We describe our experiences with deploying a vehicular Internet access service on public transit buses. Our system, called WiRover, has been running on these buses since April 2010 for about 18 months till date providing a WiFi hotspot to which bus passengers can connect. As of Dec. 1, 2011 we have observed 17,567 unique client devices connect to the WiRover system. These devices have downloaded more than 337.53 GB and uploaded 48.19 GB of content through our system. Since the initial deployment, the buses have logged more than 9,331 hours of operation and have traveled over much of the northern Midwest of the United States. Th- rough this paper we provide different insights acquired in deploying and running a continuous service with real users, present various user and usage characteristics in these systems, discuss various design and management strategies for these networks, and explore different network traffic optimizations possible.
Public Review uploaded by JeffreyPang:
This public review was prepared by Jeffrey Pang.
The use of WiFi on various forms of transportation has drawn considerable interest both in the research and commercial space. The central contribution of this paper is a report on the deployment and experience of running one WiFi bus system for a period of 18 months. While this is not the first WiFi bus system to be deployed nor are the optimization techniques used significantly novel, the sheer size and duration of the study provides a number of real-world observations useful to others that would want to build a similar system. Furthermore, the paper validates the utility of optimization techniques that had previously only been demonstrated on a small scale, such as multiple radios and caching in the wild. The MobiSys community certainly values the experience gained from deployed systems such as this.
Despite the effort that went into this study, however, the reported findings are not particularly surprising. The system uses known techniques for optimization and failure robustness, such as multiple radios, compression, periodic reporting, forced reboots, hardware swapping, etc., but the utility of most of these techniques was already known to some extent. Moreover, the usage patterns of users on the system are not out of the ordinary. The novel observations come from the combination of techniques that ended up being effective and the discoveries that the authors had along the way.
Finally, this paper sets an important bar for traffic characterization studies for users on buses. The results should help both implementors of such systems and researchers looking to understand "bus traffic" better. It will be interesting to see what else can be learned from the data.
We are glad that the public review succinctly describes key aspects of the paper. We want to reiterate that our long-term vehicular system can provide a useful basis from which a deeper understanding of such operations can be gained. Many challenges exist when building and deploying such systems. In this work we have highlighted challenges we have faced that could also be stumbling blocks for others that decide to build, deploy, and operate similar vehicular systems.
We hope that the challenges we have highlighted will encourage others to engage in discussing solutions or even to focus their efforts to studying these challenges.