Method and apparatus of transmitting frames in cognitive radio system

PURPOSE: A frame transmission method in a wireless communication system is provided to control transmission power by preventing the overlap of an interference signal. CONSTITUTION: A node determines bandwidth(S310). The node senses adjacent channels(S320). In case the extension of the bandwidth is unavailable, the node maintains the current bandwidth(S330,S340). In case the extension of the bandwidth is available, the node extends the bandwidth (S350). In case the reduction of the bandwidth is necessary, the node reduces the bandwidth(S360,S380). In case the reduction of the bandwidth is unnecessary, the node maintains the bandwidth(S370).