broadband technologies and adsl ver 3

7/23/2019 Broadband Technologies and ADSL Ver 3

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Broadband Technologies

Broadband

Technologies

ITI LimitedRaebareliIssue: 01

1 ITI Limited, Raebareli


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Contents


Introduction

Competing Broadband Technologies

Wireless Technologies

Fixed Line Technologies

Broadband Technology Comparison

Future Perspectives

ADSL

Introduction

DSL connectivity

DSL ! "et#or$ and rchitecture

Carrierless mplitude Phase

Discrete %ulti!tone &D%T'

Data over DSL

PPPo(



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IntroductionThe broadband revolution is )orcing the competition in the broadband servicemar$et and broadband service providers to plan their strategies )or delivery o)services #ith voice* data and video provided by a single connection+ ,ver recent

years* as the internet and intranets have evolved* increasing re-uirements )orband#idth intensive applications such as peer to peer )ile sharing and tele!#or$inghave resulted in relentlessly increasing demands )or higher broadband band#idthprovisioning+ .o#ever* it is the band#idth re-uired by next generation T/and video services* such as /ideo on Demand &/oD'* and more signi)icantly*high de)inition T/ &.DT/' #hich have recently begun to place the mostpressure on band#idth provisioning in broadband net#or$s+ (ven #ith thelatest data compression techni-ues* .DT/ re-uires in the order o) 01 to 23%bps o) do#nstream band#idth and this is testing the capabilities o) anumber o) broadband technologies+There are -uite a )e# competing technologies #hich can provide the band#idthre-uired to deliver broadband services* but each technology has its limits in termso) band#idth* reliability* cost or coverage+ ,ptical )iber o))ers almost limitlessband#idth capabilities* has excellent reliability and is becoming increasinglyeconomical to install+ Conse-uently )iber seems to be unsurpassed in itssuperiority over the other broadband technologies+ .o#ever* many competitivecopper and #ireless technologies are developing at a signi)icant pace and sometechnologies have so )ar managed to continually meet the ever increasingband#idth re-uirements o) the consumer+The latest developments in the broadband access technologies and #e #illmeat the )uture re-uirements o) the broadband users+ (ach one has some

advantages over the other technologies+Competing Broadband TechnologiesIn general broadband solutions can be classi)ied in t#o groups4

Fixed line technologies Wireless technologies

The )ixed line solutions communicate via a physical net#or$ that provides adirect 5#ired6 connection )rom the customer to the service provider+ The bestexample o) this is the plain old telephone system &P,TS' #here the customer isphysically connected to the operator by a pair o) t#isted copper cables+ Wirelesssolutions use radio or micro#ave )re-uencies to provide a connection bet#eenthe customer and the operator7s net#or$8 mobile phone connectivity is a primeexample+

Fixed Line TechnologiesFixed line broadband technologies rely on a direct physical connection to thesubscriber7s residence or business+ %any broadband technologies such ascable modem* xDSL &digital subscriber line' and broadband po#erline haveevolved to use an existing )orm o) subscriber connection as the medium )orcommunication+ Cable modem systems use existing hybrid )iber!coax Cable T/net#or$s+ xDSL systems use the t#isted copper pair traditionally used )orvoice services by the P,TS+Broadband po#erline broadband technology uses the po#er lines )eeding into

the subscriber7s home to carry broadband signals+ In general* all threea)orementioned technologies strive to avoid any upgrades to the existingnet#or$ due to the inherent implications )or capital expenditure+ By contrast*)iber to the home &FTT.' or )iber to the curb &FTTC' net#or$s re-uire the



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installation o) a ne# &)iber' lin$ )rom the local exchange &central o))ice' directlyto or closer to the subscriber+ Conse-uently* although )iber is $no#n to o))er theultimate in broadband band#idth capability and the installation costs o) suchnet#or$s have* up until recently* been prohibitively high+The )ixed line technologies evaluated here include4

!brid Fiber Coax "FC#: Cable T$ % Cable &odems 'igital (ubscriber Line "x'(L# Broadband )o*er Line "B)L# Fiber to the ome+Curb "FTT+FTTC#

!brid Fiber Coax "FC#: Cable T$ % Cable &odemsDigital cable T/ net#or$s are able to o))er bi!directional data trans)erband#idth in addition to voice and digital T/ services+ 9sing a cable modem inthe customer premise and a Cable %odem Termination System &C%TS' at thenet#or$7s head!end* the #ell established .FC standard* D,CSIS 0+0* provides )ora data transmission service #ith speeds o) up to a :3 %bps on one ; %. encoding algorithm and o))ers 0@@ $bps )or both uploadingand do#nloading+

