- Figure shows the network architecture of the Evolved Packet Core (EPC). The EPC consists of three main nodes: the Mobility Management Entity (MME), the Serving Gateway (SGW) and the Packet Data Network Gateway (PGW). The MME may be co-located with the SGW, and the SGW may be co-located with the PGW. Hence, the standard allows a completely collapsed ‘one-node’ core network or a distributed (easily scalable) core network, or any possible ‘combination’ in-between.
- The MME connects to the E-UTRAN via the S1-MME interface and is present solely in the CP. It is responsible for handling mobility and security procedures, such as network Attach, Tracking Area updates (similar to Location/Routing Area updates) and authentication. The MME also connects to the SGSN via the S3-interface.
- The SGW connects to the E-UTRAN via the S1-U interface and is present solely in the UP. Its prime responsibility is routing and forwarding of user IP-packets. It acts as a UP anchor when the UE moves between 3GPP radio access technologies (S4-interface).
- The PGW connects to the SGW via the S5-interface and to external packet data networks (or IMS) via the SGi-interface. It is responsible for the enforcing of QoS and charging policies. It also acts as a UP anchor when the UE moves between 3GPP and non-3GPP radio access (S2-interface).
- It should be noted that additional network nodes/functions, not shown in figure , might be present as well. For example, a Packet Data Gateway (PDG) is needed for non-trusted IP access and a Policy and Charging Rules Function (PCRF) is required for IMS controlled QoS and charging mechanisms.
Network Architecture in LTE
LTE (Long-Term Evolution) network architecture is designed to support high-speed data, improved spectral efficiency, and low-latency communication. It is built around a simplified, all-IP (Internet Protocol) structure, which improves performance and scalability. The key components of the LTE architecture are as follows:
- E-UTRAN (Evolved UMTS Terrestrial Radio Access Network):
- The E-UTRAN is responsible for providing the radio access to the LTE network.
- It consists of eNodeBs (evolved Node Bs) that communicate directly with User Equipment (UE) and handle tasks like radio resource management, scheduling, and mobility management.
- EPC (Evolved Packet Core):
- The EPC is the core network that supports LTE data transmission and services.
- Key elements in the EPC include the MME (Mobility Management Entity), SGW (Serving Gateway), PGW (Packet Gateway), PCRF (Policy and Charging Rules Function), and HSS (Home Subscriber Server).
- User Equipment (UE):
- The UE includes mobile devices such as smartphones, tablets, or any other device that connects to the LTE network.
- It connects to the E-UTRAN (via eNodeBs) for communication and relies on the EPC for network services and management.
The architecture ensures seamless communication with high data rates and minimal latency. The E-UTRAN manages the radio interface, while the EPC handles core network functions, making the LTE system more efficient and scalable.