The Access and Mobility Management function (AMF) includes the following functionality. Some or all of the AMF functionalities may be supported in a single instance of an AMF:

• Termination of RAN CP interface (N2).
• Termination of NAS (N1), NAS ciphering and integrity protection.
• Registration management.
• Connection management.
• Reachability management.
• Mobility Management.
• Lawful intercept (for AMF events and interface to LI System).
• Provide transport for SM messages between UE and SMF.
• Transparent proxy for routing SM messages.
• Access Authentication.
• Access Authorization.
• Provide transport for SMS messages between UE and SMSF.
• Security Anchor Functionality (SEAF) as specified in TS 33.501.
• Location Services management for regulatory services.
• Provide transport for Location Services messages between UE and LMF as well as between RAN and LMF.
• EPS Bearer ID allocation for interworking with EPS.
• UE mobility event notification.
• S-NSSAIs per TA mapping notification.
• Support for Control Plane CIoT 5GS Optimisation.
• Support for User Plane CIoT 5GS Optimisation.
• Support for restriction of use of Enhanced Coverage.
• Provisioning of external parameters (Expected UE Behaviour parameters or Network Configuration parameters).
• Support for Network Slice-Specific Authentication and Authorization.
• Support for charging.
• Controlling the 5G access stratum-based time distribution based on UE's subscription data.
• Controlling the gNB's time synchronization status reporting and subscription.

In addition to the functionalities of the AMF described above, the AMF may include the following functionality to support non-3GPP access networks:

• Support of N2 interface with N3IWF/TNGF. Over this interface, some information (e.g. 3GPP Cell Identification) and procedures (e.g. Handover related) defined over 3GPP access may not apply, and non-3GPP access specific information may be applied that do not apply to 3GPP accesses.
• Support of NAS signalling with a UE over N3IWF/TNGF. Some procedures supported by NAS signalling over 3GPP access may be not applicable to untrusted non-3GPP (e.g. Paging) access.
• Support of authentication of UEs connected over N3IWF/TNGF.
• Management of mobility, authentication, and separate security context state(s) of a UE connected via a non-3GPP access or connected via a 3GPP access and a non-3GPP access simultaneously.
• Support as described in clause 5.3.2.3 a co-ordinated RM management context valid over a 3GPP access and a Non 3GPP access.
• Support as described in clause 5.3.3.4 dedicated CM management contexts for the UE for connectivity over non-3GPP access.
• Determine whether the serving N3IWF/TNGF is appropriate based on the slices supported by the N3IWFs/TNGFs as specified in clause 6.3.6 and clause 6.3.12 respectively.

In addition to the functionalities of the AMF described above, the AMF may include policy related functionalities as described in clause 6.2.8 of TS 23.503. The AMF uses the N14 interface for AMF re-allocation and AMF to AMF information transfer. This interface may be either intra-PLMN or inter-PLMN (e.g. in the case of inter-PLMN mobility). In addition to the functionality of the AMF described above, the AMF may include the following functionality to support monitoring in roaming scenarios:

• Normalization of reports according to roaming agreements between VPLMN and HPLMN (e.g. change the location granularity in a report from cell level to a level that is appropriate for the HPLMN); and
• Generation of charging/accounting information for Monitoring Event Reports that are sent to the HPLMN.

In addition to the functionality of the AMF described above, the AMF may provide support for Network Slice restriction and Network Slice instance restriction based on NWDAF analytics. In addition to the functionalities of the AMF described above, the AMF may provide support for the Disaster Roaming as described in clause 5.40. In addition to the functionalities of the AMF described above, the AMF may also include following functionalities to support Network Slice Admission Control:

• Support of NSAC for maximum number of UEs as defined in clauses 5.15.11.1 and 5.15.11.3.

In addition to the functionality of the AMF described above, the AMF may include the following functionality to support SNPNs:

• Support for Onboarding of UEs for SNPNs.

In addition to the functionalities of the AMF described above, the AMF may also include following functionalities to support satellite backhaul:

• Support for reporting satellite backhaul category (i.e. GEO, MEO, LEO or OTHERSAT) and its modification based on AMF local configuration to SMF as defined in clause 5.8.2.15.

