InLTE networks, the LTE components developed from the UMTS network components are referred to as Evolved. Thus, the core structure of the System Architecture Evolution( SAE) of LTE networks is called Evolved Packet Core (EPC), the radio base station familiar from GSM networks is called Evolved Node B(eNodeB), the gateway to the exchanges is called Evolved Packet Data Gateway (EPDG), and the mobile access network is called Evolved UTRAN( E-UTRAN).
The core structure of the SAE architecture is formed by the Evolved Packet Core (EPC). The Evolved Packet Core (EPC) is a framework through which the convergence ofvoice and data in the LTE network is established. In 2nd generation( 2G) and 3rd generation( 3G) networks, voice is transmitted using circuit switching and data is transmitted using data packet switching. Convergence is achieved through the IP protocol, which the EPC framework uses to transmit voice and data.
In the EPC framework, the subscriber device is connected to the radio base station. The radio base station is the Evolved Node B( eNB). A further connection is made via the Evolved Packet Gateway (EPGW) to switching nodes of packet-switched networks or the Internet. Different mobile networks can be coordinated via the Evolved Packet Core and handover and roaming between subscribers can be performed.