5G Standalone Access Registration Signaling Messages

This document details messages involved in the 5G standalone access registration procedure. These messages are referenced from the 5G Standalone Access Registration Sequence Diagrams.

Message Path
Preamble UE ➔ gNB
PDCCH DCI Format 1_0
└Format 1_0 - CRC Scrambled with RA-RNTI		 gNB ➔ UE
Random Access Response
└MAC PDU
 └MAC Payload for Random Access Response
  └RAR UL Grant		 gNB ➔ UE
RRCSetupRequest UE ➔ gNB
PDCCH DCI Format 1_0
└Format 1_0 - CRC Scrambled with C-RNTI		 gNB ➔ UE
RRCSetup
├RadioBearerConfig
└CellGroupConfig		 gNB ➔ UE
PDCCH DCI Format 0_0
└Format 0_0 - CRC Scrambled with C-RNTI		 gNB ➔ UE
RRCSetupComplete
└Registration Request		 UE ➔ gNB
Initial UE Message
└Registration Request		 gNB ➔ New AMF
Namf_Communication_UEContextTransfer Request
└Registration Request		 New AMF ➔ Old AMF
Namf_Communication_UEContextTransfer Response
└UE Context in AMF		 Old AMF ➔ New AMF
Identity Request New AMF ➔ gNB ➔ UE
Identity Response UE ➔ gNB ➔ New AMF
Nausf_UEAuthenticate_authenticate Request New AMF ➔ AUSF
Nudm_UEAuthenticate_Get Request AUSF ➔ UDM
Nudm_UEAuthenticate_Get Response UDM ➔ AUSF
Nausf_UEAuthenticate_authenticate Response AUSF ➔ New AMF
Authentication Request New AMF ➔ gNB ➔ UE
Authentication Response UE ➔ gNB ➔ New AMF
NAS Security Mode Command New AMF ➔ gNB ➔ UE
NAS Security Mode Complete UE ➔ gNB ➔ New AMF
N5g-eir_EquipmentIdentityCheck Request New AMF ➔ 5G-EIR
N5g-eir_EquipmentIdentityCheck Response 5G-EIR ➔ New AMF
Namf_Communication_RegistrationCompleteNotify New AMF ➔ Old AMF
Nudm_UEContextManagement_Registration Request
└Amf3GppAccessRegistration		 New AMF ➔ UDM
Nudm_UEContextManagement_Registration Response UDM ➔ New AMF
Nudm_SubscriberDataManagement_Get Request New AMF ➔ UDM
Nudm_SubscriberDataManagement_Get Response
├AccessAndMobilitySubscriptionData
├SmfSelectionSubscriptionData
└UeContextInSmfData		 UDM ➔ New AMF
Nudm_UEContextManagement_Deregistration_Notify UDM ➔ Old AMF
Nsmf_PDUSession_ReleaseSMContext Old AMF ➔ SMF
Npcf_AMPolicyControl_Create Request New AMF ➔ PCF
Npcf_AMPolicyControl_Create Response
└PolicyAssociation
 └PolicyAssociationRequest		 PCF ➔ New AMF
Namf_EventExpose_Subscribe Request
└AmfCreateEventSubscription
 └AmfEventSubscription		 PCF ➔ New AMF
Namf_EventExpose_Subscribe Response
└AmfCreatedEventSubscription		 New AMF ➔ PCF
Npcf_AMPolicyControl_Delete Request Old AMF ➔ PCF
Npcf_AMPolicyControl_Delete Response PCF ➔ Old AMF
Nsmf_PDUSession_UpdateSMContext Request New AMF ➔ SMF
PFCP Session Modification Request SMF ➔ UDF
PFCP Session Modification Response UDF ➔ SMF
Nsmf_PDUSession_UpdateSMContext Response SMF ➔ New AMF
Initial Context Setup Request
└Registration Accept		 New AMF ➔ gNB
SecurityModeCommand gNB ➔ UE
SecurityModeComplete UE ➔ gNB
RRCReconfiguration
├Registration Accept
├RadioBearerConfig
├secondaryCellGroup
├MeasConfig
└masterCellGroup		 gNB ➔ UE
RRCReconfigurationComplete
└UplinkTxDirectCurrentList		 UE ➔ gNB
Initial Context Setup Response gNB ➔ New AMF
Registration Complete UE ➔ gNB
Nsmf_PDUSession_UpdateSMContext Request New AMF ➔ SMF
PFCP Session Modification Request SMF ➔ UDF
PFCP Session Modification Response UDF ➔ SMF
Nsmf_PDUSession_UpdateSMContext Response SMF ➔ New AMF

Preamble

UE ➔ gNB

TS 38.213, TS 38.321, TS 38.211

The UE picks a random preamble. The preamble is referenced with the Random Access Preamble Id (RAPID). The preamble transmission is a Zadoff-Chu sequence.

Each preamble transmission is associated with an RA-RNTI.

RA-RNTI

The RA-RNTI associated with the PRACH in which the Random Access Preamble is transmitted, is computed as:

RA-RNTI= 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id

Where:

Identifier Description
s_id Index of the first OFDM symbol of the specified PRACH (0 ≤ s_id < 14)
t_id Index of the first slot of the specified PRACH in a system frame (0 ≤ t_id < 80)
f_id Index of the specified PRACH in the frequency domain (0 ≤ f_id < 8)
ul_carrier_id Uplink carrier used for Msg1 transmission (0 for NUL carrier, and 1 for SUL carrier)

PDCCH DCI Format 1_0

gNB ➔ UE

TS 38.212

DCI Format 1_0 is used to assign downlink resources.

Format 1_0 - CRC Scrambled with RA-RNTI

In response to a PRACH transmission, a UE attempts to detect a DCI Format 1_0 with PDCCH CRC scrambled by
the RA-RNTI corresponding to the RACH transmission. The UE looks for message during a configured window of length ra-ResponseWindow.

The RA-RNTI scrambled DCI message signals the frequency and time resources assigned for the transmission of the Transport Block containing the Random Access Response message.

The following information is transmitted by means of the RA-RNTI scrambled DCI Format 1_0:

Field Bits
Frequency domain resource assignment ⌈log2(NRBDL,BWP(NRBDL,BWP + 1)/2)⌉
NRBDL,BWP is the size of CORESET 0
Time domain resource assignment 4
VRB-to-PRB mapping 1
Modulation and coding scheme 5
TB scaling 2
Reserved bits 16

Format 1_0 - CRC Scrambled with C-RNTI

The following information is transmitted by a DCI Format 1_0 with PDCCH CRC scrambled by the assigned C-RNTI:

Field Bits
Identifier of DCI formats 1
Frequency domain resource assignment ⌈log2(NRBDL,BWP(NRBDL,BWP + 1)/2)⌉
NRBDL,BWP is the size of the active DL bandwidth part in case DCI format 1_0
is monitored in the UE specific search space if DCH sizes <= 4 and DCI size with
C-RNTI <= 3. Otherwise NRBDL,BWP is the size of CORESET 0
Time domain resource assignment 4
VRB-to-PRB mapping 1
Modulation and coding scheme 5
New data indicator 1
Redundancy version 2
HARQ process number 4
Downlink assignment index 2
TPC command for scheduled PUCCH 2
PUCCH resource indicator 3
PDSCH-to-HARQ_feedback timing indicator 3

Random Access Response

gNB ➔ UE

TS 38.213, TS 38.321

  1. The UE listens on the PDCCH addressed by the RA-RNTI.
  2. Once the PDCCH with the RA-RNTI is decoded, the UE uses the RB resources in the message to receive the downlink transport block.
  3. The downlink transport block contains the MAC PDU.

