A probabilistic routing protocol in VANET

Abstract

The key attribute that distinguishes Vehicular Ad hoc Networks (VANET) from Mobile Ad hoc Networks (MANET) is scale. To wit, while MANET involve up to one hundred nodes and are short lived, being deployed in support of special-purpose operations, VANET networks involve millions of vehicles on thousands of kilometers of highways and city streets. Also, being mission-driven, MANET mobility is inherently limited by the application at hand. Indeed, in a search-and-rescue mission a search party is deployed to look, say, for children lost in the woods. It stands to reason that in such a context the mobility of individual nodes is not arbitrary, but rather restricted by the search strategy implemented. In most MANET applications, such as the one just mentioned, mobility occurs at low speed. By contrast, VANET networks involve vehicles that move at high speed, often well beyond what is reasonable or legally stipulated.Given the scale of its mobility and number of actors involved, the topology of VANET is changing constantly and, as a result, both individual links and routing paths are inherently unstable. Motivated by this latter truism, our first main contribution is to propose a probability model for link duration based on realistic vehicular dynamics and radio propagation assumptions. We then go on to show how the proposed model can be incorporated in a routing protocol that results in paths that are easier to construct and maintain, both locally and globally. Extensive simulation results confirm that our probabilistic routing protocol results in paths are that easier to maintain.