A measurement study of vehicular internet access using in situ Wi-Fi networks

Abstract

The impressive penetration of 802.11-based wireless networks in many metropolitan areas around the world offers, for the first time, the opportunity of a "grassroots" wireless Internet service provided by users who "open up" their 802.11 (Wi-Fi) access points in a controlled manner to mobile clients. While there are many business, legal, and policy issues to be ironed out for this vision to become reality, we are concerned in this paper with an important technical question surrounding such a system: can such an unplanned network service provide reasonable performance to network clients moving in cars at vehicular speeds?To answer this question, we present the results of a measurement study carried out over 290 "drive hours" over a few cars under typical driving conditions, in and around the Boston metropolitan area (some of our data also comes from a car in Seattle). With a simple caching optimization to speed-up IP address acquisition, we find that for our driving patterns the median duration of linklayer connectivity at vehicular speeds is 13 seconds, the median connection upload bandwidth is 30 KBytes/s, and that the mean duration between successful associations to APs is 75 seconds. We also find that connections are equally probable across a range of urban speeds (up to 60 km/hour in our measurements). Our end-toend TCP upload experiments had a median throughput of about 30 KBytes/s, which is consistent with typical uplink speeds of home broadband links in the US. The median TCP connection is capable of uploading about 216 KBytes of data.Our high-level conclusion is that grassroots Wi-Fi networks are viable for a variety of applications, particularly ones that can tolerate intermittent connectivity. We discuss how our measurement results can improve transport protocols in such networks.

Game-Theoretic Scalable Offloading for Video Streaming Services over LTE and WiFi Networks

“…The AP deployment algorithm based on realistic mobility characteristics was proposed in [33], and more granular deployment algorithms in a city-wide scenario was studied in [34]. In addition, the feasibility of WiFi offloading in high-speed vehicular environments was demonstrated in [35], [36], [37]. Motivated by these potential economic benefits, thus far efficient offloading mechanisms have been proposed.…”

Vehicular WiFi offloading: Challenges and solutions

“…In [3] and [32], large-scale experimental evaluations of the drive-thru Internet with multiple vehicles in urban scenarios have been conducted. Both of the data sets are collected from the city of Boston with in situ open WiFi APs.…”

“…Both of the data sets are collected from the city of Boston with in situ open WiFi APs. [3] focuses on the TCP upload performance, and shows that with fixed 1 Mbps MAC bit rate, the drive-thru Internet is able to provide an (median) upload throughput of 30 KBytes/s, and the median volume of uploading data in once drive-thru is 216 KB. The average connection and inter-connection time are 13 seconds and 75 seconds, respectively.…”

“…The advantages of WiFi access are summarized in Table 1. Recent research has demonstrated the feasibility of WiFi for outdoor Internet access at vehicular speeds [3]. The built-in WiFi radio or WiFi-enabled mobile devices on board can access the Internet when vehicles are moving in the coverage of WiFi hotspots, which is often referred to as the drive-thru Internet access [4].…”

An Experimental Performance Comparison of 3G and Wi-Fi

“…The authors of [3] took this idea into the wild and reported on 290 drivehours in urban environments and found the median connection duration to be 13 seconds. This finding is very promising for in-motion communications.…”