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TELECO M M U N ICATIO N S,TH E IN TERN ET, AN DW IRELESS TECH N O LO G Y
Chapter # 6
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Telecom m unications andN et o!"in# in Toda$%s &usiness
W o!ld Firms in the past used two fundamentally dierenttypes of networks: telephone networks
computer networks
Telephone and computer networks are slowlyconverging into a single digital network usingshared Internet-ased standards and e!uipment
"roadand:
ore than 6$% of &'(' Internet users have roadandaccess
"roadand wireless: )oice and data communication as well as Internet
access are increasingly taking place over roadandwireless platforms
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W hat is a com puter netw ork? Two or more connected computers
a*or components in simple network Client computer
+ client is a piece of computer hardware or software thataccesses a service made availale y a server' The server isoften ut not always. on another computer system/ in which
case the client accesses the service y way of a network'
(erver computer + server is a computer program or a machine that waits for
re!uests from other machines or software clients. and respondsto them' + server typically processes data' 0a1 The purpose ofa server is to share data or hardware and software resourcesamong clients'
2etwork interfaces 2ICs. + network interface card NIC. is a circuit oard or card that is
installed in a computer so that it can e connected to a network
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Connection medium 3ink through with devices communicate
2etwork operating system
+ network operating system 24(. is a computer operatingsystem that is designed primarily to support workstation/personal computer/ and/ in some instances/ older terminal thatare connected on a local area network LAN.'
5u or switch
Hubs and switches function as a common connection point forthe workstations/ printers/ le servers and other devices thatmake up a network' The main dierence etween hubs andswitches is the way in which they communicate with thenetwork' + hub functions as the central connection point of anetwork'
7outer + router 0a1 is a networking device that forwards data packets
etween computer networks' Routers perform the 8tra9cdirecting8 functions on the Internet' + data packet is typicallyforwarded from one routerto another through the networks that
constitute the internetwork until it reaches its destination node'
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Com 'onents o( a Sim 'leCom 'ute! N et o!"
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N et o!"s in la!#ecom 'anies Components can include: 5undreds of local area networks 3+2s.
linked to rm wide corporate network
)arious powerful servers
e site Corporate intranet/ e;tranet
"ackend systems
oile wireless 3+2s i-Fi networks.
)ideo conferencing system
Telephone network
ireless cell phones
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Co!'o!ateN et o!"
In(!ast!uctu!e
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)e$ di#ital net o!"in#tec*nolo#ies
Cliented mainframecomputing
The Internet: 3argest implementation ofclient
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Packet switching
ethod of slicing digital messages intoparcels packets./ sending packetsalong dierent communication pathsas they ecome availale/ and then
reassemling packets at destination
?revious circuit-switched networksre!uired assemly of complete point-
to-point circuit ?acket switching more e9cient use of
network@s communications capacity
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Packet-Sw itched Netw orks andPacket Com m unications
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TCP/IP and connectivity
Connectivity etween computers enaled y protocols ?rotocols:
7ules that govern transmission of information etween twopoints
Transmission Control ?rotocol
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Reerence m ode! or TCP/IP
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T*e T!ansm ission Cont!ol+!otocolInte!net +!otocol
-TC+I+. Re(e!ence M odel
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Com m unications N et o!"s
(ignals: digital vs' analogodem: Translates digital signals into
analog form
Types of networks 3ocal-area networks 3+2s. Client
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"unction o # $%
Netw orkTopo!ogies
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T!ansm ission M edia+ transmission medium is a material sustance solid/ li!uid/
gas/ or plasma. that can propagate energy waves' For e;ample/the transmission medium for sounds is usually air/ ut solids
and li!uids may also act as transmission media for sound'
Physical transmission media
Twisted wire
a cale consisting of two wires twisted round each other/used especially for telephone or computer applications'
Coa;ial cale
Coa;ial cales are a type of cale that is used y cale T)and that is common for data communications
Fier optics and optical networks
+ er optic cale consists of a undle of glass threads/ eachof which is capale of transmitting messages modulatedonto light waves' Fier optics has several advantages overtraditional metal communications lines: Fier optic caleshave a much greater andwidth than metal cales'
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Wireless transmission media anddevicesicrowave
!atellitesCellular telephones
"ransmission speedHert# $re%uency& the number of times
that somethin' happens durin' aparticular period
(andwidth
In computin') bandwidth is thebit*rate of available or consumedinformation capacity e+pressedtypically in metric multiples ofbits per second, -ariously)bandwidth may be characteri#ed
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'!o(a! internethat is the InternetConnecting to the Internet
Internet service providers I(?s.(ervices
=(3/ cale/ satellite/ T lines TD/ TE.Internet addressing and architecture
I? addresses
+ uni!ue string of numers separated y fullstops that identies each computer using theInternet ?rotocol to communicate over anetwork'
The domain name system =2( is an areviation for =omain 2ame (ystem/
a system for naming computers and networkservices that is organi>ed into a hierarchy ofdomains' =2( naming is used in TC?
