Question: In a scenario where a User Equipment (UE) supporting both 1.28 Mcps TDD and GSM undergoes cell re-selection from a 1.28 Mcps TDD cell to a GSM cell, what marks the end of the cell re-selection delay period?
Option 1: The moment the UE successfully sends a LOCATION UPDATING REQUEST message to perform a Location update on the new GSM cell.
Option 2: When the UE initiates the handover procedure by sending a Handover Request to the new GSM cell.
Option 3: The instant the UE loses signal completely from the original 1.28 Mcps TDD cell.
Option 4: Upon receiving the first broadcast message from the new GSM cell.
Explanation: According to telecom principles related to cell re-selection and location updating, the end of the cell re-selection delay period is marked by a specific action indicating the UE has successfully transitioned to the new cell. Sending a LOCATION UPDATING REQUEST message signifies that the UE has not only selected the new GSM cell but is also initiating the process to update its location, which aligns with the completion of the cell re-selection process. This is particularly relevant in scenarios involving dual-mode UEs (supporting both 3GPP technologies like TDD and legacy systems like GSM) where seamless handover and location management are crucial for service continuity.