Low latency communication and minimal battery consumption are key requirements of many 5G and IoT use cases, including smart transport and critical control of remote devices. Thanks to Ericsson’s 4G/5G research activities and lessons learned from legacy networks, we have identified solutions that address both of these requirements by reducing the amount of signaling required during state transitions, and shared our discoveries with the 3GPP. This Ericsson Technology Review article explains the why and how behind the new Radio Resource Control (RRC) state model in the standalone version of the 5G New Radio standard, which features a new, Ericsson-developed state called inactive. On top of overcoming latency and battery consumption challenges, the new state also increases overall system capacity by decreasing the processing effort in the network.

1. LTE/NR RAN
Legacy idle-to-connected transition New inactive-to-connected transition
NR RANCN CNUEUE
RRC connnection request
Initial radio synchronization
RRC resume request
RRC resume
RRC resume complete
UL/DL user data
RRC connection setup
RRC connection complete
(service request)
RRC security setup
RRC security complete
UL/DL user data
RRC reconfiguration
(bearer setup)
RRC reconfiguration
complete
Initial UE message
(service request)
UE context setup
(keys, bearers)
Initial radio synchronization
UE context setup complete
Initial radio synchronization
ERICSSON
TECHNOLOGY
THEINACTIVESTATE
IN5GNEWRADIO
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 | # 0 6 ∙ 2 0 1 9

2. ✱ INACTIVE STATE IN 5G NR
2 ERICSSON TECHNOLOGY REVIEW ✱ JUNE 19, 2019
Reducing the amount of signaling that occurs during state transitions
makes it possible to significantly lower both latency and battery consumption
– critical requirements for many Internet of Things and 5G use cases,
including enhanced mobile broadband.
ICARO LEONARDO
DA SILVA, GUNNAR
MILDH, PAUL
SCHLIWA-BERTLING,
MAGNUS STATTIN,
ALEXANDER VESELY
Many of the performance improvements in 5G
New Radio (NR) that are designed to support
new Internet of Things (IoT) use cases such as
critical control of remote devices and smart
transport [1] are based on lessons learned
from research and development on 4G LTE
networks. One example of this relates to the
transition of wireless devices from a power-
saving state where data is not exchanged
(idle state) to a connected state optimized for
data transmissions (connected state).
■ Studiesshowthatawirelessdevice’stransition
fromapower-saving(idle)statetoaconnectedstateis
themostfrequenthigh-layersignalingeventin
existing4GLTEnetworks,occurringabout
500-1,000timesaday.Thetransitioncomprisesan
extensivesignalingsequencebetweenthedeviceand
thenetwork,andbetweennetworknodes,whichcan
leadtoconsumerlatencyissuesandhighbattery
consumption.
Thecombinationof4G/5Gresearchactivitiesand
lessonslearnedfromlegacynetworkshasmadeit
possibletodevelopsolutionsthatreducetheamount
ofsignalingrequiredatthesetransitions,thereby
loweringbothlatencyandbatteryconsumption
significantly.Thedecreasedsignalinginthenetwork
alsoresultsinanincreaseinoverallsystemcapacity.
Ericsson’scontributionstothe3GPP
standardizationofsolutionsinthisareainclude a
newRadioResourceControl(RRC)statemodel
adoptedinthestandaloneversionofthe5GNR
WITH INACTIVE STATE
Meeting
5Glatency
requirements

3. INACTIVE STATE IN 5G NR ✱
JUNE 19, 2019 ✱ ERICSSON TECHNOLOGY REVIEW 3
standard.Improvedconnection,stateandmobility
handlingarekeyelementsofefficientsupportfor
currentandfuture5Gusecaseswithalargeand
growingnumberofdevices.
Conceptdevelopmentoftheinactivestate
Allowingwirelessdevicestoenteralow-powerstate
whentheyarenottransmittingorreceivingdatahas
alwaysbeenanimportantpartofachievingabalance
betweengoodcommunicationperformanceand
acceptablebatteryconsumption.Formanyyears,two
states–connectedandidle–weresufficienttomeet
mostneeds.
