An Optimal Opportunistic Spectrum Access Approach

Opportunistic spectrum access system allows the secondary user to access spectrum holes not being utilized by the primary user. Traditional opportunistic spectrum access approaches only sense and utilize current spectrum holes. This can result in uncontrollable collision probability, which exceed the maximum collision probability allowed by the primary user network. In this paper, we consider a cognitive radio system with one primary channel and one secondary user, and then we introduce a channel-usage pattern model and a fundamental access scheme in this system. On the basis of this model and fundamental access scheme, we study optimal opportunistic spectrum access problem and formulate it as an optimization problem that the secondary user maximizes spectrum holes utilization under the constraint of collision tolerable level. And then we solve this optimization problem in the case that the idle period is exponential distribution. Theoretical analysis and simulation results both show that the optimal opportunistic spectrum access approach can maximize spectrum holes utilization under the constraint of collision tolerable level.