NPS: Non-periodic sensing for opportunistic spectrum access

One of the most challenging issues in cognitive radio networks is when and how often to sense the availability of licensed spectrum. Adopting the fixed sensing period to detect signals, the conventional periodic spectrum sensing method is inefficient or even not able to satisfy the various demands of secondary users. In this paper, we propose a non-periodic sensing (NPS) mechanism, which reduces the sensing overhead based on the users' data rate requirement and the spectrum availability statistics. Based on the theoretic framework of NPS, we propose three specific NPS methods-Demand-oriented method, Max-oriented method and Mix method-to schedule the spectrum sensing adaptively. The simulation results shows the improvement on the sensing efficiency compared with the periodic sensing approach.