Opportunistic media access control and rate adaptation for wireless ad hoc networks

Jianfeng Wang*, Hongqiang Zhai, Yuguang Fang, Maria C. Yuang

*Corresponding author for this work

Research output: Contribution to journalConference article

51 Scopus citations


Many rate adaptation schemes at the medium access control (MAC) layer have been proposed to utilize the multi-rate capability offered by the IEEE 802.11 wireless MAC protocol through automatically adjusting the transmission rate to best match the channel conditions. In this paper, we present the Opportunistic packet Scheduling and Auto Rate (OSAR) protocol to exploit the channel variations. The basic idea of OSAR is as follows: rather than just matching the channel condition for a node pair in communications, our protocol takes advantage of the multi-user diversity as much as possible and adapt the rate accordingly, i.e., based on the channel conditions to its neighboring nodes, the sender chooses the neighboring node with channel quality better than certain level to schedule the transmissions of packets in its queue, then the overall system throughput may be increased. The key mechanisms of OSAR are channel aware media access, rate adaptation and packet bursting. We carry out several sets of ns-2 simulations and evaluate the impact of various factors such as channel condition, network topology and traffic load on the throughput of OSAR. Simulation results show that our proposed protocol can achieve much better performance than other auto rate schemes.

Original languageEnglish
Pages (from-to)154-158
Number of pages5
JournalIEEE International Conference on Communications
StatePublished - 30 Aug 2004
Event2004 IEEE International Conference on Communications - Paris, France
Duration: 20 Jun 200424 Jun 2004


  • Ad hoc networks
  • Medium access control (MAC)
  • Multiuser diveristy
  • Rate adaptation

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