1. The CUCP sends an RRC Setup Request message to the DU to establish an RRC connection for a UE including information like the serving cell, C-RNTI, and RLC configuration. 2. The DU responds with an RRC Setup Complete message along with a registration request containing UE identity, location, and capability information which is sent to the AMF via the CUCP and gNB. 3. The AMF sends a Registration Accept message to the UE containing authentication and configuration information like a 5G-GUTI and PDU session status, completing the registration procedure.

1. No Message Sequence info Participant NE's Protocol Messages or IE's
1 F1SetupRequest DU-->CUCP F1AP
Serving Cell Information, nRCGI,Serving cell PLMN Identity,nRPCI,TAC,
FreqBandNrItem(freqBandIndicatorNr: xx)
nRARFCN,measurementTimingConfiguration:MeasTiming
2 NGSetupRequest CUCP(NG-c)-->AMF NGAP
GlobalRANNodeID: globalGNB-ID: It is combination of pLMNIdentity+gNB-ID,tAC, id-
DefaultPagingDRX value
3
NGSetupResponse
AMF --> CUCP(NG-c) NGAP
AMFName,ServedGUAMIList(PLMN+AMFIdentity),GUAMIType(native)
4 F1SetupResponse CUCP --> DU F1AP
Cells-to-be-Activated-List-Item :nRCGI(PLMN Identity and nRCellIdentity), SIB
Information(SIB2,SIB3,SIB4)
5 AMFConfigurationUpdate AMF --> CUCP(NG-c) NGAP PLMN Support List, AMF TNL Association to Add List
6 AMFConfigurationUpdateAcknowledge CUCP(NG-c)-->AMF NGAP successfulOutcome:- AMFConfigurationUpdateAcknowledge
7 GNBDUConfigurationUpdate DU-->CUCP F1AP
Served-Cells-To-Modify-Item(oldNRCGI,served-Cell-
Information(PLMN,nRPCI,TAC)),nRARFCN,freqBandIndicatorNr,MeasurementTimingConfiguration
MeasurementTimingConfiguration,MIB,pdcch-ConfigSIB1,SIB1(PLMN+nRCellIdentity)
8 GNBDUConfigurationUpdateAcknowledge CUCP --> DU F1AP successfulOutcome:-gNBDUConfigurationUpdateAck
9 E1SetupRequest CUCP-->CUUP E1AP
GNB-CU-UP-ID,GNB-CU-UP-Name:UP-
2,CNSupport(CoreNetworkSupportability):(both),SupportedPLMNs,Slice-Support Info,
10 E1SetupResponse CUUP-->CUCP E1AP successfulOutcome:GNB-CU-UP-E1SetupResponse
11 RRC Setup Request DU-->CUCP F1AP/NR RRC
EstablishmentCause,UeIdentity:RandomValue,nRCGI=PLMN Identity+nRCellIdentity,C-RNTI, rlc-
BearerToAddModList=logicalChannelIdentity & srb-Identity,rlc-Config:am, mac-
LogicalChannelConfig,mac-CellGroupConfig(schedulingRequestConfig),bsr-Config,pdcch-
Config:setup,dci-Formats,pdsch-Config:setup,mcs-Table:qam256,pucch-
Config:setup,PCI:scramblingID,Config:maxMIMO-Layers,freqBand,nrofRBs,nrOfAntennaPorts: x
12 RRC Setup CUCP --> DU F1AP/NR RRC
servedRadioBearer:srb-Identity,rlc-Config,bsr-Config,mac-CellGroupConfig,phr-Config:setup,pdcch-
Config:setup,dci-Formats,pdsch-Config:setup,mcs-Table:qam256,pucch-
PowerControl,scramblingID,Setup:maxMIMO-Layers,freqBand,nrofRBs,
13 RRC Setup Complete, Registration request DU-->CUCP
F1AP/NR RRC
/NAS-5GS
PDCP-NR Configuration,registeredAMF(amf-Identifier),Non-Access-Stratum PDU,5GS registration
