Question: What is the primary purpose of the Retrieve UE Context procedure in E-UTRAN, involving the X2 Application Protocol (X2AP)?
Option 1: To transfer a UE's context from an old eNB to a new eNB for RRC connection resumption or re-establishment after a failure (e.g., Radio Link Failure - RLF).
Option 2: To establish a new S1 interface connection between the MME and a different eNB during a UE's initial attachment.
Option 3: For load balancing, to redistribute UEs' contexts among eNBs in the same tracking area.
Option 4: To update the UE's context in the MME when the UE moves to a new Tracking Area.
Explanation: The Retrieve UE Context procedure is crucial for seamless mobility and connectivity. By transferring the UE's context from the old eNB (where the RRC connection was suspended or failed) to the new eNB (where the UE attempts to resume or re-establish the RRC connection), this procedure ensures continuity of service, minimizing disruptions due to events like Radio Link Failure (RLF). This process leverages UE-associated signaling over the X2 interface, highlighting its importance in E-UTRAN's handover and recovery mechanisms.