5.31.7.4 MICO mode with Active Time

During a Registration procedure the UE may optionally request an Active Time value from the AMF as part of MICO Mode negotiation. In response, if the AMF receives an Active Time value from the UE and determines that the MICO mode is allowed for the UE, the AMF may assign an Active Time value for the UE, e.g. based on local configuration, Expected UE Behaviour if available, UE requested Active Time value, UE subscription information and network policies and indicates it to the UE during Registration procedure. When an Active Time value is assigned to the UE the AMF shall consider the UE reachable for paging after the transition from CM-CONNECTED to CM-IDLE for the duration of the Active Time. Together with the Active Time value, the UE may request a periodic registration time value as specified in clause 5.31.7.45.

When the AMF indicates MICO mode with an Active Time to a UE, the registration area may be constrained by paging area size. To avoid paging in the entire PLMN, when the AMF allocates the Active Time the AMF should not allocate "all PLMN" registration area to the UE.

The UE and AMF shall set a timer corresponding to the Active Time value negotiated during the most recent Registration procedure. The UE and AMF shall start the timer upon entering CM-IDLE state from CM-CONNECTED. When the timer expires (i.e. reaches the Active Time) the UE enters MICO mode and the AMF can deduce that the UE has entered MICO mode and is not available for paging. If the UE enters CM-CONNECTED state before the timer expires, the UE and AMF shall stop and reset the timer.

If no Active Time value was negotiated during the most recent Registration procedure the UE shall not start the timer and it shall instead enter MICO mode directly upon entering CM-IDLE state.

Active Time is not transferred between AMF and MME.