MAC PDU

subPDU 1 bit 1 bit 6-bit MAC subPDU payload
MAC subPDU 1 E T RAPID 1 MAC payload for Random Access Response
MAC subPDU 2 E T RAPID 2 MAC payload for Random Access Response
MAC subPDU 3 E T RAPID 3 MAC payload for Random Access Response
⋮
MAC subPDU n
Padding (optional)

E/T/RAPID MAC subheader

1 bit 1 bit 6-bit
E T RAPID

MAC Payload for Random Access Response

Field Description Bits
R Reserved bit (set to "0") 1
Timing Advance Command The Timing Advance Command field indicates the index value TA used to control the amount of timing adjustment that the MAC entity must apply in TS 38.213. 12
RAR UL Grant The Uplink Grant field indicates the resources to be used on the uplink in TS 38.213 27
Temporary C-RNTI The Temporary C-RNTI field indicates the temporary identity that is used by the MAC entity during Random Access. 16

RAR UL Grant

RAR grant field Number of bits
Frequency hopping flag 1
Msg3 PUSCH frequency resource allocation 14
Msg3 PUSCH time resource allocation 4
MCS 4
TPC command for Msg3 PUSCH 3
CSI request 1

RRCSetupRequest

UE ➔ gNB

38.331

The RRC Setup Request is sent with the random ue-Identity and an establishment cause. The following establishment causes are defined:

Establishment cause Description
emergency Emergency call
highPriorityAccess High priority access
mt-Access Mobile terminated access
mo-Signalling Mobile originated signaling
mo-Data Mobile Originated data
mo-VoiceCall Mobile originated voice call
mo-VideoCall Mobile originated video call
mo-SMS Mobile originated SMS (Text)
mps-PriorityAccess Multimedia priority service - priority access
mcs-PriorityAccess Mission critical service - priority access 
RRCSetupRequest ::=                 SEQUENCE {
    rrcSetupRequest                     RRCSetupRequest-IEs
}

RRCSetupRequest-IEs ::=             SEQUENCE {
    ue-Identity                         InitialUE-Identity,
    establishmentCause                  EstablishmentCause,
    spare                               BIT STRING (SIZE (1))
}

InitialUE-Identity ::=              CHOICE {
    ng-5G-S-TMSI-Part1                  BIT STRING (SIZE (39)),
    randomValue                         BIT STRING (SIZE (39))
}

EstablishmentCause ::=              ENUMERATED {
                                        emergency, highPriorityAccess, 
                                        mt-Access, mo-Signalling,
                                        mo-Data, mo-VoiceCall, 
                                        mo-VideoCall, mo-SMS, mps-PriorityAccess,
                                        mcs-PriorityAccess,
                                        spare6, spare5, spare4, 
                                        spare3, spare2, spare1}

RRCSetup

gNB ➔ UE

38.331

The RRC Setup message is sent to setup SRB1 and the master cell. The message carries the radioBearerConfig and masterCellGroup information elements.

RRCSetup ::=                        SEQUENCE {
    rrc-TransactionIdentifier           RRC-TransactionIdentifier,
    criticalExtensions                  CHOICE {
        rrcSetup                            RRCSetup-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

RRCSetup-IEs ::=                    SEQUENCE {
    radioBearerConfig                   RadioBearerConfig,
    masterCellGroup                     OCTET STRING (CONTAINING CellGroupConfig),
    lateNonCriticalExtension            OCTET STRING   OPTIONAL,
    nonCriticalExtension                SEQUENCE{}     OPTIONAL
}

RadioBearerConfig

RadioBearerConfig ::=                   SEQUENCE {
    srb-ToAddModList                        SRB-ToAddModList                                        OPTIONAL,   -- Cond HO-Conn
    srb3-ToRelease                          ENUMERATED{true}                                        OPTIONAL,   -- Need N
    drb-ToAddModList                        DRB-ToAddModList                                        OPTIONAL,   -- Cond HO-toNR
    drb-ToReleaseList                       DRB-ToReleaseList                                       OPTIONAL,   -- Need N
    securityConfig                          SecurityConfig                                          OPTIONAL,   -- Need M
    ...
}

SRB-ToAddModList ::=                    SEQUENCE (SIZE (1..2)) OF SRB-ToAddMod
SRB-ToAddMod ::=                        SEQUENCE {
    srb-Identity                            SRB-Identity,
    reestablishPDCP                         ENUMERATED{true}                                        OPTIONAL,   -- Need N
    discardOnPDCP                           ENUMERATED{true}                                        OPTIONAL,   -- Need N
    pdcp-Config                             PDCP-Config                                             OPTIONAL,   -- Cond PDCP
    ...
}

DRB-ToAddModList ::=                    SEQUENCE (SIZE (1..maxDRB)) OF DRB-ToAddMod
DRB-ToAddMod ::=                        SEQUENCE {
    cnAssociation                           CHOICE {
        eps-BearerIdentity                      INTEGER (0..15),                                    -- EPS-DRB-Setup
        sdap-Config                             SDAP-Config                                         -- 5GC
    }                                       OPTIONAL, -- Cond DRBSetup
    drb-Identity                            DRB-Identity,
    reestablishPDCP                         ENUMERATED{true}                                        OPTIONAL,   -- Need N
    recoverPDCP                             ENUMERATED{true}                                        OPTIONAL,   -- Need N
    pdcp-Config                             PDCP-Config                                             OPTIONAL,   -- Cond PDCP
    ...
}
DRB-ToReleaseList ::=                   SEQUENCE (SIZE (1..maxDRB)) OF DRB-Identity

SecurityConfig ::=                      SEQUENCE {
    securityAlgorithmConfig                 SecurityAlgorithmConfig                                 OPTIONAL,   -- Cond RBTermChange
    keyToUse                                ENUMERATED{master, secondary}                           OPTIONAL,   -- Cond RBTermChange
    ...
}

CellGroupConfig

CellGroupConfig ::=                         SEQUENCE {
    cellGroupId                                 CellGroupId,

    rlc-BearerToAddModList                      SEQUENCE (SIZE(1..maxLC-ID)) OF RLC-BearerConfig                OPTIONAL,   -- Need N
    rlc-BearerToReleaseList                     SEQUENCE (SIZE(1..maxLC-ID)) OF LogicalChannelIdentity          OPTIONAL,   -- Need N

    mac-CellGroupConfig                         MAC-CellGroupConfig                                             OPTIONAL,   -- Need M

    physicalCellGroupConfig                     PhysicalCellGroupConfig                                         OPTIONAL,   -- Need M

    spCellConfig                                SpCellConfig                                                    OPTIONAL,   -- Need M
    sCellToAddModList                           SEQUENCE (SIZE (1..maxNrofSCells)) OF SCellConfig               OPTIONAL,   -- Need N
    sCellToReleaseList                          SEQUENCE (SIZE (1..maxNrofSCells)) OF SCellIndex                OPTIONAL,   -- Need N
    ...,
    [[
    reportUplinkTxDirectCurrent-v1530           ENUMERATED {true}                                               OPTIONAL    -- Cond BWP-Reconfig
    ]]
}

-- Serving cell specific MAC and PHY parameters for a SpCell:
SpCellConfig ::=                        SEQUENCE {
    servCellIndex                       ServCellIndex                                                           OPTIONAL,   -- Cond SCG
    reconfigurationWithSync             ReconfigurationWithSync                                                 OPTIONAL,   -- Cond ReconfWithSync
    rlf-TimersAndConstants              SetupRelease { RLF-TimersAndConstants }                                 OPTIONAL,   -- Need M
    rlmInSyncOutOfSyncThreshold         ENUMERATED {n1}                             OPTIONAL,   -- Need S
    spCellConfigDedicated               ServingCellConfig                                                       OPTIONAL,   -- Need M
    ...
}

ReconfigurationWithSync ::=         SEQUENCE {
    spCellConfigCommon                  ServingCellConfigCommon                                                 OPTIONAL,   -- Need M
    newUE-Identity                      RNTI-Value,
    t304                                ENUMERATED {ms50, ms100, ms150, ms200, ms500, ms1000, ms2000, ms10000},
        rach-ConfigDedicated                CHOICE {
            uplink                              RACH-ConfigDedicated,
            supplementaryUplink             RACH-ConfigDedicated
    }                                           OPTIONAL,   -- Need N
    ...,
    [[
    smtc                                SSB-MTC OPTIONAL    -- Need S
    ]]
}

SCellConfig ::=                     SEQUENCE {
    sCellIndex                          SCellIndex,
    sCellConfigCommon                   ServingCellConfigCommon                                                 OPTIONAL,   -- Cond SCellAdd
    sCellConfigDedicated                ServingCellConfig                                                       OPTIONAL,   -- Cond SCellAddMod
    ...,
    [[
    smtc                                SSB-MTC OPTIONAL    -- Need S
    ]]
}

PDCCH DCI Format 0_0

gNB ➔ UE

TS 38.212

DCI Format 0_0 is used to assign uplink resources to the UE.

Format 0_0 - CRC Scrambled with C-RNTI

The following information is transmitted by a DCI Format 0_0 with PDCCH CRC scrambled by the assigned C-RNTI:

Field Bits
Identifier of DCI formats 1
Frequency domain resource assignment ⌈log2(NRBUL,BWP(NRBUL,BWP + 1)/2)⌉
NRBUL,BWP is the size of the active UL bandwidth part in case DCI format 0_0 is monitored in the UE specific search space if DCH sizes <= 4 and DCI size with C-RNTI <= 3. Otherwise NRBUL,BWP is the size of the initial UL bandwidth part.
Time domain resource assignment 4
Frequency hopping flag 1
Modulation and coding scheme 5
New data indicator 1
Redundancy version 2
HARQ process number 4
Downlink assignment index 2
TPC command for scheduled PUSCH 2
UL/SUL indicator 1

RRCSetupComplete

UE ➔ gNB

38.331

The UE sends the RRC Setup Complete message with a Registration Request in the dedicatedNAS-Message field.

