Editorial for special issue on "Cognitive radio ad hoc networks"

Over the past decade, cognitive radio has been an active area of research, bringing together researchers and practitioners from engineering, computer science, policy development, among other varied fields. Recent governmental regulations, standardization efforts, as well as industry prototypes have given further impetus to this technology, thus helping the transition of such radios from the laboratory to the commercial realm. The aim of this special issue is to explore the advances in the core technology as well as the challenges involved in realizing some of the applications that are made possible through distributed cognitive radio networks, a paradigm in which each node shares the responsibility of perceiving and reacting to local environmental conditions. There are 10 papers in this special issue, seven selected from an open call, and three invited papers. As guest editors of this issue, we are delighted to present works that cover a comprehensive breadth of topics, ranging from spectrum selection, spectrum decision, routing, power control, all critical enabling functions of the cognitive radio. Furthermore, this issue explores the concerns of high bandwidth multimedia delivery as well as security, which are two important topics that we believe will drive future research in this space. Along with applications, there is also a focus on modeling and analysis of such distributed cognitive radio networks, which will serve as valuable tools for future generations of network designers. The first set of the papers mentioned below is chosen from the open call, on the basis of a rigorous peer review. There are two critical approaches that may be adopted for protection to licensed users: power control in a shared channel, and selection of an entirely different channel. The first of these is used in [1] through a mobility driven power control framework for cognitive radios based on spectrum sensing, which ensures that the interference limit at the licensed receiver is respected. This work considers realistic concerns of distance dependent path loss and correlated shadowing for selecting the transmission power. The next few papers focus on spectrum sensing. A fusion role for making a collaborative spectrum decision is implemented in [2] where a node’s own local measurements of the signal to noise ratio (SNR) is compared with