The document describes the core network architecture of 3GPP's LTE wireless communication standard known as System Architecture Evolution (SAE). SAE features an all-IP network with simplified architecture and support for higher throughput, lower latency radio access networks. It consists of four main components: the Mobility Management Entity (MME) which handles mobility and security, the Serving Gateway (SGW) which manages user plane mobility, the Packet Data Network Gateway (PGW) which acts as an anchor point for external networks, and the Policy and Charging Rules Function (PCRF) which supports policy enforcement and charging control.