Enabling UMTS 900 Mobile Broadband Services with Ditech Networks
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Transcript of Enabling UMTS 900 Mobile Broadband Services with Ditech Networks
| W H I T E P A P E R |
Enabling UMTS 900 Mobile Broadband Services with Ditech Networks
October 2007
Contents
Copyright © 2007 Ditech Networks2/14
Introduction...............................................................................................................................3
BackgroundonUMTS900............................................................................................................3
UMTS900EnablesAffordableMobileBroadbandServices...............................................................3
RecentUMTS900Developments..................................................................................................4
UMTS900HandsetAvailability.....................................................................................................4
TheChallengeswithUMTS900....................................................................................................4
SpectrumIssues..........................................................................................................................4
PossibleApproachesforClearing900MHzSpectrum.....................................................................4
2GUpgradeMethods–ProsandCons..........................................................................................5
3GAcceleratedMigration–ProsandCons....................................................................................6
TheDitechSolutionforUMTS900................................................................................................7
VQA™Overview.........................................................................................................................7
ResultsfromVQADeploymentinGSMNetwork.............................................................................8
CostComparison........................................................................................................................8
Conclusions...............................................................................................................................9
References................................................................................................................................10
Enabling UMTS 900 Mobile Broadband Services with Ditech
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks �/14
Introduction
ThispaperprovidesabackgroundtothebenefitsofdeployingUMTS-basedmobilebroadbandservicesintheGSM900MHz
bandandthecurrentUMTS900developmentsindifferentcountries.
Variousmethodsavailableforclearingspectrumintheoftencrowded900MHzbandandtheassociatedcostsarediscussed,as
wellashowtominimizedisruptiontoexistingGSMservices.Acomparisonthatquantifiesthecostsofthedifferentmethods
foratypicalWestEuropeancarrierisprovidedasasummary.
ThepaperalsointroducesDitech’snewVQA™solutionforUMTS900thatfreesupspectruminthe900MHzbandbyen-
ablingincreaseduseofGSM-HRandAMR-HRcodecswhilemaintainingacceptablevoicequality,withouttheneedforexpen-
sivenewBTSsiteconstructionorupgrades.Inaddition,theDitechsolutionemployscapabilitiesthatarealreadysupportedby
existinghandsets,thusitdoesnotrequireanycostlyhandsetsubsidies.
Background on UMTS 900
UMTS 900 Enables Affordable Mobile Broadband Services
UMTScarriersarecurrentlyrollingoutmobilebroadbanddataservicesbasedontheHighSpeedDownlinkPacketAccess(HS-
DPA)technologywhichcannowdeliverpeakdataratesofupto7.2Mbps.
ThecoverageoftheseservicesisunfortunatelylimitedinthestandardUMTS2100MHzband.Thisresultsinasignificant
reductionofthepracticaldataratesthatcanbedelivered,especiallyinsidelargebuildingsaswellasinruralareas.Onecost-
effectivewaytoaddressthisissueistodeploythemobilebroadbandservicesintheGSM900MHzbandinstead,wherethe
propagationcharacteristicsaremuchmorefavorablecomparedtotheregular2100MHzband.Thissolutionisreferredtoas
UMTS900.
Studiesshowthatthenumberofbasestationsitescanbereducedby60%[1],whichmayresultincostsavingsontheorder
of$2billioninlargenetworks,accordingtoanextensivestudypublishedrecentlybytheUKregulatorOfcomonUMTS900
andtheeffectsofreleasing900MHzspectrum[2].
Figure1::UMTScoverageat900MHzand2100MHz,respectively[3].
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks 4/14
Recent UMTS 900 Developments
Theuseofthe900MHzbandinEuropehasuntilnowbeenreservedexclusivelyforGSM.However,theEuropean
Commissionisnowproposingamoreflexibleapproachtothesefrequencies,whichwouldpermittheirusefor3G/
UMTSaswell.UMTS900equipmenthasrecentlybeentrialedinFinland,France,Portugal,andtheUKwithgood
results.NationalregulatorsinEuropearegenerallyexpectedtoconsiderandauthorizeUMTSHighSpeedPacketAc-
cess(HSPA)deploymentsinthe900MHzband.UMTS900hasalsobeenrecentlytrialedinAustralia.InNewZeeland,
VodafoneisplanningtogolivewithaUMTS900servicein2008[1].
