On the cooperation between cognitive radio users and femtocell networks for cooperative spectrum sensing and self-organization

We propose a single framework for cooperative spectrum sensing of cognitive radio network as well as for the self-organization of femtocells. This constructs a large-scale spectrum database through cooperative spectrum sensing for cognitive radio network, which exploits the existing infrastructure of the two-tier (macrocell-femtocell) network and encourages a small cellular network, i.e., femtocell, to act as the rendezvous point between individual local spectrum monitors and the fusion center of spectrum database. Distributed sensing results reported from many cognitive radio users can be integrated into spectrum database via these rendezvous points. Thus the problem of the dependency of conventional cooperative spectrum sensing on common control channel is improved. Meanwhile, the interaction between cognitive radio users and femtocells can offer an intriguing possibility to improve the self-organization of femtocells by absorbing radio environment maps constructed by cognitive radio users. Game theory can be applied to formulate the mutual benefits in the cooperation between cognitive radio user and femtocell. We illustrate the numerical effects of the coalitions between cognitive radio users and femtocells.