System Architecture Evolution, or SAE, is synonymous with Evolved Packet Core, or EPC. SAE/EPC is defined by 3GPP in Release 8 (Rel-8) as an entirely new core network with a flatter all-IP architecture enabling a higher data rate, lower latency packet-optimized system that supports multiple radio-access technologies, focusing on the packet-switched domain, with the assumption that the system will support all services — including voice — in this domain.
3GPP has made significant progress in Rel- 8 towards the standards development and definition of a new flatter-IP core network to support the Evolved UMTS Terrestrial Radio Access Network (EUTRAN) through the SAE work item, which has recently been renamed the Evolved Packet Core (EPC) Architecture. In parallel, 3GPP has made significant progress towards the standards development and definition of a new OFDMA-based technology through the Long Term Evolution (LTE) work item. This new OFDMA based air interface (LTE) is also often referred to as the EUTRAN. Note that the complete packet system consisting of the EUTRAN/LTE and the SAE/EPC is called the Evolved Packet System (EPS).
The combination of LTE and SAE/EPC provides the long-term vision for 3GPP to an all-IP, packet only wideband OFDMA system expected to further improve performance by providing higher data rates, improved spectral efficiency and reduced latency. LTE’s ability to support bandwidths wider than 5 MHz is of particular importance as the demands for higher wireless data speeds and spectral efficiencies continue to grow.
As mobile operators add HSPA+ and LTE to their radio access networks, they will simultaneously evolve the rest of their networks and subscriber devices. They will beef up their core and backhaul networks to handle the exponential increases in IP traffic enabled by HSPA+ and LTE. To keep their networks performing optimally, mobile operators will flatten their core network architectures considerably by using EPC technology. EPC reduces the number of nodes in the core, which reduces latency even as the amount of data traffic increases. It simplifies deployment of IP-based networks and reduces the cost of their deployments.
EPC will use IP Multimedia Subsystem (IMS) as a component. It will also manage Quality of Service (QoS) across the whole system, which will be essential for enabling a rich set of multimedia-based services. The EPS will be optimized for all services to be delivered via IP in a manner that is as efficient as possible – through minimization of latency within the system, for example.
Although it will most likely be deployed in conjunction with LTE, EPC may also be deployed for use with HSPA+, where it would provide a stepping-stone to LTE. It will support service continuity across heterogeneous networks, important for LTE operators that must simultaneously support GSM/GPRS/EDGE/UMTS/HSPA customers.
The key features and capabilities of SAE/EPC include: