A Wi-Fi access point (AP) is provided. The Wi-Fi AP includes a femtocell signaling interface, a WAN interface, a Wi-Fi AP radio access interface, and a controller sub-system. The controller sub-system connects with a user equipment through the femtocell signaling interface, and connects with a CN through the WAN interface. The controller sub-system performs a first security establishment with the user equipment, and performs a second security establishment with the cellular core network. The controller sub-system obtains security parameters according to the first security establishment and the second security establishment. The controller sub-system performs a first Wi-Fi bearer setup procedure and a second Wi-Fi bearer setup procedure with the user equipment and the cellular core network. The controller sub-system performs a security information exchange procedure with a Wi-Fi AP radio access interface. The controller sub-system establishes a data transmission channel with the UE according to the security parameters.