3GPP 23.501 v20.2.0 — the document's own text
5.45.2 Packet delay monitoring
Taught in 14. What the network promises (The 5G system architecture, in depth).
QoS Monitoring for packet delay allows for the measurement of UL packet delay, DL packet delay or round trip packet delay between UE and PSA UPF. The details of the QoS Monitoring for packet delay are described in clause 5.33.3.
The PCF may calculate Packet Delay Variation (clause 5.37.7) and the round trip packet delay when UL and DL are on different QoS flows (clause 5.37.4) based on packet delay monitoring results of QoS flows.