Shorter site-to-site distances and higher bit rates are key trends in 5G. In light of this, the cost of using traditional leased lines as transport to every radio/antenna site in the RAN is expected to rise significantly. To cope with the large increase in required bit rate per site and achieve a cost-efficient rollout of 5G New Radio (NR), mobile operators must have a good understanding of the different RAN architecture and transport network alternatives that are available to them. This Ericsson Technology Review article presents all the available options and explains why automation and tight integration between the RAN and the transport network will be critical to achieving cost-efficient deployments. In particular, it highlights the cost-saving benefits of using self-built transport based on dark fiber when deploying 5G NR in densely populated areas.

1. CU
DU
gNB
Antenna/
hub site
CU
DU
RBU
Macro site
Street siteHLS-RBU
HLS-gNB
Backhaul
Fronthaul
CPRI/eCPRI
Fronthaul
CPRI/eCPRI
Backhaul
S1/NG
Backhaul F1Backhaul
S1/NG
Backhaul
S1/NG
Core
network
Centralized RAN
Distributed RAN Distributed RAN
+ Virtualized RAN (HLS)
Centralized RAN +
Virtualized RAN (HLS)
Small/
street site
CU
DU
Central office site
DU
Central office site
DU
Small/
street site
CU
Data center
DU
HLS-gNB
Antenna/
hub site
DU
HLS-RBU
Small/
street site
Backhaul F1
ERICSSON
TECHNOLOGY
5GNEWRADIO
RAN&TRANSPORT
OPTIONS
C H A R T I N G T H E F U T U R E O F I N N O V A T I O N | # 1 0 ∙ 2 0 1 9

2. ✱ 5G NR RAN & TRANSPORT OPTIONS 5G NR RAN & TRANSPORT OPTIONS ✱
2 NOVEMBER 7, 2019 ✱ ERICSSON TECHNOLOGY REVIEWERICSSON TECHNOLOGY REVIEW ✱ NOVEMBER 7, 2019 3
By deploying self-built transport in the RAN area instead of using leased lines,
mobile network operators gain access to the full range of 5G New Radio
RAN architecture options and minimize their total cost of ownership (TCO).
ANN-CHRISTINE
ERIKSSON,
MATS FORSMAN,
HENRIK RONKAINEN,
PER WILLARS,
CHRISTER ÖSTBERG
The 5G evolution is well underway – leading
mobile network operators (MNOs) in several
regions of the world have already launched
the first commercial 5G NR networks, and
large-scale deployments are expected in the
years ahead. The use of self-built transport in
denser areas with a suitable RAN architecture
will play a key role in ensuring cost-efficiency.
■Acost-efficient5GNRdeploymentrequires
MNOstotakeseveralfactorsintoconsideration.
Mostobviously,theyneedtomakesurethatthe5G
NRdeploymentcomplementstheirexisting4GLTE
networkandmakesuseofbothcurrent4GLTEand
new5GNRspectrumassets.Beyondthat,itisvital
toconsiderthevariousRANarchitectureoptions
availableandthewaysinwhichthetransport
networkneedstoevolvetosupportthem,alongwith
thelargeincreaseinuserdataratespersite.
Whileurbanareaswithhighuserdensitywillbe
thefirstpriorityfor5GNRdeployments,suburban
andruralareaswillnotbefarbehind.Thesethree
areatypeshavedifferentpreconditionssuchas
availabletransportsolutions,inter-sitedistance
(ISD),trafficdemandandspectrumneedsthatmust
betakenintoconsiderationatanearlystageinthe
deploymentprocess.
Predicted5Gtraffic
5Gisprojectedtoreach40percentpopulation
coverageand1.9billionsubscriptionsby2024[1],
correspondingto20percentofallmobile
subscriptions.Thosefiguresindicatethatitwillbe
thefastestglobalrolloutsofar.Thetotalmobiledata
trafficgeneratedbysmartphonesiscurrentlyabout
90percentandisestimatedtoreach95percentby
theendof2024.Withthecontinuedgrowthof
smartphoneusage,totalworldwidemobiledata
trafficispredictedtoreachabout130exabytesper
month–fourtimeshigherthanthecorresponding
figurefor2019–and35percentofthistrafficwillbe
carriedby5GNRnetworks.
