Question: In MBMS testing on MBSFN clusters, how often is the MBMS MODIFIED SERVICES INFORMATION message transmitted during a modification period when an MBMS service change occurs?
Option 1: Once per TTI (Transmission Time Interval)
Option 2: Once per modification period, only at the start
Option 3: Continuously throughout the modification and subsequent periods
Option 4: Once per repetition period, throughout the modification period
Explanation: According to MBMS testing rules on MBSFN clusters, when an MBMS service change is notified, the MBMS MODIFIED SERVICES INFORMATION message is transmitted once per repetition period. This ensures UEs are updated about the impending service change throughout the modification period, facilitating a smooth transition.