Throughput optimization in OFDMA cognitive radio networks based on node selection and power allocation

Node selection for sensing and transmission processes in cognitive radio networks, is an important problem. Due to channel impairments in wireless networks, cooperative spectrum sensing is used in orthogonal frequency division multiple access (OFDMA) cognitive radio networks. To exploit the benefits of OFDMA in cognitive radio networks, efficient managements of resources such as power and subcarrier for selected transmission nodes should be done. We have to maximize the throughput of secondary users under total power budget along with the detection performance constraints. Based on the standard optimization techniques, the optimal conditions are obtained and a closed-form equation is expressed to determine the priority of PUs for assigning the sensing nodes to them. Simulation results show that our proposed algorithms can improve the sensing and transmission performance.