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 How to Solve the Problem of Bad Performance of Cooperative Protocols at Low SNR Charlotte Hucher, Ghaya Rekaya-Ben Othman, and Jean-Claude Belfiore | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 243153 7 pages doi 2008 243153 Research Article How to Solve the Problem of Bad Performance of Cooperative Protocols at Low SNR Charlotte Hucher Ghaya Rekaya-Ben Othman and Jean-Claude Belfiore Ecole Nationale Superieure des Telecommunications 46 rue Barrault 75013 Paris Cedex 13 France Correspondence should be addressed to Charlotte Hucher hucher@ Received 1 June 2007 Accepted 27 August 2007 Recommended by Ranjan K. Mallik We propose some new adaptive amplify-and-forward AF and decode-and-forward DF protocols using a selection. The new selection criterion is a function of the instantaneous capacities of all possible transmission schemes with or without cooperation . Outage probabilities and simulation results show that the adaptive cooperation protocols solve the problem of bad performance of cooperation protocols at low SNR. Moreover they improve the asymptotic performance of their corresponding AF and DF protocols. Copyright 2008 Charlotte Hucher 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 Diversity techniques have been developed in order to combat fading on wireless channels and improve the reliability of the received message. Recently cooperation has been proposed as a new mean to obtain space-time or cooperative diversity 1 2 . Different nodes in the network cooperate in order to form a virtual MIMO system and exploit space-time diversity even if their hardware constraints do not allow them to support several antennas. Many cooperative protocols have been proposed 3-6 which can be classified in three main families amplify-and-forward AF decode-and-forward DF and compress-and-forward CF . In this paper we are interested in the two first families which are .