Thegrowingdatademandsformobilebroadband
cangenerallybemetwithlimitedsitedensification
[2].Therearebenefitstodeploying5GNRmid-
bands(3-6GHz)atexisting4Gsites,resultingina
significantperformanceboostandmaximalreuseof
siteinfrastructureinvestments.Bymeansofmassive
MIMO(multiple-input,multiple-output)
techniques,suchasbeamformingandmulti-user
MIMO,higherdownlinkcapacitycanbeachieved
alongwithimproveddownlinkdatarates–both
outdoorsandindoors.
Deepindoorcoverageismaintainedthrough
interworkingwithLTEand/orNRonlowbands
usingdualconnectivityorcarrieraggregation.
Furtherspeedandcapacityincreasescanbe
attainedbydeploying5GNRathighbands
(26-40GHz),alsoknownasmmWave.Ifadditional
spectrumdoesnotsatisfythetrafficdemand
(dueto,forexample,theintroductionoffixed
wirelessaccess)densificationwithsolutions
suchasstreetsitesmayberequired.
Increasinguserdataratesperantennasite
Theintroductionofnewspectrumfor5GNRwill
increasethecarrierbandwidthsfromthe5MHz,
10MHzand20MHzusedforLTEto50MHzand
100MHzforthemidbands(3-6GHz)and
400/800MHzforthehighbands(24-40GHz),
allowingforgigabit-per-seconddataratesperuser
equipment(UE).Inurbanareas,thetotalamount
ofspectrumwillgrowfromafewtensorhundreds
ofmegahertztoseveralhundredorthousand
megahertzperantennasite.
Simultaneously,trafficdemandspersubscriber
willincreaseexponentially.Allinall,thisimpliesthat
thebitratedemandsinthebackhaulandfronthaul
transportnetworkwillincreasesignificantly(per
antennasite,forexample).Thebitratedemandwill
bemultiplegigabitspersecond,comparedwiththe
fewhundredmegabitspersecondincurrentmobile
networks.
Thespectrumincreaseperantennasitewillbe
lessinsuburbanareas,whileinruralareasrefarming
ofcurrentspectrumorspectrumsharingbetween
LTEandNRwillbemorecommon.RANtransport
networkswillneedtoevolvetoaddresstheincrease
inaccumulateduserdatarates,particularlyinurban
areas,andinmanysuburbanonesaswell.
Transportnetworkoptions
EvolvingthetransportnetworkinthelocalRAN
areaisanimportantfirststepwhendeploying5G
ontopofLTE.
Inmostcases,themobilebackhaultransportfor
DistributedRAN(DRAN)–thearchitecture
traditionallyusedtobuildmobilenetworks–has
beenarentedpacket-forwardingservice,Ethernet
orIPbased,typicallycalledaleasedlineand
providedbytraditionalfixednetworkoperators.
Anotheroptioniswhitefiber,anopticalwavelength
serviceofferedbymanytraditionalfixednetwork
operators.
Insteadofleasingatransportservice,some
mobileoperatorsdeployself-builttransport
solutionsusingmicrowavelinks,whichusually
enablesshortinstallationleadtime.Integrated
AccessandBackhaul(IAB)isanotheroptionfor
self-builttransportin5G.WithIAB,themobile
spectrumisalsousedforbackhaul,whichis
especiallyrelevantforhigh-frequencybandswhere
thebandwidthmaybehundredsofmegahertz.
Alternatively,itispossibleforamobileoperatorto
deployaself-builttransportsolutionontopof
physicalfiber(knownasdarkfiber)thatisavailable
forrentfromfixednetworkoperators,ormore
recentlyfrompurefibernetworkoperatorsand
municipalnetworks.Themobileoperatorthen
buildsandownsthetransportequipmentina
RANarea,definedasthelocalurbanareainacity
andthesuburbanareasclosetocities.