type,5GS mobile identity(5G-TMSI),UE security capability,5GMM capability,5GS tracking area
identity - Last visited registered TAI(TAC),Network slicing indication,
14 InitialUEMessage, Registration request gNB-->AMF NGAP/NAS-5GS
RAN-UE-NGAP-ID,id: id-NAS-PDU,5GS registration type,5GS mobile identity(5G-TMSI),UE security
capability,5GMM capability,5GS tracking area identity - Last visited registered TAI(TAC), Network
slicing
indication,userLocationInformationNR=nRCGI(PLMNIdentity+NRCellIdentity)+TAI(PLMNIdentity+TA
C),RRCEstablishmentCause: mo-Signalling
15 InitialContextSetupRequest AMF-->gNB NGAP
AMF-UE-NGAP-ID,RAN-UE-NGAP-ID,GUAMI(PLMNID+AMFId),UESecurityCapabilities,SecurityKey
16 Security Mode Command CUCP --> DU F1AP/NR RRC
RRCContainer including PDCP-NR:Configuration:SRB-1,
securityAlgorithmConfig=cipheringAlgorithm: nea-x & integrityProtAlgorithm: nia-x
17
Security Mode Complete
DU-->CUCP F1AP/NR RRC
RRCContainer including PDCP-NR:Configuration:SRB-1..Bearer Id: 1 Bearer type: DCCH)
18 UE Capability Enquiry CUCP --> DU F1AP/NR RRC SRBID,rat-Type: nr,FreqBandInformation:bandInformationNR
19 UE Capability Information DU-->CUCP F1AP/NR RRC
SRBID,rat-Type: nr,UE-NR-Capability:accessStratumRelease:rel15,pdcp-Parameters(supportedROHC-
Profiles),rlc-Parameters,mac-Parameters,phy-Parameters,rf-Parameters:-bandNR,scs-15kHz,
beamManagementSSB-CSI-RS,BandCombination,ims-Parameters:-voiceOverNR: supported

2. 20 UERadioCapabilityInfoIndication gNB-->AMF NGAP
rat-Type: nr,accessStratumRelease: rel15,pdcp-Parameters (supportedROHC-Profiles),rlc-
Parameters,mac-Parameters,phy-Parameters,rf-Parameters:-bandNR,scs-
15kHz,beamManagementSSB-CSI-RS,BandCombination,ims-Parameters:-voiceOverNR: supported
21 InitialContextSetupResponse gnb-->AMF NGAP successfulOutcome:InitialContextSetup,AMF-UE-NGAP-ID,RAN-UE-NGAP-ID
22 UERadioCapabilityCheckRequest AMF-->gNB NGAP
AMF-UE-NGAP-ID,RAN-UE-NGAP-ID,rat-Type:nr,UE-NR-Capability,accessStratumRelease:rel15,pdcp-
Parameters (supportedROHC-Profiles),rlc-Parameters,mac-Parameters,phy-Parameters,rf-
Parameters:-bandNR,scs-15kHz,beamManagementSSB-CSI-RS,BandCombination,ims-Parameters:-
voiceOverNR: supported
23 UERadioCapabilityCheckResponse gNB-->AMF NGAP
successfulOutcome:UERadioCapabilityCheckResponse,AMF-UE-NGAP-ID,RAN-UE-NGAP-ID:
1,IMSVoiceSupportIndicator: supported (0)
24 DownlinkNASTransport, Registration accept AMF-->Gnb NGAP
AMF-UE-NGAP-ID,RAN-UE-NGAP-ID,id: id-NAS-PDU,5GS registration result,5GS mobile identity -
(5G-GUTI,PLMN+AMF Region Id,5G-TMSI) ,5GS tracking area identity list including
PLMN+TAC,NSSAI - Configured NSSAI,5GS network feature support,PDU session status,GPRS
Timer,5GS DRX parameters,
25 DL Information Transfer, Registration accept CUCP-->DU F1AP
SRBID,id-NAS-PDU,5GS registration result,5GS mobile identity - (5G-GUTI,PLMN+AMF Region Id,5G-
