A survey of common control channel design in cognitive radio networks

Cognitive radio networks have been recognized as a promising paradigm to address the spectrum under-utilization problem. To improve spectrum efficiency, many operations such as sharing data in cooperative spectrum sensing, broadcasting spectrum-aware routing information, and coordinating spectrum access rely on control message exchange on a common control channel. Thus, a reliable and “always on” common control channel is indispensable. Since the common control channel may be subject to primary user activity, the common control channel design in cognitive radio networks encounters unprecedented challenges: cognitive radio users are unable to negotiate a new control channel when the original one is occupied by primary users. In this paper, the problem of common control channel design is presented by its classification, design challenges, design schemes, and its applications in network protocol layers. The issues of control channel saturation, robustness to primary user activity, limited control channel coverage, control channel security are identified as design challenges. Moreover, the major control channel design schemes such as sequence-based, group-based, dedicated, and ultra wideband approaches are presented. Lastly, the relation of the common control channel with radio interface, cooperative sensing, medium access control, and routing are discussed.