Abstract: Wireless applications have been increasing rapidly due to which the available frequency is overcrowded and cannot satisfy the needs of the users. In static spectrum allocation scheme the frequency is allocated to the user on long term basis which leads to spectrum scarcity. To overcome the spectrum scarcity problem dynamic spectrum allocation came into existence. Cognitive radio network was a key enabling technology for dynamic spectrum allocation, which allows the secondary users to make use of licensed spectrum in opportunistic manner. MAC protocol plays a vital role in opportunistic spectrum utilization, primary userís interference management and secondary userís coordination. Cognitive Radio (CR) users coordinate with each other by making use of Common Control Channel (CCC), which was a common medium used to exchange the control information. When the primary user comes back or when the QOS of the current channel was not satisfied, then CCC moves on to the new available channel. The CCC coverage is one of the most challenging issues in cognitive radio networks and can be addressed by proper control channel design. In this paper, we elaborate on various controls channel design schemes and some security issues in the same.

Keywords: Cognitive Radio (CR), Common Control Channel (CCC), QOS.