TMSI),5GS tracking area identity list including PLMN+TAC,NSSAI - Configured NSSAI,5GS network
feature support,PDU session status,GPRS Timer,5GS DRX parameters,
26
UL Information Transfer, Registration
complete
DU-->CUCP F1AP
PDCP-NR([Bearer type:DCCH+Bearer Id+Direction:Uplink+Plane:Signalling),UL-DCCH-
Message:dedicatedNAS-Message,Non-Access-Stratum 5GS (NAS)PDU
27 UplinkNASTransport, Registration complete gNB-->AMF NGAP/NAS-5GS
Non-Access-Stratum 5GS (NAS)PDU,id-UserLocationInformation including
nRCGI(PLMN+nRcellIdentity) & TAI(PLMN+TAC)
28
UL Information Transfer, UL NAS transport,
PDU session establishment request
DU-->CUCP
F1AP/NR RRC
/NGAP/NAS-5GS
PDCP-NR([Bearer type:DCCH+Bearer Id+Direction:Uplink+Plane:Signalling),UL-DCCH-
Message:dedicatedNAS-Message,Non-Access-Stratum 5GS (NAS)PDU,Payload container,PDU
session type,5GSM capability,Extended protocol configuration options,PDU session
identity,Request type: Initial request
29
UplinkNASTransport, UL NAS transport, PDU
session establishment request
gNB-->AMF NGAP/NAS-5GS
id-NAS-PDU,Non-Access-Stratum 5GS (NAS)PDU,Payload container,PDU session type,5GSM
capability,Extended protocol configuration options,PDU session identity,Request type: Initial
request
30
PDUSessionResourceSetupRequest, DL NAS
transport, PDU session establishment accept
AMF-->gNB NGAP/NAS-5GS
pDUSessionID,Non-Access-Stratum 5GS (NAS)PDU,Payload container type,PDU session type,PDU
address,QoS flow description 1 - 5QI(Parameter identifier: 5QI (1))5QI: PDU session identity: PDU
session identity,transportLayerAddress,gTPTunnel(gTP-TEID),fiveQI: 9
31 BearerContextSetupRequest CUCP-->CUUP E1AP
SecurityInformation(securityAlgorithm including cipheringAlgorithm: nEA0 + uPSecuritykey
encryptionKey ,id-UEDLAggregateMaximumBitRate,BitRate,Serving PLMN-Identity,id-UE-Inactivity-
Timer:Inactivity-Timer: 10s,pDU-Session-Type: ipv4
,securityIndication:integrityProtectionIndication: not-needed & confidentialityProtectionIndication:
not-needed,gTPTunnel,gTP-TEID,dRB-ID,sDAP-Configuration,pDCP-Configuration,cell-Group-
ID,fiveQI: 9,
32 BearerContextSetupResponse CUUP-->CUCP E1AP
pDU-Session-ID,gTPTunnel:gTP-TEID,DRB-Setup-Item-NG-RAN uP-TNL-Information: gTPTunnel(dRB-
ID)qoS-Flow-Identifier: 9
33 UEContextSetupRequest CUCP-->DU F1AP
NRCGI,ServCellIndex,UE-CapabilityRAT-Container,rat-Type: nr,UE-NR-
Capability,accessStratumRelease: rel15,pdcp-Parameters,supportedROHC-Profiles,rlc-
Parameters,mac-Parameters,phy-Parameters,rf-Parameters,bandNR: 71,BandCombination,ca-
ParametersNR,ims-Parameters,voiceOverNR: supported,SRBs-ToBeSetup-Item,sRBID: 2, DRBs-
ToBeSetup-List,dRBID: 1,fiveQI: 9,gTPTunnel,gTP-TEID..ServingPLMN id,

3. 34 UEContextSetupResponse DU-->CUCP F1AP
CellGroupConfig,RLC-BearerConfig,srb-Identity:2,rlc-Config:am,servedRadioBearer: drb-Identity,drx-
Config: setup,SchedulingRequestToAddMod,bsr-Config,phr-Config: setup,maxMIMO-Layers:
