Section: 5.5.1.3.7 Abnormal cases in the UE
Content: The following abnormal cases can be identified: a) Timer T3346 is running. The UE shall not start the registration procedure for mobility and periodic registration update unless: 1) the UE is in 5GMM-CONNECTED mode; 2) the UE received a paging; 3) the UE receives a NOTIFICATION message over non-3GPP access when the UE is in 5GMM-CONNECTED mode over non-3GPP access and in 5GMM-IDLE mode over 3GPP access; 4) the UE is a UE configured for high priority access in selected PLMN or SNPN; 5) the UE has an emergency PDU session established or is establishing an emergency PDU session; 6) the UE receives a request from the upper layers to perform emergency services fallback; 7) the UE receives the CONFIGURATION UPDATE COMMAND message as specified in subclause 5.4.4.3; 8) the UE in NB-N1 mode is requested by the upper layer to transmit user data related to an exceptional event and: - the UE is allowed to use exception data reporting (see the ExceptionDataReportingAllowed leaf of the NAS configuration MO in 3GPP TS 24.368[ Non-Access Stratum (NAS) configuration Management Object (MO) ]  [17] or the USIM file EFNASCONFIG in 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [22]); and - timer T3346 was not started when N1 NAS signalling connection was established with RRC establishment cause set to "mo-ExceptionData"; or 9) the MUSIM UE needs to request a new 5G-GUTI assignment as specified in subclause 5.5.1.3.2. The UE stays in the current serving cell and applies the normal cell reselection process. NOTE 1: It is considered an abnormal case if the UE needs to initiate a registration procedure for mobility and periodic registration update while timer T3346 is running independent on whether timer T3346 was started due to an abnormal case or a non-successful case. If the registration procedure for mobility and periodic registration update was initiated for an MO MMTEL voice call (i.e. access category 4), for an MO MMTEL video call (i.e. access category 5), for an MO IMS registration related signalling (i.e. access category 9) or for NAS signalling connection recovery during an ongoing MO MMTEL voice call (i.e. access category 4), or during an MO MMTEL video call (i.e. access category 5) or during an ongoing MO IMS registration related signalling (i.e. access category 9), then a notification that the procedure was not initiated due to network congestion shall be provided to upper layers. b) The lower layers indicate that the access attempt is barred. The UE shall not start the registration procedure for mobility and periodic registration update. The UE stays in the current serving cell and applies the normal cell reselection process. Receipt of the access barred indication shall not trigger the selection of a different core network type (EPC or 5GCN). The registration procedure for mobility and periodic registration update is started, if still needed, when the lower layers indicate that the barring is alleviated for the access category with which the access attempt was associated. ba) The lower layers indicate that: 1) access barring is applicable for all access categories except categories 0 and 2 and the access category with which the access attempt was associated is other than 0 and 2; or 2) access barring is applicable for all access categories except category 0 and the access category with which the access attempt was associated is other than 0. If the REGISTRATION REQUEST message has not been sent, the UE shall proceed as specified for case b. If the REGISTRATION REQUEST message has been sent, the UE shall proceed as specified for case e and, additionally, the registration procedure for mobility and periodic registration update is started, if still needed, when the lower layers indicate that the barring is alleviated for the access category with which the access attempt was associated. For additional UE requirements for both cases see subclause 4.5.5. c) T3510 timeout. The UE shall abort the registration update procedure and the N1 NAS signalling connection, if any, shall be released locally. If the UE has initiated the registration procedure in order to enable performing the service request procedure for emergency services fallback,the UE shall inform the upper layers of the failure of the emergency services fallback (see 3GP P TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [14]). Otherwise, the UE shall proceed as described below. d) REGISTRATION REJECT message, other 5GMM cause values than those treated in subclause 5.5.1.3.5, and cases of 5GMM cause values #11, #15, #22, #31, #72, #73, #74, #75, #76, #77 and #78, if considered as abnormal cases according to subclause 5.5.1.3.5. Upon reception of the 5GMM causes #95, #96, #97, #99 and #111 the UE should set the registration attempt counter to 5. The UE shall proceed as described below. e) Lower layer failure, release of the NAS signalling connection received from lower layers or the lower layers indicate that the RRC connection has been suspended without a cell change before the REGISTRATION ACCEPT or REGISTRATION REJECT message is received. The UE shall abort the registration procedure and proceed as described below. f) Change in the current TAI. If the current TAI is changed before