Furthermore,theGSMAssociationhascalledonadministrationstoopenupthe900MHzbandto3Gworldwide[4].
UMTS 900 Handset Availability
ThefirstUMTS900handset,theNokia6121smart-phonewasrecentlyannouncedwithshipmentsstartinginQ32007
[1].AllleadingchipsetandhandsetvendorsareplanningforUMTS900,butinitialvolumesaredifficulttopredictand
maybelow,possiblylessthanafewmillionhandsetsproducedby2009,accordingtoanOvumreport[5].Also,UMTS
handsetsfortheadjacent850and1900MHzbandsarealreadycommerciallyavailableintheUS.
The Challenges with UMTS 900
Spectrum Issues
ItisclearthattherearealotofadvantageswithdeployingUMTSbroadbanddataservicesinthe900MHzband.
However,the900MHzspectrumisscarceandnationalregulatorshavealreadyallocatedmostofittoexistingGSM900
services.
Oneblockof2x5MHzisrequiredtoaccommodateasingleUMTSfrequencycarrier.TheUMTSForumsuggeststhe
followingso-called“sandwich”frequencyarrangementtominimizepossibleinterferencebetweenUMTS900witha5
MHzfrequencycarrierandexistingGSM900servicesusing200kHzcarriers[6]:
GSM UMTS GSM Figure2::SuggesteddeploymentofUMTSinthe900MHzband
Thismeansthatcarrierswillhavetofreeupaconsiderableamountoftheir900MHzspectrumthatisalreadyinuse
whileatthesametimeensuringthatthisdoesnotimpacttheirexistingGSMvoiceservices.
Possible Approaches for Clearing 900 MHz Spectrum
Therearebasicallytwopossibleapproachestofreeupspectruminthe900MHzbandaccordingtotheUKregulator
Ofcom[2]:
The“2GUpgrade”implements2GtechnologiesthatusetheremainingGSMspectrummoreefficientlytosupportthe
existingGSMusers,whilethe“3GAcceleratedMigration”movestheGSM900trafficontoanexistingUMTS2100
networkbyincreasing3Ghandsetsubsidies(assumingthecarrieroperatessuchanetwork):
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks �/14
Figure3::Strategiesforimplementing900MHzspectrumrelease[2]
Avariantofthe2GUpgradeisthemethodproposedbytheUMTSForumwheretheGSM900trafficishandedovertoa
GSM1800network(assumingthecarrieralreadyhasaGSM1800networkinoperation):
.
Figure4::LoadbalancingbetweenGSM900andGSM1800inordertore-farmpartofGSM900spectrumforUMTS900
deployment[6].
2G Upgrade Methods – Pros and Cons
2GUpgrademethodsincreasethecapacityoftheremainingGSMspectrumandincludesSynthesizedFrequencyHopping
(SFH),increaseduseoflowbit-rateGSM-HRandAMR-HRcodecs,andCellSplittingofmacrosites.
Synthesized Frequency Hopping
SFHisacost-effectiveandwell-provenmethodforincreasingGSMcapacityandspectrumefficiency.Though,itwillobvi-
ouslyonlyworkinnetworksthathavenotyetdeployedthisfrequencyhoppingmethod.
SFHrequiresnewertypesofbasestationsthatsupportthisfeature.Olderbasestationswillrequirecostlyhardware
upgrades(replacementofcavitycombinerswithhybridcombiners)aswellassoftwareupgradesthattogetheramountto
acostofabout$26,000persite,orabout$20-50millionforatypicalnetworkintheUK[2].Theactualcostmayvary
significantlydependingonexistingGSMtrafficloadsandnumberofbasestationsthatrequireupgrades.Also,SFHmust
beimplementedinwholeclustersofcellstogettherequiredcapacitygains.
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks �/14
GSM-HR and AMR-HR
Theusehalf-ratecodecssuchasGSMHalfRate(HR)andthenewerAdaptiveMultiRate(AMR-HR)versionallows
acarriertoincreasecapacityduringbusyhourandimprovetheutilizationofitsexistingGSMinfrastructurewith-
outtheneedfornewBTSsitesandcostlyhardwareupgrades.Half-ratecodecscanalsobeemployedlocallyona
call-by-callbasisdependingoncapacitydemands.
