# Investigating and Modeling of Cooperative Vehicle-to-Vehicle Safety Stopping Distance
## 1 Introduction  
The emergence of Connected and Autonomous Vehicles (CAVs) in the motoring industry has led to a growth in research and development for vehicular network technologies. CAVs aim to ensure a safer and efficient transport system and overall safer driving experience through enabling communication between vehicles, roadside units, pedestrians, and the network [1, 2]. In addition, CAVs will reduce air pollution through improved overall traffic efficiency [3].  
Safety is critical as traffic accidents, and road congestion is still a considerable concern worldwide. As such, CAVs safety is highly critical as has a direct impact on road fatalities [4, 5]. The World Health Organization (WHO) reported that 1.35 million road-related deaths occurred in 2018 [6]. The current leading technologies for CAV deployment are Dedicated Short-Range Communication (DSRC) for Vehicle-to-Vehicle (V2V) and Cellular-Vehicle-to-Everything (C-V2X) for Vehicle-to-Infrastructure (V2I) [7, 8]. V2V is also available with C-V2X via PC5 interface (sidelink) [9].  
In this paper, we show that the stopping distance performance can be improved using DSRC communication. In addition, an investigation on the impact of consecutive packet loss on safety and stopping distance is demonstrated. In this work, an open-source DSRC Software-defined radio transceiver was utilized, and the result was gathered through field trials. We believe analyzing the reliability and the impacts of consecutive loss are vital for identifying safety-related performance aspects. The testbed used in this work has been previously demonstrated in Reference [10] and shown to perform to DSRC standards.  
This work investigates how stopping distance can be reduced, as well as the impact of consecutive packet loss or burst losses on stopping distance.  
The novelty of this paper is in two key areas, the first being an extension of previous work [10] where we will be investigating and modeling the reduction of stopping distance that can be achieved with vehicle communications. In the second, we will be modeling the impact of consecutive packet losses and how this alters the reduction we have shown is attainable with communication, and a model has been designed to allow this to be proven. This is assessed in three cases: distance independent, distance dependent, and density-based scenarios. Currently, there does not seem to be many works associated with the impacts of consecutive loss on stopping distance. All our simulated results are based upon actual field test measurements made with our Software Defined Radio (SDR) testbed and theoretical models being formed from the resulting information.  
The remainder of the paper is organized as follows. We first introduce some background behind DSRC and work relating to this study, including our previous work in Section 2. In Section 3, we give a brief description of the testbed and include some of the procedures used for measurements and testing. Section 4 is used to show the theoretical model and equations used, and Section 5 is used to show the results from the combined theoretical distance independent model and the field test distance dependent model. Section 6 is a simulated analysis based upon safety distance and the impacts of density-based losses, and Section 7 includes a combined analysis of both distance independent and density losses. Finally, Section 8 concludes the paper and gives future ideas for investigation.