Question: What triggers the increment of the "ERAB_Rel_Succ_Nbr" measurement per QCI in an E-UTRAN network?
Option 1: Receipt of a PATH SWITCH REQUEST ACKNOWLEDGE message by the eNB/RN, indicating successful release of some or all E-RABs.
Option 2: Transmission of an E-RAB RELEASE RESPONSE message by the eNodeB/RN to the MME/DeNB.
Option 3: Successful completion of an intra-eNB/RN handover, indicated by the RRCConnectionReconfigurationComplete message from the UE.
Option 4: All of the above options are correct triggers for incrementing the "ERAB_Rel_Succ_Nbr" measurement per QCI.
Explanation: The correct answer is Option 4 because all the mentioned options (receipt of PATH SWITCH REQUEST ACKNOWLEDGE, transmission of E-RAB RELEASE RESPONSE, successful completion of intra-eNB/RN handover indicated by RRCConnectionReconfigurationComplete message) are valid triggers for incrementing the "ERAB_Rel_Succ_Nbr" measurement per QCI in an E-UTRAN network.