Whilehalf-ratecodecsaredeployedinmanynetworksandarefullysupportedbytheexistinginstalledbaseof
GSMhandsets,carrierstendtousethemverycautiouslyduetovoicequalityconcerns.Althoughthesecodecs
performquitewellinidealcleanspeechconditions,theyareoptimizedforthehumanvoice,andasaresult,
degradesignificantlyinthepresenceofbackgroundnoisecommoninbusystreets,crowdedplaces,andinside
vehiclessuchascars,buses,andtrains.Inaddition,non-linearacousticechoisoftencreatedbylow-endhand-
setsandhands-freekitssuchasBluetoothheadsets.Thistendstofurtherdegradetheuserexperienceofcalls
usinglowbit-ratecodecs.
Aswillbeexplainedlateron,GSM-HRandAMR-HRcanbecombinedwithadvancednetwork-basedvoicequality
enhancementsolutionsthatincludeAdaptiveNoiseCancellation(ANC),AcousticEchoCancellation(AEC),and
EnhancedVoiceIntelligibility(EVI)tomitigatethedegradationinvoicequalitycausedbytheuseofhalf-rateco-
decs.Thus,advancedvoiceprocessingsolutionscanenableGSMcarrierstomaintainanacceptablevoicequality
alsoduringconditionswithincreaseduseofHRandAMR-HRcodecs.
Cell Splitting of Macro Sites
CellsplittingofmacrositesisthetraditionalwaytoincreasecapacityinaGSMnetwork,andthereareno
particulartechnicalproblemsassociatedwiththismethod.Thedownsideisthatcellsplittingisaveryexpensive
andtime-consumingalternative,asitcantake6-12months,orevenlonger,toacquireanewsiteandobtainthe
necessarypermissions.Theconstructioncostistypicallyaround$200,000persitewithatypical20yearNetPres-
entValue(NPV)ofabout$500,000intheUK(thisisthetotalcostofbuildingandoperatingthesiteincluding
siterentsover20years)[2].
Micro-Cells and In-Building Solutions
TheOfcomstudyconsidersotherpotentialcapacitysolutionssuchasdeploymentofmicrocellsanddedicatedin-
buildingsystems,buttheUKregulatorconcludesthatthesesolutionshavepracticallimitationsthatmakethem
lesssuitableforaddressinglarge-scalecapacitydemands.
3G Accelerated Migration - Pros and Cons
The3GAcceleratedMigrationoptionassumesthatacarriercanmovethedisplacedGSM900trafficprimarilyto
itsUMTS2100network.Thisispossibleifthefollowingtwoconditionshold,theremustbeadequate3Gcover-
ageinareaswheretheGSMcapacityisconstrained,andtheremustbesufficient3Gcompatiblehandsetsinthe
subscriberbase.
However,UMTS2100isunlikelytoprovidethesamequalityofserviceinsidebuildingsthatGSM900coulddue
tothedifferentpropagationcharacteristicsofthetwobands.Thecostofacceleratingthemigrationto3Gusing
handsetsubsidieswilldependonthepercentageofusersthatalreadyhave3Genabledphonesaswellasthe
costof3Gphonesover2Gones.Ofcomassumesapremiumofabout$200for3Gphonescomparedto2G
ones,andestimatesthetotalcostofanaccelerated3Ghandsetmigrationto$200millionormoreinatypical
UKnetwork[2].Thus,the3GAcceleratedMigrationmethodcouldbearathercostlyalternative,especiallyifad-
ditionalsiteswillhavetobebuilttocompensateforpoorercoverageat2100MHz.
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks 7/14
The Ditech Solution for UMTS 900
Ditech’ssolutionforUMTS900employsthecompany’saward-winningVoiceQualityAssurance(VQA™)to
increasetheuseofGSM-HRandAMR-HRforimprovedcapacitywhilemaintainingacceptablevoicequality,thus
enablingthedeploymentofUMTSintheGSM900MHzband
VQA™ Overview
VQAisacomprehensivesetofindustry-leadingvoiceprocessingalgorithmsincludingbi-directionalAdaptive
NoiseCancellation(ANC),AcousticEchoCancellation(AEC),andEnhancedVoiceIntelligibility(EVI)thattogether
mitigatetheproblemsofusinglowbit-ratecodecsinnoisyenvironmentscommoninmobilecalling.
