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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2006.06.005 Byline: Meng Chang Chen (a), Li-Ping Tung (b), Yeali S. Sun (c), Wei-Kuan Shih (b) Keywords: Differentiated services; Quality of Service; VoIP; Wireless LAN; IEEE 802.11 Abstract: In this paper, we propose a new per-CLAss Flow fixed proportional differentiated service model (CLAF) and a companioning medium access control scheme for multi-service wireless LANs (WLANs), based on the IEEE 802.11 framework. Different from conventional relative differentiated service, in CLAF, a fixed bandwidth quality ratio is guaranteed on per-class per-flow basis regardless of the traffic load of each service class. Specifically, each service class is assigned a number of separate coordination periods, proportional to the policy-based bandwidth quality ratio for class isolation. Each class is associated with its own contention window size which is dynamically adjusted in accordance with the number of flows in the class in such a way to minimize collision probability between flows of the same class. Simulations results of the CLAF performance as well as a comparison with IEEE 802.11e EDCA including the support of QoS-sensitive VoIP applications are presented. The results show that the proposed scheme outperforms EDCA and achieves better resource utilization efficiency. CLAF can provide users a more predictive, affirmative service guarantees than conventional relative differentiated service like IEEE 802.11e EDCA. Author Affiliation: (a) Institute of Information Science, Academia Sinica, NanKang, Taipei 115, Taiwan, ROC (b) Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan, ROC (c) Department of Information Management, National Taiwan University, Taipei, Taiwan, ROC Article History: Received 3 May 2006; Revised 13 June 2006; Accepted 18 June 2006 Article Note: (miscellaneous) Responsible Editor: X.S. Shen

ABSTRACT In this study, we propose a disruption-tolerant network based system called MetroNet, which exploits the precise schedules of metro systems to pre-fetch data and facilitate mobile Internet downloads, even if an end-to-end path between the source (i.e. content sources) and the destination (i.e. users) does not exist contemporaneously. Using a comprehensive set of simulations, as well as real-world scenarios of the Taipei and Atlanta metro systems, we demonstrate that MetroNet can handle the intermittent Internet connectivity caused by mobility and therefore provide a better mobile download service. The simulation results demonstrate that the proposed call admission control algorithm utilises the network resource effectively and provides better quality of service for mobile users than the first-come-first-serve and least-first algorithms. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]