Thedevelopmentoftheinactivestatehaslargely
beendrivenbythegrowingfieldofMachine-type
Communication(MTC).InmostMTCscenarios,
theamountofdatathatwirelessdevicestypically
exchangewiththenetworkissmallandusuallynot
urgentenoughtojustifythehighbatteryconsumption
requiredtohandleallthesignalinginvolvedinthe
legacyidle-to-connectedtransition.Toaddressthis
issue,Ericssonplayedaleadingroleindeveloping
thetransitionenhancementsthatwereintroducedin
4GLTERel-13,inwhichtwonewprocedureswere
standardized:suspendandresume.
Inthesuspendprocedure,theuserequipment
(UE)–the3GPPnameforwirelessdevices–stores
itsradioconfigurationandsecurityparameters
whenittransitionsfromconnectedtoidle.
Then,whenitneedstoconnecttothenetworkagain
(duetosomeuplink(UL)databeingavailableto
transmit,forexample)theUEtriggerstheresume
procedure.Thisinvolvesrestoringthepreviously
storedconfigurationandresumingtheconnection
withouttheneedforextensivesignalingwiththe
corenetwork(CN)orhavingtoreestablishsecurity,
forexample.Theresumeprocedureissimilartothe
sleepstateofacomputer,whichenablesworktobe
pausedandresumedlaterwithoutrepeatingtedious
start-upprocedures.
Inparallelwiththe4GLTEworkthatwas
completedin2015,Ericssonwasalsoworkingonthe
5Gconcept,whichincludedchallenginglatency
requirementsandprovidingsupportforavarietyof
newandemergingusecases.Withouttheconstraint
tocomplywithanexistingstatemodel,itwas
possibletofurtheroptimizethesuspend/resume
solutionin5GNRbyintroducinganewstateknown
asinactive.Thekeybenefitsoftheinactivestateare
thatitsignificantlyreduceslatencyandminimizes
thebatteryconsumptionofbothsmartphonesand
MTCdevices.
Inthelatterhalfof2015,webegantopromotethe
inactivestateexternallyinthecontextofthe
Ericsson-led5G-PPPEuropeanprojectMETIS-II,
themain5Gpre-standardsproject[2].Themaingoal
oftheprojectwastofacilitateresearchdiscussions
withindustryplayers(UEvendors,network
vendors,networkoperators,academicpartnersand
soon)abouttechnicalcomponentstobringtothe
3GPPduringthe5Gstandardizationwork.
Key terms
Connected state – The UE is actively involved in sending or receiving data or signaling.
Mobility is controlled by the RAN.
Idle state – The UE is in a power-saving state and is known at tracking-area level in the CN.
Inactive state – The UE is in a power-saving state and is known on RNA level in the RAN.
Transition to the connected state is optimized.

4. ✱ INACTIVE STATE IN 5G NR
4 ERICSSON TECHNOLOGY REVIEW ✱ JUNE 19, 2019
Figure1showstheallocationof basicsystem
functionsindiverseUEstates,highlightingthe
evolutionfromRel-13suspendto5Ginactive.
5GNRinactivestateprocedures
In2016,itwasagreedthattheinactivestatewouldbe
introducedin5GNR[3],andthespecificationswere
finalizedandapprovedinDecember2018[4,5].The
mostnotableenhancementsarethesuspendand
resumeprocedures,aswellasRAN-basedlocation
managementandRANpagingforUEsintheinactive
state.Inthesuspendprocedure,boththeUEandthe
RANstoreinformationabouttheUEtransitionfrom
connectedtoinactive,alongwiththeUEradio
protocolconfiguration.Theresumeprocedure
optimizesthetransitionfrominactivetoconnectedby
restoringtheUEradioprotocolconfiguration.RAN-
basedlocationmanagementandRANpagingmakeit
possibleforUEsintheinactivestatetomovearound
inanareawithoutnotifyingthenetwork.
Suspend
ThemainprincipleoftheinactivestateisthattheUE
isabletoreturntotheconnectedstateasquicklyand
efficientlyaspossible.WhentheUEtransitionsto
inactive,boththeUEandtheRANstoreallthe
informationnecessarytoquicklyresumethe
connection.ThemessagethattransitionstheUEto
inactivestatecontainsasetofparametersusedfor
inactivestateoperation,suchasaRANNotification
Area(RNA)withinwhichtheUEisallowedtomove
withoutnotifyingthenetwork.Further,itincludes
parametersusedforsecuretransitionbacktothe
connectedstate,suchasaUEidentifierandsecurity
informationneededtosupportencryptedresume
messages.
