Section: 5.4.13.5 Overload control
Content: The AMF and UE may only use the procedure defined in this clause if both the UE and AMF indicate support for "Unavailability Period Support", see clause 5.4.13.1. A UE indicating support for "Unavailability Period Support" shall support the procedures defined in this clause when leaving coverage and re-gaining coverage for an NR satellite access. In order to avoid a large number of UEs causing excessive signalling load on the network when leaving coverage or re-gaining coverage after being out of coverage, the AMF may determine a Maximum Time Offset controlling when UEs are allowed to initiate NAS signalling with the network, as described in this clause. In this case, the AMF determines this Maximum Time Offset based on network configuration, high priority access and priority service as specified in TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [17] and TS 24.501[ Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 ]  [47]. The AMF sends this Maximum Time Offset to individual UEs during the Registration procedure or UE Configuration Update procedure. If the UE receives a Maximum Time Offset from the network in a Registration Accept or UE Configuration Update Command message, the UE shall replace any previously received Maximum Time Offset on the same RAT type and PLMN with this one. When the UE knows a later time at which coverage will be lost and when the UE does not send Mobility Registration Update to the AMF in advance (see clause 5.4.13.1), the UE determines a random value up to the minimum of the latest Maximum Time Offset for this PLMN and RAT type and the time until coverage will be lost. The UE shall send the Mobility Registration Update at the time when coverage will be lost less the random value to the AMF indicating the loss of coverage. Upon returning to coverage after being out of coverage due to discontinuous coverage, the UE sets the discontinuous coverage wait timer value to a random value up to and including the latest Maximum Time Offset for this PLMN and RAT type, and starts this timer. The UE shall not initiate any NAS signalling on that RAT Type and PLMN while the discontinuous coverage wait timer is running. The UE shall stop the discontinuous coverage wait timer and initiate NAS signalling if the UE receives paging message, has pending emergency services or when UE enters a TAI outside the registration area.