What changes in architecture have been made with the EPC technology, and how do they affect network performance?
One important performance aspect of EPC is a flatter architecture. For packet flow, EPC includes two network elements, called Evolved Node B (eNodeB) and the Access Gateway (AGW). The eNodeB (base station) integrates the functions traditionally performed by the radio-network controller, which previously was a separate node controlling multiple Node Bs. The AGW integrates the functions traditionally performed by the Serving GRPS Support Node (SGSN). The AGW has both control functions, handled through the Mobile Management Entity (MME), and user plane (data communications) functions. The user plane functions consist of two elements: a serving gateway that addresses 3GPP mobility and terminates eNodeB connections, and a PDN Gateway that addresses service requirements and also terminates access by non-3GPP networks. The MME, serving gateway, and PDN gateways can be collocated in the same physical node or distributed, based on vendor implementations and deployment scenarios.