Resume
AninactiveUEmayinitiatearesumeprocedure
whenthereisaneedtotransmitdataorsignaling,for
example.Inthiscase,theUEtransmitsanRRC
resumerequestthatincludestheUEidentifier
(providedbytheservingnodetoidentifytheUE’s
configurationrepository)andasecuritytokentoverify
thelegitimacyoftheresumerequest.
Studiesof4Gnetworksshowthat,inmostcases,
UEsthatleavethepower-savingstatereturntothe
sameRANnodetheywerepreviouslyservedby.If,
however,theUEresumesinacellservedbya
differentRANnode,thattargetnodewillretrieve
theUEconfigurationfromtheservingnodebased
ontheUEidentifier.
Figure 1 Comparison of the allocation of system functions
UE RAN states
IdleSystem functions Connected Rel-13 suspend 5G inactive
CNMobility management RAN CN RAN
CNPaging trigger n/a CN RAN
CN
UE configuration
data storage CN and RAN CN and RAN CN and RAN
NoUP contexts in RAN Yes
Yes, but DL packets
not sent to RAN
Yes, DL packets
sent to RAN

5. INACTIVE STATE IN 5G NR ✱
JUNE 19, 2019 ✱ ERICSSON TECHNOLOGY REVIEW 5
AftertheUEconfigurationissuccessfully
retrieved,thetargetnoderesumesthestored
configurationattheUEandappliesanynecessary
modifications,suchastheconfigurationof
measurementsandtheadditionorremovalof
bearers.TherespectiveRRCresumemessageis
integrityprotectedandencryptedusingthesecurity
contextstoredinthenetworkandtheUE.
AsillustratedontherightsideofFigure2,the
resumeprocedurereducesthenumberofRRC
messagesexchangedovertheradiointerface
betweentheUEandtheRANtothree(downfrom
sevenforidlestate).RRCresumealsohasthe
possibilityofusingefficientdeltasignaling–inwhich
onlychangedparametersaresignaled–torestore
theconfigurationofaUEintheinactivestate.This
optionisnotpossibleforUEsintheidlestate.
ThereductioninRRCsignalingsignificantly
lowerstheaccesslatencyexperiencedbyUEs,which
leadstomoreresponsiveend-userserviceandthe
abilitytosupportnewusecases.Italsoreducesthe
powerconsumptionfordevicessuchasbattery-
poweredsensorsthatonlysendsmall,infrequent
reports(oftenlessthan100bytesofdata).
RAN-basedlocationmanagement
andRANpaging
Thetransitionfromtheconnectedtotheinactivestate
isdesignedtobeinvisibletothe5GCN.Asaresult,
evenwhentheUEisintheinactivestate,the5GCN
treatsitasthoughitwereintheconnectedstate–that
is,theUE-associatedsignalinganduser-data
connectionbetweenthe5GCNandtheRAN
continues.Mobile-terminatedsignalinganduser-
plane(UP)dataissentfromtheCNtotheRANnode
currentlyservingtheUE.
WhentheservingRANnodereceivessignalingor
dataforaUEintheinactivestate,itinitiatesRAN
paging.ThepagingisperformedinanRNAthat
consistsofoneormorecellsandwasassignedtothe
Figure 2 Comparison of signaling involved in legacy idle-to-connected transition (left) versus inactive-to-connected
transition (right)
LTE/NR RAN
Legacy idle-to-connected transition New inactive-to-connected transition
NR RANCN CNUEUE
RRC connnection request
Initial radio synchronization
RRC resume request
RRC resume
RRC resume complete
UL/DL user data
RRC connection setup
RRC connection complete
(service request)
RRC security setup
RRC security complete
UL/DL user data
RRC reconfiguration
(bearer setup)
RRC reconfiguration
complete
Initial UE message
(service request)
UE context setup
(keys, bearers)
Initial radio synchronization
UE context setup complete
Initial radio synchronization

6. ✱ INACTIVE STATE IN 5G NR
6 ERICSSON TECHNOLOGY REVIEW ✱ JUNE 19, 2019
UEwhenitwasorderedtoentertheinactivestate.
