Reliable broadcast mechanism for emergency message in urban vehicular ad hoc networks

Abstract

In urban roads, the safety service of vehicular ad hoc networks is particularly important because of the frequent traffic accidents. In order to minimise redundancy and delay of network and ensure the high reception rate of vehicles in the target area when spreading the emergency message. In this study, the authors propose a reliable broadcast mechanism based on the layout information of the road. Different from existing mechanisms, in the straight, the proposed mechanism regards effective communication distance based on prediction rather than fix distance as one of the parameters of waiting time calculation. Considering the obstacles such as buildings around the intersection in the actual urban scenario, the vehicle in the intersection area (IA) of the target area will have an additional broadcast, if there are no vehicles in the IA, the vehicle in the pre-selected area for intersections (IPA) has chance to broadcast when it enters IA, which avoids the failure of emergency message transmission in some direction because of the obstacles around the intersection and ensures the coverage and reliability of emergency message. The simulation results verify that the novel scheme has better performance than the compared schemes in terms of reliability and delay.