1. N. Devroye, P. Mitran, and V. Tarokh, “Limits on communications in a cognitive radio channel,” IEEE Commun. Mag., No. 44, 44–49 (2006).
2. Q. Zhao and B. Sadler, “Dynamic spectrum access: signal processing, networking, and regulatory policy,” IEEE Signal Process. Mag., No. 24, 79–89 (2007).
3. R. Etkin, A. Parekh, and D. Tse, “Spectrum sharing for unlicensed bands,” IEEE J. Sel. Area Commun., No. 25, 517–528 (2007).
4. S. Haykin, “Cognitive radio: brain-empowered wireless communications,” IEEE J. Sel. Areas Commun., No. 23, 201–220 (2005).
5. G. Bansal, J. Hossain, V. K. Bhargava, and T. Le-Ngoc, “Subcarrier and power allocation for OFDMA-based cognitive radio systems with joint overlay and underlay spectrum access mechanism,” IEEE Trans. Veh. Technol., 62, 1111–1122 (2013).