IEEE Communications Magazine • July 200890 0163-6804/08/$25.00 © 2008 IEEE

INTRODUCTION

The key drivers for deploying fiber to the x(FTTx) infrastructures are advanced multimediaservices (including Internet Protocol television[IPTV], high definition television [HDTV], andvideo on demand [VoD]); ultra-high-bit-rateInternet access (50–100 Mb/s); and corporatebroadband applications such as videoconferenc-ing; hosted voice-over-IP (VoIP); and IP virtualprivate networks (VPNs). Video services, in par-ticular, justify the need for the ultra-high bitrates. For some passive optical network (PON)deployments, video is driving investment intoradio frequency (RF) video for the near termand increased bandwidth on the data channels tosupport IP video in the longer term. Telecom-munication companies (telcos) and cable pro-viders appear to have settled on 100 Mb/s to theconsumer as the current target, with higher ratesto businesses (1 Gb/s).

For those densely populated regions of theworld where subscribers in high-rise multi-dwelling units (MDUs) might do a significantamount of resource sharing, traffic within onebuilding can be handled by an Ethernet switchor a remote digital subscriber line access multi-plexer (DSLAM) in the basement. In this case, adedicated single fiber link back to the centraloffice makes a lot of sense.

In this article, we give a snapshot of the cur-rent status of FTTx, the growth rate of the tech-nology, and the state of FTTx in different regionsof the world. We also take a look at next-genera-tion PON systems, as well as the environmentalimpact of gigabit passive optical network(GPON). We purposely omitted one area in thisarticle — a detailed analysis and comparison ofthe different FTTx technologies. There are num-ber of excellent articles [1–3] that cover thattopic in detail. We also take a look at what cableoperators are doing to compete with the telcos.

WHERE ARE WE TODAY ANDWHERE ARE WE GOING?

At the end of 2007, there were nearly 29 millionsubscribers connected with FTTx infrastructureworldwide. Most of the subscribers are receivingservice via fiber to the home (FTTH) or fiber tothe building (FTTB). Together, the two termscommonly are called fiber to the premise(FTTP). Figure 1 illustrates the global growth ofFTTx for the years 2005–2012. The growth isexpected to continue at a very fast pace with thenumber of FTTx subscribers expected to grow toover 100 million by the end of 2012. Today FTTxbroadband comprises 7.5 percent of all broad-band users and is expected to comprise 16 per-cent of all broadband users by 2012.

There are two fundamental FTTx architec-tures deployed in today’s access networks: pointto multipoint, which is commonly referred to asa PON and point to point (P2P, referred to asactive Ethernet). PONs have a single fiber thatruns from the central office to deep in the net-work and usually terminates at a splitter cabinet.Although the splitter cabinet typically contains a1×32 splitter, split ratios of 1×16 and 1×8 some-times are used. New standards are calling foreven larger split ratios of 1×64 and 1×128. For afuture potential upgrade to wavelength divisionmultiplexing (WDM)-PON, an arrayed waveg-uide (AWG, for wavelength multiplexing anddemultiplexing) can be colocated. From thesplitter cabinet, short runs of fiber connect eachof the homes. With the point-to-point (P2P)architecture, a single fiber runs all the way fromthe central office to the home. Both architec-tures are deployed, with P2P currently outpacingthe PON installations as can be seen in Fig. 2.The figure also shows that by 2012, PON willcatch up to P2P; and it is expected that P2P willstart to decline, and PON will continue to growand will dominate.

For those densely populated regions of theworld, MDUs can take advantage of resourcesharing through traffic aggregation with a cen-tralized Ethernet switch or DSLAM in eachbuilding. In this case, a dedicated single fiberlink back to the central office makes a lot ofsense. China-India and Asia-Pacific are currentlythe leading regions for P2P access due to theirnumerous densely populated areas. We expectWestern Europe to catch up and surpass Asia-Pacific in the future.