In addition to the functionalities of the AMF described above, the AMF may provide support for Network Slice instance change for PDU sessions as defined in clause 5.15.5.3. In addition to the functionalities of the AMF described above, the AMF may also support functionalities for Partial Network Slice support in a Registration Area as described in clause 5.15.17. In addition to the functionalities of the AMF described above, the AMF may also include functionalities to support NS-AoS not matching deployed Tracking Areas as described in clause 5.15.18. In addition to the functionalities of the AMF described above, the AMF may also include functionalities to support Network Slice Replacement as described in clause 5.15.19.

The Session Management function (SMF) includes the following functionality. Some or all of the SMF functionalities may be supported in a single instance of a SMF:

• Session Management e.g. Session Establishment, modify and release, including tunnel maintain between UPF and AN node.
• UE IP address allocation & management (including optional Authorization). The UE IP address may be received from a UPF or from an external data network.
• DHCPv4 (server and client) and DHCPv6 (server and client) functions.
• Functionality to respond to Address Resolution Protocol (ARP) requests and / or IPv6 Neighbour Solicitation requests based on local cache information for the Ethernet PDUs. The SMF responds to the ARP and / or the IPv6 Neighbour Solicitation Request by providing the MAC address corresponding to the IP address sent in the request.
• Selection and control of UP function, including controlling the UPF to proxy ARP or IPv6 Neighbour Discovery, or to forward all ARP/IPv6 Neighbour Solicitation traffic to the SMF, for Ethernet PDU Sessions.
• Configures traffic steering at UPF to route traffic to proper destination.
• 5G VN group management, e.g. maintain the topology of the involved PSA UPFs, establish and release the N19 tunnels between PSA UPFs, configure traffic forwarding at UPF to apply local switching, N6-based forwarding or N19-based forwarding, manage traffic forwarding in the case that a SMF Set or multiple SMF Sets are serving a 5G VN.
• Termination of interfaces towards Policy control functions.
• Lawful intercept (for SM events and interface to LI System).
• Support for charging.
• Control and coordination of charging data collection at UPF.
• Termination of SM parts of NAS messages.
• Downlink Data Notification.
• Initiator of AN specific SM information, sent via AMF over N2 to AN.
• Determine SSC mode of a session.
• Support for Control Plane CIoT 5GS Optimisation.
• Support of header compression.
• Act as I-SMF in deployments where I-SMF can be inserted, removed and relocated.
• Provisioning of external parameters (Expected UE Behaviour parameters or Network Configuration parameters).
• Support P-CSCF discovery for IMS services.
• Act as V-SMF with following roaming functionalities:
  • Handle local enforcement to apply QoS SLAs (VPLMN).
  • Charging (VPLMN).
  • Lawful intercept (in VPLMN for SM events and interface to LI System).
• Support for interaction with external DN for transport of signalling for PDU Session authentication/authorization by external DN.
• Instructs UPF and NG-RAN to perform redundant transmission on N3/N9 interfaces.
• Generation of the TSC Assistance Information based on the TSC Assistance Container received from the PCF.
• Support for RAN feedback for BAT offset and adjusted periodicity as defined in clause 5.27.2.5.

In addition to the functionalities of the SMF described above, the SMF may include policy related functionalities as described in clause 6.2.2 of TS 23.503. In addition to the functionality of the SMF described above, the SMF may include the following functionality to support monitoring in roaming scenarios:

• Normalization of reports according to roaming agreements between VPLMN and HPLMN; and
• Generation of charging information for Monitoring Event Reports that are sent to the HPLMN.

The SMF may also include following functionalities to support Edge Computing enhancements (further defined in TS 23.548):

• Selection of EASDF and provision of its address to the UE as the DNS Server for the PDU session;
• Usage of EASDF services as defined in TS 23.548;
• For supporting the Application Layer Architecture defined in TS 23.558: Provision and updates of ECS Address Configuration Information to the UE.

The SMF and SMF+ PGW-C may also include following functionalities to support Network Slice Admission Control:

• Support of NSAC for maximum number of PDU sessions as defined in clauses 5.15.11.2, 5.15.11.3 and 5.15.11.5.
• Support of NSAC for maximum number of UEs as defined in clauses 5.15.11.3 and 5.15.11.5.
• Support of PDU Set based QoS handling as described in clause 5.37.5.