Ditech’ssolutionistypicallydeployedonthestandardA-interfaceattheMobileSwitchingCenter(MSC)andis
abletoprocessandenhanceallcalltypesincludingmobile-to-mobileandmobile-to-PSTNcalls:
Figure5::Ditech’sSolutionatA-Interface
Thesolutionconsistsoftwosoftwarepackagesthataredeliveredononeofthreehardwareplatforms,wherethe
choiceofhardwareisbasedonnetworkinterfacerequirements:
• VoiceQualityAssurance(VQA™)–improvesthespeechqualitybyemployingbackgroundnoisecancellation,
speechenhancementforlowbitrateGSMcodecs,backgroundnoisecompensation,acousticechocontrol,voice
leveladjustment,andoptionalhybridechocancellation
• ExperienceIntelligence™(EXi)
o Quantifiesandcategorizesexternalimpairmentssuchasnoiseandechothatarepresentonlivecalls
o GeneratesacallqualityscorebasedupontheITU-TG.107E-modelstandard[7].
• Hardwareplatforms–dependentonnetworkconfiguration
o E1basedA-interface:QuadVoiceProcessor(QVP)
o STM1basedA-interface:BroadbandVoiceProcessor(BVP)
AcarriercangenerallydeploytheDitechsolutionintheentirenetworkinonly2-4monthswithaminimalimpact
onservices.TheVQAsolutionforUMTS900canpotentiallybedeployedonaBSC-by-BSCbasisinthoseareas
whereincreasedGSMcapacityisrequired.
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks �/14
Results from VQA Deployment in GSM Network
DitechrecentlyperformedanextensivenetworkauditonmillionsoflivecallsinalargeGSMnetworkinWestern
Europe.Figure6belowshowsthemeasuredcumulativequalitydistributionofcalls,wherealmost50%ofthe
half-ratecallsfallbelowaMOSof2.7(or54pointsontheRscale),accordingtotheITU-TG.107E-model.It
turnedoutthat30%ofthelivecallshadsignificantamountofbackgroundnoiseandabout10%hadobjection-
ableacousticechoasdefinedbytheITU-TG.131recommendation[8].Thus,theseimpairmentshadasignificant
impactoncustomerexperience:
Figure6::ImpactofVQAondeliveredHRandAMR-HRcallqualityat1%FERwith70%HRand30%AMR-capablehandsets
Ascanbeseenintheabovechart,VQAwasabletoremovealargeamountofthebackgroundnoiseandecho,
andasaresult,thenumberofunacceptablecallswasreducedtoonly10%.Thus,VQAwashighlyeffectivein
removingexternalimpairmentsthatwouldotherwisedegradealargepercentageoftheGSM-HRandAMR-HR
callstoanunacceptablequalitylevel.
Cost Comparison
Thissectioncomparesthedifferentmethodsandassociatedcostsforclearing900MHzspectrumdiscussedin
previoussections,assumingatypicalcarrierintheUK.
Thesecostsmayvarysignificantlyfromcarriertocarrierdependingontheamountof900MHzspectrumthat
needstobecleared,thecurrentandprojectedtrafficloadsinthe900,1800,and2100MHzbands,thenumber
ofGSM900,GSM1800,andUMTS2100basestationsites,thehardwareandsoftwarecapabilitiesofexisting
GSMbasestations,aswellascurrentandprojected3Ghandsetpenetrationnumbers.
Thefollowingtablesummarizesthecostsassociatedwiththedifferentalternatives.Thesecostsareonlyapproxi-
matebuttheyshouldatleastreflecttheorderofmagnitudeoftheexpensesrequiredforclearingnecessary900
MHzspectrumtodeployUMTS900inamaturenetworkinWesternEurope(costsforSFH,CellSplittingand
Accelerated3GHandsetMigrationbasedoninformationprovidedin[2]):
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks �/14
Method EstimatedTotal Cost
Estimated Costper Subscriber Assumptions and Comments
SFH ≥ $25 million ≥ $1.50 About 30% of base stationsneed hardware upgrades thatcost about $26,000 per site.Total cost including frequencyplanning and optimization isestimated to at least $25 millionfor an average capacitydemand scenario.
Method only works if SFH is notyet deployed.
Cell Splitting ≥ $200 million ≥ $10 At least 1,000 additional sitesrequired. Construction cost persite is $200,000 (total costsover 20 years estimated to$500,000 per site).
