A method of controlling communication modes for a wireless entity and a user equipment (UE), and a communication system using the same method. In one of the exemplary embodiments, the disclosure is directed to a method of controlling communication modes used by a wireless entity. The method would include not limited to receiving traffic loading information of a licensed spectrum used by a cellular network, detecting an interference situation of an unlicensed spectrum, selecting an operating mode from the communication modes according to the traffic loading information and the interference situation, and operating at the selected operating mode on the unlicensed spectrum.