Question: In NB-IoT, when a User Equipment (UE) experiences a Radio Link Failure (RLF) and fails to re-establish an RRC connection, how does it indicate the occurrence of an RLF failure to the eNodeB (eNB) upon reconnecting from idle mode?
Option 1: By sending an immediate RRC Connection Setup Request with embedded RLF Report.
Option 2: Through a dedicated RLF Notification message sent after the UE re-establishes its connection.
Option 3: The UE does not proactively indicate; the eNB detects it through periodic radio measurements.
Option 4: By making the RLF Report available to the eNB after reconnecting from idle mode, as part of the RRC connection setup procedure.
Explanation: According to Mobility Robustness Optimization in NB-IoT for handling Radio Link Failures, if an RRC connection re-establishment fails or isn't attempted, the UE signals the occurrence of an RLF failure by making the RLF Report available during the subsequent RRC connection setup procedure after reconnecting from idle mode, enabling the network to understand and retrieve the associated report for analysis.