RobustGeo: A Disruption-Tolerant Geo-Routing Protocol

While geo-routing is a promising routing algorithm in urban vehicular ad-hoc networks (VANETs), there is still much work to be done for it to become truly usable for such environments. One of the biggest obstacles to this goal is the intermittent nature of VANETs due to mobility. Traditional geo-routing algorithms do not perform well in these conditions because they drop packets whenever they cannot find an immediate forwarder for the packet. In this paper, we propose RobustGeo, a routing protocol that combines the simplicity and efficiency of the greedy forwarding technique in geo-routing algorithms, with the robustness of delay tolerant networks in the face of disruptions in network connectivity. When there exists a good connection between the source and destination, RobustGeo can route the packet like the traditional geo-routing algorithms, and when the network faces disruptions, RobustGeo relies upon vehicle mobility and packet replication to explore multiple georoute paths and quickly recover the packet back to greedy forwarding. We show that for a highly intermittent scenario, RobustGeo has a delivery ratio of over 20% (compared to a pure geo-routing protocol's delivery ratio of 0), and it reduces delay by over 40% as compared to a more pure delay-tolerant routing solution.