An always available control channel for cooperative sensing in cognitive radio networks

In the Cognitive Radio (CR) framework, the Opportunistic Spectrum Access (OSA) is a promising solution to increase spectral efficiency. However in an OSA network secondary unlicensed cognitive nodes have to agree on which spectral resources they are allowed to use without compromising performance of primary licensed users. This requires a common control channel for sharing spectrum sensing information. Among the ways to realize it, the utilization of Ultra-wideband (UWB) techniques has been proposed in the literature. In this paper we face the problem of dimensioning an “always on” underlay UWB signalling network for sensing information exchange among secondary CR nodes avoiding harmful interference to primary users. To this aim, we analyse the tradeoff between the connectivity degree of a multi-hop underlay signalling network, related to the bit-rate of the control channel, and its coexistence with primary licensed systems.