An access delay model for IEEE 802.11e EDCA

Dongxia Xu, Taka Sakurai, Hai L. Vu

Research output: Contribution to journalArticleResearchpeer-review

43 Citations (Scopus)


We analyze the MAC access delay of the IEEE 802.11e enhanced distributed channel access (EDCA) mechanism under saturation. We develop a detailed analytical model to evaluate the influence of all EDCA differentiation parameters, namely AIFS, CWmin, CWmax, and TXOP limit, as well as the backoff multiplier β Explicit expressions for the mean, standard deviation, and generating function of the access delay distribution are derived. By applying numerical inversion on the generating function, we are able to efficiently compute values of the distribution. Comparison with simulation confirms the accuracy of our analytical model over a wide range of operating conditions. We derive simple asymptotics and approximations for the mean and standard deviation of the access delay, which reveal the salient model parameters for performance under different differentiation mechanisms. We also use the model to numerically study the differentiation performance and find that β differentiation, though rejected during the standardization process, is an effective differentiation mechanism that has some advantages over the other mechanisms.

Original languageEnglish
Article number04585388
Pages (from-to)261-275
Number of pages15
JournalIEEE Transactions on Mobile Computing
Issue number2
Publication statusPublished - 1 Feb 2009
Externally publishedYes


  • EDCA
  • Generating function
  • IEEE 802.11e
  • Medium access delay
  • QoS
  • Service differentiation

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