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Evolved Packet Core

(also EPC)

Evolved Packet Core definition

Evolved Packet Core is the main component of the System Architecture Evolution (SAE) standard for Long-Term Evolution (LTE) networks, providing a framework for converged (as in, using the same circuit or bandwidth) voice and data transfers.

Evolved Packet Core is primarily a 4G technology — in 5G, it is being replaced by the Next-Generation Core for improved performance, flexibility, and scalability.

See also: 5G network, mobile network operator, packet switching

Evolved Packet Core functions

Evolved Packet Core is primarily responsible for managing the routing of data packets between mobile devices and external networks (such as the internet). It establishes and terminates communication sessions, tracks the device’s location and handles network handovers, and monitors the traffic’s quality of service. Evolved Packet Core is also involved in some security functions, such as authentication and encryption.

Evolved Packet Core components

  • Mobility Management Entity (MME): Tracking the location of mobile devices, performing handovers between base stations, and managing session establishments and terminations.
  • Serving Gateway (SGW): Routing and forwarding user data packets between the base station (eNodeB) and the Packet Data Network Gateway (PDN-GW).
  • Packet Data Network Gateway (PDN-GW): Connecting the EPC to external packet data networks (such as the internet), assigning and managing IP addresses.
  • Home Subscriber Server (HSS): Storing subscriber information (like user profiles), authentication and authorization data, as well as subscription information.
  • ANDSF (Access Network Discovery and Selection Function): Intelligently selecting the best available access network for the mobile device.
  • Policy and Charging Rules Function (PCRF): Enforcing rules related to service quality, prioritization, and charging based on the subscriber's plan.