The SMF may also include following functionalities:

• Providing per-QoS flow Non-3GPP QoS assistance information to the UE (e.g. PEGC) and formulation of the CN PDB based on non-3GPP delay budget from UE (e.g. PEGC) as described in clause 5.44.3.4.

In addition to the functionalities of the SMF described above, the SMF may also include functionalities to support Network Slice Replacement as described in clause 5.15.19.

The User plane function (UPF) includes the following functionality. Some or all of the UPF functionalities may be supported in a single instance of a UPF:

• Anchor point for Intra-/Inter-RAT mobility (when applicable).
• Allocation of UE IP address/prefix (if supported) in response to SMF request.
• External PDU Session point of interconnect to Data Network.
• Packet routing & forwarding (e.g. support of Uplink classifier to route traffic flows to an instance of a data network, support of Branching point to support multi-homed PDU Session, support of traffic forwarding within a 5G VN group (UPF local switching, via N6, via N19)).
• Packet inspection (e.g. Application detection based on service data flow template and the optional PFDs received from the SMF in addition).
• User Plane part of policy rule enforcement, e.g. Gating, Redirection, Traffic steering).
• Lawful intercept (UP collection).
• Traffic usage reporting.
• QoS handling for user plane, e.g. UL/DL rate enforcement, Reflective QoS marking in DL.
• Uplink Traffic verification (SDF to QoS Flow mapping).
• Transport level packet marking in the uplink and downlink.
• Downlink packet buffering and downlink data notification triggering.
• Sending and forwarding of one or more "end marker" to the source NG-RAN node.
• Functionality to respond to Address Resolution Protocol (ARP) requests and / or IPv6 Neighbour Solicitation requests based on local cache information for the Ethernet PDUs. The UPF responds to the ARP and / or the IPv6 Neighbour Solicitation Request by providing the MAC address corresponding to the IP address sent in the request.
• Packet duplication in downlink direction and elimination in uplink direction in GTP-U layer.
• NW-TT functionality.
• High latency communication, see clause 5.31.8.
• ATSSS Steering functionality to steer the MA PDU Session traffic, refer to clause 5.32.6.
• Inter PLMN UP Security (IPUPS) functionality, specified in clause 5.8.2.14.
• event exposure, including exposure of network information, i.e. the QoS monitoring information, as specified in clause 5.8.2.18, events as specified in clause 5.2.26.2 of TS 23.502, exposure of data collected for analytics, as specified in clause 5.2.26.2 of TS 23.502 and exposure of the TSC management information as specified in clause 5.8.5.14.
• Exposure of the UE IP address translation information as specified in clause 5.2.26.3 of TS 23.502 and clause 4.15.10 of TS 23.502 if Network address translation (i.e. NAT) functionality of the UE IP address is deployed within UPF.
• Support PDU Set Handling as defined in clause 5.37.5.

The Policy Control Function (PCF) includes the following functionality:

• Supports unified policy framework to govern network behaviour.
• Provides policy rules to Control Plane function(s) to enforce them.
• Accesses subscription information relevant for policy decisions in a Unified Data Repository (UDR).
• Support PDU Set Handling as defined in clause 5.37.5.

The details of the PCF functionality are defined in clause 6.2.1 of TS 23.503.

The Unified Data Management (UDM) includes support for the following functionality:

• Generation of 3GPP AKA Authentication Credentials.
• User Identification Handling (e.g. storage and management of SUPI for each subscriber in the 5G system).
• Support of de-concealment of privacy-protected subscription identifier (SUCI).
• Access authorization based on subscription data (e.g. roaming restrictions).
• UE's Serving NF Registration Management (e.g. storing serving AMF for UE, storing serving SMF for UE's PDU Session).
• Support to service/session continuity e.g. by keeping SMF/DNN assignment of ongoing sessions.
• MT-SMS delivery support.
• Lawful Intercept Functionality (especially in outbound roaming case where UDM is the only point of contact for LI).
• Subscription management.
• SMS management.
• 5G-VN group management handling.
• Support of external parameter provisioning (Expected UE Behaviour parameters or Network Configuration parameters).
• Support for the Disaster Roaming as described in clause 5.40.
• Support for the control of time synchronization service based on subscription data as described in clause 5.27.1.11.

To provide this functionality, the UDM uses subscription data (including authentication data) that may be stored in UDR, in which case a UDM implements the application logic and does not require an internal user data storage and then several different UDMs may serve the same user in different transactions.