WhenaUEintheinactivestatemovestoacellthatis
notpartofitscurrentlyassignedRNA,theUE
performsalocation-updateprocedurethatenables
theRANtoupdatetheassignedRNAtotheUE.
Asinearliercellularsystems,thereisatrade-off
betweenthepagingloadandtheamountoflocation-
updatesignaling.Largerpagingareashavemore
pagingloadbutlesslocationupdatesignalingthan
smallerpagingareas.
Keytechnologyaspects
ThemostnotabletechnologyaspectswithintheNR
inactivestateconceptadoptedby3GPParesupport
forencryptedresponsemessages,smartRANpaging,
RANarchitecturesupportandfallbacktolegacy
procedure.
Supportforencryptedresponsemessages
OneofthemaincomponentsdrivenbyEricssoninthe
NRinactivestateconceptadoptedin3GPPisthe
abilitytoencrypttheresponsemessage(resumeor
suspend/release)fromthenetwork.Thisdiffersfrom
the4GLTEresumeconceptadoptedinRel-13,
wherethismessageisintegrityprotected,butsent
unencrypted.
Toenabletheencryptioncapability,the3GPP
adoptedasolutionproposedbyEricssoninwhich
thenetworkprovidestheUEwithasecurity
parameterinthereleasemessagetotheinactive
state.TheUEusesthesecurityparametertocalculate
anewsecuritykeytobeusedwhenitresumes.
Theabilitytoencrypttheresumeresponse
messagein5GNRisadvantageousbecauseitmakes
itpossibletouseasingle,securemessageto:
❭❭ Reconfigure any parameter in the UE when
transitioning to the connected state.
❭❭ Release the UE to the idle state (the release
message could also include redirection
information to another frequency or radio
access technology that could be used for voice
fallback to LTE, for example).
❭❭ Resuspend the UE to the inactive state when
it is performing a location-update procedure,
for example, so that it only consumes two
messages in total (request and response).
SmartRANpaging
ForanyUEintheconnectedstate,theRANnode
receivespagingassistanceinformationrelatedto
potentialpagingtriggers,suchasQoSflowsor
signaling,fromthe5GCN.Thisinformation,in
combinationwithotherinformationthattheRANhas
abouttheUE,canbeusedbytheRANnodetoselect
andapplyasmartpagingstrategythatisalignedwith
thecharacteristicsandrequirementsoftheUEand
paging-triggeringservices.
Forexample,theRANcanconfigureUE-specific
RNAsthatmakeitpossibletoreducethetotal
signalingloadbyconfiguringsmallRNAsfor
stationaryUEs(optimizedforlowpagingload)and
largerRNAsformovingUEs(optimizedforlow
locationupdatesignalingload).
Terms and abbreviations
AMF – Access and Mobility Function | CA – Carrier Aggregation | CN – Core Network | CP – Control Plane |
CU – Central Unit | DC – Dual Connectivity | DL – Downlink | DRX – Discontinuous Reception |
DU – Distributed Unit | EDT – Early Data Transmission | E-UTRA – Evolved Universal Terrestrial Radio Access |
GNB – GNodeB | IOT – Internet of Things | MAC – Medium Access Control (protocol) | MTC – Machine-type
Communication | NB-IOT – Narrowband Internet of Things | NG-RAN – Next-Generation RAN| NR – New
Radio | PPP – Public-private Partnership | RNA – RAN Notification Area | RRC – Radio Resource Control |
UE – User Equipment | UL – Uplink | UP – User Plane | UPF – User-plane Function

7. INACTIVE STATE IN 5G NR ✱
JUNE 19, 2019 ✱ ERICSSON TECHNOLOGY REVIEW 7
RANarchitecturesupport
TheRANofthe5Gsystem–knownasnext-
generationRAN(NG-RAN)–consistsofRAN
nodesthatserveeitherEvolvedUniversalTerrestrial
RadioAccess(E-UTRA)orNRcells.Thebottom
leftcornerofFigure3illustrateshowRANnodes
(gNBs)thatserveNRcellscanbesplitintocentral
units(CUs)ordistributedunits(DUs).ADUhosts
functionsrelatedtolowerradioprotocollayers,while
aCUhostsfunctionsrelatedtohigherradioprotocol
layers(RRCandServiceDataAdaptationProtocol/
PacketDataConvergenceProtocol).SeveralDUs
areconnectedtotheirservingCUnodesviatheF1
interface,whileRANnodesmaybeinterconnected
bymeansoftheXninterface.ACUmaybefurther
splitintoacontrolplane(CP)part(CU-CP)and
severalUPparts(CU-UP).
