Question: When a UE moves to ECM-IDLE state, triggering buffering in SGW-U, what action is taken by SGW-U regarding packet/byte measurement for a session?
Option 1: SGW-U discards all buffered packets without measurement.
Option 2: SGW-U measures packets/bytes but only reports upon explicit request from SGW-C.
Option 3: SGW-U measures the number of packets/bytes buffered or discarded and reports to SGW-C based on predefined criteria within the Usage Reporting Rule.
Option 4: SGW-U pauses all buffering until UE returns to a connected state.
Explanation: This is correct because, when the SGW-C activates buffering in SGW-U for the session (upon the UE moving to ECM-IDLE state), it instructs SGW-U to buffer and measure packets/bytes that are buffered or discarded. SGW-U reports this usage information back to SGW-C once predefined reporting triggers within the Usage Reporting Rule are met, highlighting a proactive measurement and reporting approach based on set criteria.