Automatic Emergency Braking: Realistic Analysis of Car Dynamics and Network Performance

Safety applications are among the key drivers in vehicular ad hoc network (VANET) research, and their true performance can be only assessed if the application and the communication network are jointly considered. This paper presents a simulation study of an emergency braking (EB) application accomplished by embedding mobility, cars´ dynamic, and drivers´ behavior models into a detailed networking simulator (ns-3). The overall system allows capturing the interactions of the communications with the car´s automated braking mechanism (ABM) and the driver´s behavior. At the same time, it yields very detailed information on the communication level. In addition to the integrated tool, this paper presents a novel and simple message aggregation mechanism to empower message repropagation while controlling the network congestion during the peak load due to EB. Then, it discusses the effectiveness of such applications as a function of the market penetration rate (MPR), showing that even cars that are not equipped with communication devices benefit from the smoother and earlier reaction of the cars that can communicate. Fading phenomena and sensitivity to the radio transmitted power are analyzed, whereas the fine-grained dynamics of cars´ collisions, taking into account different masses and different elastic coefficients, are introduced to evaluate the severity of impacts.