ThefunctionaldecompositionofNG-RANnodes
servesamultitudeofdifferentdeploymentoptions,
includingthosewhereaCUisdeployedtoservea
largenumberofDUscorrespondingtoalarge
servingarea.Forexample,theCUwouldbeableto
veryefficientlycontrolUEmobilitywhile
minimizingsignalingtraffictowardthe5GCNand
betweenRANnodes.
Withregardtotheinactivestate,theCUwouldbe
abletocontroltaskssuchastheassignmentofthe
UE’sRNAbasedontheUE’smobilitybehaviorand
certainRANtopologyknowledge.Basedon
Ericsson’sproposal,boththeCPandUPresources
canremainconfiguredintheCUwhentheUEisin
theinactivestate.Thebenefitofthisisareductionin
processingandsignalingiftheUEreturnstothe
sameCU,whichishighlylikelyinthistypeof
deployment.
Fallbacktolegacyprocedure
If,foranyreason,theUEandtheRANendupinan
unsynchronizedstateandtheresumeprocedurefails,
theUEwillautomaticallyswitchovertothelegacy
idle-to-connectedtransitionprocedurethatinvolves
CNsignaling.Thissolutioncouldalsobeusefulifthe
RANisunabletoretrievetheUEconfigurationor
theUEconfigurationhasbeenactivelydiscarded.
Figure 3 NG-RAN architecture
AMF/UPF
gNB
gNB-CU-
UP
E1
Xn
NG
NGNG
NG
NGNG
Xn Xn
F1-C F1-U
gNB-DUgNB-DU
gNB
gNB
gNB
AMF/UPF
5G CN
NG-RAN
gNB-CU-
CP

8. ✱ INACTIVE STATE IN 5G NR
8 ERICSSON TECHNOLOGY REVIEW ✱ JUNE 19, 2019
Inthesesituations,thenetworkwillrespondwithan
RRCconnectionsetupmessageinsteadofanRRC
resumemessagewhentheUEsendstheRRC
resumerequest.WhentheUEreceivesthesetup
message,itwilldiscardtheoldRAN-relatedUE
configurationandproceedaccordingtothelegacy
idle-to-connectedprocedure.
UEsintheinactivestatewilllistenforbothRAN-
andCN-triggeredpaging,sothattheCNisableto
makecontactwithinactiveUEsiftheRAN
configurationislostordiscarded.Thiscapabilityis
alsousefulifaUEhasbeenoutofradiocoverageand
missedRANpaging,resultingintheRANnode
releasingtheUEconfiguration.ToreduceUE
batteryconsumption,thesolutionprovidesa
mechanismfortheRANandCNtocoordinatethe
pagingoccasions,sothattheUEonlyneedstowake
uponcetolistentoboth.
Futureenhancements
Whiletheessentialcomponentsfortheinactivestate
aresupportedinRel-15,thereisanopportunityfor
furtherenhancementsoftheNRstandardinlater
releases.Thereareseveralusecasesandscenarios
thatwouldbenefitfromenhancementstothe
applicabilityandefficiencyoftheinactivestate,
particularlyintheareasofearlydatatransmission
(EDT),earlymeasurementsandlongdiscontinuous
reception(DRX).
Earlydatatransmission
Tomeetthemorestringentrequirementsoffuture
5Gusecases,itwillsoonbenecessarytoreduceUL
latencyevenfurther.EDTisafeaturethatwould
allowopportunisticdatatransmissiontocommence
duringtheconnectionresumeprocedure.Withthe
resumeprocedureasspecifiedinRel-15,connection
resumeproceduresarecompletedbeforedata
transmissioncanstart.WithEDT,datatransfercan
begininparallelwithtransmissionoftheresume
requestmessageintheULandtheresumemessage
inthedownlink(DL).Securityandradiobearersare
resumedbeforesubmittingtheresumerequest
messagetolowerlayers,whichallowsmultiplexingof
datawithsignalingintheMediumAccessControl
(MAC)layer.
