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Opportunistic Media Access for Multirate Ad Hoc Networks (2002)
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BibTeX
@MISC{Sadeghi02opportunisticmedia,
author = {B. Sadeghi and V. Kanodia and A. Sabharwal and E. Knightly},
title = {Opportunistic Media Access for Multirate Ad Hoc Networks},
year = {2002}
}
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Abstract
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 nonmobile 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.
Keyphrases
multirate ad hoc network channel condition opportunistic medium access multiple back-to-back data packet exploit duration channel coherence time high-quality channel condition multiple data rate single-rate ieee wireless medium access standard medium access layer oar protocol significant throughput gain opportunistic auto rate state-of-the-art auto-rate adaptation mechanism multi-rate capability time scale physical layer compliant manner node velocity channel quality key mechanism transmission rate nonmobile user auto-rate adaptation scheme various auto rate adaptation mechanism multiple packet transmission time channel access ns-2 simulation extensive set