The PON market worldwide is expected to

ABSTRACT

By the end of 2007, there were 29 millionsubscribers to services supplied by FTTx equip-ment, and by 2012, it is expected the number willgrow to over 100 million subscribers. In thispaper, we review the current status of FTTx andanalyze what is taking place in different regionsof the world. We view the future for FTTx interms of growth and the types of FTTx productswe might see.

INDUSTRY ANALYST FORUM

Lynn Hutcheson, Ovum

FTTx: Current Status and the Future

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

IEEE Communications Magazine • July 2008 91

grow at a compound annual growth rate(CAGR) of 15 percent between 2005 and 2012.North America will be more aggressive in itsdeployment of PONs over the forecast period,whereas Asia-Pacific PON deployments willremain relatively steady. The fastest-growingregions for PON sales are forecasted to be West-ern Europe and North America. Starting in2007, the migration from broadband passiveoptical network (BPON) to GPON in NorthAmerica began as the pricing of GPON becamemore attractive. Asia-Pacific and China-Indiawill continue to favor Ethernet passive opticalnetwork (EPON), although GPON will make itspresence known in the later years of the fore-cast. The forecast for PON equipment sales byPON type is shown in Fig. 3.

Those in the telecommunications industrygenerally agree that fiber all the way to thehome or premises (usually abbreviated FTTH) isthe ultimate broadband architecture for fixedaccess networks. The Fiber-to-the-Home Councilis promoting the deployment of FTTH world-wide by tracking the increasing subscriber num-bers on FTTH and its increasing market share ofall broadband.

Figure 4 shows the latest figures from theFTTH Council [4], released at the FTTH Coun-cil meeting in Paris in February 2008. To contin-ue a tradition started at the Asia-Pacific FTTHCouncil meeting held in Beijing, China in July2007, the three FTTH councils — North Ameri-ca, Asia-Pacific, and Europe — performed ajoint study to determine worldwide ranking ofcountries or economies that have FTTH sub-scribers. They then rank the countries that havegreater than 1 percent FTTH penetration basedupon the number of households in each country.In July 2007, eleven countries or economies hadgreater than 1 percent FTTH penetration. In thesix months since then, the number of countrieshaving a greater than 1 percent penetration rateincreased to 14.

REGULATIONIn North America, regulations regarding whichcompanies can provide video service are easing,and this has given Verizon added momentum forincreasing fiber optic service (FiOS) customers.High-bit-rate data services are no longer themain telco offering. In North America, telcooperators (Verizon, in particular) are continuingto win over cable TV customers with their triple-play service option, which has provided strongcompetition for the cable operators. Verizon’svideo service is an RF overlay provided on athird wavelength. Similar to Verizon, Japan’sNippon Telegraph & Telephone (NTT) providesa third wavelength for video overlay, but regula-tions require customers to have a separate receiv-er at the home to comply with regulationsforbidding NTT from offering TV service. In thismanner, NTT provides the physical plant for itspartner, SkyPerfectTV to deliver the TV services.NTT, China Telecom, Korea Telecom, and othertelcos continue to test video delivery, demon-strating their long-term interest despite currentregulatory barriers. In Korea, the regulatory envi-ronment is making it easier to deliver video.

North American regulations have becomemuch clearer and made it easier for the telcos toroll out IPTV services. The Federal Communica-tions Commission (FCC) ruled that local author-ities must decide on video franchise applicationswithin 90 days, and the number of states withstatewide franchises continues to increase. Withthe presidential elections approaching, we mighthear more about net neutrality, particularly if aDemocrat wins. However, there are some cau-tionary notes in the online content revenuesmodel. Wal-Mart, for example, recently pulledits online video download program, which didnot appear to be profitable.

In Australia, the change in government isexpected to provide a fresh perspective and

■ Figure 1. Cumulative global growth of FTTx for the years 2005–2012.

2005

11,170Cumulative FTTx

2006

Cumulative FTTx

19,413

2007

28,593

2008

40,288

2009

54,522

2010

71,502

2011

87,983

2012

108,262

40,000

Thou

sand

s

20,000

0

60,000

80,000

100,000

120,000

■ Figure 2. Capital equipment expenditures for PON and point-to-point.

