Content for TR 23.700-61 Word version: 18.0.0
7 Overall Evaluation p. 23
| Summary | System impacts | AF interaction | |
|---|---|---|---|
|
Solution #1:
Usage of MICO mode for UE unavailability period management
| UE provides unavailability period via Registration UE requests MICO and release all PDU Sessions UE stores MM context AMF sets periodic registration timer considering unavailability period | UE provides unavailability period in Registration | No interaction |
|
Solution #2:
UE provided Unavailability Period
| UE provides unavailability period via Registration Capability negotiation between UE and AMF AMF sets periodic registration timer considering unavailability period HLCom for DL data | UE provides unavailability period in Registration Capability negotiation | No interaction |
|
Solution #3:
Determination of unavailability period in 5GS
| Capability negotiation between UE and AMF AMF may reject UE request to become unavailable and optionally provide a back off timer If AMF accepts unavailability period, UE triggers deregistration. Alternatively, MUSIM connection release and paging restriction can be used instead of performing deregistration. | UE provides unavailability period in Registration Capability negotiation AMF may reject unavailability period and provide back off timer UE needs to support unavailability back off timer | No interaction |
|
Solution #4:
Exposing UE provided unavailability period via Loss of Connectivity event subscription
| UE provides unavailability period If Loss Of Connectivity event exists, the AMF sends notification. | UE provides unavailability period in Registration or Deregistration If Loss of Connectivity Event subscription is exist, the AMF reports notification when the UE provided unavailability period | Report unavailability period to the AF via Loss of Connectivity event subscription |
|
Solution #5:
Determination of unavailability period in 5GS for a specific UE
| UE reports unavailability period to the AF via application layer signalling. AF provides unavailability period to the UDR / NWDAF For critical service, the AF negotiates BDT | AF provisions unavailability period provisioning via external parameter provisioning procedure Critical indication in BDT negotiation | Negotiate BDT time window considering unavailability period |
|
Solution #6:
Determination of unavailability period in 5GS for a specific UE
| AF provides unavailability period to the UDM/UDR. UDM/UDR provides unavailability period to the AMF via subscription or AM Policy association UDM/PCF provides unavailability period to the UE via UPU / Policy delivery AMF / UE uses the unavailability period to determine whether deregistration can be executed | AF provisions unavailability period provisioning via external parameter provisioning procedure AMF, UE use the unavailability period whether to trigger deregistration | AF determines unavailability period |
8 Conclusions p. 23
8.1 Conclusions for Key Issue #1 p. 23
During Registration procedure, the UE provides indication of support of "Unavailability Period" in Registration Request message, and the AMF indicates the support of the "Unavailability Period" in Registration Accept message.
If UE and network support "Unavailability Period" and an event is triggered in the UE that would make the UE unavailable for a certain period of time (e.g. for OS upgrade or device reboot), the UE may store its MM context in USIM or Non Volatile memory to be able to reuse it after its unavailability period. When the UE is ready to execute the event, the UE triggers mobility registration or deregistration procedure including the unavailability period. The AMF may provide Periodic Registration Update timer based on unavailability period indicated by the UE, e.g. the AMF may provide a Periodic Registration Update time larger than unavailability period. If the UE is not deregistered, the AMF stores the information that the UE is unavailable in UE context, and considers the UE is unreachable until the unavailability period has passed or the UE enters CM-CONNECTED state. While the UE is unreachable, all high latency communication solutions (see clause 5.31.8 of TS 23.501) may apply if supported, e.g. extended data buffering, downlink data buffering status report, etc. If there is "Loss of Connectivity" event subscription for the UE by AF, the AMF triggers "Loss of Connectivity" event report and includes unavailability period towards the NEF and the unavailability period is reported to the respective subscribed AF.
When the UE is ready to execute the event (e.g. for OS upgrade or device reboot), the UE may choose to store the UE contexts (MM and SM context).
Once the event which makes the UE unavailable is completed in the UE or the event is delayed to a future time or cancelled in the UE (e.g. due to insufficient storage capacity, insufficient battery level or the event which makes the UE unavailable is completed), the UE triggers registration procedure to resume regular service. The UE does not include the Unavailability Period in the Registration Request message. Depending on the state the UE ends up after the event, the registration procedure can be Initial Registration procedure or Mobility Registration Update procedure.
$ Change history p. 25
