Discriminating Non-Congestion Losses by Exploiting Adaptive Initial/Maximum Backoff Window for IEEE 802.16 BWA Systems

  • Authors:

  • K. Sakthi Mala;P. Navaneethan

  • Affiliations:

  • Coimbatore Institute of Technology, Coimbatore, India;PSG College of Technology, Coimbatore, India

  • Venue:
  • Wireless Personal Communications: An International Journal
  • Year:
  • 2014

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Abstract

In IEEE 802.16 BWA systems, the mandatory method of contention resolution is based on Truncated Binary Exponential Backoff (TBEB), with the initial backoff-window and the maximum backoff-window controlled by the BS. The values for these window parameters are announced by the BS in the Uplink Channel Descriptor (UCD) message. However, the specification has not mentioned the way to choose the optimal values for the said backoff parameters. In this paper, the optimal values for the parameters in terms of the number of active Best-Effort (BE) connections when Code Division Multiple Access (CDMA) based contention mechanism is used, are derived. With simulation, it is shown that tuning the parameters adaptively improves the upper-layer throughput. By exploiting the adaptive window parameters, this paper proposes a scheme to discriminate wireless-losses from congestion-losses. It is also shown that when the proposed method is employed in an Explicit Loss Notification method, named, TCP-WLAware, enhances the Transmission Control Protocol (TCP)'s throughput.