Adaptive spectrum sensing for cognitive radio systems in a fading environment

Cognitive radio (CR) has been emerging as a new technology enabling unlicensed secondary users (SUs) to dynamically access licensed spectrum bands underutilized by primary users (PUs). Spectrum sensing plays an important role in CR systems to detect PU inactivity and the resulting spectrum holes that allow dynamic spectrum access by SUs. In most existing spectrum sensing schemes, dynamics of the channel in a fading environment have not been fully addressed, thus leading to inefficient spectrum utilization. This paper proposes a dynamic sensing scheme that can adaptively schedule sensing duration according to channel dynamics in a fading environment while mitigating the effect of sensing errors (i.e., false alarm and miss-detection). We introduce a sensing duration bound to facilitate the optimization of spectrum utilization. Both simulation and analytical results verify the improvement on spectrum utilization offered by the proposed scheme while achieving target sensing requirements, as compared to the existing sensing schemes.