Tech-invite  3GPPspecsRELsGlossariesSIP
Info21222324252627282931323334353637384‑5x

full Contents for  TS 23.501  Word version:   16.4.0

Top   Up   Prev   Next
1…   3…   4…   4.2.4   4.2.5…   4.2.8…   4.2.8.2.2   4.2.8.2.3…   4.2.8.4…   4.2.9…   4.3…   4.3.3   4.3.4   4.3.5   4.4…   4.4.6…   4.4.8   5…   5.3…   5.3.3…   5.4…   5.5…   5.6…   5.6.7…   5.7…   5.7.2…   5.7.3…   5.7.4   5.7.5…   5.8…   5.8.2.11…   5.9…   5.10…   5.11…   5.15…   5.16…   5.17…   5.18…   5.19…   5.21…   5.22…   5.27…   5.28…   5.29…   5.30…   5.31…   5.32…   5.33…   5.34…   5.35…   6…   6.3…   7…   7.2…   8…   8.2.4   8.2.5…   8.3…   A…   D…   E…   F   G…   G.3   G.4…   J…

 

5.22  System Enablers for priority mechanism
5.22.1  General
The 5GS and the 5G QoS model allow classification and differentiation of specific services such as listed in clause 5.16, based on subscription-related and invocation-related priority mechanisms. These mechanisms provide abilities such as invoking, modifying, maintaining, and releasing QoS Flows with priority, and delivering QoS Flow packets according to the QoS characteristics under network congestion conditions.
Subscription-related Priority Mechanisms include the ability to prioritize flows based on subscription information, including the prioritization of RRC Connection Establishment based on Unified Access Control mechanisms and the establishment of prioritized QoS Flows.
Invocation-related Priority Mechanisms include the ability for the service layer to request/invoke the activation of prioritized QoS Flows through an interaction over Rx/N5 and packet detection in the UPF.
QoS Mechanisms applied to established QoS Flows include the ability to fulfil the QoS characteristics of QoS Flows through preservation of differentiated treatment for prioritized QoS Flow and resource distribution prioritization.
Messages associated with priority services that are exchanged over service-based interfaces may include a Message Priority header to indicate priority information, as specified in TS 23.502 and TS 29.500.
In addition, the separation of concerns between the service classification provided by the core network through the association of Service Data Flows to QoS, and the enforcing of QoS differentiation in (R)AN through the association of QoS Flows to Data Radio bearers, supports the prioritization of QoS Flows when a limitation of the available data radio bearers occurs.
In addition, it also includes the ability for the service layer to provide instructions on how to perform pre-emption of media flows with the same priority assigned through an interaction over Rx as defined in TS 23.503.
Up
5.22.2  Subscription-related Priority Mechanisms
Subscription-related mechanisms which are always applied:
  • (R)AN: During initial Access Network Connection Establishment, the Establishment Cause is set to indicate that special treatment is to be applied by the (R)AN in the radio resource allocation as specified in clause 5.2 for 3GPP access.
  • AMF: Following Access Network Connection Establishment, the receipt of the designated Establishment Cause (i.e. high priority access) by the AMF will result in priority handling of the "Initial UE Message" received as part of the Registration procedures of clause 4.2.2 of TS 23.502 and the Service Request procedures of clause 4.2.3 of TS 23.502. In addition, certain exemptions to Control Plane Congestion and Overload Control are provided as specified in clause 5.19.
  • Subscription-related mechanisms which are conditionally applied:
  • UE: When barring control parameters are broadcast by the RAN, access barring based on Access Identity(es) configured in the USIM and/or an Access Category is applied prior to an initial upstream transmission for the UE which provides a mechanism to limit transmissions from UEs categorized as non-prioritized, while allowing transmissions from UEs categorized as prioritized (such as MPS subscribed UEs), during the RRC Connection Establishment procedure as specified in clause 5.2.
