Rank-based dynamic frequency hopping without strict coordination in IEEE 802.22 WRAN system
International Journal of Communication Systems
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The primary object of cognitive radio is to increase spectral efficiency, while causing limited interference to primary users who are using the spectrum. Hence, an essential part of cognitive radio is a spectrum sensing that determines whether a particular spectrum is occupied or not by a primary user. However, the sensing decision of a local secondary user alone may not be reliable enough due to shadowing and multipath fading of wireless channels. Recently, cooperative spectrum sensing has emerged as a remedy to the problems of local sensing. To sense the spectrum in a cooperative manner, secondary users report their local decisions to a cognitive base station through a feedback channel that is subject to fading and shadowing. Therefore, though the local sensing result is obtained accurately, it might not be suitable for making a cooperative decision due to feedback error. To alleviate this problem, we propose a hard decision combining-based cooperative spectrum sensing scheme in the presence of a feedback error caused by imperfect channel condition. In the proposed scheme, only the most favorable secondary users, those whose reporting channel conditions are peak, are allowed for cooperation. Through the proposed scheme, we can maximize the detection probability while guaranteeing that the desired false alarm probability is maintained. The simulation results show that the proposed scheme provides better spectrum sensing performance than the conventional scheme. Copyright © 2010 John Wiley & Sons, Ltd. In this paper, we propose a cooperative spectrum sensing scheme in the presence of reporting errors in cognitive radio networks. Accurate local sensing results may not directly be applied to cooperative sensing due to reporting errors. We consider the cooperative spectrum sensing that utilizes local sensing results in good reporting channel condition. Finally, simulation results show that the proposed scheme can maximize the detection probability while guaranteeing the desired false alarm probability. Copyright © 2010 John Wiley & Sons, Ltd.