Question: Upon receiving an indication of uplink synchronization loss due to satellite switch with re-synchronization from upper layers, what actions does the MAC entity take regarding HARQ buffers and uplink transmission on the Serving Cell?
Option 1: Update NTA value to a predefined non-zero value for PTAG and continue uplink transmission with adjusted settings.
Option 2: Flush all HARQ buffers and suspend uplink transmission on the Serving Cell until synchronization is regained.
Option 3: Temporarily hold new data in HARQ buffers but allow ongoing transmissions to complete before suspending uplink activity.
Option 4: Immediately restart uplink transmission with a new Differential Koffset value without altering HARQ buffer contents.
Explanation: When the MAC entity receives an indication of uplink synchronization loss, including cases due to satellite switch with re-synchronization, it must ensure data integrity and prevent erroneous transmissions. Flushing all HARQ buffers eliminates potential corrupted or outdated data, while suspending uplink transmission on the affected Serving Cell prevents further errors until synchronization is restored, aligning with efficient and reliable telecom network operation principles.