3GPP 23.501 v20.2.0 — the document's own text
5.31.7.3 MICO mode with Extended Connected Time
Taught in 25. Small devices, small messages (The 5G system architecture, in depth).
When a UE, using MICO mode, initiates MO signalling or MO data and the AMF is aware of pending or expected MT traffic, the AMF may keep the UE in CM-CONNECTED state and the RAN may keep the UE in RRC_CONNECTED state for an Extended Connected Time period in order to ensure the downlink data and/or signalling is delivered to the UE. The Extended Connected Time is determined by the AMF and is based on local configuration and/or the Maximum Response Time, if provided by the UDM.
The AMF maintains the N2 connection for at least the Extended Connected Time and provides the Extended Connected Time value to the RAN. The Extended Connected Time value indicates the minimum time the RAN should keep the UE in RRC_CONNECTED state regardless of inactivity. The Extended Connected Time value is provided to the RAN together with the
- NAS Registration Accept message; or
- NAS Service Accept message.
At inter-RAN node handovers, if some signalling or data are still pending, the target AMF may send the Extended Connected Time value to the target RAN node.