Access system determining device based on wlan signal strength in wireless local area network/mobile phone interworking system and method and mobile terminal therefor

PURPOSE: A method for an access system determining device based on WLAN(Wireless LAN) signal strength in a wireless LAN/mobile phone interworking system is provided to activate a driving module according to a determined service, and to access the service, thereby supplying an efficient roaming service between a WLAN service and a mobile phone service. CONSTITUTION: An access controller performs an initialization process, measures signal strength for a WLAN, and displays the measured signal strength(S100). The access controller decides whether a signal strength value of the WLAN is bigger than a set value for setting a WLAN mode(S101). If so, the access controller maintains an active state of a WLAN driving module(S102). The access controller measures a signal for the WLAN(S103), and determines whether to maintain a WLAN communication state or convert into a mobile phone mode(S104). If the signal gets lower, the access controller activates a mobile phone driving module and inactivates the WLAN driving module(S105). If communication is incapable to the WLAN, the access controller measures the WLAN signal(S107) and determines whether to convert into the WLAN communication mode(S108). If so, the access controller activates the WLAN driving module and inactivates the mobile phone driving module(S109).