2005 2006 2007 2008 2009 2010 2011 2012$292FTTx (PON) $398 $407 $478 $612 $732 $845 $918

$399 $532 $625 $645 $807 $884 $900 $916

$200

$ m

illio

ns

$-

$400

$600

$800

$1,000

FTTx (Ethernet pt-to-pt)

■ Figure 3. Capital equipment spending by PON type.

2005 2006 2007 2008 2009 2010 2011 2012

$141BPON $203 $161 $40 $23 $18 $9 $3

$148 $182 $154 $149 $156 $159 $161 $161

$3 $13 $92 $289 $433 $554 $674 $753

$200

$ m

illio

ns

$100

$0

$300

$400

$500

$600

$700

$800

EPON/GE-PON

GPON

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

IEEE Communications Magazine • July 200892

urgency to Telstra’s fiber to the node/neighbor-hood (FTTN) next-generation rollout, but nag-ging questions such as competitor access andwholesale tariffs remain to be resolved.

Regulation continues to be a major factor inEurope, despite the recently released EuropeanCommission (EC) telecom reform proposals.Commissioner Viviane Reding said that, onaverage, 89.5 percent of direct access is stilldominated by incumbents in the EuropeanCommunity, still far from ideal. Therefore,Reding strongly believes in functional separa-tion — that is, separating telecom networksfrom services and having different managementstructures for each — as a last-resort remedy totackle the most persistent bottlenecks andensure fair and effective competition. Function-al separation is being opposed by the EuropeanTelecommunications Network Operators Asso-ciation (ETNO), the representative for incum-bent operators, as being too costly. Whenmentioned as a possible template of regulationacross Europe, some regulators expressed seri-ous doubts over functional separation. Howev-er, the European Regulators Group iscommitted to providing guidelines to assistnational regulatory authorities (NRAs) in mak-ing a cost/benefit analysis.

The EC strongly believes in fostering compe-tition and preventing monopolies. It accom-plished this very effectively with its local loopunbundling policy, under which incumbent oper-ators must provide competitors with access totheir copper infrastructure. Whereas that policywill continue for copper local loops, it likely willchange for FTTH. Vivian Reding spoke viavideo at the European FTTH conference [4] onFebruary 28, 2008 and announced that the ECwill be publishing a new policy on how to handleFTTH sometime near the middle of 2008. Shedid reinforce the European Union (EU)’s policyof promoting competition and stifling monopo-lies but emphasized the importance of the FTTH

role in keeping Europe competitive with the restof the world, while at the same time growing theeconomy.

The proposal before the European Parlia-ment and by member governments in the Euro-pean Council will be debated. There will be aperiod of at least two years before the NRAs areable to mandate functional separation. By then,the overseas performance of Australia and NewZealand, which are splitting up their incumbentsbased on the UK model of functional separation(Openreach), most likely will provide analyticalevidence of the successes and failures of thepractice. In the EU, the Swedish regulator iswaiting for its parliament to approve the rele-vant legislation; in Italy, the CommunicationsRegulatory Authority (AGCOM) is startingnegotiations with Telecom Italia; and Poland isconsidering similar measures. Since thesereforms are newly released, it is not clear yet towhat extent incumbents will go ahead with theirnext-generation rollout plans, but we can expectfurther delays and scaling down of deploymentsuntil this is resolved.

COSTS TO DEPLOY FTTXThere are a number of factors that affect thecost to install FTTx infrastructure and equip-ment, such as whether the installation is aerialor buried. There is not much one can do toreduce the cost of hanging or burying fibercable or reducing the actual cost of the fibercable, as they are well down the maturity curve.However, there have been some fairly simpleimprovements in reducing the amount of laborrequired to install the equipment. For example,Tellabs has started fitting its optical networkterminals (ONTs) with a single screw mountthat provides for automatic self-leveling.Another labor-saving implementation is theuse of preconnectorized fiber drops. ADCTelecommunications claims that in 2006 theirshipments for preconnectorized fixed length(the company has 13 different lengths) fiberdrops grew substantially. This replaces the tra-ditional technique of fiber splicing in the field.It also saves on wasted fiber because whensplicing in the field, the installers cut the fiberto fit the installation.

