Joint spectrum sensing and transmit power adaptation in interference‐aware cognitive radio networks

Abstract

ABSTRACTCognitive radio networks (CRNs) have been recognised as a promising solution to address the spectrum shortage problem by allowing secondary users to opportunistically utilise the temporally and/or spatially unused spectrum holes without causing unacceptable interference to the primary users. Spectrum sensing is known as one of the key enabling technologies for identifying the spectrum holes in CRNs. In this article, the limitations of conventional spectrum sensing at discovering spatial spectrum hole are highlighted and an interference‐aware sensing metric is adopted to maximise the spectrum hole utilisation for a secondary user. Specifically, we introduce a new degree of freedom, transmit power adaptation, into the issue of interference‐aware spectrum sensing and develop a joint optimization problem to maximise the interference‐free throughput of the secondary user while satisfying the quality of service constraints of both the primary and secondary transmissions. Moreover, observing that the transmit power lies within a strict finite interval, the jointly optimal strategy of sensing threshold and transmit power is proved to be tractable by sequential optimization. Compared against the existing sensing techniques presented in related work, we show through numerical simulations that the proposed technique results in better spectrum hole utilisation for the secondary user without sacrificing the desired degree of protection for primary users. Copyright © 2012 John Wiley & Sons, Ltd.