4. Secure and Energy-Efficient Collaborative Spectrum Sensing

By enpowering the capability of CR, sensor nodes in CRSNs can sense the availability of licensed channels and access the idle channels for data transmission. However, due to channel fading and shadowing, spectrum sensing by individual sensor node has inevitable sensing errors, which adversely impact the performance of both the CRSN and the primary users (PUs) of the licensed channels. To overcome the limitation of individual spectrum sensing, collaborative spectrum sensing is generally employed in CRSNs to improve the spectrum sensing accuracy [1, 2]. However, since sensor nodes may be compromised by adversaries, these nodes can send false sensing results, making CRSNs vulnerable to spectrum sensing data falsification (SSDF) attack [3–5]. In SSDF attacks, compromised nodes may operate independently or collaboratively to mislead the channel availability decision, which can significantly reduce spectrum utilization and degrade overall network performance [6]. To resist SSDF attacks, a number of countermeasures, including trust/reputation based approaches [7–10], abnormal statistical-behavior detection based approaches [11–15] and clustering based approaches [16, 17], have been proposed in cognitive radio networks (CRNs), which could be applied into CRSNs. But few of the related works consider energy efficiency in SSDF attack countermeasure design [18, 19].