Urbanareastendtohavemultiplefibernetwork
operatorsthatdeployfibertoeverystreet,which
meansthatdarkfiberisreadilyavailableforrent.
Whiledarkfiberislesscommoninsuburbanareas,
CHOICES THAT MINIMIZE TCO
5GNewRadio
RAN&transport
TRAFFICDEMANDSPER
SUBSCRIBERWILLINCREASE
EXPONENTIALLY

3. ✱ 5G NR RAN & TRANSPORT OPTIONS 5G NR RAN & TRANSPORT OPTIONS ✱
4 NOVEMBER 7, 2019 ✱ ERICSSON TECHNOLOGY REVIEWERICSSON TECHNOLOGY REVIEW ✱ NOVEMBER 7, 2019 5
infrastructureinvestments.Thebackhaul–thatis,
thetransportbetweentheRANandthecore
network(CN)–usesanS1/NGinterface[3].
DRANiswellsuitedforuseinallareas(urban,
suburbanandrural)andcanusealargevarietyof
transportsolutions.DRANreuseslegacy
infrastructureinvestments,suchasexistingsites
andoperationsandmaintenancestructure,andis
ofparticularvalueinareaswherethepopulation
densityislowandtheusersarescattered.
Theutilizationofstatisticalvariationsintraffic
forthedimensioningofself-builtpackettransport
intheRANareatransportnetworkisanother
benefitofDRAN.
Wheredensificationisneededforcoverageor
capacity,DRANstreetsitesfitwelltogetherwiththe
existingDRANmacrosites.SpecificDRANunits
tailoredforstreetsites,denotedasRBUinFigure1,
havebenefitssuchasintegratedbasebandfunctions,
simpleinstallationandreducedstreetsitespace.
CentralizedRAN
CentralizedRAN(CRAN)ischaracterizedby
centralizedbasebandformultiplepiecesofradio
equipment.WithaCRANdeployment,the
basebandunitslocatedinacentralsiteandtheradio
equipmentlocatedattheantennasitesare
interconnectedwithatransportnetwork
denominatedfronthaul,eitherCommonPublic
RadioInterface(CPRI)orevolvedCPRI(eCPRI)[4].
InareaswithsmallISDsandaccesstodarkfiber
(urbanandinsomecasesdensesuburbanareas),
centralizingandpoolingthebasebandunitstoan
aggregationsitecanbeagoodoption.Theuseof
CRANcanleadtoreducedcostsforsitespaceand
energyconsumptionattheantennasites,aswellas
easierinstallation,operationandmaintenance.
CRANprovidesefficientcoordination(via
interbandcarrieraggregationandCoMP–
coordinatedmultipoint–forexample)between
physicallyseparatedantennasites.Italsoenables
dimensioningofabasebandpooltohandlemoreand
largerantennasitesduetostatisticalvariationsof
trafficpersite,whichalsomakesbasebandresource
expansioneasierwhentrafficgrowsintheCRAN
area.Resilienceandenergyefficiencyareother
benefits,asthebasebandpoolservesmanyantenna
sites.Thestatisticalvariationoftrafficpersitemay
alsobeutilizedinRANareatransportnetwork
dimensioning.
InenvironmentswhereCRANisdeployed,adark
fibertransportsolutionisrequiredforthefronthaul.
Theconnectedradiositesalsoneedtobewithinthe
latencylimitrequiredbythebasebandunits.Theuse
ofdarkfiberisagoodfitwiththenewwideNR
frequencybandsandtheexpansionofthefronthaul
duetotheuseofadvancedantennasystems[5].
WhendeployingCRAN,itismostbeneficialto
connectsitesinthesameareatothesamebaseband
pool.Incaseswhereitisdifficulttodeployadark
fibertransportsolution,eitheraDRANorahigh-
layersplitvirtualizedRAN(HLS-VRAN)
architecturemaybedeployedforthosesites,
coexistingwithotherCRAN-connectednodes.
