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

2. 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.edu/pubs/fp02-hull.pdf

4. 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

5. CarTel In A Nutshell

6. 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

7. CarTel Example

8. 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

9. 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

10. Network Activity Timeline

11. Geographic Coverage

12. IP Address Acquisition Latency

13. Effects of Speed

14. AP Connectivity

15. Throughput

16. 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”

17. Wardriving

18. 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