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A novel contention window control scheme for IEEE 802.11 WLANs

Balador, A ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.4103/0256-4602.98862
  3. Publisher: 2012
  4. Abstract:
  5. In the IEEE 802.11 standard, network nodes experiencing collisions on the shared medium need a mechanism that can prevent collisions and improve the throughput. Furthermore, a backoff mechanism is used that uniformly selects a random period of time from the contention window (cw) that is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. Prior research has proved that the BEB scheme suffers from a fairness problem and low throughput, especially under high traffic load. In this paper, we present a new backoff control mechanism that is used with the IEEE 802.11 distributed coordination function (DCF). In particular, we propose a dynamic, deterministic contention window control (DDCWC) scheme, in which the backoff range is divided into several small backoff sub-ranges. In the proposed scheme, several network levels are introduced, based on an introduced channel state vector that keeps network history. After successful transmissions and collisions, network nodes change their cw based on their network levels. Our extensive simulation studies show that the DDCWC scheme outperforms four other well-known schemes: Multiplicative Increase and Linear Decrease, Double Increment Double Decrement, Exponential Increase Exponential Decrease, and Linear/Multiplicative Increase and Linear Decrease. Moreover, the proposed scheme, compared with the IEEE 802.11 DCF, gives 30.77% improvement in packet delivery ratio, 31.76% in delay, and 30.81% in throughput
  6. Keywords:
  7. Backoff algorithm ; IEEE 802.11 ; Wireless ad-hoc network ; Backoff algorithms ; Backoff mechanism ; Binary exponential backoff algorithms ; Channel state ; Contention window ; Control mechanism ; Exponential increase exponential decrease ; Extensive simulations ; Fairness problem ; IEEE 802.11 DCF ; Ieee 802.11 distributed coordination functions ; IEEE 802.11 standards ; IEEE 802.11s ; Linear decrease ; MAC layer ; Network level ; Network node ; Packet delivery ratio ; Random periods ; Traffic loads ; Algorithms ; Wireless ad hoc networks ; Standards
  8. Source: IETE Technical Review (Institution of Electronics and Telecommunication Engineers, India) ; Volume 29, Issue 3 , 2012 , Pages 202-212 ; 02564602 (ISSN)
  9. URL: http://www.tandfonline.com/doi/abs/10.4103/0256-4602.98862