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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 Beamforming in Ad Hoc Networks: MAC Design and Performance Modeling | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 839421 15 pages doi 10.1155 2009 839421 Research Article Beamforming in Ad Hoc Networks MAC Design and Performance Modeling Khalil Fakih Jean-Francois Diouris and Guillaume Andrieux Institut de Recherche en Electrotechnique et Electronique de Nantes Atlantique IREENA Ecole polytechnique de l Universite de Nantes BP 50609 44306 Nantes Cedex3 France Correspondence should be addressed to Khalil Fakih khalil.fakih@univ-nantes.fr Received 1 February 2008 Revised 1 September 2008 Accepted 4 January 2009 Recommended by Sangarapillai Lambotharan We examine in this paper the benefits of beamforming techniques in ad hoc networks. We first devise a novel MAC paradigm for ad hoc networks when using these techniques in multipath fading environment. In such networks the use of conventional directional antennas does not necessarily improve the system performance. On the other hand the exploitation of the potential benefits of smart antenna systems and especially beamforming techniques needs a prior knowledge of the physical channel. Our proposition performs jointly channel estimation and radio resource sharing. We validate the fruitfulness of the proposed MAC and we evaluate the effects of the channel estimation on the network performance. We then present an accurate analytical model for the performance of IEEE 802.11 MAC protocol. We extend the latter model by introducing the fading probability to derive the saturation throughput for our proposed MAC when the simplest beamforming strategy is used in real multipath fading ad hoc networks. Finally numerical results validate our proposition. Copyright 2009 Khalil Fakih 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 Ad hoc networks seem to