RRCSetupComplete ::=                SEQUENCE {
    rrc-TransactionIdentifier           RRC-TransactionIdentifier,
    criticalExtensions                  CHOICE {
        rrcSetupComplete                    RRCSetupComplete-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

RRCSetupComplete-IEs ::=            SEQUENCE {
    selectedPLMN-Identity               INTEGER (1..maxPLMN),
    registeredAMF                       RegisteredAMF                                   OPTIONAL,
    guami-Type                          ENUMERATED {native, mapped}                     OPTIONAL,
    s-nssai-List                        SEQUENCE (SIZE (1..maxNrofS-NSSAI)) OF S-NSSAI  OPTIONAL,
    dedicatedNAS-Message                DedicatedNAS-Message,
    ng-5G-S-TMSI-Value                  CHOICE {
        ng-5G-S-TMSI                        NG-5G-S-TMSI,
        ng-5G-S-TMSI-Part2                  BIT STRING (SIZE (9))
    }                   OPTIONAL,
    lateNonCriticalExtension            OCTET STRING                                    OPTIONAL,
    nonCriticalExtension                SEQUENCE{}                                      OPTIONAL
}

RegisteredAMF ::=                   SEQUENCE {
    plmn-Identity                       PLMN-Identity                                   OPTIONAL,
    amf-Identifier                      AMF-Identifier
}

Registration Request

UE ➔ RRCSetupComplete ➔ gNB ➔ NGAP Initial UE Message ➔ New AMF ➔ Namf_Communication_UEContextTransfer Request ➔ Old AMF

TS 24.501

The Registration Request NAS message is carried from the UE to the newly assigned AMF. The message will also be passed to the old AMF to retrieve the AMF context for the UE.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Registration request message identity Message type
5GS registration type
  • initial registration
  • mobility registration updating
  • periodic registration updating
  • emergency registration
ngKSI NAS key set identifier
Spare half octet
5GS mobile identity
Non-current native NAS key set identifier NAS key set identifier
5GMM capability
UE security capability
Requested NSSAI NSSAI
Last visited registered TAI 5GS tracking area identity
S1 UE network capability
Uplink data status
PDU session status
MICO indication
UE status
Additional GUTI 5GS mobile identity
Allowed PDU session status
UE's usage setting
Requested DRX parameters DRX parameters
EPS NAS message container
LADN indication
Payload container

Initial UE Message

gNB ➔ New AMF

TS 38.413

The gNB sends the Initial UE Message to the selected AMF. The message carries the Registration Request that was received from the UE in the RRC Setup Complete message. The "RAN UE NGAP ID" and the "RRC Establishment Cause" are also included in the message.

The AMF will use the "RAN UE NGAP ID" to address the UE context on the gNB.

Field Description
Message Type
RAN UE NGAP ID
NAS-PDU Registration Request
User Location Information
RRC Establishment Cause OCTET STRING
5G-S-TMSI
AMF Set ID
UE Context Request Indicates that a UE context including security information needs to be setup at the NG-RAN.
Allowed NSSI

Namf_Communication_UEContextTransfer Request

New AMF ➔ Old AMF

29.502, 29.518

New AMF requests context transfer from the Old AMF. The complete NAS registration request message received from the UE is included in the context request.

Field Description
5G-GUTI
Reason
Registration Request Integrity protected message from the UE that triggers the context transfer.

Namf_Communication_UEContextTransfer Response

Old AMF ➔ New AMF

29.502, 29.518

The Old AMF passes the AMF UE Context to the new AMF.

Field Description
UE Context in AMF Integrity protected message from the UE that triggers the context transfer.
Mobile Equipment Identifier Optional
Allowed NSSAI
Mapping Of Allowed NSSAI

UE Context in AMF

The complete UE context maintained at the AMF. The AMF passes this context to a "New AMF" if the UE is attempts registration in the "New AMF".

Field Description
SUPI SUPI (Subscription Permanent Identifier) is the subscriber's permanent identity in 5GS.
SUPI-unauthenticated-indicator This indicates whether the SUPI is unauthenticated.
GPSI The GPSI(s) of the UE. The presence is dictated by its storage in the UDM.
5G-GUTI 5G Globally Unique Temporary Identifier.
PEI Mobile Equipment Identity
Internal Group ID-list List of the subscribed internal group(s) that the UE belongs to.
UE Specific DRX Parameters UE specific DRX parameters.
UE MM Network Capability Indicates the UE MM network capabilities.
5GMM Capability Includes other UE capabilities related to 5GCN or interworking with EPS.
Events Subscription List of the event subscriptions by other CP NFs. Indicating the events being subscribed as well as any information on how to send the corresponding notifications

AM Policy Association Information includes the AM Policy Information and the PCF ID(s) below

Field Description
AM Policy Information Information on AM policy provided by PCF. Includes the Policy Control Request Triggers and the Policy Control Request Information. Includes the authorized RFSP and the authorized Service Area Restrictions.
PCF ID(s) The identifier of the PCF for AM Policy. In roaming, the identifier of V-PCF and H-PCF.
Subscribed RFSP Index An index to specific RRM configuration in the NG-RAN that is received from the UDM.
RFSP Index in Use An index to specific RRM configuration in the NG-RAN that is currently in use.
MICO Mode Indication Indicates the MICO Mode for the UE.
Voice Support Match Indicator An indication whether the UE radio capabilities are compatible with the network configuration. The AMF uses it as an input for setting the IMS voice over PS Session Supported Indication over 3GPP access.
Homogenous Support of IMS Voice over PS Sessions Indicates per UE if "IMS Voice over PS Sessions" is homogeneously supported in all TAs in the serving AMF or homogeneously not supported, or, support is non-homogeneous/unknown.
UE Radio Capability for Paging Information Information used by the NG-RAN to enhance the paging towards the UE.
Information on Recommended Cells And RAN nodes For Paging Information sent by the NG-RAN, and used by the AMF when paging the UE to help determining the NG-RAN nodes to be paged as well as to provide the information on recommended cells to each of these NG-RAN nodes, in order to optimize the probability of successful paging while minimizing the signaling load on the radio path.
UE Radio Capability Information Information sent by the NG-RAN node and stored in the AMF. The AMF sends this information to the NG-RAN node within the UE context during transition to CM-CONNECTED state.
SMSF Identifier The Identifier of the SMSF serving the UE in RM REGISTERED state.
SMSF Address The Address of the SMSF serving the UE in RM-REGISTERED state.
SMS Subscription Indicates subscription to any SMS delivery service over NAS irrespective of access type.
SEAF data Master security information received from AUSF
Last used EPS PLMN ID The identifier of the last used EPS PLMN

For each access type level context within the UE access and mobility context:

Field Description
Access Type Indicates the access type for this context.
RM State Registration management state.
Registration Area Current Registration Area (a set of tracking areas in TAI List).
TAI of last Registration Update TAI of the TA in which the last registration request was initiated.
User Location Information Information on user location.
Mobility Restrictions Mobility Restrictions restrict mobility handling or service access of a UE. It consists of RAT restriction, Forbidden area, Service area restrictions and Core Network type restriction.
Expected UE Behavior Parameters for AMF Indicates per UE the Expected UE Behavior Parameters and their corresponding validity times.
Security Information for CP Control plane security information.
Security Information for UP User plane security information.
Allowed NSSAI Allowed NSSAI consisting of one or more S-NSSAIs for serving PLMN in the present Registration Area.
Mapping Of Allowed NSSAI Mapping Of Allowed NSSAI is the mapping of each S-NSSAI of the Allowed NSSAI to the S-NSSAIs of the Subscribed S-NSSAIs.
AMF UE NGAP ID Identifies the UE association over the NG interface within the AMF as defined in TS 38.413.
RAN UE NGAP ID Identifies the UE association over the NG interface within the NG-RAN node as defined in TS 38.413.
Network Slice Instance(s) The Network Slice Instances selected by 5GC for this UE.

For each PDU Session level context:

Field Description
S-NSSAI(s) The S-NSSAI(s) associated to the PDU Session.
DNN The associated DNN for the PDU Session.
Network Slice Instance id The network Slice Instance information for the PDU Session
PDU Session ID The identifier of the PDU Session.
SMF Information The associated SMF identifier and SMF address for the PDU Session.
Access Type The current access type for this PDU Session.
EBI-ARP list The allocated EBI and associated ARP pairs for this PDU session.
5GSM Core Network Capability The UEs 5GSM Core Network Capability as defined in TS 23.501.