4,gTPTunnel,gTP-TEID,
35 BearerContextModificationRequest CUCP-->CUUP E1AP
id-System-BearerContextModificationRequest,pDU-Session-ID,dRB-ID,dRB-To-Modify-List-NG-
RAN,gTPTunnel,gTP-TEID cell-Group-ID
36 BearerContextModificationResponse CUUP-->CUCP E1AP
uccessfulOutcome:BearerContextModificationResponse,Item 0: id-PDU-Session-Resource-Modified-
List,pDU-Session-ID,DRB-Modified-Item-NG-RAN,dRB-ID: 1
37
RRC Reconfiguration, DL NAS transport, PDU
session establishment accept
AMF-->gNB
F1AP/NR RRC
/NGAP
PDCP-NR [Direction:Downlink,Plane:Signalling,Bearer type:DCCH,Bearer Id: 1], DL-DCCH-
Message,radioBearerConfig,srb-ToAddModList,srb-Identity: 2,drb-ToAddModList,sdap-Config,pdu-
Session: 1,drb-Identity: 1,pdcp-Config,drb, headerCompression: notUsed,cipheringDisabled:
true,measConfig--
>MeasObjectToAddMod,measObjectId,ssbFrequency:xxxxx,ReportConfigToAddMod,reportConfigId
: 1,eventTriggered,eventId: eventA2 (1),eventA2(a2-Threshold: rsrp) reportConfigId:
2,eventA3,rsrp: 3.0dB (6),CellGroupConfig,RLC-BearerConfig,srb-Identity: 2,rlc-Config:
am,servedRadioBearer: drb-Identity,drb-Identity: 1,mac-LogicalChannelConfig,drx-Config: setup
(1),bsr-Config,maxMIMO-Layers: 4,DedicatedNAS-Message-->PDU address,S-NSSAI,Session-AMBRS-
NSSAI,5QI: 9,PDU session identity 2 - PDU session ID
38 RRC Reconfiguration Complete DU-->CUCP F1AP/NR RRC
SRBID: 1,PDCP-NR [Direction:Downlink,Plane:Signalling,Bearer type:DCCH,Bearer Id: 1],UL-DCCH-
Message,rrcReconfigurationComplete
39 PDUSessionResourceSetupResponse gNB-->AMF NGAP pDUSessionID: 1,gTPTunnel,gTP-TEID: yyyyy,qosFlowIdentifier: 9
40 UEContextModificationRequest CUCP-->DU F1AP RRCReconfigurationCompleteIndicator: true, id-UEContextModification
41
UEContextModificationResponse
DU-->CUCP F1AP
F1AP-PDU:successfulOutcome,CellGroupConfig,cellGroupId: 0,
42 BearerContextInactivityNotification CUCP-->CUUP E1AP ActivityInformation: uE-Activity,uE-Activity: not-active
43 UEContextReleaseRequest gNB-->AMF NGAP pDUSessionID, Release-Cause, Cause: radioNetwork radioNetwork: user-inactivity (20)
44 UEContextReleaseCommand AMF-->gNB NGAP Release Cause: radioNetwork,radioNetwork: user-inactivity
45 RRC Release CUCP-->DU F1AP/ NR RRC
Release Cause: radioNetwork,radioNetwork: normal-release (10), rrcRelease,SRBID: 1, PDCP-NR
[Configuration: SRB-1 (direction=Downlink, plane=Signalling)]
46 UEContextReleaseComplete DU-->CUCP F1AP F1AP-PDU: successfulOutcome,
47 BearerContextReleaseCommand CUCP-->CUUP E1AP Release Cause: radioNetwork,radioNetwork: normal-release
48 BearerContextReleaseComplete CUUP-->CUCP E1AP E1AP-PDU: successfulOutcome:bearerContextRelease
49 UEContextReleaseComplete gNB-->AMF NGAP
NGAP-PDU: successfulOutcome:UEContextRelease userLocationInformationNR including nR-
CGI+nRCellIdentity, tAI including
pLMNIdentity+tAC,PDUSessionResourceItemCxtRelCpl,pDUSessionID: 1