In this paper, cognitive radio technology is considered, which has gained much attention around the world. The coexistence between decentralized cognitive radio and primary radio systems is focused. Specifically, by introducing two benchmarks, the network performance without and with cognitive radio technology with the function of detecting radio signals to avoid the primary radio system is studied. From these results, it is shown that cognitive radio can avoid interference. However, according to the condition, cognitive radio cannot get the opportunity of communication. Therefore, an additional function for the sake of avoiding an unavailable arbitrary spectrum band is proposed. Moreover, we show that cognitive radio technology cannot avoid the interference to primary systems whenever hidden primary terminals exist in the network.
['Kotaro Watanabe', 'Koji Ishibashi', 'Ryuji Kohno']
Performance of Cognitive Radio Technologies in the Presence of Primary Radio Systems