Identity Request

New AMF ➔ DL NAS Transport ➔ gNB ➔ DLInformationTransfer ➔ UE

TS 24.501

The New AMF requests UE identity (SUCI) from the UE via a NAS message.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Identity request message identity Message type
Identity type 5GS identity type
Spare half octet

Identity Response

UE ➔ ULInformationTransfer ➔ gNB ➔ UL NAS Transport ➔ New AMF

TS 24.501

The UE responds to the Identity Request with SUCI. The SUCI is derived from the public key of the Home PLMN.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Identity response message identity Message type
Mobile identity 5GS mobile identity

Nausf_UEAuthenticate_authenticate Request

New AMF ➔ AUSF

TS 33.501

The AMF requests UE authentication vectors and algorithm information from the AUSF - Authentication Server Function.

Resource URI: {apiRoot}/nausf-auth/v1/ue-authentications

Scenario Authentication Method Inputs
Initial authentication request SUPI (Subscription Permanent Identifier) or SUCI (Subscription Concealed Identifier)
Subsequent authentication request 5G AKA Authentication confirmation message with RES*
Subsequent authentication request EAP-AKA’ EAP packet as described in RFC 4187 and RFC 5448

Nudm_UEAuthenticate_Get Request

AUSF ➔ UDM

TS 29.503

The Authentication Server Function (AUSF) requests authentication vectors from the UDM - Unified Data Management function.

Field Presence Description
SUPI or SUCI, serving network name Required Subscriber Permanent Identifier (SUPI) or Subscriber Concealed Identifier (SUCI)
Synchronization Failure Optional Synchronization Failure indication and related information (i.e. RAND/AUTS).

Nudm_UEAuthenticate_Get Response

UDM ➔ AUSF

TS 29.503, TS 33.501

The UDM returns the authentication vectors to the AUSF.

Field Presence Description
Authentication method and data Required Authentication method and corresponding authentication data for a certain UE as identified by SUPI or SUCI input.
SUPI Optional Subscriber Permanent Identifier. Present if SUPI was specified in the input.

Nausf_UEAuthenticate_authenticate Response

AUSF ➔ New AMF

TS 33.501

The response returns the master key which is used by AMF to derive NAS security keys and other security key(s).

Field Authentication Method Outputs
Authentication response 5G AKA Authentication vector, or Authentication confirmation acknowledge message.
Authentication response EAP-AKA’ EAP packet as described in RFC 4187 and RFC 5448
Authentication result Master key which is used by AMF to derive NAS security keys and other security key(s).

Authentication Request

New AMF ➔ DL NAS Transport ➔ gNB ➔ DLInformationTransfer ➔ UE

TS 24.501

Initiate the authentication procedure with the UE. Send the key selector, RAND and AUTN to the UE.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Authentication request message identity Message type
ngKSI NAS key set identifier
Spare half octet
Authentication parameter RAND (5G authentication challenge) Authentication parameter RAND
Authentication parameter AUTN (5G authentication challenge) Authentication parameter AUTN
ABBA
EAP message

Authentication Response

UE ➔ ULInformationTransfer ➔ gNB ➔ UL NAS Transport ➔ New AMF

TS 24.501

The UE responds to the authentication challenge.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Authentication response message identity
Authentication response parameter
EAP message

NAS Security Mode Command

New AMF ➔ DL NAS Transport ➔ gNB ➔ DLInformationTransfer ➔ UE

TS 24.501

The AMF signals the selected NAS security algorithm to the UE. The AMF also requests the IMEISV from the UE.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Security mode command message identity
Selected NAS security algorithms
ngKSI
Spare half octet
Replayed UE security capabilities
IMEISV request
HashAMF
Selected EPS NAS security algorithms
Additional 5G security information
EAP message

NAS Security Mode Complete

UE ➔ ULInformationTransfer ➔ gNB ➔ UL NAS Transport ➔ New AMF

TS 24.501

The UE signals the completion of the NAS security procedure. The message contains the IMEISV.

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Security mode complete message identity Message type
IMEISV 5G mobility identity
NAS message container

N5g-eir_EquipmentIdentityCheck Request

New AMF ➔ 5G-EIR

TS 23.502

This service is provided by the 5G-EIR to check the PEI and determine whether the PEI is blacklisted.

Inputs Outputs
PEI and SUPI PEI checking result

N5g-eir_EquipmentIdentityCheck Response

5G-EIR ➔ New AMF

TS 23.502

5G-EIR responds to the PEI blacklisting check.

Inputs Outputs
PEI and SUPI PEI checking result

Namf_Communication_RegistrationCompleteNotify

New AMF ➔ Old AMF

29.518, 23.502

Field Presence Description
5G-GUTI Required 5G Globally Unique Temporary Identity
PDU Session ID(s) Optional Indicates the PDU Session(s) to be released
PCF ID Optional Indicates that the PCF ID that handles the AM Policy association has changed

Nudm_UEContextManagement_Registration Request

New AMF ➔ UDM

TS 29.503

Resource URI for 3GPP access:

//{apiRoot}/nudm_uecm/v1/{ueid}/registrations/amf-3gpp-access

Here:

{ueid} Represents the Subscription Identifier SUPI or GPSI (see 3GPP TS 23.501) SUPI (i.e. imsi or nai) is used with the PUT and PATCH methods; GPSI (i.e. msisdn or extid) is used with the GET method. The ueid pattern is:

"(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-.+|.+)"
HTTP/Custom method Description Body datastructure
PUT Update the AMF registration for 3GPP access Amf3GppAccessRegistration
PATCH Modify the AMF registration for 3GPP access Amf3GppAccessRegistrationModification
GET Retrieve the AMF registration information for 3GPP access.

Amf3GppAccessRegistration

Attribute name Data type Presence Cardinality Description
amfInstanceId NfInstanceId M 1 T The identity the AMF uses to register in the NRF.
supportedFeatures SupportedFeatures O 0..1
purgeFlag PurgeFlag O 0..1 This flag indicates whether or not the AMF has deregistered. It shall not be included in the Registration service operation.
pei Pei O 0..1 Permanent Equipment Identifier.
imsVoPS ImsVoPS O 0..1 Indicates per UE if "IMS Voice over PS Sessions" is homogeneously supported in all TAs in the serving AMF, or homogeneously not supported.
deregCallbackUri Uri M 1 A URI provided by the AMF to receive (implicitly subscribed) notifications on deregistration.
pcscfRestorationCallbackUri Uri O 0..1 A URI provided by the AMF to receive (implicitly subscribed) notifications on the need for P-CSCF Restoration.
guami Guami C 0..1 This IE shall contain the serving AMF's GUAMI.
backupAmfInfo array(BackupAmfInfo) C 0..N This IE shall be included if the NF service consumer is an AMF and the AMF supports the AMF management without UDSF for the first interaction with UDM. The UDM uses this attribute to do an NRF query in order to invoke later services in a backup AMF, e.g. Namf_EventExposure.

Nudm_UEContextManagement_Registration Response

UDM ➔ New AMF

TS 29.503

Data type Presence Cardinality Response codes Description
n/a 204 No Content Upon success, an empty response body shall be returned
ProblemDetails M 1 404 Not Found The "cause" attribute shall be set to the following application error:
  • USER_NOT_FOUND
ProblemDetails M 1 403 Forbidden The "cause" attribute shall be set to one of the following application errors:
  • UNKNOWN_5GS_SUBSCRIPTION
  • NO_PS_SUBSCRIPTION
  • ROAMING_NOT_ALLOWED
  • ACCESS_NOT_ALLOWED
  • RAT_NOT ALLOWED
  • REAUTHENTICATION_REQUIRED

Nudm_SubscriberDataManagement_Get Request

New AMF ➔ UDM

TS 29.503

Requested Data HTTP Verb URI
Access and Mobility Subscription data GET ../{supi}/am-data
SMF Selection Subscription data GET ../{supi}/smf-select-data
UE Context In SMF Data Retrieval GET ../{supi}/ue-context-in-smf-data

Nudm_SubscriberDataManagement_Get Response

UDM ➔ New AMF

TS 29.503

Provided Data HTTP Verb Provided Data Type
Access and Mobility Subscription data 200 OK AccessAndMobilitySubscriptionData
SMF Selection Subscription data 200 OK SmfSelectionSubscriptionData
UE Context In SMF Data Retrieval 200 OK UeContextInSmfData

