Question: In a UTRAN to GSM cell handover scenario for a combined FDD and GSM User Equipment (UE), what marks the starting point for measuring the handover delay?
Option 1: Reception of the first TTI on the new RAT channel
Option 2: End of the last Transmission Time Interval (TTI) containing an RRC message implying hard handover
Option 3: Initiation of the handover request by the UE
Option 4: Completion of the RRC connection release in the source UTRAN cell
Explanation: The correct starting point for measuring the UTRAN to GSM cell handover delay is defined as the end of the last Transmission Time Interval (TTI) that contains an Radio Resource Control (RRC) message which implies a hard handover. This marks the moment when the UE is instructed to switch to the new Radio Access Technology (RAT), and from this point, the time taken to successfully transmit on the channel of the new RAT is measured. This definition ensures the delay accounts for the time the UE takes to comply with the handover instruction and establish transmission on the new network.