Recent effort related to cognitive radio systems has lead to an in-depth analysis of context information management and exploitation based on a cognitive control channel for enhancement of management needed for, say, suitable link selection in a heterogeneous radio framework, dynamic radio resource management, and distributed sensing. Concerning the actual implementation of such a CCC, the focus was recently moved toward an in-band solution, where the information is transported building on existing radio access technologies. In this scope, this article illustrates relevant technical scenarios in which CCCs can be exploited and outlines a set of derived system requirements. The article provides an overview of various possible RAT independent and dependent implementation options, such as Diameter, distributed agents, 3GPP radio resource control(RRC) mechanisms, IEEE 802.21, IEEE 802.11, WiMedia UWB, and Bluetooth. The advantages and drawbacks of the various options are discussed.