Question: In a UE supporting both 1.28 Mcps TDD and FDD, what is the maximum additional delay (TCSI) when cell re-selection indication is sent in enhanced CELL_FACH state during handover from TDD to FDD?
Option 1: Up to one frame (10 ms)
Option 2: Equal to the random access procedure delay (TRA)
Option 3: Sum of one subframe and TRA (5ms + TRA)
Option 4: Either up to one subframe (5ms) or the delay caused by the random access procedure (TRA), whichever is applicable
Explanation: According to the TDD-FDD cell re-selection requirements for UEs supporting both modes, TCSI (the additional delay in case the cell re-selection indication shall be sent in enhanced CELL_FACH state) can indeed vary. Specifically, it is defined as being either up to one subframe (5ms), which reflects a fixed maximum duration, or alternatively, it can be the delay caused by the random access procedure (TRA), indicating variability based on procedural timing. This dual definition accommodates different operational scenarios, hence making Option 4 the accurate and comprehensive choice.