There are four network architectures current-ly being deployed for FTTx that are consideredin this analysis; BPON, GPON, EPON, and Eth-ernet point to point. The three PON architec-tures are very similar in terms of infrastructure,design, and installation. A single fiber is termi-nated at an optical line termination/terminal(OLT) in the central office and connected to apassive splitter deep in the network. Typically,the splitter is a 1×32 but can be 1×16, 1×8, or1×4. The split ratio is largely dependent on theoptical power budget and the distance from thecentral office to the furthest customer. Forexample, Verizon uses a 1×32 splitter for dis-tances of 11 km or shorter and a 1×16 splitterfor distances greater than 11 km. About 85 per-cent of Verizon’s installations fall into the short-er distance category. The standards are nowincorporating the ability to use larger split ratiossuch as 1×64, and there are discussions to go as

■ Figure 4. Economies having greater than 1 percent FTTH/FTTB householdpenetration.

Economies with the highest penetration of fiber-to-the-home / building+LAN

Hong

Kong

5%Hou

seho

ld p

enet

rati

on

0%

10%

15%

20%

Year end 2007 rankingSource: Fiber-to-the-Home CouncilFebruary 2008

25%

35%

30%

Economies where majority architectureis fiber to the homeEconomies where majority architectureis fiber to the building + LAN

Sout

h Ko

rea

Japa

n

Swed

en

Taiw

an

Norway

Denm

ark

United

Stat

es

Slova

kia

Icelan

d

P. R.

Chin

a

The N

ethe

rland

sIta

ly

Singa

pore

Economies with greaterthan 1% household penetration

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

IEEE Communications Magazine • July 2008 93

high as 1×128. There are variations on how 1x32splitters are deployed. For example, in Japan alarge portion of their EPON installations use a1x4 in or near the central office followed by four1×8s deeper in the network.

There is no difference in the splitters used forthe three PON architectures except for the splitratio. The price and time to install do notdepend on which PON technology is deployed.The average price of a splitter varies betweenUS$7.50 and US$10 per port depending on splitratio. The reason for the variation is due topackaging costs.

As an example, let us consider what Verizonhas achieved in costs to install the infrastructureand to purchase capital equipment, the passives,and the electronics on a per passing basis. Veri-zon has been the predominant operator deploy-ing BPON technology, with more than onemillion customers served and more than sevenmillion homes passed. Since 2004, Verizon hasbeen able to reduce their per-passing cost bymore than 36 percent. Figure 5 shows the instal-lation costs for Verizon. This figure requirescareful reading. The cost per home passed showsthe costs of the fiber and installation to passeach home. The cost per home connected isthen the additional cost to provide service toeach home served. Thus, Verizon projects thatby 2010 their installed cost per home served willbe US$1,350. Verizon has broken down theirper-passing cost into three categories — infra-structure, passives, and electronics. The infra-structure represents 50 percent of the cost,whereas electronics makes up 35 percent of thecost, and the remaining 15 percent of the cost isfor the passives.

All of the PON architectures are virtually thesame from an infrastructure and installationstandpoint. The only real significant difference isthe electronics. Therefore, one would expect themajor differences in cost between the variousPON products to be the difference in labor costsfrom country to country and the electronic costdifferences between the various PON products.The installation of GPON products is just start-ing to take off, so there is not much history, butVerizon has said it expects to be able to installGPON for much the same cost as BPON, mean-ing the electronics for BPON and GPON are thesame.

Japan has been deploying GE-EPON tech-nology for almost five years, and it is well downthe maturity curve, much like Verizon’s BPONdeployments. Today’s GE-EPON installationcosts in Japan are at US$1,350 per passing,which is about an 18 percent reduction over thelast two years. The electronics cost is US$290per passing, and the cost of the passive splitter(one 1×8 and eight 1×4s) is US$270, which leavesthe cost of installing the infrastructure atUS$790. This is very close to what the infra-structure installation cost is in the United States.

