Femto BS for reducing inter-cell interference and method for transmitting signal using the same

A signal transmission method includes determining whether there is a User Equipment (UE) within an area of the femto BS, determining whether the UE is in an active mode, operating in a first mode of alternating a first Available Interval (AI) with a first UnAvailable Interval (UAI) in time, if no UE exists within the area of the femto BS, operating in a second mode of alternating a second AI with a second UAI shorter than the first UAI in time, if a UE exists within the area of the femto BS and operates in an inactive mode and operating in a third mode of continuously transmitting a signal, if a UE exists within the area of the femto BS and operates in the active mode.