5)J. Naganawa, H. Kim, S. Saruwatari, H. Onaga, and H. Morikawa:"Distributed spectrum sensing utilizing heterogeneous wireless de-vices and measurement equipment", Proceedings of the 5th IEEESymposium on New Frontiers in Dynamic Spectrum AccessNet-works(DySPAN'11),pp.173-184, Aachen, Germany(May 2011)