Question: Upon receiving a request from upper layers to release an RLC (Radio Link Control) entity, what actions must a User Equipment (UE) take regarding its data units and the RLC entity itself?
Option 1: The UE shall buffer all existing RLC SDUs (Service Data Units), segments, and PDUs (Protocol Data Units) for potential retransmission and then release the RLC entity.
Option 2: The UE shall discard all RLC SDUs, RLC SDU segments, and RLC PDUs, if any, and then release the RLC entity.
Option 3: The UE may choose to either discard or buffer all RLC SDUs, segments, and PDUs before releasing the RLC entity, depending on its current operational mode.
Option 4: Releasing an RLC entity does not affect the handling of existing RLC SDUs, segments, and PDUs; the UE only terminates the entity without altering data unit states.
Explanation: When upper layers request an RLC entity release, the UE must take a definitive action to manage its resources efficiently. Discarding all RLC SDUs, segments, and PDUs (if any) ensures a clean slate before releasing the RLC entity, which is crucial for resource management and preventing potential data inconsistencies or leaks, especially in contexts requiring efficient resource utilization.