Question: During PDCP data recovery for an AM (Acknowledged Mode) Data Radio Bearer (DRB), what action does the transmitting PDCP entity take regarding previously submitted PDCP Data PDUs without confirmed delivery?
Option 1: Discard all previously submitted PDCP Data PDUs to prevent duplication.
Option 2: Retransmit all previously submitted PDCP Data PDUs in ascending order of their associated COUNT values.
Option 3: Hold retransmission until explicit lower layer confirmation for all pending PDUs is received.
Option 4: Proceed with new transmissions without retransmitting unconfirmed PDUs to avoid delay.
Explanation: In Acknowledged Mode (AM) for Data Radio Bearers (DRBs), ensuring reliable data transfer is crucial. During a PDCP data recovery, the transmitting PDCP entity must guarantee that all data is delivered successfully. Retransmitting previously submitted PDCP Data PDUs in ascending order of their COUNT values ensures that data integrity and sequence are maintained, aligning with the principles of acknowledged mode transmissions where reliability is paramount. This approach prevents data loss and ensures that the receiver can correctly reassemble the data stream.