Signalling method of detecting hidden incumbent system in cognitive radio environment and channel fractioning method used to enable the method

A signaling method for detecting a hidden incumbent system in a CR(Cognitive Radio) environment and a channel division method adopted to the method are provided to enable a CR base station to know the hidden incumbent system, so that detection and avoidance can be quickly performed, thereby minimizing influence on the incumbent system in the CR environment. An EOS(Explicit Outband Signal) is broadcasted to more than one outband channel according to a predetermined period(800). A sensing report signal for an incumbent system using a channel is received from a CR terminal communicating through the predetermined channel(801). The channel of the CR terminal is switched to the outband channel(802-804). The predetermined period is determined by requisite detection time of the incumbent system. Under a cognitive radio environment, a frame of an orthogonal frequency division multiplexing access method is transceived, and the EOS is transmitted to the CR terminal through the downlink of the frame and the sensing report signal is transmitted to the CR base station through the uplink of the frame.