Using dead drops to improve data dissemination in very sparse equipped traffic

We study the dissemination of data in a vehicular network in which the density of equipped vehicles, or all vehicles, is very low, and in which there is no centrally connected infrastructure, such as a network of gateways. In this environment, a vehicle is rarely in communication range of another vehicle, so that protocols based on forwarding messages along a chain of vehicles in communication range are not effective. Similarly, the lack of centrally connected network infrastructure precludes protocols that use a fixed network of gateways to transfer messages. Our solution is based on using a collection of stationary, stand-alone dead drops that exchange data with vehicles that pass by them. Although the dead drops do not communicate among themselves or with a central network, their limited ability to store and forward data can improve the connectivity of a vehicular network. We use simulation-based experiments to demonstrate that the use of dead drops results in significant improvements in both the rate of data dissemination and the robustness to frequent changes in the set of participating vehicles.