Toachievethebenefitsofstatisticalmultiplexing
oftrafficto/fromtheradioequipmentinthe
transportnetworkandinthebasebandpool,itis
necessarytouseanEthernet-basedfronthaulsuch
aseCPRI[4].Theradioequipmentattheantenna
sitesmayeitherhavesupportforeCPRIorinclude
aconverterfromCPRItoeCPRI.Itisalsopossible
tomixeCPRIandCPRIradioequipment,usingan
opticalfronthaultransportsolution,butwithout
transportmultiplexinggains.
CRANrequiressuitablesites(suchascentral
officesites)tocolocatethebasebandunits.Thesize
anddensityofthesecentralofficesitesdependson
eachsituation,butatypicalcasecouldbecentral
officesiteswithanISDoflessthan1kmuptoafew
kilometersinanarea.
Higher-layersplitappliedasavirtualizedRAN
deployment
ForbothDRANandCRAN,itispossibletoadda
VRANbyimplementinganHLSwherethegNB
itsavailabilityissteadilyincreasing.Inruralareas,
thereisoftenonlyonefiberoperator,andfiberis
onlydeployedtospecificsitessuchasbusinesses
andschools.Inthesecases,darkfiberisusuallynot
providedasaservice.
Ontopofdarkfiber,mobileoperatorscandeploy
anoptical(passiveoractive)orapacket-forwarding
solution.Thepassiveopticalsolutionusescolored
smallform-factorpluggabletransceivers(SFPs)in
theendpointsandopticalfiltersinbetweenforadd/
droptosubtendedsites/equipmentalongthefiber
path.AnactiveopticalsystemusesgraySFPsinthe
endpointsandactiveopticalswitchingequipmentto
generatewavelengthsandperformopticalswitching
onthesites/equipmentonthefiber.Thepacket-
forwardingsolutioncanbeanEthernetorIP
solutionwithpacket-forwardingcapabilities
onallsites/equipmentalongthefiberpath.
RANarchitectureoptions
Figure1illustratesDRANalongwiththeother
RANarchitectureoptionsavailableforusein5G
NR.Theoptionthatismostappropriatefora
particulardeploymentwilllargelydependonthe
typeofdeploymentarea(urban,suburbanorrural)
andtheavailabilityofdarkfiber.
Inalloptions,outdoorsitedeploymentscanbe
eithermacrosites(typicallymountedonrooftopsor
antennamastscoveringalargerarea)orstreetsites
(typicallymountedonpoles,wallsorstrands
coveringsmallerareasorspots).
TheflexibilityoflocatingRANfunctionalityin
differentlocationsin5GNRRANarchitectureand
theabilitytosupportmoreradiositesincreasesthe
needfornetworkautomation,makingitnecessaryto
simplifytheinstallation,deploymentandoperation
ofboththeRANandtransportpieces.Forexample,
theautomationcapabilitiesusedtosimplify
installationintheRANmustalsobeintroducedinto
transporttoimprovetheinteractionbetweenthetwo.
DistributedRAN
DRANwithunitaryeNodeBbasestationshasbeen
thedominantarchitecturefor4GLTE.DRANwill
alsobeacommonlyusedarchitecturein5GNR
deployments,withthebenefitofreusingthelegacy
Figure 1 RAN architecture deployment options
CU
DU
gNB
Antenna/
hub site
CU
DU
RBU
Macro site
Street siteHLS-RBU
HLS-gNB
Backhaul
Fronthaul
CPRI/eCPRI
Fronthaul
CPRI/eCPRI
Backhaul
S1/NG
Backhaul F1Backhaul
S1/NG
Backhaul
S1/NG
Core
network
Centralized RAN
Distributed RAN Distributed RAN
+ Virtualized RAN (HLS)
Centralized RAN +
Virtualized RAN (HLS)
Small/
street site
CU
DU
Central office site
DU
Central office site
DU
Small/
street site
CU
Data center
DU
HLS-gNB
Antenna/
hub site
DU
HLS-RBU
Small/
street site
Backhaul F1
THEUSEOFDARKFIBERIS
AGOODFITWITHTHENEWWIDE
NRFREQUENCYBANDS...

