Wireless unfairness: alleviate MAC congestion first!

  • Authors:

  • Kan Cai;Michael Blackstock;Reza Lotun;Michael J. Feeley;Charles Krasic;Junfang Wang

  • Affiliations:

  • University of British Columbia, Vancouver, BC, Canada;University of British Columbia, Vancouver, BC, Canada;University of British Columbia, Vancouver, BC, Canada;University of British Columbia, Vancouver, BC, Canada;University of British Columbia, Vancouver, BC, Canada;University of Cincinnati, Cincinnati, OH

  • Venue:
  • Proceedings of the second ACM international workshop on Wireless network testbeds, experimental evaluation and characterization
  • Year:
  • 2007

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Abstract

It is well known that competition between 802.11 wireless flows can lead to severe unfairness problems. In this paper we show that certain flows can be denied from their fair share of network access for long periods of time due toinequitable channel conditions. We argue that this unfairness problem is likely to get worse as the use of wireless in terms of number of devices and bandwidth continues to grow. To address unfairness, we rely on a common network management technique called traffic shaping. Instead of designing new MAC protocols or introducing complex wireless fair queuing or adaptation algorithms, we argue that 802.11, TCP and a well-understood wired fair queuing scheme can provide fairness even in unfavourable network topologies as long as we can prevent MAC-layer congestion from happening. This shaping approach has the advantage of being easily deployed in existing network management systems, requiring no change to the end-user devices or access points. We have proven the effectiveness of this cross-layer approach using a wireless testbed, and are currently in the process of incorporating this scheme into a large-scale campus wireless network.