AccessAndMobilitySubscriptionData

Attribute name Data type Presence Cardinality Description
supportedFeatures SupportedFeatures O 0..1
gpsis array(Gpsi) O 0..N List of Generic Public Subscription Identifier; see 3GPP TS 29.571
internalGroupIds array(InternalGroupId) O 0..N List of internal group identifier; see 3GPP TS 23.501
subscribedUeAmbr Ambr O 0..1
nssai Nssai O 0..1 Network Slice Selection Assistance Information
ratRestrictions array(RatType) O 0..N List of RAT Types that are restricted; see 3GPP TS 29.571
forbiddenAreas array(Area) O 0..N List of forbidden areas
serviceAreaRestrictions ServiceAreaRestriction O 0..1 Subscribed Service Area Restriction
coreNetworkTypeRestrictions array(CoreNetworkType) O 0..N List of Core Network Types that are restricted
rfspIndex RfspIndex O 0..1 Index to RAT/Frequency Selection Priority
subsRegTimer DurationSec O 0..1 Subscribed periodic registration timer; see 3GPP TS 29.571
ueUsageType UeUsageType O 0..1
mpsPriority MpsPriorityIndicator O 0..1
activeTime DurationSec O 0..1 subscribed active time for PSM UEs
dlPacketCount DlPacketCount O 0..1 DL Buffering Suggested Packet Count indicates whether extended buffering of downlink packets for High Latency Communication is requested.
sorInfo SorInfo O 0..1 This IE shall be present if the UDM shall send the information for Steering of Roaming during registration or the subscription data update to the UE.
micoAllowed MicoAllowed O 0..1 Indicates whether the UE subscription allows MICO mode.
sharedDataIds array(SharedDataId) O 0..N Identifier of shared data 
/{supi}/am-data:
    get:
      summary: retrieve a UE's Access and Mobility Subscription Data
      operationId: Get
      tags:
        - Access and Mobility Subscription Data Retrieval
      parameters:
        - name: supi
          in: path
          description: Identifier of the UE
          required: true
          schema:
            $ref: 'TS29571_CommonData.yaml#/components/schemas/Supi'
        - name: supported-features
          in: query
          description: Supported Features
          schema:
             $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'
        - name: plmn-id
          in: query
          description: serving PLMN ID
          content:
            application/json:
              schema:
                $ref: 'TS29571_CommonData.yaml#/components/schemas/PlmnId'
      responses:
        '200':
          description: Expected response to a valid request
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AccessAndMobilitySubscriptionData'
        '404':
          description: User (SUPI) does not exist
        default:
          description: Unexpected error
          content:
            application/problem+json:
              schema:
                $ref: 'TS29571_CommonData.yaml#/components/schemas/ProblemDetails'

SmfSelectionSubscriptionData

Attribute name Data type Presence Cardinality Description
supportedFeatures SupportedFeatures O 0..1
subscribedSnssaiInfos array(SnssaiInfo) O 0..N List of S-NSSAIs and associated information (DNN Info); see 3GPP TS 23.501 
/{supi}/smf-select-data:
    get:
      summary: retrieve a UE's SMF Selection Subscription Data
      operationId: Get
      tags:
        - SMF Selection Subscription Data Retrieval
      parameters:
        - name: supi
          in: path
          description: Identifier of the UE
          required: true
          schema:
            $ref: 'TS29571_CommonData.yaml#/components/schemas/Supi'
        - name: supported-features
          in: query
          description: Supported Features
          schema:
             $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'
        - name: plmn-id
          in: query
          description: serving PLMN ID
          content:
            application/json:
              schema:
                $ref: 'TS29571_CommonData.yaml#/components/schemas/PlmnId'
      responses:
        '200':
          description: Expected response to a valid request
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SmfSelectionSubscriptionData'
        '404':
          description: User (SUPI) does not exist
        default:
          description: Unexpected error
          content:
            application/problem+json:
              schema:
                $ref: 'TS29571_CommonData.yaml#/components/schemas/ProblemDetails'

UeContextInSmfData

Attribute name Data type Presence Cardinality Description
pduSessions map(PduSession) O 0..N A map (list of key-value pairs where pduSessionId converted from integer to string serves as key) of PduSessions.
pgwInf array(PgwInfo) O 0..N Information about the DNNs/APNs and PGW-C+SMF FQDNs used in interworking with EPS 
  /{supi}/ue-context-in-smf-data:
    get:
      summary: retrieve a UE's UE Context In SMF Data
      operationId: Get
      tags:
        - UE Context In SMF Data Retrieval
      parameters:
        - name: supi
          in: path
          description: Identifier of the UE
          required: true
          schema:
            $ref: 'TS29571_CommonData.yaml#/components/schemas/Supi'
        - name: supported-features
          in: query
          description: Supported Features
          schema:
             $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'
      responses:
        '200':
          description: Expected response to a valid request
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/UeContextInSmfData'
        '404':
          description: User (SUPI) does not exist
        default:
          description: Unexpected error
          content:
            application/problem+json:
              schema:
                $ref: 'TS29571_CommonData.yaml#/components/schemas/ProblemDetails'

Nudm_UEContextManagement_Deregistration_Notify

UDM ➔ Old AMF

TS 29.503

The following procedure using the DeregistrationNotification service operation is supported:

  1. The UDM sends a POST request to the callbackReference as provided by the Old AMF during the registration (See Amf3GppAccessRegistration deregCallbackUri field) .
  2. The Old AMF service consumer responds with "204 No Content".

Nsmf_PDUSession_ReleaseSMContext

Old AMF ➔ SMF

TS 23.502

This message allows to release the AMF-SMF association for a certain PDU Session because the PDU Session has been released.

Input Presence
SUPI Required
PDU Session ID Required
UE location information Optional
AN type Optional
UE Time Zone Optional

Npcf_AMPolicyControl_Create Request

New AMF ➔ PCF

29.513, 29.507

URI organization:

{apiRoot}/{apiName}/{apiVersion}/{apiSpecificResourceUriPart}
Resource name Resource URI HTTP method or custom operation Description
AM Policies {apiRoot}/npcf-am-policy-control/v1/policies/ POST Create a new Individual AM Policy
Individual AM Policy {apiRoot}/npcf-am-policy-control/v1/policies/{polAssoId} GET Read the Individual AM Policy resource.
Individual AM Policy {apiRoot}/npcf-am-policy-control/v1/policies/{polAssoId} DELETE Delete the Individual AM Policy resource.
Individual AM Policy {apiRoot}/npcf-am-policy-control/v1/policies/{polAssoId}/update update (POST) Report observed event trigger and obtain updated policies.

Npcf_AMPolicyControl_Create Response

PCF ➔ New AMF

29.513, 29.507

Data type Presence Cardinality Response codes Description
PolicyAssociation M 1 200 OK

PolicyAssociation

Attribute name Data type Presence Cardinality Description
request PolicyAssociationRequest O 0..1 The information provided by the NF service consumer when requesting the creation of a policy association
uePolicy FFF O 0..1 The UE policy as determined by the PCF.
triggers array(RequestTrigger) O 1..N Request Triggers that the PCF subscribes. Only values "LOC_CH" and "PRA_CH" are permitted.
servAreaRes FFS O 0..1 Service Area Restriction as part of the AMF Access and Mobility Policy as determined by the PCF
rfsp RfspIndex O 0..1 RFSP Index as part of the AMF Access and Mobility Policy as determined by the PCF.
pras map(PresenceInfo) C 1..N If the Trigger "PRA_CH" is provided, the presence reporting area(s) for which reporting is requested shall be provided. The praId attribute within the PresenceInfo data type shall also be the key of the map. The praStatus attribute within the PresenceInfo data type shall not be supplied.
suppFeat SupportedFeatures M 1 Indicates the negotiated supported features.

