Question: In an Inter-RAT environment, what is a primary condition for detecting ping-pongs as part of Mobility Robustness Optimisation, where a UE's handover between two different RATs (e.g., E-UTRAN to UTRAN and back to E-UTRAN) is considered problematic?
Option 1: The UE's handovers occur without any change in the used service.
Option 2: The coverage of the source RAT was sufficient for the service used by the UE during the handovers.
Option 3: The time between the two consecutive handovers exceeds a predefined extended duration.
Option 4: The UE's handovers involve more than two different types of RATs.
Explanation: Detecting Inter-RAT ping-pongs involves identifying unnecessary handovers between different RATs. A key aspect of this is verifying if the initial return to the source RAT could have been avoided, given its coverage was adequate for the UE's service needs at the time of the handover. This condition (coverage sufficiency) is crucial for determining whether a ping-pong event constitutes a problem that warrants optimization.