The Authentication Server Function (AUSF) supports the following functionality:

• Supports authentication for 3GPP access and untrusted non-3GPP access as specified in TS 33.501.
• Supports authentication of UE for a Disaster Roaming service as specified in TS 33.501.

The functionality of N3IWF in the case of untrusted non-3GPP access includes the following:

• Support of IPsec tunnel establishment with the UE: The N3IWF terminates the IKEv2/IPsec protocols with the UE over NWu and relays over N2 the information needed to authenticate the UE and authorize its access to the 5G Core Network.
• Termination of N2 and N3 interfaces to 5G Core Network for control - plane and user-plane respectively.
• Relaying uplink and downlink control-plane NAS (N1) signalling between the UE and AMF.
• Handling of N2 signalling from SMF (relayed by AMF) related to PDU Sessions and QoS.
• Establishment of IPsec Security Association (IPsec SA) to support PDU Session traffic.
• Relaying uplink and downlink user-plane packets between the UE and UPF. This involves:
  • De-capsulation/ encapsulation of packets for IPSec and N3 tunnelling.
• Enforcing QoS corresponding to N3 packet marking (e.g. DSCP), taking into account QoS requirements associated to such marking received over N2. QoS includes 5QI, the Priority Level (if explicitly signalled) and optionally, the ARP priority level.
• Packet marking, e.g. setting the DSCP value based on the Establishment cause on N2, and based on 5QI, the Priority Level (if explicitly signalled) and optionally, the ARP priority level on N3.
• Local mobility anchor within untrusted non-3GPP access networks using MOBIKE per RFC 4555.
• Supporting AMF selection.

The functionality of TNGF in the case of trusted non-3GPP access includes the following:

• Terminates the N2 and N3 interfaces.
• Terminates the EAP-5G signalling and behaves as authenticator when the UE attempts to register to 5GC via the TNAN.
• Implements the AMF selection procedure.
• Transparently relays NAS messages between the UE and the AMF, via NWt.
• Handles N2 signalling with SMF (relayed by AMF) for supporting PDU sessions and QoS.
• Transparently relays PDU data units between the UE and UPF(s).
• Implements a local mobility anchor within the TNAN.
• Packet marking in the downlink, and the uplink on N2 and N3, as for the N3IWF (clause 6.2.9).

The Application Function (AF) interacts with the 3GPP Core Network in order to provide services, for example to support the following:

• Application Function influence on traffic routing (see clause 5.6.7);
• Application Function influence on Service Function Chaining (see clause 5.6.16.2);
• Accessing Network Exposure Function (see clause 5.20);
• Interacting with the Policy and charging control framework (see clause 5.14);
• Time synchronization service (see clause 5.27.1.8);
• IMS interactions with 5GC (see clause 5.16).
• Support PDU Set Handling as defined in clause 5.37.5.

Based on operator deployment, Application Functions considered to be trusted by the operator can be allowed to interact directly with relevant Network Functions. Application Functions not allowed by the operator to access directly the Network Functions shall use the external exposure framework (see clause 7.3) via the NEF to interact with relevant Network Functions. The functionality and purpose of Application Functions are only defined in this specification with respect to their interaction with the 3GPP Core Network.

The Unified Data Repository (UDR) supports the following functionality:

• Storage and retrieval of subscription data by the UDM.
• Storage and retrieval of policy data by the PCF.
• Storage and retrieval of structured data for exposure.
• Application data (including Packet Flow Descriptions (PFDs) for application detection, AF request information for multiple UEs, 5G-VN group information for 5G-VN management).
• Storage and retrieval of NF Group ID corresponding to subscriber identifier (e.g. IMPI, IMPU, SUPI).

The Unified Data Repository is located in the same PLMN as the NF service consumers storing in and retrieving data from it using Nudr. Nudr is an intra-PLMN interface.

The UDSF is an optional function that supports the following functionality:

• Storage and retrieval of information as unstructured data by any NF. Notify a NF consumer if information validity has expired.
• Timer service to any NF.

