Evolved Packet Core (EPC) with flat network structure controls and bears separation based on completed IP structure, which only has packet domain but no circuit domain. EPC mainly includes MMe, SGW, PGW, and PCRF. As the fourth generation of mobile communication technology, 4G can rapidly transmit voice, text, video and image information. International Telecommunication Union regard 4G system as the system that accord with data transmission speed of 100 Mbit/s and it is high-speed dialogue between machines.
2. Elements of EPC
Main elements of EPC: MME、SGW、PGW、PCRF
MME (Mobility Management Entity): originally control function of SGSN in 3G network.
SGW (Serving Gateway): known as S-GW, originally user plane function of SGSN in 3G network.
PGW (PDN Gateway): known as P-GW, originally function of GGSN in 3G network.
PCRF (Policy and Charging Rules Function): completion of message strategy and billing control of user’s data.
3. Characteristics of EPC
1) Convergence of core network, routing of switching function;
2) Complete separation between business plane and control plane;
3) Minimize the number of network elements and optimize level of network protocol;
4) Flat network with completed IP.