A measurement driven, 802.11 anti-jamming system
FREE-DOWNLOADK Pelechrinis, I Broustis, SV Krishnamurthy Arxiv preprint arXiv: , 2009 arxiv.org
The widespread proliferation of 802.11 wireless networks makes them an attractive target for saboteurswith jamming devices . Numerous jamming attackshave been reported in the recent past ; thismakes the defense against such attacks very critical. Ajammer transmits either dummy packets or simply electromagnetic energy to hinder legitimate communicationson the wireless medium. A jamming attack can causethe following e?ects in an 802.11 network: (a) Due tocarrier sensing, co-channel transmitters detect activityon the medium and thus, defer their packet transmissions for prolonged periods. (b) The jamming signalcollides with legitimate packets at receivers. As a consequence, the throughput is signi?cantly reduced because of these e?ects. Frequency hopping techniqueshave been previously proposed for avoiding jammers [5][6]. Such schemes however, are not e?ective in scenarios with wide-band jammers . Furthermore, giventhat 802.11 operates on relatively few frequency channels, multiple jamming devices operating on di?erentchannels can signi?cantly hurt performance in spite ofusing frequency hopping . More than that, althoughFrequency Hopping Spread Spectrum was available inthe initial 802.11 standard, it was not later included inthe 802.11a/b/g standards that are popular today
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