Question: How does the Broadcast Multicast Service Centre (BM-SC) notify User Equipment (UEs) about updates to a file that has been registered for, when delivery over Multimedia Broadcast/Multicast Service (MBMS) is deemed beneficial?
Option 1: By sending a dedicated unicast notification message directly to each UE.
Option 2: Through periodic MBMS service announcements over broadcast channels.
Option 3: Via updates to the file itself, which UEs detect upon next access.
Option 4: By updating the Schedule Description metadata fragment of the keep-updated service USD using MBMS service announcement procedures over unicast.
Explanation: This is the correct method as per the specified telecom protocol. The BM-SC utilizes existing MBMS service announcement procedures but delivers them over unicast to inform registered UEs about forthcoming file updates, ensuring targeted notification without immediate broadcast of the updated content itself. This approach efficiently manages network resources while keeping UEs informed.