@article{oai:nagoya.repo.nii.ac.jp:00012079,
 author = {Naganawa, Jun and Yamazato, Takaya and Katayama, Masaaki},
 journal = {IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications},
 month = {Sep},
 note = {This manuscript proposes a cognitive radio system that shares a frequency with an existing primary system. In the proposed method, a secondary transmitter relays the primary signal and piggybacks its own data on it. Symbol error probabilities of the system are derived analytically. The result shows that the proposed system can communicate at a relatively high speed on the same frequency of the primary system without harm to it.},
 pages = {147--151},
 title = {Cognitive radio with relay of a primary signal and piggyback modulation},
 year = {2009}
}