4. ✱ 5G NR RAN & TRANSPORT OPTIONS 5G NR RAN & TRANSPORT OPTIONS ✱
6 NOVEMBER 7, 2019 ✱ ERICSSON TECHNOLOGY REVIEWERICSSON TECHNOLOGY REVIEW ✱ NOVEMBER 7, 2019 7
isdividedintoacentralunit(CU)anddistributed
units(DUs).ThisisknownasHLS-VRAN.
TheDUsandtheCUareseparatedbytheF1
interface,carriedonabackhaultransportnetwork.
ThesearedenotedHLS-gNBformacroand
HLS-RBUforstreetsitesinFigure1.
Whenacloudinfrastructurealreadyexistsin
thenetwork,theHLS-VRANdeploymentmaybe
beneficialfromanoperationalandmanagement
pointofview.ForaDRANdeployment,adding
HLS-VRANcouldresultindualconnectivitygains
ifitisexpectedthatitwillbecommonforUEstobe
connectedtodifferentbasebandsites.
Inareaswhereastreetsitedeploymentisneeded
asacoverageorcapacitycomplementtothemacro
sitedeployment,astreetHLS-VRANdeployment
fitswellwithmacroHLS-VRAN.SpecificHLS-
VRANunitstailoredforstreetsites,denotedas
HLS-RBUinFigure1,havethesamebenefits
astheRBU.
5GNewRadiototalcostofownership
Amobileoperator’sTCOfor5GNRintroductionin
aRANareaincludesbothcapitalexpenses(one-
timecosts)andoperatingexpenses(recurringcosts).
Typicalcapitalexpensesincluderadio/RANand
transportequipment,siteconstruction,installation
costsandsiteacquisition.Typicaloperating
expensesincludecostsforaleasedline,darkfiber
rental,spectrumforwirelesstransport,siterental,
energyconsumption,operationandmaintenance
costsandvendorsupport.SincetheRANareatype
anddeploymentsolutionalternativesaffecttheTCO,
itisusefultocomparetheTCOofthedeployment
solutionalternativesindifferentRANareas.
BasedonEricssoncustomerpriceinformation
andinternalanalysis,Figure2presentstherelative
operatorTCOcoveringallcapitalexpensesand
operatingexpensesforanurbanlocalRANareaina
high-costmarket.Differentregionsandcustomers
havevariationsincoststructure.Localdeviations
canbesignificant,leadingtoreduceddifferencesbut
withthesamerelationintherelativecoststructures.
Thelargestcostcomponentsaretransportrentcost,
siterental,energyconsumptionandradio/RAN
equipment.Thegraphindicatesthatusingself-built
transportinthelocalRANareaisamuchmorecost-
efficientapproachthanusingaleasedlinetoevery
site,bothinDRANandCRANarchitectures.The
costdifferenceisespeciallylargeinhigh-costmarkets.
Thereasonforthisisthattheintroductionof5G
NRsignificantlyincreasestheradiobandwidth
comparedwithpreviousgenerations,whichresults
inincreasedtransportbitratedemands.While
typicaltransportbandwidthtoaradiositeranged
from10sto100sofMbpsin2G-4G,itistypicallyup
tomultiplegigabitspersecondin5G.Inthelower
rangeofthebandwidthscale,thetraditionalleased
linecosthasbeenmanageable.Butatsiteswherethe
requiredtransportbitratereachesgigabits-per-
secondrates,therelativecostfortheleasedline
increasesdramatically,accountingforasmuchas
70-80percentoftheRANareaTCO.
Thesecondlargestcostinthe“DRANwithleased
linetoeverysite”example(andthelargestinthe
othertwoexamples)issiterental.Somescenarios
willrequiredensificationwithnewsites,whichcould
beamixofbothmacrositesandsmallersitetypes
(streetsites).However,networkdensificationislikely
tofacechallengesduetothehighcostofsiterental
andlimitedsiteavailability.