EDThasalreadybeenintroducedinLTE-Mand
Narrowband-IoT(NB-IoT),wheretrafficisexpected
tocomprisethetransmissionofsmallamountsof
dataandoneoftheprimaryobjectivesislongUE
batterylife.Forusecaseswheretrafficconsistsof
onlyoneULand/oroneDLdatapacket,EDT
improvesenergyefficiencybyenablingthenetwork
toreleasetheUEtotheinactivestatewithoutthe
needforintermediateresumeandresumecomplete
messages.
Earlymeasurements
NRRel-15alreadysupportstheaggregatingof
multiplecarriersforhigherdatathroughputusing
eithercarrieraggregation(CA)ordualconnectivity
(DC).Whentransitioningfromtheinactiveoridle
statetoconnectedstate,however,theUEonlyhas
accessthroughonecarrier.FastersetupofCAor
DCwouldmakeitpossibletofurtherreducethe
sessionsetuplatency.However,theusefulnessof
CAandDCdependsonthenetworkunderstanding
oftheradioenvironment.
Earlymeasurementreportingisafeature
currentlybeingstandardizedinRel-16toimprove
thesetupofCAandDCbyenhancingNRtosupport
earlyradiomeasurementreportsduringthe
transitionfromtheinactivetoconnectedstate–that
is,inparallelwiththeresumecompletemessage.
ThiswouldbepossibleinNRbecausewhentheUE
issuspended,itreceivesthesecurityparameters
neededtoencryptthesensitivemeasurement
report.Whensecurityisactivated,early
measurementreportscanbemultiplexedwitha
resumerequestormultiplexedwitharesume
completemessage(ifrequestedbytheRANinthe
resumemessage).
THECNISABLETOMAKE
CONTACTWITHINACTIVEUEs
IFTHERANCONFIGURATION
ISLOSTORDISCARDED

9. INACTIVE STATE IN 5G NR ✱
JUNE 19, 2019 ✱ ERICSSON TECHNOLOGY REVIEW 9
Longdiscontinuousreception
DRX,afeaturethatenablestheUEtoturnoffits
receiver,isimperativeinusecaseswheredevice
energyefficiencyandbatterylifeareimportant
considerations.Thelongerthetransmitterand
receivercanbeturnedoff,themoreenergytheUE
cansave(thelongerthebatterylife).LongDRXhas
traditionallybeensupportedintheidlestate.
Toenjoythebenefitsofbothsignalingreductions
andlongDRX,itisdesirabletoextendDRXcyclesin
theinactivestatetothesamelengthasDRXcyclesin
theidlestate.Akeyaspectoftheinactivestate,
however,isthat,fromtheCNpointofview,theUE
remainsconnectedandDLdataarrivingtotheCN
wouldnormallybeforwardedtotheRANnode
servingtheUE.TheRANwouldbufferthedata
untiltheUEisreachable.
WithshortDRX,theamountofdatathatwould
needtobebufferedislimited.WithverylongDRX,
however,thebufferingrequirementsintheRAN
growandmayexceedwhatisnormallyneeded,
whichwouldbecomecostly.Tomitigatethisand
makeuseof(alreadyexisting)CNbuffering
capability/capacity,theRANmayindicatetotheCN
thattheUEisnotavailableforDLdatawhileinthe
inactivestate.Inthisevent,theCNwillbufferthe
dataandnotifytheRAN,sothattheRANcan
informtheCNwhentheUEbecomesavailable
again.ItisanticipatedthattheuseoflongDRXinthe
inactivestatewithbufferingoffloadedtotheCN
wouldfurtherimprovebatterylife,whileenabling
efficient(re)useofbufferingcapabilitiesinthe
network.
Conclusion
Improvedconnection,stateandmobilityhandlingare
keyrequirementsofmanycurrentandfuture5Guse
cases,includingsmarttransportandcriticalcontrolof
remotedevices.AtEricsson,our4G/5Gresearch
activitiesandlessonslearnedfromlegacynetworks
haveenabledustoidentifysolutionsthatsignificantly
lowerbothlatencyandbatteryconsumptionby
reducingtheamountofsignalingrequiredduring
statetransitions.Asaresultofthiswork,the
standaloneversionofthe5GNRstandardincludesa
newRadioResourceControlstatemodelthatfeatures
anewstatecalledinactive.