The SMSF supports the following functionality to support SMS over NAS:

• SMS management subscription data checking and conducting SMS delivery accordingly.
• SM-RP/SM-CP with the UE (see TS 24.011).
• Relay the SM from UE toward SMS-GMSC/IWMSC/SMS-Router.
• Relay the SM from SMS-GMSC/IWMSC/SMS-Router toward the UE.
• SMS charging.
• Lawful Interception.
• Interaction with AMF and SMS-GMSC for notification procedure that the UE is unavailable for SMS transfer (i.e, notifies SMS-GMSC to inform UDM when UE is unavailable for SMS).

The Network Slice Selection Function (NSSF) supports the following functionality:

• Selecting the set of Network Slice instances serving the UE;
• Determining the Allowed NSSAI and, if needed, the mapping to the Subscribed S-NSSAIs;
• Determining the Configured NSSAI and, if needed, the mapping to the Subscribed S-NSSAIs;
• Determining the AMF Set to be used to serve the UE, or, based on configuration, a list of candidate AMF(s), possibly by querying the NRF;
• The NSSF may provide support for Network Slice restriction and Network Slice instance restriction based on NWDAF analytics.
• Determining whether an S-NSSAI has to be replaced and providing to the AMF the indication that the S-NSSAI is unavailable and a corresponding Alternative S-NSSAI, e.g. based on received NWDAF analytics (e.g. for Service Experience for a Network Slice or Slice load level), or local trigger from the OAM system.

The 5G-EIR is an optional network function that supports the following functionality:

• Check the status of PEI (e.g. to check that it has not been prohibited).

The functionality of LMF is defined in clause 4.3.8 of TS 23.273.

The functionality of GMLC is defined in clause 4.3.8 of TS 23.273.

The Security Edge Protection Proxy (SEPP) is a non-transparent proxy and supports the following functionality:

• Message filtering and policing on inter-PLMN control plane interfaces.
• Topology hiding.

Detailed functionality of SEPP, related flows and the N32 reference point, are specified in TS 33.501. The SEPP applies the above functionality to every Control Plane message in inter-PLMN signalling, acting as a service relay between the actual Service Producer and the actual Service Consumer. For both Service Producer and Consumer, the result of the service relaying is equivalent to a direct service interaction. Every Control Plane message in inter-PLMN signalling between the SEPPs may pass via IPX entities. More details on SEPPs and the IPX entities are described in TS 29.500 and TS 33.501.

NWDAF represents operator managed network analytics logical function. The NWDAF includes the following functionality:

• Support data collection from NFs and AFs;
• Support data collection from OAM;
• NWDAF service registration and metadata exposure to NFs and AFs;
• Support analytics information provisioning to NFs and AFs;
• Support Machine Learning (ML) model training and provisioning to NWDAFs (containing Analytics logical function);
• Support accuracy information about Analytics IDs provisioning for NFs;
• Support accuracy information about ML model provisioning for NFs.
• Support roaming exchange capability to exchange data and analytics between PLMNs.

The details of the NWDAF functionality are defined in TS 23.288.

The Service Communication Proxy (SCP) includes one or more of the following functionalities. Some or all of the SCP functionalities may be supported in a single instance of an SCP:

• Indirect Communication (see clause 7.1.1 for details).
• Delegated Discovery (see clauses 7.1.1 and 6.3.1 for details).
• Message forwarding and routing to destination NF/NF service.
• Message forwarding and routing to a next hop SCP.
• Communication security (e.g. authorization of the NF Service Consumer to access the NF Service Producer API), load balancing, monitoring, overload control, etc.
• Optionally interact with UDR, to resolve the UDM Group ID/UDR Group ID/AUSF Group ID/PCF Group ID/CHF Group ID/HSS Group ID based on UE identity, e.g. SUPI or IMPI/IMPU (see clause 6.3.1 for details).

The SCP may be deployed in a distributed manner. SCPs can be deployed at PLMN level, shared-slice level and slice-specific level. It is left to operator deployment to ensure that SCPs can communicate with relevant NRFs. In order to enable SCPs to route messages through several SCPs (i.e. next SCP hop discovery, see clause 6.3.16), an SCP may register its profile in the NRF. Alternatively, local configuration may be used.

The functionality of W-AGF is specified in TS 23.316.

