Question: What triggers the RN (Relay Node) to update the X2 availability and configuration data for a neighbouring eNB (eNodeB) in an E-UTRAN network?
Option 1: Receipt of an S1 Setup request from the MME (Mobility Management Entity)
Option 2: Detection of a neighbouring cell's broadcasted system information
Option 3: Handover of a UE (User Equipment) to the neighbouring eNB
Option 4: Reception of an ENB CONFIGURATION UPDATE message via X2, containing served cells of the neighbouring eNB
Explanation: The correct answer is Option 4 because, according to the specified procedure, when an RN receives an ENB CONFIGURATION UPDATE message over the X2 interface and identifies that the served cells listed belong to a neighbouring eNB (not the DeNB it's connected to), it updates its records on the availability of the X2 interface with that neighbour, along with other pertinent configuration details. This process ensures seamless communication and resource allocation between base stations in the network for efficient user equipment management.