Question: Which of the following statements accurately describes how NAS CN signalling data (e.g., Call Control, Session Management) is handled over the Iu interface in a UTRAN network?
Option 1: Dedicated Iu interface channels are allocated for each type of NAS CN signalling data to ensure prioritization.
Option 2: A shared Iu interface channel is used exclusively for NAS CN signalling data, separate from UTRAN-CN signalling.
Option 3: The same Iu interface channel used for UTRAN-CN signalling is also utilized for transparently conveying NAS CN signalling data between the CN and the UE.
Option 4: NAS CN signalling data is not conveyed over the Iu interface; instead, it uses a direct CN-UE link.
Explanation: This option correctly reflects the principle that the same Iu interface channel employed for UTRAN-CN signalling is also used for transparently conveying various types of NAS CN signalling data (such as Call Control, Session Management, Mobility Management, etc.) between the Core Network (CN) and the User Equipment (UE). This approach ensures efficiency in resource utilization while maintaining the transparency required for effective signalling.