SDSL ! SDSL #as an attractive option )or small businesses loo$ing to replacetheir expensive T0 lines+ SDSL is symmetric in nature* #hich insimple language means you get the same band#idth in bothupstream and do#nstream direction+ With SDSL* the maximumband#idth that can be achieved is 2+: %bps+ The typical maximum

reach )or SDSL is approximately @ $m* or 02*333 )eet++shdsl ! The highly anticipated + shdsl standard )rom the IT9 #as

developed to replace or enhance many previous DSL standards*ma$ing DSL roll out much easier and addressing the interoperabilityissues at the same time+ It is multi rate because it supports datarates )rom 0E2 $bps to 2+: %bps+ +shdsl uses +hs &handsha$e' tonegotiate the )raming protocol+Protocols supported include T%* T0* (0* ISD"* and IP+ The )lexibilityo) +shdsl enables the transport o) virtually any type o) service+ Itma$es use o) Trellis Coded Pulse mplitude %odulation &TC!P%' linecoding that enables interoperation due to the lo# complexity level o)the transceivers+ +shdsl is suppose to deliver approximately :3percent greater reach than currently employed transporttechnologies+ +shdsl is expected to rapidly replace the proprietarySDSL implementations o) today and is mainly used )or business !class users+

ll xDSL )lavors* such as DSL* SDSL* and IDSL* sit at the physical layer o) the,SI re)erence model+ xDSL technology is simply a transmission technology*much li$e T0(0+ DSL technology in its simplest )orm is nothing but a modemtechnology+ Data )rom the subscriber gets modulated by the subscriber endDSL modem be)ore being put on the physical copper loop+ The C, e-uipment

at the other end ! comprised o) ban$s o) modems ! demodulates the signalsand ma$es necessary s#itching decisions based on the transport layer used+



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'(L connecti2it!To understand any DSL connectivity* you must understand the components o)the entire DSL net#or$* as sho#n in )igure belo#4

For any DSL connectivity* you have a DSL modem at the subscriber end at a

minimum* noted in the diagram as an T9!? &DSL termination unit!remote'and more commonly $no#n as customer premises e-uipment &CP('+ t theC,* a corresponding DSL modem demodulates the signals modulated by thesubscriber modem+ The C, is e-uipped #ith a digital subscriber line accessmultiplexer &DSL%'* #hich consists o) ban$s o) T9!Cs &DSL terminationunit!central'+ Depending on the region that C, is serving* the DSL% shouldhave a corresponding T9!C )or each T9!? at the subscriber end+ Because#e are depicting DSL in the diagram* #e made re)erence to DSLtermination units+ I) the Flavor o) DSL is SDSL* the subscriber!end modemthen #ould be called ST9!? and so )orth+

The splitters sho#n in Figurere)lect a device that di))erentiates DSL data )romthe regular analog voice+ It is important to note here that any DSL )lavorusually ma$es use o) the )re-uency spectrum* #hich is higher than that usedby regular analog voice &typically @ $.


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5'(L 9et*or3 and 5rchitecture

DSL is the most #idely deployed )lavor o) xDSL today+ The reason )or this issimple4 DSL provides the right suite o) band#idth both in upstream anddo#nstream directions* re-uired by the most consumers today+ DSL hasgained popularity in todayOs consumer space* not only as the al#ays!ontechnology but also as a cheaper and more suitable alternative to the

common dial modem technology+ In addition* DSL is being o))ered andgaining popularity as a cheaper alternative to the traditional T0Frame ?elaycircuits )or small o))ices* home o))ices* and business customer space+

DSL has become a relatively mature technology having already beenthrough several years o) development and physical deployment by manyservice providers+ DSL can o))er rates o) ; %bps in the do#nstream directionand approximately 0 %bps in the upstream direction+

5'(Lis a )orm o) DSL* a data communications technology that enables)aster data transmission over copper telephone lines

DSL is capable o) providing up to 12 %bps* and supports voice* video

and data+ DSL is the 0 Broadband Choice in the World #ith over =3Q mar$et

share

DSL is no# available in every region o) the #orld

What does 5'(L mean< symmetric ! The data can )lo# )aster in one direction than the other+

Data transmission has )aster do#nstream to the subscriber thanupstream

Digital ! "o type o) communication is trans)erred in an analog method+ll data is purely digital* and only at the end* modulated to be carried

over the line+ Subscriber Line ! The data is carried over a single t#isted pair copper

loop to the subscriber premises+

5'(L standards

Comparison o7 5'(L (peed



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5'(L Range In general* the maximum range )or DSL #ithout a repeater is 1+1 $m s distance decreases to#ard the telephone company o))ice* the data

rate increases

'ata Rate Wire gauge Wire si?e 'istance

0+1 or 2 %bps 2@ W 3+1 mm 1+1 $m

0+1 or 2 %bps 2= W 3+@ mm @+= $m

=+0 %bps 2@ W 3+1 mm :+ $m

0+1 or 2 %bps 2= W 3+@ mm 2+

For larger distances* you may be able to have DSL i) your phonecompany has extended the local loop #ith optical )iber cable

5'(L (peed Factor

The distance )rom the local exchange

The type and thic$ness o) #ires used The number and type o) oins in the #ire

The proximity o) the #ire to other #ires carrying DSL* ISD" and othernon!voice signals +

The proximity o) the #ires to radio transmitters

5'(L net*or3 components

The DSL modem at the customer premises&T9!?'

The modem o) the central o))ice &T9!C'

DSL access multiplexer &DSL%'

Broadband ccess Server &BS'

Splitter ! an electronic lo# pass )ilter that separates the analogue voiceor ISD" signal )rom DSL data )re-uencies DSL%+



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5'(L Loop 5rchitecture

5'(L Reuirements

Phone!line* activated by your phone company )or DSL

Filter to separate the phone signal )rom the Internet signal

DSL modem

Subscription #ith an ISP supporting DSLo* does 5'(L *or3

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