Theinactivestatein5GNRisakeyenablerfor
emergingusecasesthatrequirelowlatency
communicationandminimalbatteryconsumption.
Anadditionalbenefitofthenewstateisthatthe
decreasedprocessingeffortinthenetworkresultsin
anincreaseinoverallsystemcapacity.
Rel-15includesalltheessentialcomponentsfor
theinactivestate.Futurereleasesshouldfocuson
providingapplicabilityandefficiencyenhancements,
particularlyintheareasofearlydatatransmission,
earlymeasurementsandlongdiscontinuous
reception.
References
1. Ericsson, 5G use cases, available at: https://www.ericsson.com/en/5g/use-cases
2. 2016 IEEE International Conference on Communications Workshops (ICC), A novel state model for 5G
Radio Access Networks, Da Silva, I.L.; Mildh, G; Säily, M; Hailu, S, abstract available at: https://ieeexplore.
ieee.org/document/7503858
3. Ericsson, Handling of inactive UEs, 2016, 3GPP RAN2#94, R2-163998, available at: http://www.3gpp.org/
ftp/TSG_RAN/WG2_RL2/TSGR2_94/Docs/R2-163998.zip
4. 3GPP, TS 38.300, NR; Overall description; Stage-2, available at: https://portal.3gpp.org/desktopmodules/
Specifications/SpecificationDetails.aspx?specificationId=3191
5. 3GPP, TS 38.331, NR; Radio Resource Control (RRC); Protocol specification,available at: https://
portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3197

10. ✱ INACTIVE STATE IN 5G NR
10 ERICSSON TECHNOLOGY REVIEW ✱ JUNE 19, 2019
Icaro Leonardo
Da Silva
◆ joined Ericsson Research
in 2010 and currently serves
as a master researcher in
radio network architecture
and protocols. His work
has largely focused on
standardization and
concept development
for LTE and 5G NR, and in
particular on CP topics in
3GPP RAN2, for which he
was awarded the Inventor
of the Year prize for 2018.
Da Silva led the 5G CP
in the EU project on 5G
RAN architecture, METIS-
II, which is part of the
5G-PPP framework. He
holds an M.Sc. in electrical
engineering from the
Federal University of Ceará
(UFC), in Fortaleza, Brazil.
Gunnar Mildh
◆ is an expert in radio
network architecture in
the Network Architecture
and Protocols department
at Ericsson Research.
He joined the company
in 2000 and has worked
on standardization and
concept development for
GSM/EDGE, HSPA, LTE(-A)
and 5G NR. His focus areas
include radio network
architecture and protocols,
and more recently 5G
architecture including RAN
and Packet Core. Mildh
holds an M.Sc. in electrical
engineering from KTH Royal
Institute of Technology,
Stockholm, Sweden.
Paul Schliwa-
Bertling
◆ joined Ericsson in 1996
and currently serves as an
expert in mobile networks
architecture and signaling
at Ericsson Research in
Linköping, Sweden. He has
worked extensively with
the development of RAN
product and system-level
concepts as well as 3GPP
standardization across
multiple generations of RAN
and CN. His current work
focuses on the evolution
of network architecture
and the related signaling
aspects contributing to
3GPP standardization. He
holds an M.Sc. in electrical
engineering from the
University of Duisburg-
Essen in Germany.
Magnus Stattin
◆ joined Ericsson
Research in 2005, where
he currently serves as a
principal researcher. Over
the years his work has
focused on research in the
areas of radio resource
management and radio
protocols of various
wireless technologies. He
is also active in concept
development and 3GPP
standardization of LTE,
NB-IoT, NR and future
wireless technologies.
Stattin holds a Ph.D. in radio
communication systems
from KTH Royal Institute of
Technology in Stockholm.
Alexander Vesely
◆ joined Ericsson in 2013
after working at other
major mobile network
vendors for more than
20 years. He currently
serves as the company’s
principal researcher for
standardization. He has also
held offices in the 3GPP
for approximately eight
years, and is still actively
contributing. Vesely holds a
Dipl.Ing. in communications
engineering from the
Technical University in
Vienna, Austria.
theauthors

11. ISSN 0014-0171
284 23-3330 | Uen
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