Minimum transmission delay via spectrum sensing in cognitive radio networks

Spectrum sensing is one of the most important components of cognitive radio (CR) technology. In this paper, we investigate the design of the sensing time to minimize the secondary user (SU) transmission delay under the condition of sufficient protection to primary users (PUs). It has been proven that there exists one optimal sensing time which yields the minimum transmission delay. Then, a novel cooperative spectrum sensing (CSS) framework is proposed. In the novel CSS framework, one SU´s reporting time is also used for other SUs´ sensing. For time varying channels, the novel multi-slot CSS is derived. In order to minimize the transmission delay, some algorithms are derived to obtain the optimal fusion scheme. Computer simulations show that fundamental improvement of delay performance can be achieved by the optimal fusion scheme. In addition, the novel multi-slot CSS scheme shows a much lower transmission delay than CSS based on general frame structure.