PolicyAssociationRequest

Attribute name Data type Presence Cardinality Description
notificationUri Uri M 1 Identifies the recipient of Notifications sent by the PCF.
altNotifIpv4Addrs array(Ipv4Addr) O 1..N Alternate or backup IPv4 Addess(es) where to send Notifications.
altNotifIpv6Addrs array(Ipv6Addr) O 1..N Alternate or backup IPv6 Addess(es) where to send Notifications.
supi Supi C 0..1 Subscription Permanent Identifier (~IMSI in 4G).
gpsi Gpsi C 0..1 Generic Public Subscription Identifier.
accessType AccessType C 0..1 The Access Type where the served UE is camping.
pei Pei C 0..1 The Permanent Equipment Identifier of the served UE.
userLoc UserLocation C 0..1 The location of the served UE.
timeZone TimeZone C 0..1 The time zone where the served UE is camping.
servingPlmn NetworkId C 0..1 The serving PLMN where the served UE is camping.
ratType RatType C 0..1 The RAT Type where the served UE is camping.
groupId GroupId C 0..1 Internal Group Identifier of the served UE.
hPcfId string C 0..1 H-PCF Identifier.
servAreaRes ServiceAreaRestriction C 0..1 Service Area Restriction as part of the AMF Access and Mobility Policy.
rfsp RfspIndex C 0..1 RFSP Index as part of the AMF Access and Mobility Policy.
uePolReq UePolicyRequest C 0..1 A request for UE Policies. Shall be provided when the AMF receives an "UPSI LIST TRANSPORT" message.
guami Guami C 0..1 The Globally Unique AMF Identifier (GUAMI) shall be provided by an AMF as service consumer.
serviceName string O 0..1 If the NF service consumer is an AMF, it should provide the name of a service produced by the AMF that makes use of information received within the Npcf_AMPolicyControl_UpdateNotify service operation.
suppFeat SupportedFeatures M 1 Indicates the features supported by the service consumer.
traceReq TraceData C 0..1 Trace control and configuration parameters information defined in 3GPP TS 32.422 shall be included if trace is required to be activated.

Namf_EventExpose_Subscribe Request

PCF ➔ New AMF

29.518, 23.502

Applications can subscribe to AMF events by sending a Subscription Request.

Resource URI: {apiRoot}/namf-evts/v1/subscriptions

The PCF can register for the following events:

Event Description
Location-Report A NF subscribes to this event to receive the Last Known Location of a UE or a group of UEs, and Updated Location of the UE or any UE in the group when AMF becomes aware of a location change of the UE.
Presence-In-AOI-Report A NF subscribe to this event to receive the current present state of a UE in a specific Area of Interest (AOI), and notification when a specified UE enters or leaves the specified area. The area could be identified by a TA list, an area ID or specific interested area name like "LADN".
Time-Zone-Report A NF subscribes to this event to receive the current time zone of a UE or a group of UEs, and updated time zone of the UE or any UE in the group when AMF becomes aware of a time zone change of the UE.
Access-Type-Report A NF subscribes to this event to receive the current access type(s) of a UE or a group of UEs, and updated access type(s) of the UE or any UE in the group when AMF becomes aware of the access type change of the UE.
Registration-State-Report A NF subscribes to this event to receive the current registration state of a UE or a group of UEs, and report for updated registration state of a UE or any UE in the group when AMF becomes aware of a registration state change of the UE.
Connectivity-State-Report A NF subscribes to this event to receive the current connectivity state of a UE or a group of UEs, and report for updated connectivity state of a UE or any UE in the group when AMF becomes aware of a connectivity state change of the UE.
Reachability-Report A NF subscribes to this event to receive the current reachability of a UE or a group of UEs, and report for updated reachability of a UE or any UE in the group when AMF becomes aware of a reachability change of the UE.
Subscribed-Data-Report A NF subscribes to this event to receive the current Subscribed Data for the UE(s) received from UDM, and notification when AMF received updated subscribed data for the UE(s) from UDM.
Communication-Failure-Report A NF subscribes to this event to receive the Communication failure report of a UE or group of UEs or any UE.
UEs-In-Area-Report A NF subscribes to this event to receive the number of UEs in a specific area. A NF may ask AMF for the UEs within the area based on Last Known Location or it may request AMF to actively look for the UEs within the area based on Current Location.

URI: .../subscriptions (AmfCreateEventSubscription)

AmfCreateEventSubscription

Attribute name Data type Presence Cardinality Description
subscription AmfEventSubscription M 1 Represents the AMF Event Subscription resource to be created.
supportedFeatures SupportedFeatures C 0..1 This IE shall be present if at least one optional feature is supported.

AmfEventSubscription

Attribute name Data type Presence Cardinality Description
eventList array(AmfEvent) M 1..N Describes the events to be subscribed for this subscription.
notifyUri Uri M 1 Identifies the recipient of notifications sent by AMF for this subscription (NOTE 1)
notifyCorrelationId string M 1 Identifies the notification correlation ID. The AMF shall include this ID in the notifications.
nfId NfInstanceId M 1 Indicates the instance identity of the network function creating the subscription.
subsChangeNotifyUri Uri C 0..1 This IE shall be present if the subscription is created by an NF service consumer on behalf of another NF (e.g UDM creating event subscription at AMF for event notifications towards NEF). When present, this IE Identifies the recipient of notifications sent by AMF for change of subscription ID (e.g during mobility procedures involving AMF change).
subsChangeNotifyCorelationId string C 0..1 This IE shall be present when an NF Service Consumer (e.g. UDM) is subscribing for events on behalf of another NF Service Consumer (e.g. NEF). When present, this IE shall contain the notification correlation ID. The AMF shall include it in the notifications for change of subscription ID.
supi Supi C 0..1 Subscription Permanent Identifier
groupId GroupId C 0..1 Identifies a group of UEs.
gpsi Gpsi C 0..1 Generic Public Subscription Identifier
pei Pei C 0..1 Permanent Equipment Identifier
anyUE boolean C 0..1 This IE shall be present if the event subscription is applicable to any UE. Default value "FALSE" is used, if not present (NOTE 2)
options AmfEventMode O 0..1 This IE may be included if the NF service consumer wants to describe how the reports of the event to be generated.

Namf_EventExpose_Subscribe Response

New AMF ➔ PCF

29.518, 23.502

Response code: 201 Created is returned with AmfCreatedEventSubscription

A "201 Created" code signals successful subscription.

AmfCreatedEventSubscription

Attribute name Data type Presence Cardinality Description
subscription AmfEventSubscription M 1 Represents the newly created AMF Event Subscription resource.
reportList array(AmfEventReport) O 0..N Represents the immediate event reports (i.e. the current value
supportedFeatures SupportedFeatures C 0..1 This IE shall be present if at least one optional feature is supported.

Npcf_AMPolicyControl_Delete Request

Old AMF ➔ PCF

29.513, 29.507

The Old AMF requests that the policy association is deleted as the corresponding UE context is terminated.

The old AMF will initiate the delete using the following URI:

{apiRoot}/npcf-am-policy-control/v1/policies/{polAssoId}

Npcf_AMPolicyControl_Delete Response

PCF ➔ Old AMF

29.513, 29.507

PCF signals successful delete with 204 No Content cause code.

Data type Presence Cardinality Response codes Description
n/a 204 No Content Upon success, an empty response body shall be returned

Initial Context Setup Request

AMF ➔ eNB

38.413

The purpose of the Initial Context Setup procedure is to establish the necessary overall initial UE Context at the NG-RAN node, when required, including PDU session context, the Security Key, Mobility Restriction List, UE Radio Capability and UE Security Capabilities, etc.

The AMF initiates a session setup with the gNB. The message typically contains the Registration Accept NAS message. The message carries one or more PDU Session setup requests. Each PDU session is addressed with the "PDU Session ID".

Field Type
Message Type
AMF UE NGAP ID
RAN UE NGAP ID
Old AMF AMF Name
UE Aggregate Maximum Bit Rate
Core Network Assistance Information
GUAMI
PDU Session Resource Setup Request List

PDU Session Resource Setup Request Item [PDU Session Id]

Field Type
NAS-PDU
PDU Session ID
S-NSSAI
PDU Session Resource Setup Request Transfer OCTET STRING
Field Type
Allowed NSSAI
UE Security Capabilities
Security Key
Trace Activation
Mobility Restriction List
UE Radio Capability
Index to RAT/Frequency Selection Priority
Masked IMEISV
NAS-PDU
Emergency Fallback Indicator
RRC Inactive Transition Report Request

Registration Accept

New AMF ➔ Initial Context Setup Request ➔ gNB ➔ RRCReconfiguration ➔ UE

TS 24.501

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Registration accept message identity
5GS registration result
5G-GUTI 5GS mobile identity
Equivalent PLMNs PLMN list
TAI list 5GS tracking area identity list
Allowed NSSAI NSSAI
Rejected NSSAI
Configured NSSAI NSSAI
5GS network feature support
PDU session status
PDU session reactivation result
PDU session reactivation result error cause
LADN information
MICO indication
Network slicing indication
Service area list
T3512 value GPS timer 3
Non-3GPP de-registration timer value GPRS timer 2
T3502 value GPRS timer 2
Emergency number list
Extended emergency number list
SOR transparent container
EAP message

SecurityModeCommand

gNB ➔ UE

38.331

The SecurityModeCommand message is used to command the activation of AS security.

