Question: In an E-UTRAN, when should an eNB set the Congestion Experienced (CE) codepoint ('11') in PDCP SDUs for downlink or uplink transmission?
Option 1: Always, for all types of IP packets to ensure congestion awareness.
Option 2: Only for non-latency sensitive applications to prioritize buffer allocation.
Option 3: For PDCP SDUs with one of the two ECN-Capable Transport (ECT) codepoints set, indicating radio congestion in the respective direction.
Option 4: Never, as congestion signaling is more effectively handled through packet loss and retransmission.
Explanation: Setting the Congestion Experienced (CE) codepoint ('11') in PDCP SDUs with ECT codepoints helps avoid packet losses that would necessitate retransmissions, particularly beneficial for latency-sensitive applications like real-time voice, video, chat, and gaming. This approach aligns with recommendations for Explicit Congestion Notification (ECN) to manage radio congestion efficiently in both downlink and uplink directions without relying on packet loss as a congestion signal.