Receiver Consensus: On-Time Warning Delivery for Vehicular Ad-Hoc Networks

To improve safety, a warning message in VANETs should be delivered both reliably and urgently. Existing solutions either tend to compromise propagation delay or do not reach high reliability due to broadcast storm problem caused by excessive retransmissions. We propose Receiver Consensus, which exploits geographical information to help nodes autonomously achieve agreement on forwarding strategies. Each forwarding candidate ranks itself and its neighbors (who affirmatively or potentially received the message already) by distance to the centroid of neighbors in need of message, to assign different priority in forwarding among neighboring nodes and remarkably suppress unnecessary retransmission, while enabling best nodes to transmit the packet without waiting. The effectiveness and efficiency of this method are validated through extensive simulations under 802.11p settings. The results demonstrate that the proposed protocol achieves the high reliability of leading state-of-the-art solutions, while at the same time significantly enhances timeliness, dedicating itself to disseminating emergency messages in 2D vehicular networks. Our solution is also superior to all existing solutions in 1-D scenarios. The algorithm is also generalized for vehicles with heterogeneous transmission ranges as follows. Candidate neighbors are ranked using d-r instead of d for ranking, where d is the distance to the ideal forwarding location and r is the communication range of a node.