A new perspective on spectrum sensing for cognitive sensor networks

We address an important aspect of spectrum sensing that has been often overlooked by researches. While the cognitive radio is supposed to be aware of its surrounding, existing works do not consider the characteristics of secondary users to find the optimal sensing period. In this paper, a hybrid sensing method is presented that finds the optimal sensing period according to the characteristics of both primary and secondary users. Based on a continuous time Markov chain model, the proposed method adaptively varies its parameters to avoid unnecessary sensing tasks. In addition, the proposed method guarantees the priority of licensed users and spectrum opportunities to be discovered by cognitive users. Finally, the hybrid method is compared with a non-hybrid technique. It is concluded that the proposed method outperforms the non-hybrid method in terms of transmission efficiency.