5.4.4.6 Abnormal cases on the network side

The following abnormal cases can be identified:

• Expiry of timer T3555.

The network shall, on the first expiry of the timer T3555, retransmit the CONFIGURATION UPDATE COMMAND message and shall reset and start timer T3555. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3555, the procedure shall be aborted. In addition, if the CONFIGURATION UPDATE COMMAND message includes the 5G-GUTI IE, the network shall behave as described in case b)-1) below.

• Lower layer failure.

If a lower layer failure is detected before the CONFIGURATION UPDATE COMPLETE message is received and:

• if the CONFIGURATION UPDATE COMMAND message includes the 5G-GUTI IE, the old and the new 5G-GUTI shall be considered as valid until the old 5G-GUTI can be considered as invalid by the AMF. If a new TAI list was provided in the CONFIGURATION UPDATE COMMAND message, the old and new TAI list shall also be considered as valid until the old TAI list can be considered as invalid by the AMF.

If the Updated PEIPS assistance information IE in the CONFIGURATION UPDATE COMMAND message includes a new PEIPS assistance information and the UE is previously assigned a different PEIPS assistance information then, the AMF shall consider both, the old and new PEIPS assistance information as valid until the old PEIPS assistance information can be considered as invalid by the AMF.

If the Updated LP-WUSPS assistance information IE in the CONFIGURATION UPDATE COMMAND message includes a new LP-WUSPS assistance information and the UE is previously assigned a different LP-WUSPS assistance information then, the AMF shall consider both, the old and new LP-WUSPS assistance information as valid until the old LP-WUSPS assistance information can be considered as invalid by the AMF.

If the LP-WUS status IE in the CONFIGURATION UPDATE COMMAND message includes a new LP-WUS status and the UE was previously assigned a different LP-WUS status then the AMF shall consider both, the old and new LP-WUS status as valid until the old LP-WUS status can be considered as invalid by the AMF.

During this period the AMF:

• may first use the old 5G-S-TMSI from the old 5G-GUTI, the old Paging subgroup ID received as part of the old PEIPS assistance information IE, if any, the old LP-WUSPS paging subgroup ID received as part of the old LP-WUSPS assistance information IE, if any, and the old LP-WUS status, if any, for paging within the area defined by the old TAI list for an implementation dependent number of paging attempts for network originated transactions. If a new TAI list was provided in the CONFIGURATION UPDATE COMMAND message, the new TAI list should also be used for paging. Upon response from the UE, the AMF may re-initiate the CONFIGURATION UPDATE COMMAND message. If the Updated PEIPS assistance information IE in the CONFIGURATION UPDATE COMMAND message includes a new Paging subgroup ID, then the AMF may re-initiate the CONFIGURATION UPDATE COMMAND message. If the Updated LP-WUSPS assistance information IE in the CONFIGURATION UPDATE COMMAND message includes a new LP-WUSPS assistance information, then the AMF may re-initiate the CONFIGURATION UPDATE COMMAND message. If the LP-WUS status IE in the CONFIGURATION UPDATE COMMAND message includes a new LP-WUS status, then the AMF may re-initiate the CONFIGURATION UPDATE COMMAND message. If the response is received from a tracking area within the old and new TAI list, the network shall re-initiate the CONFIGURATION UPDATE COMMAND message. If no response is received to the paging attempts, the network may use the new 5G-S-TMSI from the new 5G-GUTI, the new Paging subgroup ID received as part of Updated PEIPS assistance information IE, if any, the new LP-WUSPS paging subgroup ID received as part of the Updated LP-WUSPS assistance information IE, if any, and the new LP-WUS status, if any, for paging for an implementation dependent number of paging attempts. In this case, if a new TAI list was provided with new 5G-GUTI in the CONFIGURATION UPDATE COMMAND message, the new TAI list shall be used instead of the old TAI list. Upon response from the UE the AMF shall consider the new 5G-GUTI, the new PEIPS assistance information, the new LP-WUSPS assistance information and the new LP-WUS status as valid and the old 5G-GUTI, the old PEIPS assistance information, the old LP-WUSPS assistance information, and the old LP-WUS status as invalid. If the new LP-WUS status is "LP-WUS disabled", the AMF shall store "LP-WUS disabled" in the 5GMM context of the UE. If the new LP-WUS status is "LP-WUS enabled", the AMF shall remove "LP-WUS disabled" in the 5GMM context of the UE, if any.
• shall consider the new 5G-GUTI as valid if it is used by the UE and, additionally, the new TAI list as valid if it was provided with this 5G-GUTI in the CONFIGURATION UPDATE COMMAND message; and

iii) may use the identification procedure followed by a new generic UE configuration update procedure if the UE uses the old 5G-GUTI; or

• if the CONFIGURATION UPDATE COMMAND message does not include the 5G-GUTI IE and:
• the CONFIGURATION UPDATE COMMAND message does not contain the Allowed NSSAI IE, the Rejected NSSAI IE, the Extended rejected NSSAI IE, the Updated PEIPS assistance information IE, the Updated LP-WUSPS assistance information IE or the LP-WUS status IE, the network shall abort the procedure; or
• the CONFIGURATION UPDATE COMMAND message contains the Allowed NSSAI IE, the Rejected NSSAI IE, the Extended rejected NSSAI IE, the Updated PEIPS assistance information IE, the Updated LP-WUSPS assistance information IE, or the LP-WUS status IE, the network shall either abort the procedure or retransmit the CONFIGURATION UPDATE COMMAND message on expiry of the timer T3555. The retransmission shall not be repeated more than four times. If the retransmission is repeated for four times, the network shall abort the procedure.
• Generic UE configuration update and UE initiated de-registration procedure collision.

If the network receives a DEREGISTRATION REQUEST message before the ongoing generic UE configuration update procedure has been completed, the network shall abort the generic UE configuration update procedure and shall progress the de-registration procedure.

• Generic UE configuration update and registration procedure for mobility and periodic registration update collision

If the network receives a REGISTRATION REQUEST message before the ongoing generic UE configuration update procedure has been completed, the network shall abort the generic UE configuration update procedure and shall progress the registration procedure for mobility and periodic registration update procedure.

• Generic UE configuration update and service request procedure collision

If the network receives a SERVICE REQUEST message before the ongoing generic UE configuration update procedure has been completed and the SERVICE REQUEST message does not include UE request type IE with Request type value set to "NAS signalling connection release", both the procedures shall be progressed.

If the network receives a SERVICE REQUEST message before the ongoing generic UE configuration update procedure has been completed and the SERVICE REQUEST message includes UE request type IE with Request type value set to "NAS signalling connection release", the network shall abort the generic UE configuration update procedure and shall progress the service request procedure.

• Lower layers indication of non-delivered NAS PDU due to handover.

If the CONFIGURATION UPDATE COMMAND message could not be delivered due to an intra AMF handover and the target TA is included in the TAI list, then upon successful completion of the intra AMF handover the AMF shall retransmit the CONFIGURATION UPDATE COMMAND message if still needed. If a failure of handover procedure is reported by the lower layer and the N1 NAS signalling connection exists, the AMF shall retransmit the CONFIGURATION UPDATE COMMAND message.