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%om ain nam e system
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Internet Architecture Trunk lines ackone networks. Transcontinental/ Gmps to H'G gps
7egional networks I(?s
Internet .overnance2o formal management?olicies estalished y professional/ government
organi>ations I+"
anage overall structure of internet
IC+22
+ssign I? addresses
EC
(ets standards for 5T3 and other programminglanguages
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"he $uture Internet IPv/ I?v6 is the successor to the rst addressing
infrastructure of the Internet/ Internet ?rotocolversion I?v.' In contrast to I?v/ whichdened an I? address as a EH-it value/ I?v6addresses have a si>e of DH its'
Therefore/I?v6 has a vastly
enlarged address space compared to I?v' Internet0) N.I InternetH is a not-for-prot &nited (tates
computer networking consortium led ymemers from the research and education
communities/ industry/ and government' The 2e;t Jeneration Internet ?rogram also 2JI/2JI Initiative. was a &nited (tates Jovernmentpro*ect intended to drastically increase the speedof the Internet'
For high andwidth H'G gps to K'6 gps Aective routin /
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Inte!net se!/ices andcom m unication tools
A-mail messages distriuted y electronic means from onecomputer user to one or more recipients via anetwork'
Chatting and instant messaging
Typically/ the instant messa'in' system alerts youwhenever someody on your private list is online' Lou canthen initiate a chat session with that particular ?erson
3ive/ interactive conversation 2ewsgroups
+ news'roup is a discussion aout a particularsu*ect consisting of notes written to a centralInternet site and redistriuted through &senet/ aworldwide network of news discussion groups'&senet uses the 2etwork 2ews Transfer ?rotocol
22T?.'
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Telnet"elnet is a user command and an underlying TC?
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0oice o/e! I+ -0oI+.
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)irtual private networks )?2s.)?2/ or virtual private network / is a
network that is constructed y using pulic
wires N usually the Internet N to connect to aprivate network/ such as a companyMs internalnetwork' There are a numer of systems thatenale you to create networks using theInternet as the medium for transporting data'
orld ide e The orld ide e . is an open
source information space where
documents and other we resources areidentied y &73s/ interlinked yhyperte;t links/ and can e accessedvia the Internet' It has ecome known
simply as the e'
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T*e W o!ld W ide W e1 5T3 5yperte;t arkup 3anguage.:
Formats documents for display on e 5yperte;t Transfer ?rotocol 5TT?.:
Communications standard used fortransferring e pages
&niform resource locators &73s.: +ddresses of e pages
A'g'/http:
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!earch en'ines
(tarted in early DKK$s as relatively simple
software programs using keyword inde;es Today/ ma*or source of Internet
advertising revenue via search enginemarketing/ using comple; algorithms andpage ranking techni!ues to locate results
(hopping ots
&se intelligent agent software for
searching Internet for shoppinginformation
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W e1 234 (econd-generation interactive Internet-ased
services enaling people to collaorate/ shareinformation/ and create new services online
Cloud computing
(oftware mashups and widgets
"logs: informal e sites created y individualsusing easy-to-use welog pulishing tools
7(( Rich !ite !ummaryO originally R1$ !ite!ummaryO often called Really !imple!yndication. uses a family of standard we feed
formats to pulish fre!uently updated information:log entries/ news headlines/ audio/ videos
ikis: Collaorative e sites where visitorscan add/ delete/ or modify content on the site
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Intranets &se e;isting network infrastructure with
Internet connectivity standards softwaredeveloped for the e
Create networked applications that canrun on many types of computers
?rotected y rewalls 2+tranets +llow authori>ed vendors and customers
access to an internal intranet
&sed for collaoration +lso su*ect to rewall protection
T* W i l R l ti
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T*e W i!eless Re/olution ireless devices
?=+s/ "lack"erry/ smart phones
Cellular systems
Competing standards for cellularservice &nited (tates: C=+
ost of rest of world: J(
Third-generation EJ. networks
5igher transmission speeds suitale forroadand Internet access
C=+
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C=+ C=+ Code-=ivision ultiple +ccess. refers to any of
several protocols used in second-generation HJ. and third-generation EJ. wireless communications' +s the term
implies/ C=+ is a form of multiple;ing/ which allowsnumerous signals to occupy a single transmission channel/optimi>ing the use of availale andwidth' The technologyis used in ultra-high-fre!uency &5F. cellular telephonesystems in the $$-5> and D'K-J5> ands'
.! Jloal (ystem for oile communication. is a digital
moile telephony system that is widely used in Aurope andother parts of the world' .! uses a variation of timedivision multiple access T=+.
EJ The term EJ internet refers to the third generation of
moile phone standards/ as set y the International Telecommunications &nion IT&.' EJ technologies allowmoile operators to oer more service options to theirusers/ including moile roadand'
T* W i l R l ti
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T*e W i!eless Re/olutionWireless computer networks and Internet access
"luetooth $H'DG.
(luetooth is a wireless technolo'y standard fore;changing data over short distances using short-wavelength &5F radio waves in the I( and from H' toH'G J5>. from ;ed and moile devices/ and uildingpersonal area networks ?+2s.'
3inks up to devices in D$-m area using low-power/ radio-ased communication
&seful for personal networking ?+2s.
i-Fi $H'DD.
(et of standards: $H'DDa/ $H'DD/ $H'DDg/ $H'DDn &sed for wireless 3+2 and wireless Internet access
&se access points: =evice with radio receiver
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) *!uetooth Netw ork +P)N,
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)n .011 W ire!ess 2)N
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W iM A5
WiA3 orldwide Interoperailityfor icrowave +ccess. is a wirelessindustry coalition dedicated to theadvancement of IAAA $H'D6standards for roadand wirelessaccess "+. networks'
ireless access range of ED miles7e!uire ia; antennas
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Radio (!e6uenc$identi(ication -R7ID . &se tiny tags with emedded microchips
containing data aout an item and location/ andantenna
Tags transmit radio signals over short distances
to special 7FI= readers/ which send data overnetwork to computer for processing
Common uses:
+utomated toll-collection
Tracking goods in a supply chain
7e!uires companies to have special hardwareand software
7eduction in cost
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Radio (!e6uenc$identi(ication -R7ID .