On-Demand MPS Service

The invocation-related priority mechanisms for prioritized services are based on communication with an Application Server and between the Application Server and the PCF over Rx or N5 interface (as described in 3GPP TS 23.228, clause 5.21, in the case of MPS using IMS).

Invocation-related mechanisms for Mobile Originations (for example, through SIP or IMS) are explained as follows:

  • PCF:

    • When an indication for a session reaches over the Rx or N5 interface and the UE does not have priority for the signaling QoS Flow, the PCF derives the ARP and 5QI parameters plus associated QoS characteristics as appropriate, as per the Service Provider policy (specified in 3GPP TS 23.503, clause 6.1.3.11).

    • For MPS sessions, when establishing or modifying a QoS Flow as part of the session origination procedure, the PCF selects the ARP and 5QI parameters, and the associated QoS characteristics, as appropriate, to provide priority to the QoS Flows.

    • When all active sessions to a particular DN are released and the UE is not configured for priority treatment to that particular PDU session, the PCF downgrades the IMS Signaling QoS Flows from appropriate settings of the ARP and 5QI parameters and the associated QoS characteristics, as appropriate, to those entitled by the UE based on subscription.

Invocation-related mechanisms for Mobile Terminations (for example, through SIP or IMS) are explained as follows:

  • PCF: When an indication for a session reaches over the Rx or N5 interface, the 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 (specified in 3GPP TS 23.502, clause 4.2.3.3.

  • SMF: If the SMF receives the "Data Notification" message for a QoS Flow associated with an ARP priority level value for priority use, delivery of priority indication during the Paging procedure is provided by inclusion of the ARP in the N11 interface "N1N2MessageTransfer" message (specified in 3GPP TS 23.502, clause 4.2.3.3).

  • AMF: If the AMF receives the "N1N2MessageTransfer" message containing an ARP priority level value for priority use, the AMF handles the request with priority. AMF also includes the "Paging Priority" IE in the N2 "Paging" message configured to a value assigned to indicate about an existing IP packet at the UPF requiring higher priority (specified in 3GPP TS 23.502, clause 4.2.3.3).

  • SMF: For a UE that is not configured for a higher priority, upon receiving the "N7 Session Management Policy Modification" message from the PCF with an ARP priority level for priority use, the SMF sends an "N1N2MessageTransfer" to update the ARP for the Signaling QoS Flows (specified in 3GPP TS 23.502, clause 4.3.3.2).

  • AMF: After receiving the "N1N2MessageTransfer" message from the SMF with an ARP priority level for priority use, the AMF updates the ARP for the Signaling QoS Flows (specified in 3GPP TS 23.502, clause 4.3.3.2).

  • (R)AN: Inclusion of the "Paging Priority" in the N2 "Paging" message triggers priority handling of paging during congestion at the (R)AN (specified in 3GPP TS 23.502, clause 4.2.3.3).

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 Flows controlled by the Priority PDU connectivity services are established or modified to have the service appropriate configuration of the ARP and 5QI parameters and the associated QoS characteristics, using the PDU Session Modification procedure (specified in of 3GPP TS 23.502, clause 4.3.3).

    • If the state of Priority PDU connectivity services is modified from enabled to disabled, the QoS Flows controlled by the Priority PDU connectivity services are modified from service appropriate configuration of the ARP and 5QI parameters and the associated QoS characteristics, to those entitled by the UE as per subscription, using the PDU Session Modification procedure (specified in 3GPP TS 23.502 clause 4.3.3).