ork WLAN Control Plane Wi-Fi Protected Access Weighed Random Early Discard eXtensible Markup Language Introduction The proliferation of mobile applications has increased the amount of data in the 4G mobile network. With the adoption of smartphones and broadband services, such as video streaming, cellular network resources are increasingly constrained. Wi-Fi technology is ideally positioned to add capacity to the cellular network. It is necessary to improve the interworking between the 4G mobile network and the Wi-Fi network in order to offer a global and consistent broadband access to the end-user. In addition to growing traffic, users expect unrestricted access to applications whether at home, in a business or on the road. For this reason, Wi-Fi technology, providing additional coverage, is an appropriate solution for roaming users. The ability to exploit unlicensed frequency bands in addition to the spectrum allocated to cellular networks is of obvious appeal to network operators, who see Wi-Fi as another means of accessing the 4G mobile network. Many mobile phones currently sold include both cellular and Wi-Fi radio access and are capable of simultaneously using both radios. This makes it possible to direct certain services to Wi-Fi access and others to the cellular radio access. xxiv Wi-Fi Integration to the 4G Mobile Network The various standardization bodies, IEEE (Institute of Electrical and Electronics Engineers), WFA (Wi-Fi Alliance) and 3GPP (3rd Generation Partnership Project), paved the way for the integration of Wi-Fi technology into the cellular network, allowing the mobile to access its services through Wi-Fi access. I.1. 4G mobile network I.1.1. Network architecture The 4G mobile network, which is called EPS (Evolved Packet System), consists of an evolved packet core (EPC) and an evolved universal terrestrial radio access network (E-UTRAN) (Figure I.1). The E-UTRAN access network provides the connection of the user equipment (UE). The core network EPC interconnects access networks, provides the in