Multi-Channel Cognitive Radio Ad Hoc Networks
The seven papers included in this special section focus on Cognitive radio ad hoc networks (CRAHNS). CRAHNs are equipped with the intrinsic capabilities of cognition and self-organization, providing a flexible spectrum- aware communication paradigm in wireless networks. Since available spectrum mostly manifests as several discontinuous frequency ranges, CRAHNs should be able to operate on multiple frequency channels. Multi-channel CRAHNs can alleviate interference and improve the spectrum utilization with greater fl exibility for channel access. The promising applications of multi-channel CRAHNs include large-scale machine-to-machine (M2M) communication, the Internet of Things (IoTs), high-density Wi-Fi, and unmanned aerial vehicle (UAV) swarms. Multi-channel CRAHNs impose unique challenges due to the distributed dynamic network topology and the temporal or spatial variations in spectrum availability. To overcome these challenges, fundamental problems in multi-channel CRAHNs have to be carefully resolved with respect to spectrum sensing, convention resolution, network topology maintenance, and application support.