The UCMF is used for storage of dictionary entries corresponding to either PLMN-assigned or Manufacturer-assigned UE Radio Capability IDs. An AMF may subscribe with the UCMF to obtain from the UCMF new values of UE Radio Capability ID that the UCMF assigns for the purpose of caching them locally. Provisioning of Manufacturer-assigned UE Radio Capability ID entries in the UCMF is performed from an AF that interacts with the UCMF either directly or via the NEF (or via Network Management) using a procedure defined in TS 23.502. A UCMF that serves both EPS and 5GS shall require provisioning the UE Radio Capability ID with the TS 36.331 format or TS 38.331 format or both the formats of the UE radio capabilities. The UCMF also assigns the PLMN-assigned UE Radio Capability ID values. Each PLMN-assigned UE Radio Capability ID is also associated to the TAC of the UE model(s) that it is related to. When an AMF requests the UCMF to assign a UE Radio Capability ID for a set of UE radio capabilities, it indicates the TAC of the UE that the UE Radio Capability information is related to. The UCMF stores a Version ID value for the PLMN assigned UE Radio Capability IDs so it is included in the PLMN assigned UE Radio Capability IDs it assigns. This shall be configured in the UCMF. The UCMF may be provisioned with a dictionary of Manufacturer-assigned UE Radio Capability IDs which include a "Vendor ID" that applies to the Manufacturers of these UE, and a list of TACs for which the PLMN has obtained-Manufacturer-assigned UE Radio Capability IDs. A PLMN-assigned UE Radio Capability IDs is kept in the UCMF storage as long as it is associated with at least a TAC value. When a TAC value is related to a UE model that is earmarked for operation based on Manufacturer assigned UE Radio Capability IDs, this TAC value is disassociated in the UCMF from any PLMN assigned UE Radio Capability IDs. For the case that the PLMN is configured to store PLMN assigned IDs in the Manufacturer Assigned operation requested list defined in clause 4.4.1a, the UCMF does not remove from storage any PLMN assigned UE Radio Capability ID no longer used, and rather quarantines it to avoid any future reassignment. A UCMF dictionary entry shall include also the related UE Radio Capability for Paging for each RAT.

The functionality of Trusted WLAN Interworking Function (TWIF) is specified in clause 4.2.8.5.3.

The Network Slice-specific and SNPN Authentication and Authorization Function (NSSAAF) supports the following functionality:

• Support for Network Slice-Specific Authentication and Authorization as specified in TS 23.502 with a AAA Server (AAA-S). If the AAA-S belongs to a third party, the NSSAAF may contact the AAA-S via a AAA proxy (AAA-P).
• Support for access to SNPN using credentials from Credentials Holder using AAA server (AAA-S) as specified in clause 5.30.2.9.2 or using credentials from Default Credentials Server using AAA server (AAA-S) as specified in clause 5.30.2.10.2. If the Credentials Holder or Default Credentials Server belongs to a third party, the NSSAAF may contact the AAA server via a AAA proxy (AAA-P).

The Data Collection Coordination Function (DCCF) supports the following functionality:

• Determining Data Sources that can provide data for a received data request.
• Determining whether data is already being collected from a data source.
• Instructing a Messaging Framework to send data to consumers or notification endpoints.
• Instructing a Messaging Framework to do formatting and processing of the data sent via the Messaging Framework.
• Formatting and processing of data.
• Sending data to consumers or notification endpoints.
• Registering NWDAFs and ADRFs that are already receiving data from a Data Source.

The DCCF functionality is specified in TS 23.288.

The Messaging Framework Adaptor Function (MFAF) supports the following functionality:

• Interfacing with a DCCF that controls how a messaging framework will process, format and send data to consumers or notification endpoints.
• Receiving data from Data Sources via services offered by those Data Sources.
• Sending data received from Data Sources to a messaging framework (outside the scope of 3GPP).
• Receiving data from a messaging framework (outside the scope of 3GPP).
• Processing, formatting and sending data to specified consumers or notification endpoints.

The MFAF functionality is specified in TS 23.288.

The Analytics Data Repository Function (ADRF) supports the following functionality:

• Storage and retrieval of analytics generated by NWDAFs and collected data.
• Storage and retrieval of ML model files trained by NWDAFs containing MTLF.

The Analytics Data Repository Function (ADRF) is specified in TS 23.288.

The functionality of MB-SMF is specified in TS 23.247.

The functionality of MB-SMF is specified in TS 23.247.

