = P tt - - LLbobo - - LLfbfb + + GG tx tx

-d'>-d'> -d'> -d'> -d' -d'-d' -d' -d'-d'

G 10 logG 10 log "7"7 -10x10-10x10 ** & 3 & 4 K40 & 3 & 4 K40

G 40 &3 & 4 K 40G 40 &3 & 4 K 40 GG 3 d'>3 d'>



Example 2Exam ple 2 satellite transponder has a gain of !0 d'. ,ts recei+ing and satellite transponder has a gain of !0 d'. ,ts recei+ing and

transmitting antenna ha+e equal gain of ;0 d'. ,f thetransmitting antenna ha+e equal gain of ;0 d'. ,f the

recei+ing antenna recei+es a signal power of 10 u> from therecei+ing antenna recei+es a signal power of 10 u> from theearth transmitter% determine the signal power at the outputearth transmitter% determine the signal power at the outputof the satellite transmitting antenna.of the satellite transmitting antenna.

SolutionSolution ::

Satellite Transponder

1ain 4 1s 4 56 dBReceiving

antenna1r476 dB

Trans&itting

antenna1t476 dB

Po4 8Pin496 u:

2plink +o$nlink

) i d %) i+ d % ii GG 10 >10 >



)ecei+ed power%)ecei+ed power% inin GG 10 u>10 u>GG 10 log1010 log10 10 x 1010 x 10 &A&A >>

1 x 101 x 10 &3&3 >>GG &;0 d'm&;0 d'm

oror inin GG 10 log1010 log10 10 x 1010 x 10 &A&A >> 1 >1 >

GG +.7 d2@+.7 d2@

$otal gain$otal gain @$@$ GG @r K @s K @t@r K @s K @tGG ;0 K !0 K ;0;0 K !0 K ;0GG D7 d2D7 d2

'ut% o'ut% o GG inin KK @$@$GG -&!0 d'>-&!0 d'> KK E0 d'E0 d'GG 40 d'>40 d'>GG "7"7 ,, @ or "7 !@@ or "7 !@

A li i f lli i i



Applications of satellite communicationsApplications of satellite communications

ome of the applications of satellite communications are:ome of the applications of satellite communications are:

-i-i *igital audio broadcasting*igital audio broadcasting-ii-ii $ele+ision broadcasting$ele+ision broadcasting-iii-iii er+ing remote areaser+ing remote areas

-i+-i+ >eather satellites>eather satellites-+-+ )emote monitoring and control)emote monitoring and control-+i-+i ehicle trac(ingehicle trac(ing-+ii-+ii 2obile communications2obile communications-+iii 2aritime and air na+igation-+iii 2aritime and air na+igation

-ix-ix ideo teleconferencingideo teleconferencing-x-x *efence communications.*efence communications.

Comparisons et9een satellite s'stem andComparisons et9een satellite s'stem and



Comparisons et9een satellite s stem andComparisons et9een satellite s stem andterrestrial micro9a%e s'stemterrestrial micro9a%e s'stem

d+antages of a satellite system include:d+antages of a satellite system include:

1.1. ,t can access to wide geographical area.,t can access to wide geographical area.;.;. >ide bandwidth>ide bandwidth3.3. "igh reliability"igh reliability4.4. *istance insensiti+e cost.*istance insensiti+e cost.!.!. ,ndependent of terrestrial infrastructure,ndependent of terrestrial infrastructureA.A. )apid installation% and low cost per added site)apid installation% and low cost per added site

.. Iniform ser+ice characteristicsIniform ser+ice characteristicsD.D. ingle pro+ideringle pro+ider

*isad+antages of a satellite system include:*isad+antages of a satellite system include:

1.1. "igh initial cost"igh initial cost;.;. ,t has propagation delay,t has propagation delay3.3. )egulatory licensing requirement and limited orbital)egulatory licensing requirement and limited orbital

par(ing slots.par(ing slots.

ecm chapter 5

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