Cognitive radio with relay of a primary signal and piggyback modulation. - Jun Naganawa; Takaya Yamazato; Masaaki Katayama (PIMRC, 2009)

Spectrum Sharing Overlay System with a Repeater for the Primary Signal. - Jun Naganawa; Kentaro Kobayashi; Hiraku Okada; Masaaki Katayama (IEICE Trans. Fundam. Electron. Commun. Comput. Sci., 2014)