1️⃣ Uu Interface: The air interface connecting User Equipment (UE) and the eNodeB, responsible for data transmission, control signaling, and radio resource management.
2️⃣ S1-MME Interface: Connects Mobility Management Entity (MME) and eNodeB, exchanging messages related to mobility management, handovers, and paging.
3️⃣ S1-U Interface: Carries user data between eNodeB and Serving Gateway (SGW), handling data forwarding, routing, and charging.
4️⃣ S11 Interface: Links MME and SGW, exchanging session management messages like bearer creation, modification, and mobility management.
5️⃣ S5/S8 Interface: Connects SGW and Packet Data Network Gateway (PGW), facilitating user data transfer for both control plane and user plane communication.
6️⃣ S6a Interface: Connects MME and Home Subscriber Server (HSS), enabling authentication, authorization, and mobility-related information exchange.
7️⃣ X2 Interface: Connects two eNodeBs, supporting handover preparation, execution, and neighbor relation management.
8️⃣ SGi Interface: Connects the P-GW to PDN, responsible for IP address allocation, packet routing.