Thereare,however,ongoingdiscussionsin
severalregionsaboutregulatingthehighsiterental
feeforantennasites,whichwouldsignificantly
increasetheopportunitytodensifywithnewsites.
Thecleartrendoftowercompaniestakingoverthe
operationofphysicalsitesandofferingsitesharing
mayalsodecreasesiterentcost.
RANequipmentandenergyrankasthethirdand
fourthlargestcostsinallthreeexamples.Thesecost
componentsaredependentonthedeployedRAN
architecture.Duetodifferentpricesindifferent
marketsandareas,DRANismorecost-efficientin
somecases,whileCRANisinothers.Thisexplains
whythechoicemaydifferbetweenMNOs.
Leasedlineversusdarkfiber
Leasedlineisahighvaluetypeofserviceandthefee
increaseswiththerequiredbitrate,makingitabig
challengefor5GRAN,astheneededtransport
bitratesaremuchhigherthaninprevious
generations.Whitefiberhasbasicallythesamecost
challengesasleasedlines,becauseitisaservicewith
aServiceLevelAgreement.
Figure 2 Relative operator TCO for 5G NR introduction in an urban local RAN area
DRAN leased
line to every site
DRAN self-built
transport in
local RAN area
Leased line cost
Dark fiber rent
Site rent
RAN equipment
Energy
All other TCO costs
CRAN self-built
transport in
local RAN area
Terms and abbreviations
CN – Core Network | CO – Central Office | CPRI – Common Public Radio Interface | CRAN – Centralized
RAN | CU – Central Unit | DRAN – Distributed RAN | DU – Distributed Unit | eCPRI – Evolved CPRI |
F1 – Interface CU – DU | gNB – GNodeB | HLS – Higher-Layer Split | IAB – Integrated Access and Backhaul |
ISD – Inter-Site Distance | LoS – Line-of-Sight | MNO - Mobile Network Operator | NG – Interface gNB -
CN | NR – New Radio | RBU – Radio Base Unit | S1–InterfaceeNB-CN| SFP – Small Form-factor Pluggable
Transceiver | TCO – Total Cost of Ownership | UE – User Equipment | VRAN – Virtualized RAN
USINGSELF-BUILT
TRANSPORTINTHELOCAL
RANAREAISAMUCHMORE
COST-EFFICIENTAPPROACH

5. ✱ 5G NR RAN & TRANSPORT OPTIONS 5G NR RAN & TRANSPORT OPTIONS ✱
8 NOVEMBER 7, 2019 ✱ ERICSSON TECHNOLOGY REVIEWERICSSON TECHNOLOGY REVIEW ✱ NOVEMBER 7, 2019 9
Darkfiberrentalalsohasaratherhighcost
structure,butthetransportfeeisindependentof
bitratesandinsteadbasedonthefiberdistance.
DarkfibersolutionsthereforefitwellinRANareas
withshortdistancesandarepreferablydeployed,so
thatthesamefibercanbeshared,tosomeextent,by
multiplesites.Figure3illustratesthedifference
betweenatraditionalleased-lineapproachandself-
builttransportbasedondarkfiber.Figure4shows
whichofthesetwotransportsolutionsismostcost-
efficientdependingondataratetositeandsitedistance.
Aself-builttransportnetworkbasedondarkfiber
maybedeployedwithdifferentfiberandradiosite
structuressuchasstar,subtendorringtopology.The
mostcost-efficienttopologyissubtending,where
multiplesitessharefiber.Ifnetworkresiliencyis
required,aringtopologyissuitableattheexpenseof
greaterfiberlength.Apurestartopologygives
maximumresiliencebuthasthegreatestfiberlength
andisthereforethemostexpensivechoice.
Figure4illustratesthetypicalfiberlengthpersite,
wheretheshortestlengthsappearinurbanareas
usingthesubtendingtopology,andthelongest
distancesinsuburbanareasusingthestartopology.
