How Penalty Leads to Improvement: a Measurement Study of Wireless Backoff

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2014
Major/Subject
Mcode
Degree programme
Language
en
Pages
16
Series
Abstract
Despite much theoretical work, different modifications of backoff protocols in 802.11 networkslack empirical evidence demonstrating their real-life performance. To fill the gap we have set out to experiment with performance of exponential backoff by varying its backoff factor. Despite the satisfactory results for throughput, we have witnessed poor fairness manifesting in severe capture effect. The design of standard backoff protocol allows already successful nodes to remain successful, giving little chance to those nodes that failed to capture the channel in the beginning. With this at hand, we ask a conceptual question: Can one improve the performance of wireless backoff by introducing a mechanism of self-penalty, when overly successful nodes are penalized with big contention windows? Our real-life measurements using commodity hardware demonstrate that in many settings such mechanism not only allows to achieve better throughput, but also assures nearly perfect fairness. We further corroborate these results with simulations and an analytical model. Finally, we present a backoff factor selection protocol which can beimplemented in access points to enable deployment of the penalty backoff protocol to consumer devices.
Description
Keywords
Wireless networks, channel access, performance measurement and modeling, protocol design
Other note
Citation
Kuptsov, Dmitriy & Nechaev, Boris & Lukyanenko, Andrey & Gurtov, Andrei. 2014. How Penalty Leads to Improvement: a Measurement Study of Wireless Backoff.