Section: 5.3.15 Transmission failure abnormal case in the UE
Content: The abnormal case 5GMM uplink message transmission failure indication by lower layers can be identified for 5GMM procedures: When it is specified in the relevant procedure that it is up to the UE implementation to re-run the ongoing procedure that triggered that procedure, the procedure can typically be re-initiated using a retransmission mechanism of the uplink message (i.e. the one that has previously failed to be transmitted) with new sequence number and message authentication code information thus avoiding to re-start the whole procedure. NOTE: The transmission failure can happen due to TAI change. The lower layer might take some time to read the system information and determine if the current TAI is changed. Therefore, the information of TAI change can be sent to the NAS layer a little after receiving the transmission failure indication from the lower layer. How to handle the retransmission procedure caused by the possible delayed TAI change information is up to UE implementation.