MAC access delay of IEEE 802.11 DCF

Taka Sakurai, Hai L. Vu

Research output: Contribution to journalArticleResearchpeer-review

166 Citations (Scopus)


The MAC access delay in a saturated IEEE 802.11 DCF wireless LAN is analyzed. We develop a unified analytical model and obtain explicit expressions for the first two moments as well as the generating function. We show via comparison with simulation that our model accurately predicts the mean, standard deviation, and distribution of the access delay for a wide range of operating conditions. In addition, we show that the obtained generating function is much more accurate than others that have appeared in the literature. Using our model, we prove that the binary exponential backoff mechanism induces a heavy-tailed delay distribution for the case of unlimited retransmissions. We show using numerical examples that the distribution has a truncated power-law tail when a retransmission limit exists. This finding suggests that DCF is prone to long delays and not suited to carrying delay-sensitive applications.

Original languageEnglish
Pages (from-to)1702-1710
Number of pages9
JournalIEEE Transactions on Wireless Communications
Issue number5
Publication statusPublished - 1 May 2007
Externally publishedYes


  • Generating function
  • Heavy tail
  • IEEE 802.11
  • Medium access delay
  • Performance analysis
  • Wireless LAN

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