Sensing-Throughput Tradeoff in Cognitive Radio Networks: How Frequently Should Spectrum Sensing be Carried Out?

We consider a cognitive radio (CR) network that makes opportunistic access to a spectrum licensed to the primary users. During its operation, the CR network carries out spectrum sensing on a frame-by-frame basis to detect active primary users, thereby avoiding interfering with them. We formulate a collision-throughput tradeoff problem which, based on the sensing time requirement and the traffic pattern of primary users, finds optimal value for the frame duration of CR operation so that the throughput of the CR network is maximized, yet the collision probability of the primary users is not greater than a threshold. We derive the theoretical formula for achievable throughput of CR network and find the optimal solution for frame duration. Computer simulations are presented to evaluate the performance of our approach.