Figure4alsoshowsthetypicaluserdataratesfor5G.
Darkfiberismorecost-efficientthanleasedlinesin
denserareaswherethefiberlengthpersiteislow,
andthedataratesarehigh.Ifthefiberlength
becomeslonger,orthedataratesaresmaller,leased
linesaremorecost-efficient.
Forthedifferenttechnologyoptionsontopofdark
fiber,thepassiveopticalsolutionisthemostcost-
efficientself-builtopticalsolution.Thisassumesthat
thenumberofsitesandequipmentsubtendedonthe
fiberiswithinthescalingofwavelengthsinthe
system.
Thealternativeself-builtpacket-basedsolution
hastheadvantagesofstatisticalmultiplexing
throughoutthenetworkandcanbeanL2Ethernet
switchedand/orL3IProutedsolution.Itassumes
thatallradioequipmentsupportsapacket-
forwardinginterface.
Alternatively,whendarkfiberisnotavailableor
toocostly,wirelesstransportsuchasIABor
microwavelinksmaybeused.Theserequireline-
of-sight(LoS)ornear-LoS.
Conclusion
Ouranalysisindicatesthatduetothelargeincrease
inrequiredbitratepersitefor5GNR,theuseof
traditionalleasedlinesastransporttoeveryradio/
antennasiteintheRANwillbeassociatedwitha
highcostindenserareas.Self-builttransportinthe
RANareaisasignificantlymorecost-efficient
alternativeformobileoperators.Darkfiberis
oneself-builttransportalternative;microwave
linksisanother.
Sincedarkfiberscaleswithdistanceratherthan
bandwidth,andthetrendwith5Gistowardshorter
site-to-sitedistancesandhigherbitrates,darkfiber
willbesignificantlymorecost-efficientthanleased
linesinmanyscenarios.Further,thelargenumber
offiberprovidershasboostedavailabilityand
competition,resultinginadecreaseinfiberrental
costinmosturbanareas,aswellasinsomesuburban
ones.BeyondtheRANareawherethelocaltrafficis
aggregatedandself-builttransportisterminated,
traditionalleasedlineservicestothemobilecore
continuetobeareasonablesolution.
DistributedRAN(DRAN),whichworkswell
overbothfiberandwirelesstransportsolutions,
willcontinuetobethedominantdeployment
architectureinmostsituations.CentralizedRAN
(CRAN)isaninterestingdeploymentarchitecture
forregionsorhigh-trafficareaswheredarkfiber
transportisavailable.CRANoffersoperational
Figure 4 Relative costs for leased lines and dark fiber
Dark fiber most cost-efficient
Date rate to site
(Gbps)
10
5 10
5
1
Typical fiber length
per urban/suburban site
Typical 5G user
data rates
Equal TCO
Fiber length
(km)
Leased line most cost-efficient
Figure 3 Traditional leased-line approach versus self-built transport in local RAN area
Leased-line sites to CN
Self-built to aggregation site,
leased lines to CN
Local RAN area
A few hundred meters -> a few kilometers
CN
CN
Agg/
CO

6. ✱ 5G NR RAN & TRANSPORT OPTIONS 5G NR RAN & TRANSPORT OPTIONS ✱
10 NOVEMBER 7, 2019 ✱ ERICSSON TECHNOLOGY REVIEWERICSSON TECHNOLOGY REVIEW ✱ NOVEMBER 7, 2019 11
Ann-Christine
Eriksson
◆ is a senior specialist
in RAN and service layer
interaction at Business
Area Networks. She joined
Ericsson in 1988 and has
worked with research and
development within RAN
of the 2G, 3G, 4G and 5G
mobile network generations.
Her focus areas include QoS,
radio resource handling and
RAN architecture. In her
current role, she focuses on
evaluating different 5G RAN
architecture deployment
options with the goal of
optimizing RAN efficiency,
performance and cost.
Eriksson holds an M.Sc.
in physical engineering
from KTH Royal Institute of
Technology in Stockholm,
Sweden.
