A cluster-based recursive broadcast routing algorithm to propagate emergency messages in city VANETs

Vehicular ad hoc network (VANET) becomes a promising research field, since the number of vehicles increases every day. In city scenarios, intermittent connectivity, traffic light, traffic accident and 3D scenarios are the major issues to impact the performances of exciting routing protocols, especially in emergency message broadcasting scenario. Delay time and delivery ratio are important performance characters that should be considered mostly. So, a cluster-based recursive broadcast (CRB) algorithm is proposed to solve above problems. With benefit of this algorithm, only the selected vehicles perform a re-broadcasting received emergency event among the vehicles in the transmission range. Moreover, taking considered into the traffic light problem, the CRB not only improves the efficiency of message transmission, but also achieves the ability of directional broadcast. Simulation results showed that the proposed CRB algorithm outperforms traditional flooding one both in delay time and delivery ratio.