Question: In a combined TDD 1.28Mcps and GPRS User Equipment (UE), what marks the starting point for measuring the UTRAN to GPRS cell change order procedure delay?
Option 1: Transmission start of the first TTI on the GPRS channel
Option 2: Receipt of the CELL CHANGE ORDER FROM UTRAN message by the UE
Option 3: End of the last Transmission Time Interval (TTI) containing the CELL CHANGE ORDER FROM UTRAN message
Option 4: Initiation of the cell change order procedure by the network
Explanation: The correct starting point for measuring the delay is the end of the last TTI that contains the CELL CHANGE ORDER FROM UTRAN message, as this event triggers the UE's transition process to the GPRS cell. This specific moment is crucial because it marks the completion of the instruction receipt and the beginning of the UE's action to switch, making it the logical starting point for measuring the procedure's delay in the context of combined TDD 1.28Mcps and GPRS UEs.