EPS (Evolved Packet System) is the name of the 4G mobile network. It consists of an evolved packet core (EPC) and an evolved universal terrestrial radio access network (E-UTRAN).
The E-UTRAN network presents the LTE (Long-Term Evolution) radio interface to the mobile.
Wi-Fi (Wireless Fidelity) interface is subsequently integrated into the EPS network and is a component of a set of technologies grouped under the term Non-3GPP Access.
Its introduction has an impact on the core network (EPC) architecture, which has several variants depending on the following characteristics:
The functional architecture based on the S2a interface corresponds to trusted Wi-Fi access and network-based mobility (Figure 1.1).
The mobile stream travels through the Wi-Fi radio interface and the S2a tunnel to access the packet data network (PDN). The PGW (PDN Gateway) entity is an IP (Internet Protocol) router that acts as a gateway for the mobile stream.
The home subscriber server (HSS) and the AAA (Authentication, Authorization and Accounting) server provide the following functions: