Question: In a scenario utilizing UE-assisted local cache to mitigate backhaul latency, what triggers the eNB to determine if uplink data should be transferred to the local cache entity?
Option 1: Receipt of a specific PDCP PDU size from the UE
Option 2: Periodic network polls for connected UEs
Option 3: Assistance information bit indicated in the uplink PDCP PDU by the UE
Option 4: Automatic eNB configuration based on operator implementation
Explanation: The correct answer is Option 3 because, according to the described functionality of UE-assisted local cache, the decision for the eNB to transfer uplink data to the local cache entity is directly influenced by the assistance information bit that the UE includes in the uplink PDCP (Packet Data Convergence Protocol) PDU. This bit serves as a signal from the UE, based on application layer service requests that support local cache handling, prompting the eNB to take appropriate action regarding data transfer to the local cache entity.