A subcarrier and Power Allocation based on Variational inequality in Cooperative Cognitive OFDM Systems

In this paper, cognitive user collaboration between subcarrier and power allocation problem is researched based on the collaborative cognitive OFDM networks. Cognitive radio users opportunely access free authorized frequency band, and improve the spectrum utilization. Cognitive users may retransmit data as a relay for other users at any time. We improve transmission efficiency and system throughput by introducing cooperation communication technology. The key problem is how to carry out the effective joint subcarrier selection and power distribution to improve cognitive network cooperation efficiency, considering the main user system interference. In this paper, we suppose the scene including multiple primary users and cognitive users. In the collaborative communication problems of the cognitive OFDM system, three-node cooperation relay cognitive network is equivalent to two-node noncooperation cognitive network. To maximize the channel capacity, the resource allocation model is established based on the cooperation game in cognitive radio system. Using the variational inequality theory Nash equilibrium existence and uniqueness is strictly prooved. At last, it puts forward a kind of iterative joint subcarrier selection and power allocation algorithm, and gets the optimal resource allocation method. At the same time we ensure that the temperature interference of multiple main users system is kept in a certain threshold value range.