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tham khảo đề tài: Research Article Outage Probability versus Fairness Trade-off in Opportunistic Relay Selection with Outdated CSI | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 412837 10 pages doi 2009 412837 Research Article Outage Probability versus Fairness Trade-off in Opportunistic Relay Selection with Outdated CSI Jose Lopez Vicario Albert Bel Antoni Morell and Gonzalo Seco-Granados Group of Signal Processing for Communications and Navigations SPCOMNAV Autonomous University of Barcelona 08193 Bellaterra Cerdanyola del Valles Barcelona Spain Correspondence should be addressed to Jose Lopez Vicario Received 1 July 2008 Revised 18 November 2008 Accepted 20 January 2009 Recommended by Alagan Anpalagan We analyze the existing trade-offs in terms of system performance versus fairness of a cooperative system based on opportunistic relay selection ORS and with outdated channel state information CSI . In particular system performance is analytically evaluated in terms of outage probability and the fairness behavior is assessed based on the power consumption at the different relays. In order to improve the fairness behavior of ORS while keeping the selection diversity gain we propose a relay selection mechanism where the relay with the highest normalized signal-to-noise ratio SNR is selected for relaying the source s information. The proposed strategy is compared with existing relay selection strategies by adopting a novel graphical representation inspired by expected profit versus risk plots used in modern portfolio theory. As shown in the paper this strategy allows operating the system in more favorable points of the outage versus fairness region. Copyright 2009 Jose Lopez Vicario 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. 1. Introduction Cooperative diversity has been shown to be an efficient way to combat wireless impairments .
