Question: What action does the UE take if there is a transmission failure of SECURITY MODE COMPLETE message or SECURITY MODE REJECT message indication from lower layers during a tracking area updating procedure?
Option 1: The UE shall abort the security mode control procedure and re-initiate the attach procedure.
Option 2: The UE shall abort the security mode control procedure and re-run the ongoing service request procedure.
Option 3: The UE shall abort the security mode control procedure and re-initiate the tracking area updating procedure.
Option 4: The UE shall ignore the transmission failure and continue with the current procedure.
Explanation: According to the specified abnormal case, if there is a transmission failure of SECURITY MODE COMPLETE message or SECURITY MODE REJECT message indication from lower layers during a tracking area updating procedure, the UE shall abort the security mode control procedure and re-initiate the tracking area updating procedure. This ensures that the UE can still complete the necessary procedures for tracking area updates despite the security mode control procedure failure.