Question: What triggers the counting of a successful channel switch from E-DCH to DCH in the serving E-DCH cell?
Option 1: Receipt by the RNC of a RRC message CELL UPDATE from UE
Option 2: Detection of packet loss exceeding a certain threshold during an active session
Option 3: Completion of a voice call using the DCH channel
Option 4: Receipt by the RNC of specific RRC messages (e.g., RADIO BEARER RECONFIGURATION COMPLETE, RADIO BEARER SETUP COMPLETE, etc.) from UE, indicating channel switch completion
Explanation: The correct answer is Option 4 because the counting of a successful channel switch from E-DCH to DCH is triggered by the receipt of specific RRC messages by the RNC from the UE. These messages signify the completion of the channel switch process, ensuring optimal network operation and user experience.