Question: What type of interfaces does a Relay Node (RN) in E-UTRAN support, in addition to partially supporting UE functionality to connect to a Donor eNB (DeNB)?
Option 1: Only the Un interface and S1 interface for direct core network connectivity.
Option 2: Modified E-UTRA radio interface (Un) for connection to DeNB, but not S1 or X2 interfaces.
Option 3: The Un interface to connect to DeNB, plus S1 and X2 interfaces similar to eNB functionality.
Option 4: Only UE-specific interfaces (e.g., NAS, RRC) without any eNB-like network interfaces.
Explanation: This is correct because, according to the specifications, a Relay Node (RN) supports the modified E-UTRA radio interface (Un) for its connection to the Donor eNB (DeNB). Additionally, it terminates radio protocols and supports S1 and X2 interfaces, similar to an eNB, to facilitate network integration and communication with other eNBs and the core network. This dual functionality (partial UE and partial eNB) enables the RN to both connect to the DeNB wirelessly and serve UEs.