Abstract
In cognitive radio networks, the spectrum utilization can be improved by cognitive users opportunistically using the idle channels licensed to the primary users. However, the new arrived cognitive users may not be able to use the channel immediately since the channel usage state is random. This will impose additional time delay for the cognitive users. Excessive waiting delay can make cognitive users miss the spectrum access chances. In this paper, a discrete-time Markov queuing model from a macro point of view is provided. Through the matrix-geometric solution theory, the average sojourn time for cognitive users in the steady state before accessing the spectrum is obtained. Given the tolerant delay of cognitive users, the macro-based throughput is derived and an access control mechanism is proposed. The numerical results show the effects of service completion probability on average sojourn time and throughput. It is confirmed that the throughput can be obviously improved by using the proposed access control mechanism. Finally, the performance evaluations based on users are compared to that based on data packets.
Highlights
IntroductionCognitive radio (CR) is an important technique to improve spectrum utilization efficiency, which employs spectrum sensing, spectrum decision and spectrum
An opportunistic spectrum access status based on macroscopic users (MU) is analyzed in this paper
An access control method based on MU is proposed to improve the throughput
Summary
Cognitive radio (CR) is an important technique to improve spectrum utilization efficiency, which employs spectrum sensing, spectrum decision and spectrum. One of the most effective and actual performance analysis method for opportunistic spectrum access and multiple spectrum handoff is based on dynamic Markov queuing model, which has been the popular issues in recent years [13] [14]. The authors of [15] carried out a complex queuing analysis for spectrum utilization of PUs and CUs in CR cellular networks, and obtained the average packet queue length, the average packet waiting time and packet losing rate of CUs. up to present, the performance analysis studies for opportunistic spectrum access of CUs are almost all based on data packet. The transmission intact ratio of MU-based spectrum access outperforms the DP-based These analytical results can guide to design the spectrum access mechanism for CUs in CR networks.
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