Mats Forsman
◆ joined Ericsson in 1999
to work with intelligent
networks. Since then he
has worked within the
areas of IP, broadband and
optical networks. Today, his
focus is on new concepts
for transport within mobile
networks at Business Area
Networks; one such concept
area is 5G RAN transport and
automation. Forsman holds
an M.Sc. in mathematics and
natural science from Umeå
University, Sweden.
Henrik Ronkainen
◆ joined Ericsson in 1989
to work with software
development in telecom
control systems but soon
followed the journey of
mobile systems evolution
as a software and system
architect for the 2G and
3G RAN systems. With the
introduction of HSDPA,
he worked as a system
architect for 3G and 4G
UE modems but rejoined
Business Area Networks
in late 2014, focusing on
analysis and solutions for the
architecture, deployment
and functionality targeted
for the 5G RAN. Ronkainen
holds a B.Sc. in electrical
engineering from the Faculty
of Engineering at Lund
University, Sweden.
Per Willars
◆ is an expert in network
architecture and radio
network functionality at
Business Area Networks.
He joined Ericsson in 1991
and has worked intensively
with RAN issues ever since.
This includes leading the
definition of 3G RAN, before
and within the 3GPP, and
more lately indoor solutions.
He has also worked with
service layer research and
explored new business
models. In his current role, he
analyzes the requirements
for 5G RAN (architecture
and functionality) with the
aim of simplifying 5G. Willars
holds an M.Sc. in electrical
engineering from KTH Royal
Institute of Technology.
Christer Östberg
◆ is an expert in the physical
layer of radio access at
Business Area Networks.
He joined Ericsson in
1997 with a 10-year
background in developing
2G prototypes and playing
an instrumental role during
the preassessment of 3G.
At Ericsson, Östberg began
with algorithm development
and continued as a system
architect, responsible for
modem parts of 3G and
4G UE platforms. He joined
Business Area Networks in
2014, focusing on analysis
and solutions for the
architecture, deployment
and functionality targeted
for the 5G RAN. Östberg
holds an M.Sc. in electrical
engineering from the Faculty
of Engineering at Lund
University.
theauthors
benefitsbypoolingallbasebandtoacentralsite,
whichresultsinpotentialcostsavingsinsiterental
andenergy,andmaximizestheopportunityfor
inter-sitecoordinationfeatures.Incaseswherea
networkhasanexistingcloudinfrastructure,the
operatormaybenefitfromaddingahigh-layersplit
virtualizedRANdeploymenttoaDRANorCRAN
architecture.
Becausetheflexibilityofthe5GNRarchitecture
enablesmuchgreaterdistributionofequipmentand
sitesthaneverbefore,itisnecessarytosimplifythe
installation,deploymentandoperationofboththe
RANanditstransport.Ahighdegreeofautomation
andtightintegrationbetweenthetwowillbecritical
toachievingcost-efficientdeployments.
Further reading
❭❭ Learn more about building 5G networks at: https://www.ericsson.com/en/5g/5g-networks
References
1. Ericsson Mobility Report, June 2019, available at: https://www.ericsson.com/en/mobility-report/reports/
june-2019
2. Ericsson Technology Review, The advantages of combining 5G NR with LTE, November 5, 2018,
Kronestedt, F, et al., available at: https://www.ericsson.com/en/ericsson-technology-review/archive/2018/
the-advantages-of-combining-5g-nr-with-lte
3. 3GPP, TS Group RAN; NR; Overall Description; Stage 2, available at: https://portal.3gpp.org/
desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3191
4. CPRI Common Public Radio Interface, available at: http://cpri.info/index.html
5. Ericsson white paper, Advanced antenna systems for 5G networks, available at: https://www.ericsson.
com/en/white-papers/advanced-antenna-systems-for-5g-networks
...AUTOMATIONANDTIGHT
INTEGRATIONWILLBECRITICAL
TOACHIEVINGCOST-EFFICIENT
DEPLOYMENTS

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