DECA: Density-aware reliable broadcasting in vehicular ad hoc networks

Reliable broadcasting in vehicular ad hoc networks is challenging due to its unique characteristics including intermittent connectivity and various vehicular scenarios (car traffic is possibly very dense in urban areas or very sparse on highways). In this paper, we propose a new reliable broadcast protocol which is suitable for such characteristics. To address the issue of various vehicular scenarios, our protocol performs periodic beaconing to gather local density information of 1-hop neighbors and uses such information to adapt its broadcast decision dynamically. Specifically, before broadcasting each message, a node selects a neighbor with the highest density. Upon the reception of the broadcast message, each node checks if it is the selected neighbor. If so, it is responsible for rebroadcasting the message immediately. Otherwise, it stores the message for possible rebroadcasting. To address the issue of intermittent connectivity, message information in beacons is used to discover new neighbors, which have not yet received the message. Simulation results show that, in both highway and urban scenarios, our proposed protocol outperforms other competing solutions in terms of reliability, overhead and speed of data dissemination.