Question: In a scenario where a User Equipment (UE) camps on a 3.84 Mcps Time Division Duplexing (TDD) cell and then reselects to a Frequency Division Duplexing (FDD) cell, what event marks the end of the cell re-selection delay?
Option 1: When the UE's cell quality level monitoring detects a better ranked FDD cell.
Option 2: When the UE starts sending preambles on the Physical Random Access Channel (PRACH) for sending the Radio Resource Control (RRC) CONNECTION REQUEST message to perform a Location Registration on the new FDD cell.
Option 3: Immediately after the UE switches its receiver to the frequencies of the target FDD cell.
Option 4: When the UE completes the Location Registration process on the new FDD cell.
Explanation: The correct answer is Option 2 because, according to the provided context, the cell re-selection delay ends when the change in cell quality levels prompts the UE to take action by sending preambles on the PRACH for the purpose of initiating a connection (via an RRC CONNECTION REQUEST message) on the newly selected, better-ranked FDD cell. This marks the transition from evaluating cell quality to actively engaging with the new cell, thus concluding the re-selection delay period.