Question: What triggers the MBMS Session Update procedure in a UTRAN Iu interface, according to RANAP signalling protocols?
Option 1: Changes in the RA List of Idle Mode UEs, initiated by the Radio Network Controller (RNC)
Option 2: Periodic updates from the User Equipment (UE) to the Core Network (CN)
Option 3: The MBMS Session Update procedure is triggered by the Core Network (CN), specifically in the PS domain
Option 4: Handover of an Idle Mode UE between different Radio Access Networks (RANs)
Explanation: In the context of UTRAN Iu interface RANAP signalling, the MBMS Session Update procedure is specifically triggered by the Core Network (CN) when there are changes in the RA List of Idle Mode UEs during an ongoing MBMS session. This highlights the CN's role in managing and updating sessions based on network conditions, ensuring efficient resource allocation and service delivery.