A measurement study of vehicular internet access using in situ wi fi network
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A Measurement Study of Vehicular Internet Access using In Situ Wi-Fi Network. Vladimir Bychkovsky, Bret Hull, Allen Miu, Hari Balakrishnan and Samuel Madden Presented By: Galileo Namata. Basic Problem.

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A Measurement Study of Vehicular Internet Access using In Situ Wi-Fi Network

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A Measurement Study of Vehicular Internet Access using In Situ Wi-Fi Network

Vladimir Bychkovsky, Bret Hull, Allen Miu, Hari Balakrishnan and Samuel Madden

Presented By: Galileo Namata


Basic Problem

  • Can a “grassroots” wireless Internet service, provided by users who “open-up” their 802.11 (Wi-Fi) AP, be created for mobile clients?

  • Can such an unplanned network service provide reasonable performance to clients at vehicular speeds?

  • What is the expected performance for users in automobiles as they move?


Motivation

  • Cartel

    • Cartel is a mobile sensor computing system designed to collect, process, deliver and visualize data from in car sensors

    • Reference:

      • Bret Hull, Vladimir Bychkovskiy, Kevin Chen, Michel Goraczko, Eugene Shih, Yang Zhang, Hari Balakrishnan, Samuel Madden. CarTel: A Distributed Mobile Sensor Computing System. In Proceedings of SenSys, 2006. http://db.csail.mit.edu/pubs/fp02-hull.pdf


CarTel In A Nutshell

  • Computer

    • 266 MHz with 128 MB of RAM and 1 GB of flash memory

  • Varied Sensors

    • GPS Receiver, OBD-II Interface, Wi-Fi Interface, Digital Camera


CarTel In A Nutshell


CarTel In A Nutshell

  • Commute Time Analysis

    • Researcher shortened his commute

  • Traffic Hot Spot Heuristic

    • Identify Traffic Areas automatically

  • Image Acquisition

    • Google Maps with Pictures

  • Wi-Fi Measurement

  • Automotive Diagnostics


CarTel Example


Communication

  • CarTel data is set up to be automated

    • Don’t need to be plugged in to get data

    • Want to be able to get current data

  • Use In Situ Wi-Fi Networks

    • In Situ – Latin “in the place”

    • All data, sent through open networks

      • Updates and queries to CarTel nodes

      • Data from sensors to main server


What’s the Performance?

  • Experiment:

    • Use CarTel system in and around Boston Metropolitan Area and Seattle

      • 9 cars total, 290 “drive hours”

    • Measure Time For:

      • Scan

      • Association

      • Address Configuration

      • Single End to End Ping

      • Connectivity and uploads


Network Activity Timeline


Geographic Coverage


IP Address Acquisition Latency


Effects of Speed


AP Connectivity


Throughput


Related Work

  • Ott and Kutscher – Controlled experiment measuring network connection from fixed test bed

  • Gass et al – Similar measurement but in California desert

  • “War Driving Maps”


Wardriving


Discussion

  • Open Wi-Fi Networks

    • Don’t wanna get sued

      • “Safe Harbor” Laws

    • Don’t wanna get in trouble with ISP

      • Fon System (http://en.fon.com)

    • Public Free Internet?

      • Google in SF

    • Don’t Wanna Get Hacked?

      • Specialized, easy to manage hardware


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