Ethernet P2P is a totally different architec-ture, which means we cannot use any of theassumptions used for PON. However, we doknow that the electronics ranges betweenUS$300 and $400 per passing. There is no split-ter in P2P, which has a price of approximatelyUS$250 for a 1×32 or $7.80/port. The additional

cost difference between PON and P2P is theamount of fiber that must be installed. Insteadof one fiber from the central office to the split-ter cabinet and 32 short extensions from thesplitter cabinet to the home, we have 32 fibersall the way from the central office to the home.The additional installed fiber cost is stronglydependent on whether it is aerial or buried con-struction. It has been estimated that on average,the additional cost is approximately 25 percent.Some reports have indicated that this cost canbe higher than that but again, there are alwaysvariances in labor cost. Pulling all these factorsand cost variances together puts the per passingcost of installing and connecting service to thehome with P2P at approximately US$1350.

NEXT-GENERATION PONService providers are starting to study and evalu-ate their options for upgrading their networks toeven higher data rates to plan for increased takerates and next-generation services. There areseveral technologies being investigated for next-generation PON.

10GEPONThe 10 gigabit Ethernet passive optical network(GEPON) will be an extension of the IEEE802.3av EPON standard that will increase thedownstream data rate from 1.25 Gb/s to 10 Gb/s.There will be other changes to the standardbesides the data rate. The standard is slated tobe approved by the IEEE standards committeeearly in 2008 and may be approved by the timethis article is published. NTT is currently evalu-ating 10 GEPON but has not announced whenthey will start deploying it in any kind of volume.

10GPONThis will be an extension of the ITU-T G.984GPON standard that will increase the down-stream data rate from 2.5 Gb/s to 10 Gb/s. Therealso will be other changes included in the stan-dard besides the data rate. This standard has notbeen finalized and is not as far along as theIEEE standard, but 10GPON equipment cur-rently is being evaluated by Verizon in their lab-oratories.

■ Figure 5. Verizon's installation costs per passing broken down by passing ahome and connecting a home.

Cost per home passed Cost per home connected

$1400

$200

$0

$400

$600

$800

$1000

$1200

$1400

$1600

2004 2005 2006 2010 2004 2005 2006 2010

$1,021

$700$700

$1200 $1163

$880

$650

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

IEEE Communications Magazine • July 200894

WDM-PON

This has quite often been referred to as thefuture-proof FTTx network as it has the abilityto deliver >1 Gb/s symmetrical to each home orbusiness. It uses dense wavelength division mul-tiplexing (DWDM) technology that has longbeen used in the long haul and metro markets.Logically, it is a P2P system because it delivers adedicated wavelength to each premise, althoughphysically, it is point to multipoint. Korea Tele-com [5] has installed 150,000 lines of WDM-PON systems with a product from Novera Opticsand is continuing to deploy WDM-PON in limit-ed quantities.

Novera Optics [6] has taken a first step in sig-nificantly reducing the cost of the WDM-PONproducts by developing a technology that elimi-nates the requirement for a wavelength specificlaser (such as a distributed feedback [DFB]laser) in the ONT. The company uses a tech-nique known as wavelength locking, which has acontinuous wave (CW) broadband light sourcelocated at the OLT that is used to generate aseed signal for locking the wavelengths of theremotely located Fabry-Perot (FP) lasers in theONT. The seed signal is transmitted downstreamthrough a single fiber into a wavelength demulti-plexer that divides the signal into a number(equal to the number of ONTs) of narrowbandDWDM channels. Each spectral slice then istransmitted through a single distribution fiberand injected into a remotely located FP laserdiode. When the FP laser is current modulatedwith the electrical data signal, the injected seedsignal forces the laser to operate in a narrowwavelength range defined by the optical pass-band of the DWDM transmission link. Thiswavelength-locking process can be understoodeasily when one realizes that the FP laser basi-cally acts as an optical amplifier that modulates,amplifies, and reflects the injected broadbandlight source seeding signal. The FP laser is notcapable of free lasing due to the gain saturationcaused by the amplified seeding signal. Thisresults in a stable narrowband output data sig-nal, free from any of the noise associated withmode hopping found in standard free-runningFP lasers.

