Abstract: Based on the characteristics of cognitive radio and transmission properties of OFDM, an adaptive resource allocation algorithm in OFDM cognitive radio system is proposed. By keeping the interference introduced to the primary users within a tolerable range in sub-carrier allocation and power allocation, the proposed algorithm maximizes the system throughout. In addition, this scheme can guarantee quality of service(QoS)
among secondary users based on a fairness principle. Simulation results show performance and effectiveness of this algorithm.