The UE performs the following actions on receiving the Security Mode Command:

Reference: 3GPP TS 33.501 V15.2.0 (2018-09)

SecurityModeCommand ::=             SEQUENCE {
    rrc-TransactionIdentifier           RRC-TransactionIdentifier,
    criticalExtensions                  CHOICE {
        securityModeCommand                 SecurityModeCommand-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

SecurityModeCommand-IEs ::=         SEQUENCE {
    securityConfigSMC                   SecurityConfigSMC,

    lateNonCriticalExtension            OCTET STRING         OPTIONAL,
    nonCriticalExtension                SEQUENCE{}           OPTIONAL
}

SecurityConfigSMC ::=               SEQUENCE {
    securityAlgorithmConfig             SecurityAlgorithmConfig,
    ...
}

SecurityModeComplete

UE ➔ gNB

38.331

The SecurityModeComplete message is used to confirm the successful completion of a security mode command. Ciphering will be enabled after sending this message. The Security Mode Complete message is itself not ciphered. The message is however integrity protected.

SecurityModeComplete ::=            SEQUENCE {
    rrc-TransactionIdentifier           RRC-TransactionIdentifier,
    criticalExtensions                  CHOICE {
        securityModeComplete                SecurityModeComplete-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

SecurityModeComplete-IEs ::=        SEQUENCE {
    lateNonCriticalExtension            OCTET STRING         OPTIONAL,
    nonCriticalExtension                SEQUENCE{}           OPTIONAL
}

RRCReconfiguration

gNB ➔ UE

38.331

The purpose of this message is to modify an RRC connection, e.g. to establish/modify/release RBs, to perform reconfiguration with sync, to setup/modify/release measurements, to add/modify/release SCells and cell groups. As part of the procedure, NAS dedicated information may be transferred from the Network to the UE.

The message carries the following fields:

RRCReconfiguration ::=              SEQUENCE {
    rrc-TransactionIdentifier           RRC-TransactionIdentifier,
    criticalExtensions                  CHOICE {
        rrcReconfiguration                  RRCReconfiguration-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

RRCReconfiguration-IEs ::=          SEQUENCE {
    radioBearerConfig                       RadioBearerConfig                                      OPTIONAL, -- Need M
    secondaryCellGroup                      OCTET STRING (CONTAINING CellGroupConfig)              OPTIONAL, -- Need M
    measConfig                              MeasConfig                                             OPTIONAL, -- Need M
    lateNonCriticalExtension                OCTET STRING                                           OPTIONAL,
    nonCriticalExtension                    RRCReconfiguration-v1530-IEs                           OPTIONAL
}

RRCReconfiguration-v1530-IEs ::=            SEQUENCE {
    masterCellGroup                         OCTET STRING (CONTAINING CellGroupConfig)              OPTIONAL, -- Need M
    fullConfig                              ENUMERATED {true}                                      OPTIONAL, -- Cond FullConfig
    dedicatedNAS-MessageList                SEQUENCE (SIZE(1..maxDRB)) OF DedicatedNAS-Message     OPTIONAL, -- Cond nonHO
    masterKeyUpdate                         MasterKeyUpdate                                        OPTIONAL, -- Cond MasterKeyChange
    dedicatedSIB1-Delivery                  OCTET STRING (CONTAINING SIB1)                         OPTIONAL, -- Need N
    dedicatedSystemInformationDelivery      OCTET STRING (CONTAINING SystemInformation)            OPTIONAL, -- Need N
    otherConfig                             OtherConfig                                            OPTIONAL,   -- Need N
    nonCriticalExtension                    SEQUENCE {}                                            OPTIONAL
}

MasterKeyUpdate ::=                 SEQUENCE {
    keySetChangeIndicator           BOOLEAN,
    nextHopChainingCount            NextHopChainingCount,
    nas-Container                   OCTET STRING                                                   OPTIONAL,    -- Cond securityNASC
    ...
}

MeasConfig

MeasConfig ::=                      SEQUENCE {
    measObjectToRemoveList              MeasObjectToRemoveList                OPTIONAL,   -- Need N
    measObjectToAddModList              MeasObjectToAddModList                OPTIONAL,   -- Need N

    reportConfigToRemoveList            ReportConfigToRemoveList              OPTIONAL,   -- Need N
    reportConfigToAddModList            ReportConfigToAddModList              OPTIONAL,   -- Need N

    measIdToRemoveList                  MeasIdToRemoveList                    OPTIONAL,   -- Need N
    measIdToAddModList                  MeasIdToAddModList                    OPTIONAL,   -- Need N

    s-MeasureConfig                     CHOICE {
        ssb-RSRP                            RSRP-Range,
        csi-RSRP                            RSRP-Range
    }         OPTIONAL,   -- Need M

    quantityConfig                      QuantityConfig                        OPTIONAL,   -- Need M

    measGapConfig                       MeasGapConfig                         OPTIONAL,   -- Need M
    measGapSharingConfig                    MeasGapSharingConfig              OPTIONAL,   -- Need M
    ...
}

MeasObjectToRemoveList ::=              SEQUENCE (SIZE (1..maxNrofObjectId)) OF MeasObjectId

MeasIdToRemoveList ::=                  SEQUENCE (SIZE (1..maxNrofMeasId)) OF MeasId

ReportConfigToRemoveList ::=            SEQUENCE (SIZE (1..maxReportConfigId)) OF ReportConfigId

RRCReconfigurationComplete

gNB ➔ New AMF

38.331

The RRC Reconfiguration Complete message is used to confirm the successful completion of an RRC connection reconfiguration.

RRCReconfigurationComplete ::=              SEQUENCE {
    rrc-TransactionIdentifier                   RRC-TransactionIdentifier,
    criticalExtensions                          CHOICE {
        rrcReconfigurationComplete                  RRCReconfigurationComplete-IEs,
        criticalExtensionsFuture                    SEQUENCE {}
    }
}

RRCReconfigurationComplete-IEs ::=          SEQUENCE {
    lateNonCriticalExtension                    OCTET STRING                              OPTIONAL,
    nonCriticalExtension                        RRCReconfigurationComplete-v1530-IEs      OPTIONAL
}

RRCReconfigurationComplete-v1530-IEs ::=    SEQUENCE {
    uplinkTxDirectCurrentList                   UplinkTxDirectCurrentList                 OPTIONAL,
    nonCriticalExtension                        SEQUENCE {}                               OPTIONAL
}

UplinkTxDirectCurrentList

UplinkTxDirectCurrentList ::=           SEQUENCE (SIZE (1..maxNrofServingCells)) OF UplinkTxDirectCurrentCell

UplinkTxDirectCurrentCell ::=           SEQUENCE {
    servCellIndex                           ServCellIndex,
    uplinkDirectCurrentBWP                  SEQUENCE (SIZE (1..maxNrofBWPs)) OF UplinkTxDirectCurrentBWP,
    ...
}

UplinkTxDirectCurrentBWP ::=            SEQUENCE {
    bwp-Id                                  BWP-Id,
    shift7dot5kHz                           BOOLEAN,
    txDirectCurrentLocation             INTEGER (0..3301)
}

Initial Context Setup Response

eNB ➔ AMF

38.413

This message is sent by the NG-RAN node to confirm the setup of a UE context.

Field Description
Message Type
AMF UE NGAP ID Identifes the UE context on the AMF.
RAN UE NGAP ID Identifies the UE context on the RAN (gNB)
PDU Session Resource Setup Response List

PDU Session Resource Setup Response Item [PDU Session Id]

Field Description
PDU Session ID Identifies a PDU session
PDU Session Resource Setup Response Transfer

PDU Session Resource Failed to Setup List

PDU Session Resource Failed to Setup Item [PDU Session ID]

Field Description
PDU Session ID Identifies PDU session
PDU Session Resource Setup Unsuccessful Transfer

Criticality Diagnostics

Registration Complete

UE ➔ ULInformationTransfer ➔ gNB ➔ UL NAS Transport ➔ New AMF

TS 24.501

Field Type
Extended protocol discriminator
Security header type
Spare half octet
Registration complete message identity Message type
SOR transparent container

Nsmf_PDUSession_UpdateSMContext Request

New AMF ➔ SMF

TS 23.502

This message updates the AMF-SMF association to support a PDU Session. The message also provides SMF with N1/N2 SM information received from the UE or from the AN.

Input Presence
SUPI Required
Operation Type
  • UP activate
  • UP deactivate
  • UP To Be Switched
PDU Session ID Optional
N1 SM container received from the UE Optional
N2 SM information received from the AN Optional
Serving GW Address(es) and Serving GW DL TEID(s)
for data forwarding during HO from 5GS to EPS.		 Optional
UE location information Optional
AN type Optional
UE Time Zone Optional
H-SMF identifier/address Optional
EBI(s) to be revoked, PDU Session(s) to be re-activated Optional
Direct Forwarding Flag Optional
ARP list Optional
S-NSSAI Optional
Data Forwarding Tunnel (setup/release) Optional
UE presence in LADN service area Optional
Target ID Optional
Target AMF ID Optional
GUAMI Optional
Backup AMF(s) (if NF Type is AMF) Optional

PFCP Session Modification Request

SMF ➔ UPF

TS 29.244

The PFCP Session Modification Request is used over the Sxa, Sxb, Sxc and N4 interface by the CP function to request the UP function to modify the PFCP session.

