Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Performance analysis of spectrum sharing mechanisms in cognitive radio networks | Peipei et al. EURASIP Journal on Wireless Communications and Networking 2011 2011 129 EURASIP Journal on . http jwcn.eurasipjournals.eom content 2011 1 129 Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Performance analysis of spectrum sharing mechanisms in cognitive radio networks Chen Peipei Zhang Qinyu Zhang Yalin and Wang Ye Abstract In this article a non-preemptive NP mechanism is proposed to improve the quality-of-service QoS of secondary users SUs in joint leasing and sensing-based cognitive radio networks CRNs . In this spectrum-sharing mechanism a primary user PU could not forcibly terminate a SU with ongoing transmission. Both the typical preemptive and the proposed NP mechanisms are modeled by multi-dimensional Markov chains with three state variables. A decomposition-approximated method is used to derive the closed-form solutions of the steady-state probabilities in the Markov chains. The analytical results are verified by numerical results. System parameters that affect performance metrics are also investigated in these two mechanisms. The simulation results show that in the proposed mechanism the performance metrics of SUs such as force-termination probability and mean system delay are improved significantly with an acceptable loss of PUs QoS in terms of mean waiting time and blocking probability. A QoS tradeoff can be achieved between the primary and the secondary systems. For QoS improvement of SUs the proposed NP mechanism outperforms the preemptive mechanism in joint leasing and sensing-based CRNs. Keywords cognitive radio networks joint leasing and sensing non-preemptive mechanism QoS tradeoff 1. Introduction Cognitive radio CR has been considered as a viable technique to improve the utilization of spectral resources in a licensed primary system 1 . The secondary users SUs in the unlicensed secondary system are allowed to opportunistically utilize the spectrum holes that are temporarily unoccupied by primary .