  • UDM: One or more ARP priority levels are assigned for prioritized or critical services. The ARP of the prioritized QoS Flows for each DN is set to an appropriate ARP priority level. The 5QI is from the standard value range as specified in clause 5.7.2.7. In addition, Priority Level may be configured for the standardized 5QIs, and if configured, it overwrites the default value specified in the QoS characteristics Table 5.7.4-1.
  • PCF: The "IMS Signalling Priority" information is set for the subscriber in the UDM, and the PCF modifies the ARP of the QoS Flow used for IMS signalling, for each DN which supports prioritized services leveraging on IMS signalling, to an appropriate ARP priority level assigned for that service.
Up
5.22.3  Invocation-related Priority MechanismsWord-p. 256
The generic mechanisms used based on invocation-related Priority Mechanisms for prioritised services are based an interaction with an Application Server and between the Application Server and the PCF over Rx/N5 interface, as described in TS 23.228, clause 5.21 in the case of MPS using IMS.
NOTE:
Clause 5.21 in TS 23.228 is applicable to 5GS, with the understanding that the term PCRF corresponds to PCF in the 5GS.
Invocation-related mechanisms for Mobile Originations e.g. via SIP/IMS:
  • PCF: When an indication for a session arrives over the Rx/N5 Interface and the UE does not have priority for the signalling QoS Flow, the PCF derives the ARP and 5QI parameters, plus associated QoS characteristics as appropriate, of the QoS Flow for Signalling as per Service Provider policy as specified in clause 6.1.3.11 of TS 23.503.
  • PCF: For sessions such as MPS, when establishing or modifying a QoS Flow for media as part of the session origination procedure, the PCF selects the ARP and 5QI parameters, plus associated QoS characteristics as appropriate, to provide priority treatment to the QoS Flow(s).
  • PCF: When all active sessions to a particular DN are released, and the UE is not configured for priority treatment to that particular PDU Session for a DN, the PCF will downgrade the IMS Signalling QoS Flows from appropriate settings of the ARP and 5QI parameters, plus associated QoS characteristics as appropriate, to those entitled by the UE based on subscription.
Invocation-related mechanisms for Mobile Terminations e.g. via SIP/IMS:
  • PCF: When an indication for a session arrives over the Rx/N5 Interface, mechanisms as described above for Mobile Originations are applied.
  • UPF: If an IP packet arrives at the UPF for a UE that is CM-IDLE, the UPF sends a "Data Notification" including the information to identify the QoS Flow for the DL data packet to the SMF, as specified in clause 4.2.3.3 of TS 23.502.
  • SMF: If a " Data Notification" message arrives at the SMF for a QoS Flow associated with an ARP priority level value that is entitled for priority use, delivery of priority indication during the Paging procedure is provided by inclusion of the ARP in the N11 interface "N1N2MessageTransfer" message, as specified in clause 4.2.3.3 of TS 23.502.
  • AMF: If an "N1N2MessageTransfer" message arrives at the AMF containing an ARP priority level value that is entitled for priority use, the AMF handles the request with priority and includes the "Paging Priority" IE in the N2 "Paging" message set to a value assigned to indicate that there is an IP packet at the UPF entitled to priority treatment, as specified in clause 4.2.3.3 of TS 23.502.
  • SMF: For a UE that is not configured for priority treatment, upon receiving the "N7 Session Management Policy Modification" message from the PCF with an ARP priority level that is entitled for priority use, the SMF sends an "N1N2MessageTransfer" to update the ARP for the Signalling QoS Flows, as specified in clause 4.3.3.2 of TS 23.502.
  • AMF: Upon receiving the "N1N2MessageTransfer" message from the SMF with an ARP priority level that is entitled for priority use, the AMF updates the ARP for the Signalling QoS Flows, as specified in clause 4.3.3.2 of TS 23.502.
