Disclosed is a method of allocating radio resources, including: acquiring available channel information of a cognitive radio small cell; analyzing a channel characteristic based on the available channel information and dividing a required transmission rate of the cognitive radio small cell into required transmission rates for each available channel; and performing a power control for each available channel based on the divided required transmission rates for each available channel. The method of allocating radio resources may be performed under an interference environment in which a plurality of cognitive radio small cells is present and the plurality of cognitive radio small cells shares an available channel.