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Systems-Level Support for Mobile Device Connectivity.

dc.contributor.authorNicholson, Anthony J.en_US
dc.date.accessioned2009-02-05T19:32:51Z
dc.date.availableNO_RESTRICTIONen_US
dc.date.available2009-02-05T19:32:51Z
dc.date.issued2008en_US
dc.date.submitted2008en_US
dc.identifier.urihttps://hdl.handle.net/2027.42/61718
dc.description.abstractThe rise of handheld computing devices has inspired a great deal of research aimed at addressing the unique problems posed by their mobile, "always-on" nature. In order to help mobile devices navigate a complex world of overlapping, uneven public wireless coverage, one must be mindful of the distinction between nomadic usage and true mobility. Accordingly, systems research must move beyond simply optimizing for a set of local conditions (e.g., finding the best access point for a laptop user in a stationary location) to considering the "derivative of connectivity" when network conditions are constantly in flux. This dissertation presents a new paradigm for networking support on mobile devices. This project has several complementary aspects. As devices encounter network connectivity our system both evaluates the application-level quality of WiFi access points and updates a device-centric mobility model. Together, this mobility model and AP quality database yield "connectivity forecasts," which let applications optimize not just for current network conditions but for the expected big picture to come. Results of a prototype deployment in several cities shows that considering the application-level quality of APs (rather than just signal strength) significantly boosts the success rate of finding a usable access point. Furthermore, this dissertation shows how connectivity forecasts---even with minimal model training time---allow several applications commonly found on mobile devices to reap significant benefits, such as extended battery life. Mobile devices are often within range of multiple connectivity options, however, and choosing just one therefore ignores potential connectivity. This dissertation describes a virtual link layer for Linux, called Juggler, that uses one network card to simultaneously associate with many WiFi APs, ad hoc groups or mesh networks. The results show how Juggler can boost effective bandwidth by striping data across multiple APs, enable seamless 802.11 handoff by preemptively associating with the "next" AP before the current one become unusable, and maintain a modest side-channel to the user's personal area network or mesh network without impacting foreground bandwidth to infrastructure.en_US
dc.format.extent886398 bytes
dc.format.extent1373 bytes
dc.format.mimetypeapplication/pdf
dc.format.mimetypetext/plain
dc.language.isoen_USen_US
dc.subjectMobile Computingen_US
dc.subjectWireless Networkingen_US
dc.subjectDerivative of Connectivityen_US
dc.subjectConnectivity Forecasten_US
dc.subjectJuggleren_US
dc.subjectBreadCrumbsen_US
dc.titleSystems-Level Support for Mobile Device Connectivity.en_US
dc.typeThesisen_US
dc.description.thesisdegreenamePhDen_US
dc.description.thesisdegreedisciplineComputer Science & Engineeringen_US
dc.description.thesisdegreegrantorUniversity of Michigan, Horace H. Rackham School of Graduate Studiesen_US
dc.contributor.committeememberNoble, Brian D.en_US
dc.contributor.committeememberFlinn, Jason Nelsonen_US
dc.contributor.committeememberLiu, Mingyanen_US
dc.contributor.committeememberMao, Zhuoqingen_US
dc.subject.hlbtoplevelEngineeringen_US
dc.description.bitstreamurlhttp://deepblue.lib.umich.edu/bitstream/2027.42/61718/1/tonynich_1.pdf
dc.owningcollnameDissertations and Theses (Ph.D. and Master's)


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