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Báo cáo hóa học: " Research Article Towards a Collision-Free WLAN: Dynamic Parameter Adjustment in CSMA/E2CA"

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 Towards a Collision-Free WLAN: Dynamic Parameter Adjustment in CSMA/E2CA | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2011 Article ID 708617 11 pages doi 10.1155 2011 708617 Research Article Towards a Collision-Free WLAN Dynamic Parameter Adjustment in CSMA E2CA Jaume Barcelo 1 Boris Bellalta 2 Cristina Cano 2 Anna Sfairopoulou 2 Miquel Oliver 2 and Kshitiz Verma1 3 1Departamento deIngenieria Telematica Universidad Carlos III de Madrid 28911 Leganes Madrid Spain 2Departamento de Tecnologies de la Informacio i les Comunicacions Universitat Pompeu Fabra 08018 Barcelona Spain 3Institute IMDEA Networks 28918 Leganes Madrid Spain Correspondence should be addressed to Boris Bellalta boris.beUalta@upf.edu Received 24 November 2010 Accepted 9 February 2011 Academic Editor Alexey Vinel Copyright 2011 Jaume Barcelo 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. Carrier sense multiple access with enhanced collision avoidance CSMA ECA is a distributed MAC protocol that allows collision-free access to the medium in WLANs. The only difference between CSMA ECA and the well-known CSMA CA is that the former uses a deterministic backoff after successful transmissions. Collision-free operation is reached after a transient state during which some collisions may occur. This paper shows that the duration of the transient state can be shortened by appropriately setting the contention parameters. Standard absorbing Markov chain theory is used to describe the behaviour of the system in the transient state and to predict the expected number of slots to reach the collision-free operation. The paper also introduces CSMA E2CA in which a deterministic backoff is used two consecutive times after a successful transmission. CSMA E2CA converges quicker to collision-free operation and delivers higher performance than CSMA ECA specially in harsh wireless