Multicasting in cognitive radio networks: Algorithms, techniques and protocols

Multicasting is a fundamental networking primitive utilized by numerous applications. This also holds true for cognitive radio networks which have been proposed as a solution to the problems that emanate from the static non-adaptive features of classical wireless networks. A prime application of cognitive radio networks is dynamic spectrum access, which improves the efficiency of spectrum allocation by allowing a secondary network, comprising secondary users, to share spectrum licensed to a primary licensed network comprising primary users. Multicasting in cognitive radio networks is a challenging problem due to the dynamic nature of spectrum opportunities available to the secondary users. Various approaches, including those based on optimization theory, network coding, algorithms, have been proposed for performing efficient multicast in cognitive radio networks. In this paper, we provide a self-contained tutorial on algorithms and techniques useful for solving the multicast problem, and then provide a comprehensive survey of protocols that have been proposed for multicasting in cognitive radio networks. We conclude this paper by identifying open research questions and future research directions.