  • (R)AN: Inclusion of the "Paging Priority" in the N2 "Paging" message triggers priority handling of paging in times of congestion at the (R)AN as specified in clause 4.2.3.3 of TS 23.502.
Invocation-related mechanisms for the Priority PDU connectivity services:
  • PCF: If the state of the Priority PDU connectivity services is modified from disabled to enabled, the QoS Flow(s) controlled by the Priority PDU connectivity services are established/modified to have the service appropriate settings of the ARP and 5QI parameters, plus associated QoS characteristics as appropriate, using the PDU Session Modification procedure as specified in clause 4.3.3 of TS 23.502.
  • PCF: If the state of Priority PDU connectivity services is modified from enabled to disabled, the QoS Flow(s) controlled by the Priority PDU connectivity services are modified from service appropriate settings of the ARP and 5QI parameters, plus associated QoS characteristics as appropriate, to those entitled by the UE as per subscription, using the PDU Session Modification procedure as specified in clause 4.3.3 of TS 23.502.
Up
5.22.4  QoS Mechanisms applied to established QoS FlowsWord-p. 257
Mechanisms applied to established QoS Flows:
  • (R)AN: QoS Flows requested in the Xn "Handover Request" or N2 "Handover Request" which are marked as entitled to priority by virtue of inclusion of an ARP value from the set allocated by the Service Provider for prioritised services are given priority over requests for QoS Flows which do not include an ARP from the set as specified in clause 4.9 of TS 23.502.
  • SMF: Congestion management procedures in the SMF will provide priority to QoS Flows established for sessions during periods of extreme overload. Prioritised services are exempt from any session management congestion controls. See clause 5.19.
  • AMF: Congestion management procedures in the AMF will provide priority to Mobility Management procedures required for the prioritised services during periods of extreme overload. Prioritised services are exempt from Mobility Restrictions and any Mobility Management congestion controls. See clauses 5.3.4.1.1 and 5.19.5.
  • QoS Flows whose ARP parameter is from the set allocated by the Service Provider for prioritised services' use shall be exempt from release during QoS Flow load rebalancing.
  • (R)AN, UPF: IMS Signalling Packets associated with prioritised services' use are handled with priority. Specifically, during times of severe congestion when it is necessary to drop packets on the IMS Signalling QoS Flow to ensure network stability, these FEs shall drop packets not associated with priority signalling such as MPS or Mission Critical services before packets associated with priority signalling. See clause TBD.
  • (R)AN, UPF: During times of severe congestion when it is necessary to drop packets on a media QoS Flow to ensure network stability, these FEs shall drop packets not associated with priority sessions such as MPS or Mission Critical services before packets associated with sessions. See clause TBD.
Up
5.23  Supporting for Asynchronous Type Communication
Asynchronous type communication (ATC) enables 5GC to delay synchronizing UE context with the UE, so as to achieve an efficient signalling overhead and increase system capacity.
5GC supports asynchronous type communication with the following functionality:
  • Capability to store the UE context based on the received message, and synchronize the UE context with the involved network functions or UE later;
For network function (e.g. PCF, UDM, etc.) triggered signalling procedure (e.g. network triggered Service Request procedure, network triggered PDU Session Modification procedure, etc.), if the UE CM state in the AMF is CM-IDLE state, the AMF updates and stores the UE context based on the received message without paging UE immediately. When the UE CM state in the AMF enters CM-CONNECTED state, the AMF forwards N1 and N2 message to synchronize the UE context with the (R)AN and/or the UE.
Up
5.24  3GPP PS Data OffWord-p. 258
This feature, when activated by the user, prevents traffic via 3GPP access of all IP packets, Unstructured and Ethernet data except for those related to 3GPP PS Data Off Exempt Services. The 3GPP PS Data Off Exempt Services are a set of operator services, defined in TS 22.011 and TS 23.221, that are the only allowed services when the 3GPP PS Data Off feature has been activated by the user. The 5GC shall support 3GPP PS Data Off operation in both non-roaming and roaming scenarios.
