P in the IP tunnel of the mobile stream (Figure 1.10). Wi-Fi Integration to the 4G Mobile Network Control plane MIPv4 MIPv4 MIPv4 MIPv4 802.11 802.11 Trusted Wi-Fi Access Figure 1.9. Protocol architecture based on S2a interface Control plane for MIPv4 FA mechanism User plane IP packet 802.11 802.11 Trusted Wi-Fi Access Figure 1.10. Protocol architecture based on S2a interface User plane for MIPv4 FA mechanism MIPv4 signaling is exchanged, on the one hand, between the mobile and trusted Wi-Fi access and, on the other hand, between the trusted Wi-Fi access and the PGW entity. The MIPv4 protocol allows Wi-Fi access, playing the role of a foreign agent, to assign the mobile an IPv4 address in a foreign network. The MIPv4 protocol makes it possible to register with the PGW entity, which plays the role of a home agent, the correspondence between the mobile IPv4 address in the home network, provided by the PGW entity, and the IPv4 address in the foreign network. Architecture Based on Wi-Fi Access 1.2.1.3. GTPv2 mechanism The GTPv2 (GPRS Tunneling Protocol version 2) mechanism is based on the GTPv2-C (Control) signaling exchanged between the trusted Wi-Fi access and the PGW entity (Figure 1.11) and on the GTP-U (User) tunnel of the mobile flow (Figure 1.12). Control plane Trusted Wi-Fi Access Figure 1.11. Protocol architecture based on S2a interface Control plane for GTPv2 mechanism User Plane IP packet GTP-U GTP-U 802.11 802.11 GTP-U GTP tunnel Trusted Wi-Fi Access Figure 1.12. Protocol architecture based on S2a interface User plane for GTPv2 mechanism The GTPv2-C protocol allows the activation or deactivation of a session as well as the creation, modification or release of GTP-U bearers. The PMIPv6 and GTPv2 mechanisms can transport IPv4 or IPv6 streams in IPv4 or IPv6 tunnels. The MIPv4 mechanism allows the transport of only IPv4 streams in IPv4 tunnels. Wi-Fi Integration to the 4G Mobile Network 1.2.2. Architecture based on the S2b interface The S2b interface is the point of reference between the PGW and ePDG entitie