A traffic flow density adaptive broadcast protocol for VANETs

A traffic density adaptive broadcast protocol(TDABP)for vehicular ad hoc networks (VANETs) is proposed to realize their fast, effective broadcasting of safety messages in a traffic environment with the variable traffic flow density to enhance the road traffic safety. The protocol is designed as a distributed scheme to cater with the characteristics of VANET environments, in which it is difficult for every node to master the topologies of whole networks. An on-demand mechanism is employed in exchanging connectivity information between neighbors to get their coverage information. Consequently, the additional overhead for updating neighbor knowledge is reduced and the effects of broadcast storm are relieved efficiently at different density scenarios. The theoretical analysis and simulation experiments show that this protocol can meet the real-time performance and reliability requirements of VANET broadcasting in variable density traffic flow conditions. The protocol gains good scalability and high efficiency.