the registration procedure for mobility and periodic registration update is completed, the registration procedure for mobility and periodic registration update shall be aborted and re-initiated immediately. The UE shall set the 5GS update status to 5U2 NOT UPDATED. g) Registration procedure for mobility and periodic registration update and de-registration procedure collision. If the UE receives a DEREGISTRATION REQUEST message without 5GMM cause value #11, #12, #13 or #15 before the registration procedure for mobility and periodic registration update has been completed, the registration procedure for mobility and periodic registration update shall be aborted and the de-registration procedure shall be progressed. If the UE receives a DEREGISTRATION REQUEST message with 5GMM cause value #11, #12, #13 or #15 before the registration procedure for mobility and periodic registration update has been completed, the registration procedure for mobility and periodic registration update shall be progressed and the de-registration procedure shall be aborted. NOTE 2: The registration procedure for mobility and periodic registration update shall be aborted only if the DEREGISTRATION REQUEST message indicates in the access type that the access in which the registration procedure for mobility and periodic registration update was attempted shall be de-registered. Otherwise both the procedures shall be progressed. h) Void i) Transmission failure of REGISTRATION REQUEST message indication from the lower layers or the lower layers indicate that the RRC connection has been suspended with a cell change. The registration procedure for mobility and periodic registration update shall be aborted and re-initiated immediately. The UE shall set the 5GS update status to 5U2 NOT UPDATED. j) Transmission failure of REGISTRATION COMPLETE message indication with change in the current TAI. If the current TAI is not in the TAI list, the registration procedure for mobility and periodic registration update shall be aborted and re-initiated immediately. The UE shall set the 5GS update status to 5U2 NOT UPDATED. If the current TAI is still part of the TAI list, it is up to the UE implementation how to re-run the ongoing procedure. k) Transmission failure of REGISTRATION COMPLETE message indication without change in the current TAI. It is up to the UE implementation how to re-run the ongoing procedure. l) UE-initiated de-registration required. De-registration due to removal of USIM or entry update in the "list of subscriber data" or due to switch off: The registration procedure for mobility and periodic registration update shall be aborted, and the UE initiated de-registration procedure shall be performed. De-registration not due to removal of USIM or entry update in the "list of subscriber data" and not due to switch off: the UE initiated de-registration procedure shall be initiated after successful completion of the registration procedure for mobility and periodic registration update. m) Timer T3447 is running The UE shall not start any mobility and periodic registration update procedure with Uplink data status IE or Follow-on request indicator set to "Follow-on request pending" unless: - the UE received a paging; - the UE is a UE configured for high priority access in selected PLMN; - the UE has an emergency PDU session established or is establishing an emergency PDU session; - the UE receives a request from the upper layers to perform emergency services fallback; or - the MUSIM UE needs to request a new 5G-GUTI assignment as specified in subclause 5.5.1.3.2. The UE stays in the current serving cell and applies the normal cell reselection process. The mobility and periodic registration update procedure is started, if still necessary, when timer T3447 expires or timer T3447 is stopped. n) Timer T3448 is running The UE in 5GMM-IDLE mode shall not start any mobility and periodic registration update procedure with Follow-on request indicator set to "Follow-on request pending" unless: 1) the UE is a UE configured for high priority access in selected PLMN; 2) the UE which is only using 5GS services with control plane CIoT 5GS optimization received a paging request; or 3) the UE in NB-N1 mode is requested by the upper layer to transmit user data related to an exceptional event and the UE is allowed to use exception data reporting (see the ExceptionDataReportingAllowed leaf of the NAS configuration MO in 3GPP TS 24.368[ Non-Access Stratum (NAS) configuration Management Object (MO) ]  [17] or the USIM file EFNASCONFIG in 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [22]). The UE stays in the current serving cell and applies the normal cell reselection process. The mobility and periodic registration update procedure is started, if still necessary, when timer T3448 expires. o) UE is not registered to the access other than the access the REGISTRATION ACCEPT message is received and the 5GS registration result value in the 5GS registration result IE value in the REGISTRATION ACCEPT message is set to "3GPP access and non-3GPP access". The UE shall consider itself as being registered to only the access where the REGISTRATION ACCEPT message is received. p) Access for localized services in current SNPN is no longer allowed. If the