A Novel Position-based Multi-hop Broadcast Protocol for Vehicular Ad Hoc Networks

Vehicular Ad Hoc Networks (VANETs) are considered as a promising scheme to actively guarantee vehicle safety, and broadcast is a key technology for warning message dissemination in VANETs. This paper proposes a novel Position-based Multi-hop Broadcast (PMB) protocol for VANETs in view of some shortcomings of existing broadcast protocols for VANETs, such as ignoring the differences of transmission range among different nodes (vehicles), and disseminating warning messages only with the help of nodes in the one-way lane, PMB calculates waiting time to select the rebroadcast nodes based on additional coverage area of adjacent nodes considering the transmission ranges of nodes together with the inter-vehicle spacing, to guarantee less nodes used to rebroadcast warning packets. Besides, it guarantees the reliability of warning message dissemination by adopting the alternative answering mechanism named implicit ACK and explicit ACK adaptively and rebroadcast packets based on nodes in the two-way lane. The simulation results show that PMB outperforms existing broadcast protocols for warning message dissemination in VANETs in terms of suppression of broadcast redundancy, real-time performance and reliability even if all nodes have different transmission ranges.