A Transmission Range Adaptive Broadcast Algorithm for Vehicular Ad Hoc Networks

In view of some shortcomings of existing broadcast algorithms for Vehicular Ad Hoc Networks (VANET), including ignoring the differences of transmission range among different vehicles, and disseminating emergency messages based only on vehicles in the one-way lane etc., a novel broadcast algorithm for VANET called Transmission Range Adaptive Broadcast (TRAB) is proposed in this paper. Considering the transmission ranges of vehicles together with the inter-vehicle distances, TRAB calculates waiting time to select the relay nodes in accordance with additional coverage area of adjacent nodes to ensure that less relay nodes will be used to forward the emergency packets. In addition, it guarantees the dissemination reliability by adopting two types of answering mechanism called implicit ACK and explicit ACK adaptively and forwarding packets based on vehicles in the two-way lane. The simulation results show that TRAB outperforms existing typical broadcast algorithms for VANET in terms of suppression of broadcast redundancy, real-time performance and reliability even if all vehicles have different transmission ranges.