A Measurement Study of Vehicular Internet Access using In Situ WiFi Network

1
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

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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?

3
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.e
  du/pubs/fp02-hull.pdf

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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

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CarTel In A Nutshell
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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

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CarTel Example
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Communication

• CarTel data is set up to be automated
• Dont 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

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Whats 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

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Network Activity Timeline
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Geographic Coverage
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IP Address Acquisition Latency
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Effects of Speed
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AP Connectivity
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Throughput
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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

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Wardriving
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Discussion

• Open Wi-Fi Networks
• Dont wanna get sued
• Safe Harbor Laws
• Dont wanna get in trouble with ISP
• Fon System (http//en.fon.com)
• Public Free Internet?
• Google in SF
• Dont Wanna Get Hacked?
• Specialized, easy to manage hardware