HYBRID WDM-PONHybrid WDM-PON basically combines a GPONtopology with a WDM-PON topology. A WDM-PON system is connected to an OLT just as inthe standard WDM-PON system. Each wave-length is then fed into its own dedicated GPONsystem. This can significantly increase the num-ber of ONTs per OLT port. If there are 16 wave-lengths and a 1×32 splitter, then the number ofONTs fed by a single port OLT can be as highas 512.

LONG REACH PONThere has been a strong desire by some coun-tries to reduce the number of central offices toconsolidate operations and reduce cost. TheUnited Kingdom started discussing this possibili-ty over 15 years ago. It has about 5,000 centraloffices and would like to reduce that number to50–100 or even less, if possible. One idea that

was promoted is extending the reach of the exist-ing PON technology from 20 km to 100 km.Alphion, a U.S. company, recently introduced along reach PON product using semiconductoroptical amplifier (SOA) technology to extendthe reach of GPON to 80–100 km.

OCDMA-PONA relatively new FTTx architecture, optical(O)CDMA, which uses code division multiplex-ing access (CDMA) has started gaining atten-tion. This is much the same technique as used inmobile wireless technology. This techniquepromises very secure signals [7] and very highdata rates. It is quite complicated and is in itsinfancy.

CABLE OPERATORS INTRODUCINGPON PRODUCTS

Much of what has been discussed in this articleis related to products and technology deployedby the telcos. What are cable operators doing tocompete with the telcos? A new data-over-cableservice interface specification (DOCSIS) 3.0standard that has the capability of providing 150Mb/s to the end user is being introduced. Thisstandard uses a technology called channel bond-ing that combines up to four 38.5 Mb/s channelsinto a single data stream. Currently, cable opera-tors are just starting to test equipment that isDOCSIS 3.0 compliant. They say full-scale roll-out will start in 2009. Another technology that isbeing introduced into the market and one thathas been around for quite some time is video ondemand (VoD). Even though VoD has beenaround for a long time, it has not received a lotof attention. However, with the introduction ofHDTV and its high bandwidth requirements,VoD appears to be a satisfactory solution to pro-viding high-data rate, triple-play services.

In the United States, cable operators havespent billions of dollars over the past couple ofdecades upgrading their networks to hybrid fibercoax (HFC) with fiber from the head end or hubto very deep in the network and then, coax forthe last kilometer to the home. The problem isthat most of the Greenfield housing develop-ments are demanding that the communicationsinfrastructure be all fiber, which means therewill be no coax for the MSOs to provide servicesin these new developments. A number of equip-ment suppliers have addressed this by introduc-ing their own brand of PON; for example, cablePON (CPON) by Motorola, DOCSIS PON(DPON) by Scientific Atlanta of Cisco, and RFover glass (RFOG) by AllOptic. This PON net-work uses the same existing cable modem termi-nation system (CMTS) and cable modemproducts that are used in the HFC networks,which means no new product development isrequired.

IT IS GREENER ON THE GPON FTTH SIDEHigher speed equals higher power consumption.With the focus on delivering much higher band-width, there has been a drastic increase in theamount of power consumed at the central office.Along with this comes a drastic increase in thecost to supply that power, both in terms of dol-

The real impact for

you and me is not

the increased cost of

higher power

consumption but the

impact this increased

power consumption

has on the

environment.

Through the analysis

performed, it can be

seen that deploying

GPON results in a

significant reduction

in carbon dioxide

emissions.

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

IEEE Communications Magazine • July 2008 95

lars and eventually, the impact on the environ-ment. Much emphasis is being placed on globalwarming and other environmental effects today;it appears that GPON may have a much lessnegative impact than other broadband technolo-gies. A paper [8] presented by Dan Parsons ofBroadlight at IEEE Globecom 2007 elucidatesjust how environmentally friendly GPON tech-nology can be.

