Adaptive message forwarding for avoiding broadcast storm and guaranteeing delay in active safe driving VANET

Active safe driving has been extensively studied to avoid vehicle accidents or traffic jam by using the inter-vehicle communications (IVC) in Vehicular Adhoc NETworks and Intelligent Transport Systems (ITSs). In IVC, the shared emergency message certainly brings several advantages: achieving active safe driving, avoiding vehicle accidents, avoiding blind-driving in traffic jam, balancing vehicle traffic loads, etc. However, the shared (emergency) message always forwarded through broadcasting that suffers from broadcast storm and flooding of messages, and then yields a long forwarding delay and degrades the synchronization interval of the application of adaptive cruise control. Thus, to guarantee real-time forwarding of emergency messages (EMs) needs to be addressed for successfully achieving an efficient active safe driving in ITS. This paper thus proposes the Adaptive Forwarding message and Cooperative Safe driving (namely AFCS) for achieving active safe driving mechanism. AFCS avoids flooding the broadcast-type Ems, and then guarantees QoS transmissions of EMs and the real-time driving video information sharing among vehicles. Furthermore, we model an analytical model to analyze several important parameters: packet forwarding delay, packet connectivity probability, number of forwarded messages, etc. Additionally, the proposed approach is applied to cooperate with the cooperative-based ACC to reduce the butterfly effect when vehicles suddenly brake. Numerical results demonstrate that AFCS outperforms the compared approaches in transmission range, connectivity probability, total number of forwarding messages, number of hop-counts, the end-to-end delay, and the butterfly effect. The analysis result is close to the simulation result, and thus justifies the claims of the analytical model.