Systems-Level Support for Mobile Device Connectivity.

Mobile Computing;Wireless Networking;Derivative of Connectivity;Connectivity Forecast;Juggler;BreadCrumbs;Engineering;Computer Science & Engineering

Nicholson, Anthony J.Mao, Zhuoqing ;

University of Michigan

关键词: Mobile Computing;    Wireless Networking;    Derivative of Connectivity;    Connectivity Forecast;    Juggler;    BreadCrumbs;    Engineering;    Computer Science & Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/61718/tonynich_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The rise of handheld computing devices has inspired a great deal of research aimed at addressing the unique problems posed by theirmobile, ;;always-on;; nature. In order to help mobile devices navigate a complex world of overlapping, uneven public wireless coverage, onemust be mindful of the distinction between nomadic usage and true mobility. Accordingly, systems research must move beyond simplyoptimizing 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 networkconditions are constantly in flux.This dissertation presents a new paradigm for networking support on mobile devices. This project has several complementary aspects. Asdevices 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 forthe 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 thecurrent one become unusable, and maintain a modest side-channel to the user;;s personal area network or mesh network without impactingforeground bandwidth to infrastructure.