A data dissemination protocol for urban Vehicular Ad hoc Networks with extreme traffic conditions

Broadcast data dissemination is a fundamental building block for many applications in Vehicular Ad hoc Networks. In the literature, there are solutions to deal with data dissemination in urban environments, but they solely focus on either intermittently connected topologies or well-connected topologies. However, depending on the time of day or the geographical location in a city, the network topologies can change dramatically. Hence, protocols proposed to operate under these networks should be able to adapt themselves to the traffic condition at hand. To tackle this problem, we propose U-HyDi, a broadcast data dissemination protocol suited for urban scenarios with zero infrastructure support. By using solely one-hop neighbor information, U-HyDi can seamless operate under intermittently connected networks by applying store-carry-forward techniques to deliver messages even when there is no end-to-end path. Moreover, under well-connected networks, U-HyDi employs a combination of sender-based and receiver-based broadcast suppression techniques to avoid excessive contention at the link layer. Simulation results show that U-HyDi has a low overhead and a low delivery delay. Furthermore, U-HyDi is able to deliver messages to almost all vehicles in a given region of interest.