Question: What is the primary factor that determines the maximum allowable time (Dhandover) for a UE to start transmitting on the uplink PRACH channel in E-UTRAN after receiving a handover command from NR to E-UTRAN?
Option 1: The sum of the RRC procedure delay (TRRC_procedure_delay) and the interruption time (Tinterrupt)
Option 2: The RRC procedure delay (TRRC_procedure_delay) alone, which is a fixed value of 50ms
Option 3: The interruption time (Tinterrupt) alone
Option 4: A static, predefined handover delay specific to each UE device model
Explanation: The correct answer is the sum of two components because Dhandover is specifically defined as the combination of TRRC_procedure_delay (a fixed RRC procedure delay of 50ms) and Tinterrupt (the variable time between the end of the RRC command on NR PDSCH and the start of PRACH transmission in E-UTRAN, excluding TRRC_procedure_delay). This composite measurement accounts for both the standardized procedural delay and the dynamic interruption period, ensuring a comprehensive handover timing calculation.