Mobile Networks and Applications

, Volume 11, Issue 3, pp 391–403 | Cite as

FHCF: A Simple and Efficient Scheduling Scheme for IEEE 802.11e Wireless LAN



The IEEE 802.11e medium access control (MAC) layer protocol is an emerging standard to support quality of service (QoS) in 802.11 wireless networks. Some recent work shows that the 802.11e hybrid coordination function (HCF) can improve significantly the QoS support in 802.11 networks. A simple HCF referenced scheduler has been proposed in the 802.11e which takes into account the QoS requirements of flows and allocates time to stations on the basis of the mean sending rate. As we show in this paper, this HCF referenced scheduling algorithm is only efficient and works well for flows with strict constant bit rate (CBR) characteristics. However, a lot of real-time applications, such as videoconferencing, have some variations in their packet sizes, sending rates or even have variable bit rate (VBR) characteristics. In this paper we propose FHCF, a simple and efficient scheduling algorithm for 802.11e that aims to be fair for both CBR and VBR flows. FHCF uses queue length estimations to tune its time allocation to mobile stations. We present analytical model evaluations and a set of simulations results, and provide performance comparisons with the 802.11e HCF referenced scheduler. Our performance study indicates that FHCF provides good fairness while supporting bandwidth and delay requirements for a large range of network loads.


IEEE 802.11e WLAN medium access control (MAC) quality of service (QoS) 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    IEEE 802.11 WG: IEEE Std 802.11-1999, Part 11, Wireless LAN MAC and physical layer specifications. Reference number ISO/IEC 8802-11:1999 (E), (1999).Google Scholar
  2. 2.
    Q. Ni, L. Romdhani and T. Turletti, A survey of QoS enhancements for IEEE 802.11 wireless LAN, Wiley Journal of Wireless Communications and Mobile Computing (JWCMC), John Wiley & Sons Publisher, 4 (5) (2004) 547–566.CrossRefGoogle Scholar
  3. 3.
    IEEE 802.11 WG: IEEE 802.11e/D4.1, Wireless MAC and physical layer specifications: MAC enhancements for QoS (Feb. 2003).Google Scholar
  4. 4.
    S. Mangold, S. Choi, P. May, et al., IEEE 802.11e wireless LAN for Quality of Service. Proceeding of European Wireless 1 (2002) 32–39.Google Scholar
  5. 5.
    A. Grilo, M. Macedo and M Nunes, A scheduling algorithm for QoS support in IEEE 802.11e networks, IEEE Communication Magazine 10 (2003) 36–43.Google Scholar
  6. 6.
    P. Garg, R. Doshi, R. Greene, et al., Using IEEE 802.11e MAC for QoS over wireless. IEEE IPCCC (2003).Google Scholar
  7. 7.
    S. McCanne, and V. Jacobson, VIC: A flexible framework for packet video, ACM Multimedia (1995).Google Scholar
  8. 8.
    ITU-T Recommendation H.261, Video codec for audiovisual services at p×64 kb/s. (1993).Google Scholar
  9. 9.
    P. Ansel, Q. Ni and T. Turletti, FHCF: A fair scheduling scheme for 802.11e WLAN, INRIA Research Report No. 4883, July 2003. Implementation and NS simulation codes available from
  10. 10.
    ISO/IEC JTC1/SC29/WG11: MPEG4 coding of audio visual objects: Visual (1998).Google Scholar
  11. 11.
    P. M. Soni, and A. Chockalingam, Performance analysis of UDP with energy efficient link layer on Markov fading channels, IEEE Transactions on Wireless Communications 1 (2002).Google Scholar
  12. 12.
    R. Jain, The Art of Computer Systems Performance Analysis (John Wiley & Sons publisher, 1991).Google Scholar
  13. 13.
    J. Jacod, and P. Protter, Probability Essentials. (Springer Publisher, 2003).Google Scholar

Copyright information

© Springer Science + Business Media, LLC 2006

Authors and Affiliations

  1. 1.Planète ProjectINRIA Sophia AntipolisFrance
  2. 2.Electronic and Computer EngineeringBurnel UniversityWest London
  3. 3.Electronic and Computer Engineering, School of Engineering and DesignBurnel UniversityWest LondonUK

Personalised recommendations