Question: Which Xn-U protocol procedure is utilized for providing feedback regarding downlink data delivery from the corresponding node to the node hosting the NR (New Radio) PDCP (Packet Data Convergence Protocol) entity?
Option 1: Transfer of Upstream User Data
Option 2: Transfer of Assistance Information
Option 3: Downlink Data Delivery Status procedure
Option 4: Transfer of PDU Session Information
Explanation: The correct answer is the Downlink Data Delivery Status procedure. This procedure is specifically designed to enable the corresponding node (typically an NG-RAN node not hosting the NR PDCP entity) to provide feedback or status updates regarding the delivery of downlink data to the node that hosts the NR PDCP entity, ensuring efficient management and potential retransmission of undelivered packets in a 5G network.