For example, in one European country, theincumbent service provider consumes more than2 TW-hours (2,000,000 MW-hours) of energy.With the rising cost of power, the serviceprovider is very concerned about what the impactwill be on its energy bill when implementing newhigh-speed technologies. The cost of migratingfrom asymmetric DSL (ADSL2) to very high bit-rate DSL (VDSL2) increases the power require-ment by more than a factor of two.

To put this in perspective, a service providerwith six million ADSL subscribers will draw 9,600kW-hours (1.6 W per ADSL subscriber) of ener-gy at a cost of about $8 million per year. If onemigrates to VDSL2 at 3.6 W per subscriber, thepower costs increase by more than a factor oftwo. This is probably not very significant becausethe service provider has a budget in the billionsof dollars, and it can probably recoup some or allof the additional power cost due to increased tar-iffs for additional or expanded services.

The real impact for you and me is not theincreased cost of higher power consumption butthe impact this increased power consumptionhas on the environment. At the end of 2007,there were about 250 million DSL subscribersworldwide requiring central offices (COs) todeliver about 400 MW of power. This analysis isfor equipment and does not include air condi-tioning. According to the telcos, it takes 60W ofAC to cool 100W from equipment. Thus, a 60percent premium is required every time morepower is added to the CO. This power require-ment has an energy impact which translates intoan environmental carbon footprint that can becalculated via a Web site maintained by the U.S.utility, Pacific Gas and Electric (PG&E). Theenergy consumed at the CO to power the 250million DSL subscribers contributes over 850,000tons of carbon dioxide to the environment everyyear. To put this in perspective, this figure isequivalent to the burning of 90,000,000 gallonsof gasoline or the carbon dioxide contribution of

500,000 homes in the United States over thecourse of a year.

Through the analysis performed, it can beseen that deploying GPON results in a signifi-cant reduction in carbon dioxide emissions asshown in Table 1. The table shows just howmuch the emissions are reduced per one millionGPON subscribers as compared to ADSL2,VDSL2, and Ethernet P2P.

REFERENCES[1] The Book on FTTx, ADC Telecommunications, 2005.[2] “GPON vs. EPON: The Battle Lines are Drawn”; http://

www.fibers.org, Dec. 19, 2005.[3] S. McClelland, “The FTTH Cost Challenge,” Telecommun.

Online, May 31, 2007.[4] Euro. FTTH Council Conf., Paris, France, Feb. 27–28, 2008.[5] C.-H. Lee et al., “WDM-PON Experiences in Korea,” J.

Opt. Networking, May 2007.[6] Novera Optics Web site; see whitepapers.[7] X. Wang et al., “Demonstration of Over 128-Gb/s-

Capacity (12-User x 10.71-Gb/s/User) AsynchronousOCDMA Using FEC and AWG-Based Multiport OpticalEncoder/Decoders,” IEEE Photonics Tech. Lett., Aug. 1,2006.

[8] D. Parsons, “GPON — Reversing the Power BandwidthTrend: In Other Words, Saving the Environment,” IEEEGLOBECOM ’07, Washington, DC, Nov. 28–30, 2007.

BIOGRAPHYLYNN HUTCHESON (lynn.hutcheson@ovum.com) is currentlyvice president, communication components at Ovum RHK.He focuses his efforts on the technology, market trends,vendors, service providers, and so on for next-generationoptical access. He has over 30 years of research, productdevelopment, and executive management experience infiber optic technologies, photonics, access networks, andHFC systems technologies.

■ Table 1. Comparison of GPON vs. other high-speed access technologies forpower and emission savings.

GPON vs. Power savings Power costsavings CO2 savings

ADSL2 ~11 MWh $1.2M ~4.8M lbs CO2 or 250kgallons of gas

VDSL2 ~29 MWh $2.9M ~13.6M lbs CO2 or 700kgallons of gas

E-FTTH ~27 MWh $2.7M ~12.7M lbs CO2 or 655kgallons of gas

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageIEEE

Communications BA

M SaGEF

____

________________