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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 Bandwidth Optimization in Centralized WLANs for Different Traffic Types | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2007 Article ID 23917 14 pages doi 10.1155 2007 23917 Research Article Bandwidth Optimization in Centralized WLANs for Different Traffic Types R. J. Haines N. Fanning T. Lewis and J. Coon Telecommunications Research Laboratory Toshiba Research Europe Ltd. 32 Queen Square Bristol BS1 4ND UK Received 31 May 2006 Revised 24 November 2006 Accepted 10 January 2007 Recommended by Wei Li Allocating bandwidth between different forms of coexisting traffic such as web-browsing streaming and telephony within a wireless LAN is a challenging and interesting problem. Centralized coordination functions in wireless LANs offer several advantages over distributed approaches having the benefit of a system overview at the controller but obtaining a stable configuration of bandwidth allocation for the system is nontrivial. We present review and compare different mechanisms to achieve this end and a number of different means of obtaining the configurations themselves. We describe an analytical model of the system under consideration and present two mathematical approaches to derive solutions for any system configuration and deployment along with an adaptive feedback-based solution. We also describe a comprehensive simulation-based model for the problem and a prototype that allows comparison of these approaches. Our investigations demonstrate that a self-adaptive dynamic approach far outperforms any static scheme and that using a mathematical model to produce the configurations themselves confers several advantages. Copyright 2007 R. J. Haines 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 The IEEE802.11 protocols 1 have become the dominant standard for wireless local area networks WLANs . These protocols have
