Question: In a UTRAN to GSM cell handover scenario for a UE supporting both TDD and GSM, what marks the starting point for measuring the handover delay?
Option 1: Reception of the first TTI on the new RAT (GSM)
Option 2: Transmission of the last TTI containing an RRC message implying soft handover
Option 3: Initiation of the handover procedure by the UE
Option 4: End of the last TTI containing an RRC message implying hard handover
Explanation: The correct starting point for measuring the UTRAN to GSM cell handover delay is the end of the last Transmission Time Interval (TTI) that contains a Radio Resource Control (RRC) message indicating a hard handover, marking when the UE is instructed to switch to the new Radio Access Technology (RAT), with the subsequent time to successful transmission on the new channel being measured. Options 1, 2, and 3 are incorrect due to referencing pre-handover events on the new RAT, confusing hard with soft handover, or referring to an earlier process stage.