A multichain backoff mechanism for IEEE 802.11 WLANs

Shiang Rung Ye*, Yu-Chee Tseng

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Scopus citations


The distributed coordination function (DCF) of IEEE 802.11 standard adopts the binary exponential backoff (BEB) for collision avoidance. In DCF, the contention window is reset to an initial value, i.e., CWmin, after each successful transmission. Much research has shown that this dramatic change of window size may degrade the network performance. Therefore, backoff algorithms, such as gentle DCF (GDCF), multiplicative increase-linear decrease (MILD), exponential increase-exponential decrease (EIED), etc., have been proposed that try to keep the memory of congestion level by not resetting the contention window after each successful transmission. This paper proposes a multichain backoff (MCB) algorithm, which allows stations to adapt to different congestion levels by using more than one backoff chain together with collision events caused by stations themselves as well as other stations as indications for choosing the next backoff chain. The performance of MCB is analyzed and compared with those of 802.11 DCF, GDCF, MILD, and EIED backoff algorithms. Simulation results show that, with multiple backoff chains and collision events as reference for chain transition, MCB can offer a higher throughput while still maintaining fair channel access than the existing backoff algorithms.

Original languageEnglish
Pages (from-to)1613-1620
Number of pages8
JournalIEEE Transactions on Vehicular Technology
Issue number5
StatePublished - 1 Sep 2006


  • Backoff algorithms
  • Medium access control (MAC)
  • Multichain backoff (MCB)
  • Wireless local area networks (WLANs)

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