Reliable roadside-to-roadside data transfer using vehicular traffic

In this paper we consider how vehicular networking technology can be used to support roadside-to-roadside (r2r) communications. In this form of communication vehicles traveling along a road or highway are used to transport data between two fixed roadside locations that are too far apart to be connected. The basic idea is to have a roadside station give data to a moving vehicle as it gets close and then have the vehicle carry and then deliver the data to the other roadside station. In previous work we first considered the feasibility of such a service. In this paper we aim to take concrete steps towards making the deployment of such a service real and useable. We, therefore, focus on two main aspects of such a service: 1) The design of the data transfer mechanisms between the roadside stations and the vehicles assuming a standard 802.11 MAC protocol is in use, and 2) The design of schemes to insure reliable data transfer between the two roadside stations over the particularly challenging channel provided by the moving vehicles. We describe and evaluate several schemes to achieve data transfer reliability. We find that a rateless coding scheme is best for the transfer of small to moderate files, while a hybrid ARQ/data replication scheme performs well for larger file transfers.