The functionality of MB-SMF is specified in TS 23.247.

The functionality of MB-SMF is specified in TS 23.247.

The Network Slice Admission Control Function (NSACF) supports the following functionality:

• Support of monitoring and controlling the number of registered UEs per network slice.
• Support of monitoring and controlling the number of UEs with at least one PDU Session/PDN Connection per network slice in case of EPC interworking.
• Support of monitoring and controlling the number of established PDU Sessions per network slice.
• Support of event based Network Slice status notification and reports to a consumer NF.
• Acting as a Centralized NSACF in PLMNs deploying a centralized architecture as described in clause 5.15.11.0.
• Support of different type of NSAC modes for roaming UEs for the number of UEs per network slice.
• Support of different type of NSAC modes for roaming UEs for the number of PDU Sessions per network slice.
• Acting as a Primary NSACF in PLMNs deploying a hierarchal architecture as described in clause 5.15.11.0.

The details of the NSACF functionality are defined in clause 5.15.11.

The Time Sensitive Communication and Time Synchronization Function (TSCTSF) supports the following functionality:

• Associating the time synchronization service request (see clause 5.27.1.8) from the NF consumer to the AF sessions with the PCF (the session between the PCF and TSCTSF).
• Controlling time synchronization service request from the NF consumer, (g)PTP-based time distribution and ASTI-based time distribution based on subscription data. The TSCTSF may be pre-configured with one or several PTP instance configurations. For each PTP instance configuration, it may contain:
  • a reference to the PTP instance configuration.
  • PTP profile.
  • PTP domain.
• Detecting and reporting time synchronization service status based on NG-RAN and UPF/NW-TT timing synchronization status information and reporting status updates.
• Managing the DS-TT and NW-TT via exchange of PMIC and UMIC as described in Annex K.
• Detecting availability of 5GS Bridge/Router information (including user plane node ID that applies also for IP type PDU Sessions) as reported by PCF for both Ethernet and IP type PDU Sessions (including the need to (un)subscribe 5GS Bridge/Router information Notification from PCF).
• Creating the TSC Assistance Container based on individual traffic pattern parameters from the NEF/AF or DetNet controller and providing it to the PCF.
• Determining the Requested PDB by subtracting the UE-DS-TT Residence Time from the Requested 5GS Delay provided by the NEF/AF or DetNet controller and providing the determined Requested PDB to the PCF.
• Discovering the AMFs serving the list of TA(s) that comprise the spatial validity condition from the NRF and subscribing to the discovered AMF(s) to receive notifications about presence of the UE in an Area of Interest events determined by the list of TA(s) served by the AMF.
• Discovering the AMF(s) serving a UE or a list of TA(s) and subscribing to gNB's node-level timing synchronization status.
• Obtaining gNB's and UPF's node-level timing synchronization status information as defined in clause 5.27.1.12.
• Determining the spatial validity condition from the requested coverage area by the NEF/AF and enforcing time synchronization service for the requested coverage area.
• Support for RAN feedback for BAT offset and adjusted periodicity as defined in clause 5.27.2.5.
• In the case of support of integration with IETF Deterministic Networking (as depicted in clauses 4.4.8.4 and 5.28.5), acting as a stateful translator function between a DetNet controller and 5G System Network Functions and Procedures, including the NW-TT. This includes exposing the information about the 5GS router to the DetNet controller and mapping 5GS router configuration parameters provided by the DetNet controller to 5G System parameters. The details are defined in clause 5.28.5.

The functionality of 5G DDNMF is defined in TS 23.304.

The functionality of EASDF is defined in TS 23.548.

The TSN AF supports control plane translator functionality for the integration of the 5GS with a TSN network, this involves e.g.:

• 5GS Bridge management.
• Port and bridge management information exchange with DS-TT or NW-TT.
• Interactions with the CNC for 5GS Bridge configuration and reporting.
• determining the TSC Assistance Container and TSN QoS information by mapping TSN Stream(s) based on IEEE standards. The traffic pattern parameter determination may be based on PSFP (IEEE Std 802.1Q [98]) as specified in Annex I, clause I.1.

The NSWOF interfaces the WLAN access network using the SWa interface as defined in TS 23.402 and interfaces the AUSF using the Nausf SBI performing protocol translation and AUSF discovery (see clause 6.3.4).