Question: What triggers the increment of the measurement "Number of UEs with DL LWA PDUs successfully transmitted over Xw interface" in a collection period?
Option 1: Receipt of UL DATA DELIVERY STATUS frame by the eNB from WT.
Option 2: Receipt of DL DATA DELIVERY STATUS frame by the eNB from WT indicating successful transmission of downlink LWA PDUs over the Xw interface for a UE that has not been counted yet in the collection period.
Option 3: Transmission of UL LWA PDUs over the Xw interface for a UE.
Option 4: Establishment of a new EPS bearer for a UE.
Explanation: The correct answer is Option 2 because, according to the text, the measurement is incremented by 1 when the eNB receives a DL DATA DELIVERY STATUS frame from WT indicating that downlink LWA PDUs have been successfully transmitted over the Xw interface for a UE that has not been counted yet in the collection period. This specific condition triggers the increment of the measurement.