UEs may be configured with up to two lists of 3GPP PS Data Off Exempt Services and the list(s) are provided to the UEs by HPLMN via Device Management or UICC provisioning. When the UE is configured with two lists, one list is valid for the UEs camping in the home PLMN and the other list is valid for any VPLMN the UE is roaming in. When the UE is configured with a single list, without an indication to which PLMNs the list is applicable, then this list is valid for the home PLMN and any PLMN the UE is roaming in.
NOTE 1:
The operator needs to ensure coordinated list(s) of 3GPP Data Off Exempt Services provisioned in the UE and configured in the network.
The UE reports its 3GPP PS Data Off status in PCO (Protocol Configuration Option) to (H-)SMF during UE requested PDU Session Establishment procedure for establishment of a PDU Session associated with 3GPP access and/or non-3GPP access. The UE does not need to report PS Data Off status during the PDU Session Establishment procedure for handover of the PDU Session between 3GPP access and non 3GPP access if 3GPP PS Data Off status is not changed since the last report. The PS Data Off status for a PDU Session does not affect data transfer over non-3GPP access.
If 3GPP PS Data Off is activated, the UE prevents the sending of uplink IP packets, Unstructured and Ethernet data except for those related to 3GPP PS Data Off Exempt Services, based on the pre-configured list(s) of Data Off Exempt Services.
If 3GPP PS Data Off is activated for a UE with MA PDU Sessions established through the ATSSS feature (see clause 5.32), the data transferred over the non-3GPP access of the MA PDU sessions are unaffected, which is ensured by the policy for ATSSS Control as specified in clause 5.32.3.
The UE shall immediately report a change of its 3GPP PS Data Off status in PCO by using UE requested PDU Session Modification procedure. This also applies to the scenario of inter-RAT mobility to NG-RAN and to scenarios where the 3GPP PS Data Off status is changed when the session management back-off timer is running as specified in clause 5.19.7.3 and clause 5.19.7.4. For UEs in Non-Allowed Area (or not in Allowed Area) as specified in clause 5.3.4.1, the UE shall also immediately report a change of its 3GPP PS Data Off status for the PDU Session. For UEs moving out of LADN area and the PDU Session is still maintained as specified in clause 5.6.5, the UE shall also immediately report a change of its 3GPP PS Data Off status for the PDU Session.
The additional behaviour of the SMF for 3GPP PS Data Off is controlled by local configuration or policy from the PCF as defined in TS 23.503.
NOTE 2:
For the PDU Session used for IMS services, the 3GPP Data Off Exempt Services are enforced in the IMS domain as specified TS 23.228. Policies configured in the (H-)SMF/PCF need to ensure those services are always allowed when the 3GPP Data Off status of the UE is set to "activated".
Up
5.25  Support of OAM FeaturesWord-p. 259
5.25.1  Support of Tracing: Signalling Based Activation/Deactivation of Tracing
5GS supports tracing as described in TS 32.421. 5GS support may include subscriber tracing (tracing targeting a SUPI) or equipment tracing (tracing targeting a PEI) but also other forms of tracing further described in TS 32.421.
NOTE 1:
TS 23.501 / TS 23.502 / TS 23.503 only describe how 5GS signalling supports delivery of Trace Requirements about a UE (Signalling Based Activation/Deactivation of Tracing). OAM delivery of tracing requirements as well as the transfer of tracing results to one or more Operations Systems are out of scope of these documents.
The content of Trace Requirements about a UE (e.g. trace reference, address of the Trace Collection Entity, etc.) is defined in TS 32.421.
Trace Requirements about a UE may be configured in subscription data of the UE and delivered together with other subscription data by the UDM towards the AMF, the SMF and/or the SMSF.
Signalling Based Activation/Deactivation of Tracing is limited to PLMNs of a single operator.
