Distributed spectrum sensing and access with secondary channel quality in cognitive radio networks
ICACT'10 Proceedings of the 12th international conference on Advanced communication technology
IEEE Transactions on Wireless Communications
Temporal spectrum sharing based on primary user activity prediction
IEEE Transactions on Wireless Communications
Comparing particle swarm optimization variants for a cognitive radio network
Applied Soft Computing
Spectrum Sharing in Competing Wireless Systems: A Simulation Study Using WLAN and WMAN
Journal of Network and Systems Management
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We explore the performance tradeoff between opportunistic and regulated access inherent in the design of multiuser cognitive radio networks. We consider a multichannel cognitive radio system with sensing limits at the secondary users and interference tolerance limits at the primary and secondary users. Our objective is to determine the optimal amount of spectrum sharing, i.e., the number of secondary users that maximizes the total deliverable throughput in the network.We begin with the case of perfect primary user detection and zero interference tolerance at each of the primary and secondary nodes. With identical primary and secondary traffic statistics, we find that the optimal fraction of licensed users lies between the two extremes of fully opportunistic and fully licensed operation and is equal to the traffic duty cycle. When the secondary users can vary their transmission probabilities based on the number of active primary users, we find that the optimal number of opportunistic users is equal to the average number of unoccupied channels. We then consider the more involved case of imperfect sensing and non-zero interference tolerance constraints. We provide numerical simulation results to study the tradeoff between licensing and autonomy and the impact of primary user sensing and interference tolerance on the deliverable throughput for two different subchannel selection strategies at the secondary users.