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báo cáo hóa học:" Research Article Opportunistic Relay Selection with Cooperative Macro Diversity"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Opportunistic Relay Selection with Cooperative Macro Diversity | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2010 Article ID 820427 14 pages doi 10.1155 2010 820427 Research Article Opportunistic Relay Selection with Cooperative Macro Diversity Chia-Hao Yu 1 OlavTirkkonen 1 2 and Jyri Hamalainen1 1 Department of Communications and Networking School of Science and Technology Aalto University P.O. Box 11000 00076 Aalto Finland 2Nokia Research Center Helsinki Finland Correspondence should be addressed to Chia-Hao Yu chiahao.yu@tkk.fi Received 27 August 2009 Revised 21 December 2009 Accepted 25 February 2010 Academic Editor Mischa Dohler Copyright 2010 Chia-Hao Yu et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. We apply a fully opportunistic relay selection scheme to study cooperative diversity in a semianalytical manner. In our framework idle Mobile Stations MSs are capable of being used as Relay Stations RSs and no relaying is required if the direct path is strong. Our relay selection scheme is fully selection based either the direct path or one of the relaying paths is selected. Macro diversity which is often ignored in analytical works is taken into account together with micro diversity by using a complete channel model that includes both shadow fading and fast fading effects. The stochastic geometry of the network is taken into account by having a random number of randomly located MSs. The outage probability analysis of the selection differs from the case where only fast fading is considered. Under our framework distribution of the received power is formulated using different Channel State Information CSI assumptions to simulate both optimistic and practical environments. The results show that the relay selection gain can be significant given a suitable amount of candidate RSs. Also while relay selection .