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  • Research Article
  • Open Access

Size-Based and Direction-Based TCP Fairness Issues in IEEE 802.11 WLANs

EURASIP Journal on Wireless Communications and Networking20102010:818190

  • Received: 14 January 2010
  • Accepted: 20 July 2010
  • Published:


Cross-layer interaction of Distributed Coordination Function (DCF) of 802.11 MAC protocol and TCP transport protocol leads to two types of unfairness. In a mixed traffic scenario, short-lived TCP flows suffer from poor performance compared to the aggressive long-lived flows. Since the main source of Internet traffic is small file web transfers, this issue forms a major challenge in current WLANs which is called size-based unfairness. In addition, when sharing an access point bottleneck queue, upstream flows impede the performance of downstream flows resulting in direction-based unfairness. Proposed solutions in the literature mostly rely on size-based scheduling policies. However, each proposed method is able to solve any of these two mentioned aspects, none of them can provide both size-based and direction-based fairness in a unique solution. In this paper, we propose a novel queue management policy called Threshold-Based Least Attained Service-Selective Acknowledgment Filtering (TLAS-SAF). We show analytically and by simulation that TLAS-SAF is capable of providing both direction-based and size-based fairness and can be taken into account as a unique solution to be applied at access point buffers.


  • Distribute Coordination Function
  • Queue Management
  • Mixed Traffic
  • Point Buffer
  • Bottleneck Queue

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Authors’ Affiliations

Department of Informatics, University of Oslo, P.O. Box 1080, Blindern, N-0314 Oslo, Norway
Department of Communication Technology and Network, Faculty of Computer Science and Information Technology, Universiti Putra Malaysia, Serdang, Selangor, D.E 43400, Malaysia