Information Element Description
CP F-SEID Change the fully qualified Session Id
Remove PDR Remove Packet Detection Rule
Remove FAR Remove Forwarding Action Rule
Remove URR Remove Usage Reporting Rule
Remove QER Remove QoS Enforcement Rule
Remove BAR Remove Buffering Action Rule
Remove Traffic Endpoint
Create PDR Create Packet Detection Rule
Create FAR Create Forwarding Action Rule
Create URR Create Usage Reporting Rule
Create QER Create QoS Enforcement Rule
Create BAR Create Buffering Action Rule
Create Traffic Endpoint
Update PDR Update Packet Detection Rule
Update FAR Update Forwarding Action Rule
Update URR Update Usage Reporting Rule
Update QER Update QoS Enforcement Rule
Update BAR Update Buffering Action Rule
Update Traffic Endpoint
PFCPSMReq-Flags Update flags:
  • DROBU (Drop Buffered Packets)
  • QAURR (Query All URRs)
Query URR Query Usage Reporting Rule
User Plane Inactivity Timer
Query URR Reference Query Usage Reporting Rule Reference
Trace Information

PFCP Session Modification Response

UPF ➔ SMF

TS 29.244

The PFCP Session Modification Response shall be sent over the Sxa, Sxb, Sxc and N4 interface by the UP function to the CP function as a reply to the PFCP Session Modification Request.

Information Element Description
Cause Cause of acceptance or rejection of request
Offending IE Included if rejecting due to an error in a specific IE of the request.
Create PDR Create Packet Detection Rule
Load Control Information
Overload Control Information
Usage Report
Failed Rule ID This IE shall be included if the Cause IE indicates a rejection due to a rule creation or modification failure.
Additional Usage Reports Information
Created/Updated Traffic Endpoint

Nsmf_PDUSession_UpdateSMContext Response

SMF ➔ New AMF

TS 23.502

Output Presence
Result Indication Required
PDU Session ID Optional
Cause Optional
released EBI list Optional
allocated EBI information Optional
N2 SM information Optional
N1 SM container to be transferred to the AN/UE Optional

NAS Transport

NAS traffic between the UE and the AMF is carried over NAS carrier messages in downlink and uplink.

DL NAS Transport

New AMF ➔ gNB

TS 24.501

Field Type
Extended protocol discriminator
Security header type
Spare half octet
DL NAS TRANSPORT message identity Message type
Payload container type
Spare half octet
Payload container
PDU session ID PDU session identity 2
Additional information
5GMM cause
Back-off timer value GPRS Timer 3

DLInformationTransfer

gNB ➔ UE

38.331

DLInformationTransfer ::=           SEQUENCE {
    rrc-TransactionIdentifier           RRC-TransactionIdentifier,
    criticalExtensions                  CHOICE {
        dlInformationTransfer           DLInformationTransfer-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

DLInformationTransfer-IEs ::=   SEQUENCE {
    dedicatedNAS-Message                DedicatedNAS-Message    OPTIONAL,   -- Need N
    lateNonCriticalExtension            OCTET STRING            OPTIONAL,
    nonCriticalExtension                SEQUENCE {} OPTIONAL
}

ULInformationTransfer

UE ➔ gNB

38.331

ULInformationTransfer ::=           SEQUENCE {
    criticalExtensions                  CHOICE {
        ulInformationTransfer           ULInformationTransfer-IEs,
        criticalExtensionsFuture            SEQUENCE {}
    }
}

ULInformationTransfer-IEs ::=   SEQUENCE {
    dedicatedNAS-Message                DedicatedNAS-Message                OPTIONAL,
    lateNonCriticalExtension            OCTET STRING                        OPTIONAL,
    nonCriticalExtension                SEQUENCE {}                         OPTIONAL
}

UL NAS Transport

gNB ➔ New AMF

TS 24.501

Field Type
Extended protocol discriminator
Security header type
Spare half octet
UL NAS TRANSPORT message identity Message type
Payload container type
Spare half octet
Payload container
PDU session ID PDU session identity 2
Old PDU session ID PDU session identity 2
Request type
S-NSSAI
DNN
Additional information

5G Identifiers

Identifier 4G Equivalent Description
SUPI IMSI Subscription Permanent Identifier is assigned to each subscriber accessing the 5G network.
SUCI P-TMSI + MCC + MNC Subscription Concealed Identifier is a global identifier that can keep the UE identity concealed. SUCI can also be used by visiting networks to get authentication vectors from the home network.
PEI IMEI Permanent Equipment Identifier is assigned to each UE accessing the 5G network.
GPSI Generic Public Subscription Identifier is used for addressing a 3GPP subscription in non-3GPP networks.
5G-GUTI GUTI Unique global identifier for the UE that does not reveal the SUPI.
5G-S-TMSI S-TMSI Shortened form of 5G-GUTI that is used in radio signaling procedures.
<5G-S-TMSI> = <AMF Set ID><AMF Pointer><5G-TMSI>

PFCP

TS 29.244

The Packet Forwarding Control Protocol (PFCP) standardizes the signaling between control plane and the user plane functions. PDCP is used on the N4 interface between the Session Management Function (SMF) and the User Plane Function (UPF).

PFCP Header

Field Length (Octets)
Version/MP/S 1
Message type 1
Session Endpoint Identifier 8
Sequence Number 3
Message Priority/Spare 1

PFCP Messages

Packet Forwarding Control Protocol defines the following messages for Sxa, Sxb, Sxc and N4 interfaces.

Value Message Sxa Sxb Sxc N4
0 Reserved
PFCP Node related messages
1 PFCP Heartbeat Request X X X X
2 PFCP Heartbeat Response X X X X
3 PFCP PFD Management Request - X X X
4 PFCP PFD Management Response - X X X
5 PFCP Association Setup Request X X X X
6 PFCP Association Setup Response X X X X
7 PFCP Association Update Request X X X X
8 PFCP Association Update Response X X X X
9 PFCP Association Release Request X X X X
10 PFCP Association Release Response X X X X
11 PFCP Version Not Supported Response X X X X
12 PFCP Node Report Request X X X X
13 PFCP Node Report Response X X X X
14 PFCP Session Set Deletion Request X X - -
15 PFCP Session Set Deletion Response X X - -
16 to 49 For future use
PFCP Session related messages
50 PFCP Session Establishment Request X X X X
51 PFCP Session Establishment Response X X X X
52 PFCP Session Modification Request X X X X
53 PFCP Session Modification Response X X X X
54 PFCP Session Deletion Request X X X X
55 PFCP Session Deletion Response X X X X
56 PFCP Session Report Request X X X X
57 PFCP Session Report Response X X X X
58 to 99 For future use
Other messages
100 to 255 For future use

5G specifications

Specification Version Description
TS 23.502 V15.3.0 (2018-09) Procedures for the 5G System
TS 24.501 V15.1.0 (2018-09) Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3
TS 29.244 V15.3.0 (2018-09) Interface between the Control Plane and the User Plane nodes
TS 29.503 V15.1.0 (2018-09) 5G System; Unified Data Management Services; Stage 3
TS 29.507 V15.1.0 (2018-09) 5G System; Access and Mobility Policy Control Service; Stage 3
TS 29.513 V15.1.0 (2018-09) 5G System; Policy and Charging Control signalling flows and QoS parameter mapping; Stage 3
TS 29.514 V15.1.0 (2018-09) 5G System; Policy Authorization Service; Stage 3
TS 29.518 V15.1.0 (2018-09) 5G System; Access and Mobility Management Services; Stage 3
TS 33.501 V15.2.0 (2018-09) Security architecture and procedures for 5G System
TS 38.211 V15.3.0 (2018-09) NR; Physical channels and modulation
TS 38.212 V15.3.0 (2018-09) NR; Multiplexing and channel coding
TS 38.213 V15.3.0 (2018-09) NR; Physical layer procedures for control
TS 38.321 V15.3.0 (2018-09) NR; Medium Access Control (MAC) protocol specification
TS 38.331 V15.3.0 (2018-09) NR; Radio Resource Control (RRC); Protocol specification
TS 38.413 V15.1.0 (2018-09) NG-RAN; NG Application Protocol (NGAP)