Cognitive radio (CR) is an emerging technology that has been around for more than fifteen years to relieve spectrum shortages. Based on the concept of CR, multiple nodes opportunistically share the licensed spectrum over multiple licensed channels and form a multi-channel cognitive radio ad hoc networks (CRAHNs). While multicast in multi-channel CRAHNs is urgently needed, it is challenging since there are some intrinsic differences between multi-channel CRAHNs and conventional multi-channel wireless ad hoc networks (WAHNs). This article summarizes the main unique characteristics of multi-channel CRAHNs in time-, frequency- and space-domain. The key research aspects of multicast in multi-channel CRAHNs include joint multicast routing and spectrum allocation, cross-layer multicast scheduling, and multicast with QoS guarantee. The article also pays a special attention on discussing how to employ network coding techniques to improve the performance of multicast in multi-channel CRAHNs.
- Cognitive radio networks
- Network coding
ASJC Scopus subject areas
- Computer Networks and Communications