NOTE 2:
Trace Requirements are not delivered between V-SMF and H-SMF or not provided by the UDM to an AMF / SMF / SMSF of a non-equivalent (H)PLMN.
NOTE 3:
Signalling Based Activation/Deactivation of tracing for in-bound roamers is not defined in this version of the specification.
The AMF propagates Trace Requirements about a UE received from the UDM to network entities not retrieving subscription information from UDM, i.e. to the 5G-AN, to the AUSF and to the PCF. The AMF also propagates Trace Requirements to the SMF and to the SMSF.
Trace Requirements about a UE may be sent by the AMF to the 5G-AN as part of:
  • the N2 procedures used to move the UE from CM-IDLE to CM-CONNECTED or,
  • the N2 procedures to request a Hand-over from a target NG-RAN or,
  • a stand-alone dedicated N2 procedure when tracing is activated while the UE is CM-CONNECTED.
Trace Requirements about a UE sent to a 5G-AN shall not contain information on the SUPI or on the PEI of the UE. Trace Requirements are directly sent from Source to Target NG-RAN in the case of Xn Hand-Over.
The SMF propagates Trace Requirements about a UE received from the UDM to the UPF (over N4) and to the PCF. The SMF provides Trace Requirements to the PCF when it has selected a different PCF than the one received from the AMF.
Once the SMF or the SMSF has received subscription data, Trace Requirements received from UDM supersede Trace requirements received from the AMF. Trace Requirements are exchanged on N26 between the AMF and the MME.
Up
5.25.2  Support of OAM-based 5G VN group management [R16]
5GS supports 5G LAN-type service as defined in clause 5.29. 5G LAN-type service includes the 5G VN group management that can be configured by a network administrator.
The parameters for 5G VN group is defined in clause 5.29.
The 5G VN group parameters about a UE may be configured in subscription data of the UE and delivered together with other subscription data by the UDM towards the AMF and SMF.
Up
5.26  Configuration Transfer ProcedureWord-p. 260
The purpose of the Configuration Transfer is to enable the transfer of information between two RAN nodes at any time via NG interface and the Core Network. An example of application is to exchange the RAN node's IP addresses in order to be able to use Xn interface between the NG-RAN node for Self-Optimised Networks (SON), as specified in TS 38.413.
5.26.1  Architecture Principles for Configuration Transfer
Configuration Transfer between two RAN node provides a generic mechanism for the exchange of information between applications belonging to the RAN nodes.
In order to make the information transparent for the Core Network, the information is included in a transparent container that includes source and target RAN node addresses, which allows the Core Network nodes to route the messages. The mechanism is depicted in Figure 5.26.1-1.
Up
The NG-RAN transparent containers are transferred from the source NG-RAN node to the destination NG-RAN node by use of Configuration Transfer messages.
A Configuration Transfer message is used from the NG-RAN node to the AMF over N2 interface, a AMF Configuration Transfer message is used from the AMF to the NG-RAN over N2 interface, and a Configuration Transfer Tunnel message is used to tunnel the transparent container from a source AMF to a target AMF over the N14 interface.
Each Configuration Transfer message carrying the transparent container is routed and relayed independently by the core network node(s).
Up
5.26.2  Addressing, routing and relaying
5.26.2.1  Addressing
All the Configuration Transfer messages contain the addresses of the source and destination RAN nodes. An NG-RAN node is addressed by the Target NG-RAN node identifier.
5.26.2.2  RoutingWord-p. 261
The following description applies to all the Configuration Transfer messages used for the exchange of the transparent container.
The source RAN node sends a message to its core network node including the source and destination addresses. The AMF uses the destination address to route the message to the correct AMF via the N14 interface.
The AMF connected to the destination RAN node decides which RAN node to send the message to, based on the destination address.
5.26.2.3  Relaying
The AMF performs relaying between N2 and N14 messages as described in TS 38.413, TS 29.518.

Up   Top   ToC