Walid Saad Zhu Han Mérouane Debbah Are Hjørungnes Tamer Basar Coalitional Games for Distributed Collaborative Spectrum Sensing in Cognitive Radio Networks http://arxiv.org/abs/0905.2659 2009 CoRR abs/0905.2659 db/journals/corr/corr0905.html#abs-0905-2659 informal publication