Supporting platooning maneuvers through IVC: An initial protocol analysis for the JOIN maneuver

Driving vehicles in platoons has the potential to improve traffic efficiency, increase safety, reduce fuel consumption, and make driving experience more enjoyable. A lot of effort is being spent in the development of technologies, like radars, enabling automated cruise control following and ensuring emergency braking if the driver does not react in time; but these technologies alone do not empower real platooning. The initial idea of building dedicated infrastructures for platoons, has been set aside favouring the philosophy that foresees scenarios, where automated vehicles share the road with human-driven ones. This arises interesting new questions regarding the interactions between the two categories of vehicles. In this paper we focus on the analysis of interferences caused by non-automated vehicles during a JOIN maneuver. We define the application layer protocol to support the maneuver, together with situations that can prevent successful termination, and describe how they can be detected. The validity of the approach is proven by means of simulations, showing either that the maneuver can successfully be performed, or safely be aborted. Finally, we analyze the impact of the Packet Error Rate (PER) on the failure rate of the maneuver, showing that packet losses mainly affect the maneuver from a coordination point of view, rather than stability of the system, i.e., even at high loss rates, cars never violated a minimum safety distance

A Vehicular Networking Perspective on Estimating Vehicle Collision Probability at Intersections

Finding viable metrics to assess the effectiveness of Intelligent Transportation Systems (ITS) in terms of ‘safety’ is one of the major challenges in vehicular networking research. We aim to provide a metric, an estimation of the vehicle collision probability at intersections, that can be used for evaluating Inter- Vehicle Communication (IVC) concepts. In the last years, the vehicular networking community reported in several studies that safety enhancing protocols and applications cannot be evaluated based only on networking metrics like delays and packet loss rates. We present an evaluation scheme that addresses this need by quantifying the probability of a future crash, depending on the situation in which a vehicle is receiving a beacon message (e.g., a CAM or a BSM). Thus, our criticality metric also allows for fully distributed situation assessment. We investigate the impact of safety messaging between cars approaching an intersection using a modified road traffic simulator that allows selected vehicles to disregard traffic rules. As direct result we show that simple beaconing is not as effective as anticipated in suburban environments. More profoundly, however, our simulation results reveal more details about the timeliness (regarding the criticality assessment) of beacon messages, and as such, can be used to develop more sophisticated beaconing solutions

PLEXE: A Platooning Extension for Veins

Cooperative driving in general and Cooperative Adaptive Cruise Control (CACC) or platooning in particular require blending control theory, communications and networking, as well as mechanics and physics. Given the lack of an integrated modeling framework and theory as well as the prohibitively high costs of using prototypes for what-if studies, simulation remains the fundamental instrument to evaluate entire cooperative driving systems. This work presents Plexe, an Open Source extension to Veins that offers researchers a simulation environment able to run experiments in realistic scenarios, taking into account physics and mechanics of the vehicles, communications and networking impairments, and Inter-Vehicle Communication (IVC) protocol stacks. Plexe is easily extensible and already implements protocols to support platooning and cooperative driving applications and several state of the art cruise control models. We describe the structure of the simulator and the control algorithms that Plexe implements and provide two use cases which show the potential of our framework as a powerful research tool for cooperative driving systems

How Shadowing Hurts Vehicular Communications and How Dynamic Beaconing Can Help

We study the effect of radio signal shadowing dynamics, caused by vehicles and by buildings, on the performance of beaconing protocols in Inter-Vehicular Communication (IVC). Recent research indicates that beaconing, i.e., one hop message broadcast, shows excellent characteristics and can outperform other communication approaches for both safety and efficiency applications, which require low latency and wide area information dissemination, respectively. We show how shadowing dynamics of moving obstacles hurt IVC, reducing the performance of beaconing protocols. At the same time, shadowing also limits the risk of overloading the wireless channel. To the best of our knowledge, this is the first study identifying the problems and resulting possibilities of such dynamic radio shadowing. We demonstrate how these challenges and opportunities can be taken into account and outline a novel approach to dynamic beaconing. It provides low-latency communication (i.e., very short beaconing intervals), while ensuring not to overload the wireless channel. The presented simulation results substantiate our theoretical considerations

To Crash or Not to Crash: Estimating its Likelihood and Potentials of Beacon-based IVC Systems

Is it possible to estimate some ‘safety’ metric to assess the effectiveness of Intelligent Transportation Systems? In particular, we are interested in using Inter-Vehicle Com- munication (IVC) beaconing for increasing drivers’ safety at intersections. In the last couple of years, the vehicular networking community reported in several studies that simple network metrics are not sufficient to evaluate safety enhancing protocols and applications. We present a classification scheme that allows the quantification of such improvements by determining how many potential crashes happen or can be avoided by a specific IVC approach. Using a modified road traffic simulator that allowed selected vehicles to disregard traffic rules, we investigated the impact of safety messaging between cars approaching an intersection. We show that in suburban environments simple beaconing is not as effective as anticipated. Yet, simple one-hop- relaying, e.g., by vehicles parked close to an intersection, can improve drivers’ safety substantially. Since the key purpose of IVC is safety, the paper closes the loop in the evaluation of the effectiveness of vehicular networks as defined today

Vehicle Shadowing Distribution Depends on Vehicle Type: Results of an Experimental Study

Simulations play a fundamental role for the eval- uation of vehicular network communication strategies and ap- plications’ effectiveness. Therefore, the vehicular networking community is continuously seeking more realistic channel and reception models to provide more reliable results, yet maintaining scalability in terms of computational effort. We investigate the effects of vehicle shadowing on IEEE 802.11p based communica- tion. In particular, we perform a set of real world measurements on a freeway and study the impact of different obstructing vehicles on the received signal power distribution. Different vehicle types not only affect the average received power, but also its distribution, suggesting that the attenuation characteristics of the simulation model need to be tailored to the type of vehicle that is obstructs the communication path. Based on these observations, we propose a novel way to compose shadowing and fading models to reproduce the observed effects

How Shadowing Hurts Vehicular Communications and How Dynamic Beaconing Can Help

We study the effect of radio signal shadowing dynamics, caused by vehicles and by buildings, on the performance of beaconing protocols in Inter-Vehicular Communication (IVC). Recent research indicates that beaconing, i.e., one hop message broadcast, shows excellent characteristics and can outperform other communication approaches for both safety and efficiency applications, which require low latency and wide area information dissemination, respectively. To mitigate the broadcast storm problem, adaptive beaconing solutions have been proposed and designed. We show how shadowing dynamics of moving obstacles hurt IVC, reducing the performance of beaconing protocols. To the best of our knowledge, this is one of the first studies on identifying the problem and the underlying challenges and proposing the opportunities presented by such challenges. Shadowing also limits the risk of overloading the wireless channel. We demonstrate how these challenges and opportunities can be taken into account and outline a novel approach to dynamic beaconing. It provides low-latency communication (i.e., very short beaconing intervals), while ensuring not to overload the wireless channel. The presented simulation results substantiate our theoretical considerations