Channel Selection and Switching in Cognitive Radio Networks: Challenges and Approaches

In wireless networks, Cognitive Radio (CR) has came out as a resolution in order to upgrade the existing spectrum bands, usage by letting the unlicensed users i.e. Secondary Users (SU) to exploit vacant licensed bands of spectrum in an opportunistic way. CR ensures that there is no adverse hindrance in transmission to licensed User i.e. Primary User (PU). Whenever the licensed user comes back to its assigned band of spectrum, The Secondary User has to leave it instantly. Thus these unpredictable appearances of PUs lead to frequent channel switching overhead for the SUs. In this paper we present an exhaustive survey to identify the major problems in selecting the channel and switching for SUs in wireless network-Cognitive Radio Network.