prefix of the IPv6 address. The single-connection mode supports mobility between LTE and Wi-Fi accesses. This mode also supports non-seamless WLAN offload (NSWO), for which traffic is routed directly to the Internet network through TWAG function. The multiple-connection mode supports NSWO and multiple-access PDN connectivity (MAPCON), for which the various connections to the PDN network pass through the LTE (e.g. telephone service) or Wi-Fi (e.g. Internet service) interfaces according to the policy of the operator. Mobility between LTE and Wi-Fi radio accesses is possible. The connection on the Wi-Fi interface is established by the WLCP (WLAN Control Plane) protocol. The connection is identified by the MAC address of the mobile associated with a MAC address of the TWAG function. For the single- or multiple-connection mode, the IPv4 and/or IPv6 address of the mobile is provided by the PGW. Wi-Fi Integration to the 4G Mobile Network The PGW entity shall allocate the downlink packets to different S2a bearers based on the TFT (Traffic Flow Template) packet filters set up during the establishment of the S2a bearer (Figure 1.2). Flows (IP packets) Wi-Fi Layer filter bearer filter Figure 1.2. Connection to the PDN network for architecture based on the S2a interface TWAN function of the trusted Wi-Fi access shall assign the uplink packets to different S2a bearers based on the TFT packet filters set up during the establishment of the S2a bearer (Figure 1.2). 1.1.2. Architecture based on the S2b interface The functional architecture based on the S2b interface corresponds to untrusted Wi-Fi access and network-based mobility (Figure 1.3). Server Untrusted Wi-Fi e-PDG Access Figure 1.3. Functional architecture based on the S2b interface Architecture Based on Wi-Fi Access The mobile stream passes through the SWu and S2b tunnels to access the PDN network via the PGW entity. The SWu tunnel is built between the mobile and the evolved packet data gateway (ePDG). The S2b tunnel is built between the ePDG and PGW entities. The HSS en