Question: In a handover scenario from UTRAN to E-UTRAN, where the target cell is unknown but signal quality allows for successful detection on the first attempt, what is the maximum allowed interruption time (Tinterrupt) before the UE starts transmitting on the new PRACH channel, considering Tsearch and TIU values as specified?
Option 1: 100 ms (TIU of 15 ms + Tsearch of 80 ms + 5 ms margin)
Option 2: 115 ms (TIU of 15 ms + Tsearch of 80 ms + 20 ms as per Tinterrupt formula)
Option 3: 130 ms (TIU of 30 ms + Tsearch of 80 ms + 20 ms as per Tinterrupt formula)
Option 4: 145 ms (TIU of 30 ms + Tsearch of 80 ms + additional assumed processing time)
Explanation: The correct calculation for Tinterrupt when the target cell is unknown but detectable on the first attempt involves adding TIU (15 ms in this specified case), Tsearch (80 ms for first-attempt detection), and the additional 20 ms as defined by the Tinterrupt formula. This results in a total of 115 ms, which aligns with the detailed specification provided for handover scenarios in E-UTRAN.