Opportunistic Spectrum Access in Cognitive Radio System Employing Cooperative Spectrum Sensing

In cognitive radio systems, as the sensing ability of single cognitive user is limited, the opportunistic spectrum access has to allow different cognitive users to cooperatively search for and exploit instantaneous spectrum availability. In this paper, we address the design of opportunistic spectrum access for cognitive radio system employing cooperative spectrum sensing. The opportunistic spectrum access strategy contains two parts: an access policy to maximize the transmission throughput in each channel, and a cooperative spectrum sensing strategy to maximize the overall transmission throughput of the cognitive network. We first propose the optimal access policy as an optimal tradeoff point between transmission collision and overlooked opportunity in each channel. Then the optimal cooperative spectrum sensing strategy is studied to solve the following questions: to what extent each cognitive user should cooperate with others and which part of spectrum it should choose to sense. Simulation results are given to demonstrate the promising performance.