Question: In a TDD UTRAN to GSM handover scenario, what is the primary factor that determines whether the UE uses a 190ms or 90ms delay before transmitting on the new RACH of the target GSM cell?
Option 1: The type of System Information (e.g., Type 13) being read from the BCCH data.
Option 2: Whether the UE has synchronized to the GSM cell's BCCH carrier before receiving the CELL CHANGE ORDER FROM UTRAN.
Option 3: The random access procedure's additional delay in the GSM cell (TRA).
Option 4: The maximum time allowed to read BCCH data from the GSM cell (TBCCH).
Explanation: The key determinant for the delay (either 190ms or 90ms) before the UE transmits on the new RACH of the target GSM cell is whether the UE has already synchronized with the GSM cell's BCCH carrier at the time it receives the CELL CHANGE ORDER FROM UTRAN. If synchronized, the shorter 90ms delay applies; otherwise, the longer 190ms delay is used. This distinction directly impacts handover efficiency and success rates in mixed UTRAN and GSM environments.