Priority-based spectrum access in cognitive D2D networks for IoT

Device to device (D2D) communication is essential in Internet of things (IoT). Cognitive radio (CR)-enabled device is a promising technique to address D2D communications. Among all the functions supported in IoT, priority-based spectrum access is less investigated yet urgently desired in IoT. An important operation to achieve this capacity is channel hopping (CH) based rendezvous which allows two CR users to meet each other on a common available channel. Unfortunately, existing CH methods cannot help CR users achieve priority-based spectrum access due to various shortcomings. In this paper, we propose PCH, a priority-based spectrum access protocol for cognitive D2D, which can be integrated with any existing CH algorithm. PCH can support priority transmissions with a significantly reduced CH delay, as compared with non-priority transmissions. More importantly, PCH can work under practical scenarios such as the D2D both with priority packets, the D2D handoff, and the overhead/energy constraint IoT. The merits of PCH are proved theoretically and validated against extensive simulations. To the best of our knowledge, this is the first work that investigates priority communications in cognitive IoT.