Abstract: A mobile device (100) for establishing a connection with an access point (200) includes an interface module (110), an authentication module (120), and an association module (130). The interface module receives a user authentication instruction to launch authentication. The authentication module authenticates the access point via a first service set identifier (SSID) in order to acquire a second SSID and a key from the access point when the authentication is successfully launched. The association module re-associates with the access point via the second SSID and the key. A communication system and a connection establishing method are also provided.