Opportunistic media access for multirate ad hoc networks

B. Sadeghi, V. Kanodia, A. Sabharwal, E. Knightly

Research output: Contribution to conferencePaperpeer-review

565 Scopus citations


The IEEE 802.11 wireless media access standard supports multiple data rates at the physical layer. Moreover, various auto rate adaptation mechanisms at the medium access layer have been proposed to utilize this multi-rate capability by automatically adapting the transmission rate to best match the channel conditions. In this paper, we introduce the Opportunistic Auto Rate (OAR) protocol to better exploit durations of high-quality channels conditions. The key mechanism of the OAR protocol is to opportunistically send multiple back-to-back data packets whenever the channel quality is good. As channel coherence times typically exceed multiple packet transmission times for both mobile and non-mobile users. OAR achieves significant throughput gains as compared to state-of-the-art auto-rate adaptation mechanisms. Moreover, over longer time scales, OAR ensures that all nodes are granted channel access for the same time-shares as achieved by single-rate IEEE 802.11. We describe mechanisms to implement OAR on top of any existing auto-rate adaptation scheme in a nearly IEEE 802.11 compliant manner. We also analytically study OAR and characterize the gains in throughput as a function of the channel conditions. Finally, we perform an extensive set of ns-2 simulations to study the impact of such factors as node velocity, channel conditions, and topology on the throughput of OAR.

Original languageEnglish (US)
Number of pages12
StatePublished - 2002
EventProceedings of The Eight Annual International Conference on Mobile Computing and Networking - Atlanta, GA, United States
Duration: Sep 23 2002Sep 28 2002


ConferenceProceedings of The Eight Annual International Conference on Mobile Computing and Networking
Country/TerritoryUnited States
CityAtlanta, GA


  • Ad hoc networks
  • IEEE 802.11
  • Medium access
  • Scheduling
  • Wireless channels

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Computer Networks and Communications


Dive into the research topics of 'Opportunistic media access for multirate ad hoc networks'. Together they form a unique fingerprint.

Cite this