Accelerated 3G HandsetMigration
≥ $200 million > $10 Accelerate migration to UMTSby subsidizing1 million 3Ghandsets at a $200 premiumcompared to 2G phones.
Increased HR/AMR-HR usecombined with voice qualityenhancement solution suchas Ditech’s VQATM solution
< $15 million < $1.00 Increased use of HR/AMR-HRcombined with network-basedvoice quality enhancementsolution deployed in areaswhere increased GSM voicecapacity is required.
Table1::Approximatecostsforclearingspectruminthe900MHzbandforamatureWesternEuropeanGSMnetwork
Conclusions
TheabilitytodeployUMTSinthe900MHzbandprovidesmobilecarrierswithanopportunitytooffermoreaffordablebroad-
banddataserviceswithhigherdataratesandbettercoveragecomparedtodeploymentintheregular2100MHzband.
Re-farmingthe900MHzspectrumwithoutdisruptingcurrentGSMservicescanhoweverbeamajorchallenge.UMTS900
requiresatleastoneblockof2x5MHzspectrumin900MHzband.Thisisasignificantamountofspectrumthatneedsto
beclearedfromabandthatisalreadyheavilyusedbyGSM.
Therearebasicallytwoapproachestomitigatethisproblem.The“2GUpgrade”implements2Gtechnologiesthatusethe
remainingGSMspectrummoreefficiently.ThesetechnologiesincludeSynthesizedFrequencyHopping(SFH),HR/AMR-HRco-
decs,andCellSplitting,whilethe“3GAcceleratedMigration”movesGSM900voicetrafficontoanexisting3GUMTS2100
networkbyincreasing3Ghandsetsubsidies.
Enabling UMTS 900 Mobile Broadband Services with Ditech
Copyright © 2007 Ditech Networks 10/14
Eachoftheabovesolutionshasitsownsetofadvantagesanddisadvantagesandthemostsuitablesolutionmay
varyfromcarriertocarrierbasedoneachspecificsituation.
IncreasedusageofHRandAMR-HRcodecsisgenerallyaverycost-effectivemethod,provideditiscombinedwitha
voicequalityenhancementsolutiontomaintainacceptablequality.Thismethodimprovesutilizationoftheexisting
GSMinfrastructurewithouttheneedforexpensivenewBTSsiteconstructionorupgrades.Nordoesitrequireany
costlyhandsetsubsidiesasGSM-HRandAMR-HRcodecsarealreadysupportedbytheinstalledbaseofGSMhand-
sets.Also,carrierscaneasilydeploythesolutionlocallytodealwithcongestionine.g.busyurbanareas.
Ditech’sVQA™solutionforUMTS900enablesincreaseduseofHRandAMR-HRcodecsbyremovingexternal
impairmentssuchasbackgroundnoiseandacousticechothatotherwisetendtodegradethequalityoftheselow
bit-ratecodecstounacceptablelevels.Ditech’svoicequalityenhancementsolutioncanbequicklydeployedinan
entirenetworkwithin2-4monthswithoutcostlyupgradestoBTSsitesandwithminimaldisruptiontoexistingGSM
andUMTSservices.Finally,carriershavetheoptiontodeployVQAonlyinselectareasonaBSC-by-BSCbasisto
meetlocalcapacitydemands.
References
[1]GlobalmobileSuppliersAssociation(GSA),InformationPaper,September2007.
[2]ApplicationofSpectrumLiberalisationandTradingtotheMobileSector,OfficeofCommunications(Ofcom),UK,
September2007.
[3]HuaweicontributiontoUMTSForumWorkshop,June20,2007.
[4]GSMAssociationPressRelease,June25,2007.
[5]MarketStudyforUMTS900,Ovum,February,2007.
[6]DeploymentofUMTSin900MHzBand,UMTSForumWhitePaper,October2006.
[7]ITU-TRecommendationG.107(03/2005)TheE-model,acomputationalmodelforuseintransmissionplanning.
[8]ITU-TRecommendationG.131(11/2003)TalkerEchoandItsControl
Enabling UMTS 900 Mobile Broadband Services with Ditech
11/14
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Copyright © 2007 Ditech Networks. All rights reserved. Experience Intelligence, Packet Voice Processor, and VQA are trademarks of Ditech Networks. All other brands are the property of their respective owners. Specifications may change without notice. This document was last revised 10/07.