Question: Upon receiving an RRCReconfigurationFailureSidelink message, what actions does a UE in RRC_CONNECTED mode take regarding its configuration and additional procedures?
Option 1: The UE initiates a new RRCReconfiguration request, starts timer T400 for the destination, and proceeds with default sidelink settings.
Option 2: The UE stops timer T400 for the destination (if running), switches to a predefined fallback configuration, but only updates sidelink settings after a successful RRC reconnection.
Option 3: The UE ignores the failure message, continues with the attempted new configuration, and skips performing sidelink UE information procedures.
Option 4: The UE stops timer T400 for the destination (if running), continues using the prior configuration, and performs the sidelink UE information procedure for NR sidelink communication.
Explanation: This is the correct sequence of actions as per the specified behavior for a UE receiving an RRCReconfigurationFailureSidelink message while in RRC_CONNECTED mode. Stopping timer T400 (if running) prevents unnecessary timeouts, reverting to the prior configuration maintains stability, and performing sidelink UE information procedures ensures proper communication setup for NR sidelink communication.