1. CYPRUS INTERNATIONAL UNIVERSITY
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRICAL AND ELECTRONIC
ENGINEERING
Case study:Optical Technologyadvantages
By: Christian Kateule 20121866

2. 1. Introduction
The followingcase studyexplainingthe prosof a NetworkSystemthatusesopticcommunication
and the practical application.Fiberopticscommunicationisasystemwhichuseslighttotransferthe
data throughan opticfiberforthe purpose of communication[1].Humanitieshungerfor
informationthroughthe internethasprovidedahuge demandforhighspeeddataaccessoverthe
past decade orso. By the year of 2000 the evolutionof Mobile Cellularnetworkshadadvancedfrom
using1G_2.4Kbs (kilobitspersecond) and2G_64Kbs to using 3G at 2Mbs (Megabitspersecond). The
increase indatarate speedshowsu
2. Wireless communication system
The availabilityof wirelesscommunicationtoanentire populationwasmade possiblebythe
developmentof highlyreliableSolid-state Radiofrequency hardware,thishardware made itpossible
for masscellularradiospectrumallocation. Cellularradiospectrumisbasicallythe conceptof
breakingdownazone intoproportioned cells,eachportionisallocatedtothe market[2],thiscanbe
networkchannels,radiostationsetc. The figure below isanexampleof atypical cellularspectrum.
Identicallylabeledchannelsinthe two
bandsform a forwardand reverse
channel pairusedforduplex
communicationbetweenthe base station
and the signal receiver(mobilesetc)
Figure 1: Frequency spectrumallocation
Frequencyallocationenhancedthe capacityof communication whichresultedinadditionof
available channels.Howeverthisreducedthe total bandwidthavailable toeachuser,affectingthe
qualityof service.

3. 2.1. Access Technologies
The most commonanalogsystemis(FDMA) FrequencyDivisionMultiple Access,itisa technique
whichutilizesfrequencySpectrumallocation,wherebyeachdividedspectrumisdividedand
assignedtothe user.WithFDMA onlyone subscriberat anygiventime is assignedachannel.This
entailsthatthe channel therefore isclosedtootherconversationsuntil the initial call isfinished,or
handedoff toanotherchannel.If the connectionisn’tmetitisregardedas a droppedcall. Time
DivisionMultiple Access (TDMA) isthe case inwhich the spectrumissplitintotime slots which
allowsuserstoaccessthe radiofrequencyforthe entiretyof the call.
2.2. Cell configuration
In a communicationnetworksystemthe cellsare generallyorganizedinacluster,each cluster
containingaboutsevencells,these clusterscontainerabase stationwhichis sometimescalleda
“cell site”,thisisusuallypositionedatthe centerof the cell.The base stationhoststhe transmitter,
receiverantennae andthe switchingequipment. All base stationare connectedtothe centercell
whichiscalledthe Mobile Switching Center(MSC),the base stationsare linkedtothe MSO eitherby
a fixedline ormicrowaves.
Figure 2. Mobile cell configuration
The mobile switchingcentercoordinatesthe routingof callsina large service area.Ina cellularradio
systemthe MSC connectsthe cell sitestothe PublicSwitchTelephone Network(PSTN). A typical
MSC can holdabout100,000 Cellularsubscribersand5000 simultaneousconversationsata time.
3. Olympics
The 2000 Olympicgameswhere heldinSydneyAustralia,itwasthe responsibilityof the
Telecommunicationscompanytoprovide the bestservicesintermsof airingthe gamesto
approximately3.5billionviewersacrossthe world.Inthe year2000, wirelesstechnologywasjust
onlygettingaccustomedto3G mobile networks.The mainchallenge involvedthe designand
implementationof ahigh-densitymobilenetwork atthe SydneyOlympicpark.Sydneyplayedhostto

