Section: 5.4.1.6 Abnormal cases on the network side
Content: The following abnormal cases can be identified: a) Lower layer failure If a lower layer failure is detected before the GUTI REALLOCATION COMPLETE message is received, the old and the new GUTI shall be considered as valid until the old GUTI can be considered as invalid by the network. If a new TAI list was provided in the GUTI REALLOCATION 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 network. During this period the network: - may first use the old S-TMSI from the old GUTI 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 with old GUTI in the GUTI REALLOCATION COMMAND message, the new TAI list should also be used for paging. Upon response from the UE, the network may re-initiate the GUTI reallocation. If the response is received from a tracking area within the old and new TAI list, the network shall re-initiate the GUTI reallocation. If no response is received to the paging attempts, the network may use the new S-TMSI from the new GUTI for paging for an implementation dependent number of paging attempts. In this case, if a new TAI list was provided with new GUTI in the GUTI REALLOCATION COMMAND message, the new TAI list shall be used instead of the old TAI list. Upon response from the UE the network shall consider the new GUTI as valid and the old GUTI as invalid. If no response is received to the paging attempts, the network may use the IMSI for paging for an implementation dependent number of paging attempts; NOTE 1: Paging with IMSI causes the UE to re-attach as described in clause .2.2. - shall consider the new GUTI as valid if it is used by the UE and, additionally, the new TAI list as valid if it was provided with this GUTI in the GUTI REALLOCATION COMMAND message; - may use the identification procedure followed by a new GUTI reallocation if the UE uses the old GUTI; and - if the network accepted to use eDRX for the UE, may determine the next paging window from both old GUTI and new GUTI, and may first use the S-TMSI from the GUTI which led the first eDRX for paging. If no response is received to the paging attempts for the first eDRX, the network may use the other S-TMSI from the other GUTI which led the second eDRX for paging. For this paging procedure, the network shall start timer T3415 long enough to care the paging attempts for both eDRXs. NOTE 2: If the second eDRX comes during the first eDRX ongoing, the paging attempts for the second eDRX can be initiated with stopping further paging attempts for the first eDRX. b) Expiry of timer T3450 The GUTI reallocation procedure is supervised by the timer T3450. The network shall, on the first expiry of timer T3450, reset and restart timer T3450 and shall retransmit the GUTI REALLOCATION COMMAND. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3450, the network shall abort the reallocation procedure and shall follow the rules described for case a above. c) GUTI reallocation and attach procedure collision If the network receives an ATTACH REQUEST message before the ongoing GUTI reallocation procedure has been completed the network shall proceed with the attach procedure after deletion of the EMM context. d) GUTI reallocation and UE initiated detach procedure collision If the network receives a DETACH REQUEST message before the ongoing GUTI reallocation procedure has been completed, the network shall abort the GUTI reallocation procedure and shall progress the detach procedure. e) GUTI reallocation and tracking area updating procedure collision If the network receives a TRACKING AREA UPDATE REQUEST message before the ongoing GUTI reallocation procedure has been completed, the network shall abort the GUTI reallocation procedure and shall progress the tracking area updating procedure. The network may then perform a new GUTI reallocation. f) GUTI reallocation and service request procedure collision If the network receives an EXTENDED SERVICE REQUEST message for CS fallback or 1xCS fallback before the ongoing GUTI reallocation procedure has been completed, the network shall progress both procedures. g) Lower layer indication of non-delivered NAS PDU due to handover If the GUTI REALLOCATION COMMAND message could not be delivered due to an intra MME handover and the target TA is included in the TAI list, then upon successful completion of the intra MME handover the MME shall retransmit the GUTI REALLOCATION COMMAND message. If a failure of the handover procedure is reported by the lower layer and the S1 signalling connection exists, the MME shall retransmit the GUTI REALLOCATION COMMAND message. If there is a different new GUTI and optionally a new TAI list included in a subsequent GUTI REALLOCATION COMMAND message, the UE always regards the newest GUTI and the newest TAI list as valid for the recovery time.