5.22.4 QoS Mechanisms applied to established QoS Flows

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 [3].
• 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 any Mobility Management procedures required for the prioritised services during periods of extreme overload. Prioritised services are exempt from any Mobility Management congestion controls. See clause 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, or QoS Flow supporting MPS for Data Transport Service signalling, 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 clauses 5.16.5 and 5.16.6.
• (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 priority sessions. See clauses 5.16.5 and 5.16.6.