4. almost500,000 localsand international visitors,withthisinformationitwasthe jobof Telstra
(telecommunicationcompanyincharge of the airingOlympicGames) todeliveraseamless service
for organizers,athletes,spectatorsandanestimatedpeaktelevisionaudience. Fromthe past
Olympiadsthe fundamentalsof telecommunicationhadnotchangedmuch,itwas mainly the
demandformobile andIP –Basedservices thathad changed. ([3];[2])
Figure 3: Telstra millennium network data [3]
3.1 The cellular mobile network Sydney
To serve forthe extreme concentrationof handsetsanetworkwasconstructedat SydneyOlympic
Park withwhatwas conceivedasthe highestdensityof anymobile networkinthe world,itwasbuilt
t service about300,000 usersin an areaof 1.5 x 1km. To provide thisservicehundredsof base
stationswere placedinbuildingscontainingdomainareas. Game time trafficwere monitored
constantlybecause of the limitedfrequencyspectrum,asthe technique usedwas FrequencyDivision
Multiple Access. The connectionlinksbetweenthe base stationsandthe MSC(mobile switching
center) were done byinternal cables.
There wasan average of around12,000 hours of telephoneconversationseachdayonthe
millenniumNetwork.Duringthe openingceremony 500,000 callsconnectedwithinSydneyOlympic
park and itwas foundthatonly125,000 of themwhere connected.Whichputsthe drop call rate at
around75%, thismeantthat forevery100 callsmade only25 of those callswill actuallyget
connected.Afterthe 17 daysof the Olympiceventsthe dropcall rate wasrecordedat approximately
40%.[3]
4. Optical Fibers
Early application of fiber optic transmission systems were largely for of telephone lines.
These were digital links consisting of time division multiplexed voice channels at a
transmission rate of 1.544Mb/s. An optical fiber transmission link comprises of the
following:
1. Transmitter: Light source
2. Repeater: Optical receiver, Optical transmitter
3. Receiver: Photo detector, Amplifier Signal Restorer

5. The connection of these three elements is done by the optical fibers. Optical fibers are
preferred in telecommunication for the following reasons [4]:
1. Low transmission loss and higher bandwidth, thisimpliesthatmore datacan be senton
an opticfiberovera much longerdistance,therebyreducingthe numberof repeatersonthe
systemascomparedto the conventionalmethodsof usingcoppercablesorradiowaves.
Thisreducescost andcomplexitiesof the entire communicationsystem.
2. Small size/weight, optical fibers are relatively small compared to copper cables, a
fiber has low weight and is small sized (hair size) this offers a distinct advantage over
bulky wire cables in a crowded city. Optical fibers are also much preferred in
machines that are weight sensitive for instance aircrafts, satellites and ships.
3. High Security, optical signals are well confined within the waveguide (any leakage is
being contained by the opaque jacketing around the optical fiber) this provides high
degree of security. This makes fiber optics more attractive to companies with high
need for data security (banks, military).
4. Immunity to interference, one of the most important features about optical fiber is that
their dielectric (poor conductor of electricity) in nature. This makes optical
waveguides immune to electromagnetic interference, it also shows a freedom from
EMPs (Electromagnetic pulse) effects.
5. Low power,due tothe size and wiringsimplicitiesof optical fibersthere isnotmuchneed
loadsof power.
In the Beijing Olympic Games in 2008 the links between the base station and MSC
(mobile switching center) was done using optical fiber cables which increased there
bandwidth drastically compared to the Sydney and Athens Olympic games. Beijing’s
idea of using Optical cables set their call drop rate at 4%.
Conclusion
Fiber-opticsystemsare revolutionizingtelecommunicationscomparedtoconventional metal wires,
and because of thisyoutendto see fiberopticsinmanyindustriesmostnotablytelecommunications
and computernetworks,there flexibilityandhigherbandwidthcapacityrenderthempreferable to
any othermeansof data transmission.

6. References
[1]Introduction tofiber optics, 2nd edition by johncrisp2001
[2]Wireless communications principles and practice2nd edition by Rappaport
[3]http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=933440
[4]Optical-Fiber-Communications-by-Gerd-Keiser.pdf