Flow-level QoS for a dynamic load of rate adaptive sessions sharing a bottleneck link

  • Authors:
  • Steven Weber;Gustavo de Veciana

  • Affiliations:
  • Department of ECE, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, United States;Department of ECE, The University of Texas at Austin, Austin, TX 78712, United States

  • Venue:
  • Computer Networks: The International Journal of Computer and Telecommunications Networking
  • Year:
  • 2007

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Abstract

We consider the flow-level quality of service (QoS) seen by a dynamic load of rate adaptive sessions sharing a bottleneck link based on fair share bandwidth allocation. This is of interest both in considering wired networks supporting rate adaptive multimedia sessions and wireless networks supporting voice with rate adaptation to realize graceful degradation during congested periods. Two QoS metrics are considered: the time-average instantaneous utility of the allocated bandwidth, and the time-average of transition penalties associated with the changes in allocation seen by a flow. We present a simple model for rate adaptation, where (heterogeneous) flows can vary their rates within (different) ranges, and present closed-form results for these perceived flow-level QoS metrics. We then prove asymptotic results for large capacity systems exhibiting the salient features of rate adaptation in a dynamic network. Finally, we provide a concrete example, showing how the QoS seen by sessions with different degrees of adaptivity would vary under a natural fair bandwidth allocation policy.