mobility and periodic registration update is not for initiating an emergency PDU session, the registered SNPN is an SNPN selected for localized services in SNPN as specified in 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5] and: - access for localized services in SNPN is disabled; or - the validity information for the selected SNPN is no longer met; the UE shall reset the registration attempt counter, stop T3510, abort the registration procedure for mobility and periodic registration update, locally release the NAS signalling connection, if any, and enter state 5GMM-REGISTERED.LIMITED-SERVICE or 5GMM-REGISTERED.PLMN-SEARCH in order to perform SNPN selection according to 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5]. For the cases c, d and e the UE shall proceed as follows: Timer T3510 shall be stopped if still running. If the registration procedure is not for initiating an emergency PDU session, the registration attempt counter shall be incremented, unless it was already set to 5. If the registration attempt counter is less than 5: - if the TAI of the current serving cell is not included in the TAI list or the 5GS update status is different to 5U1 UPDATED or if the registration procedure was triggered due to cases c, g, n, v in subclause 5.5.1.3.2, the UE shall start timer T3511, shall set the 5GS update status to 5U2 NOT UPDATED and change to state 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE. When timer T3511 expires, the registration update procedure is triggered again. - if the TAI of the current serving cell is included in the TAI list, the 5GS update status is equal to 5U1 UPDATED, and the UE is not performing the registration procedure after an inter-system change from S1 mode to N1 mode, the UE shall keep the 5GS update status to 5U1 UPDATED and enter state 5GMM-REGISTERED.NORMAL-SERVICE or 5GMM-REGISTERED.NON-ALLOWED-SERVICE (as described in subclause 5.3.5.2). The UE shall start timer T3511. If in addition the REGISTRATION REQUEST message did not include the MICO indication IE or the Extended DRX IE, and: - the REGISTRATION REQUEST message indicated "periodic registration updating"; - the registration procedure was initiated to recover the NAS signalling connection due to "RRC Connection failure" from the lower layers; or - the registration procedure was initiated by the UE in 5GMM-CONNECTED mode with RRC inactive indication entering a cell in the current registration area belonging to an equivalent PLMN of the registered PLMN and not belonging to the registered PLMN, and none of the other reasons for initiating the registration updating procedure listed in subclause 5.5.1.3.2 was applicable, the timer T3511 may be stopped when the UE enters 5GMM-CONNECTED mode. - if the TAI of the current serving cell is included in the TAI list, the 5GS update status is equal to 5U1 UPDATED and the UE is performing the registration procedure after an inter-system change from S1 mode to N1 mode, the UE shall change the 5GS update status to 5U2 NOT UPDATED and enter state 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE. The UE shall start timer T3511. - If the procedure is performed via 3GPP access and the UE is operating in single-registration mode, the UE shall in addition handle the EPS update status as specified in 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [15] for the abnormal cases when a normal or periodic tracking area updating procedure fails and the tracking area attempt counter is less than 5 and the EPS update status is different from EU1 UPDATED. If the registration attempt counter is equal to 5 - the UE shall start timer T3502 if the value of the timer as indicated by the network is not zero, shall set the 5GS update status to 5U2 NOT UPDATED. - the UE shall delete the list of equivalent PLMNs (if any) or the list of equivalent SNPNs (if any) if the UE is not registering or has not registered to the same PLMN over both 3GPP access and non-3GPP access, and shall change to state 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE or optionally to 5GMM-REGISTERED.PLMN-SEARCH in order to perform a PLMN selection, SNPN selection or SNPN selection for onboarding services according to 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5]. - if the value of T3502 as indicated by the network is zero, the UE shall perform the actions defined for the expiry of the timer T3502. NOTE 3: For case e) if the lower layer failure is on a cell which was selected due to network slice-based cell reselection (see 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [8]), the UE can as an implementation option change the S-NSSAI(s) in the requested NSSAI to try and find a suitable NR cell. - if the procedure is performed via 3GPP access and the UE is operating in single-registration mode: - the UE shall in addition handle the EPS update status as specified in 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [15] for the abnormal cases when a normal or periodic tracking area updating procedure fails and the tracking area attempt counter is equal to 5; and - if the UE does not change to state 5GMM-REGISTERED.PLMN-SEARCH, the UE shall attempt to select E-UTRAN radio access technology. The UE may disable the N1 mode capability as specified in subclause 4.9.