Dynamic resource allocation for cognitive OFDMA networks based on “two witnesses rule” for cooperative spectrum sensing

In this paper, we propose a resource allocation scheme that maximizes the total throughput of the cognitive OFDMA system while avoiding the generation of harmful interferences to the primary users. The proposed approach is based on an imperfect knowledge of the spectrum availability. All secondary users listen to spectrum during a short period of time and apply censored energy detection, in order to reduce the overhead and ensure better credibility on the transmitted decision. As in wedding, we adopted the two witnesses rule for the cooperative spectrum sensing. Using this new rule, we established a confidence level for occupancy of each subcarrier of the OFDMA system, which will be used to adjust the transmitted power of the secondary user and hence increase the real achievable throughput of the system. Simulations were drawn in order to evaluate the accuracy of the new data fusion approach and the performance of the proposed resource allocation algorithm.