3GPP 23.501 v20.2.0 — the document's own text
5.4.3.1 General
Taught in 9. Registration, reachability and paging (The 5G system architecture, in depth), 10. Radio, Wi-Fi, cable — every way in (The 5G system architecture, in depth), 4. Knowing who you are and where you are (The 5G system architecture, overview).
Based on operator configuration, the 5GS supports the AMF and NG-RAN to apply different paging strategies for different types of traffic.
In the case of UE in CM-IDLE state, the AMF performs paging and determines the paging strategy based on e.g. local configuration, what NF triggered the paging and information available in the request that triggered the paging. If NWDAF is deployed, the AMF may also use analytics (i.e. statistics or predictions) on the UE's mobility as provided by NWDAF (see TS 23.288 [86]).
In the case of UE in CM-CONNECTED with RRC_INACTIVE state, the NG-RAN performs paging and determines the paging strategy based on e.g. local configuration and information received from AMF as described in clause 5.4.6.3 and SMF as described in clause 5.4.3.2.
In the case of Network Triggered Service Request from SMF, the SMF determines the 5QI and ARP based on the downlink packet (if the SMF performs buffering) or the Downlink Data Report received from UPF (if the UPF performs buffering). The SMF includes the 5QI and ARP corresponding to the QoS Flow of the received downlink PDU in the request sent to the AMF. If the UE is in CM IDLE, the AMF uses e.g. the 5QI and ARP to derive different paging strategies as described in clause 4.2.3.3 of TS 23.502 [3].
NOTE: The 5QI is used by AMF to determine suitable paging strategies.