A Primer on Vehicle-to-Barrier Communications: Effects of Roadside Barriers, Encroachment, and Vehicle Braking

Today, more than half of the traffic fatalities are a result of run-off-road (RoR) crashes, which usually involve a single vehicle. Roadside barriers are often the last means to mitigate the severity of a RoR crash into hazardous objects or features. While the recent research on vehicular communications primarily focus on safety related wireless communications for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) scenarios, the interactions between vehicles and barriers in next generation vehicular systems have not been well-studied. In this paper, vehicle-to-barrier (V2B) wireless communication paradigm is introduced as a potential missing link in preventing single-vehicle RoR fatalities1. V2B communications, which take place between vehicles and radios embedded in roadside barriers can contribute to keeping cars on the road and help mitigate RoR crashes. The realization of V2B communication services necessitates an in-depth understanding of the underlying physical characteristics of the environment and channel. To this end, in this paper, some of the first real world field test measurement results of V2B communications are presented. More specifically, the effects of two types of commonly-utilized barriers (rigid concrete barrier and corrugated-beam guardrail) on the V2B channel communications are illustrated. The results show that guardrail barriers exhibit a waveguiding effect on signal transmission, while higher signal attenuation is observed with rigid barriers. Moreover, experiments illustrate the characteristics of V2B orthogonal frequency-division multiplexing (OFDM) communication during vehicle encroachment and braking in terms of received signal strength, error vector magnitude, and phase error statistics. The results highlight that barrier-height antenna deployments result in high channel quality for long distances and are not influenced by mobility and vehicle brake during encroachment scenarios, making them a strong candidate for V2B communications

Modeling and Design of Millimeter-Wave Networks for Highway Vehicular Communication

Connected and autonomous vehicles will play a pivotal role in future Intelligent Transportation Systems (ITSs) and smart cities, in general. High-speed and low-latency wireless communication links will allow municipalities to warn vehicles against safety hazards, as well as support cloud-driving solutions to drastically reduce traffic jams and air pollution. To achieve these goals, vehicles need to be equipped with a wide range of sensors generating and exchanging high rate data streams. Recently, millimeter wave (mmWave) techniques have been introduced as a means of fulfilling such high data rate requirements. In this paper, we model a highway communication network and characterize its fundamental link budget metrics. In particular, we specifically consider a network where vehicles are served by mmWave Base Stations (BSs) deployed alongside the road. To evaluate our highway network, we develop a new theoretical model that accounts for a typical scenario where heavy vehicles (such as buses and lorries) in slow lanes obstruct Line-of-Sight (LOS) paths of vehicles in fast lanes and, hence, act as blockages. Using tools from stochastic geometry, we derive approximations for the Signal-to-Interference-plus-Noise Ratio (SINR) outage probability, as well as the probability that a user achieves a target communication rate (rate coverage probability). Our analysis provides new design insights for mmWave highway communication networks. In considered highway scenarios, we show that reducing the horizontal beamwidth from $90^\circ$ to $30^\circ$ determines a minimal reduction in the SINR outage probability (namely, $4 \cdot 10^{-2}$ at maximum). Also, unlike bi-dimensional mmWave cellular networks, for small BS densities (namely, one BS every $500$ m) it is still possible to achieve an SINR outage probability smaller than $0.2$.Comment: Accepted for publication in IEEE Transactions on Vehicular Technology -- Connected Vehicles Serie

Hybrid-Vehfog: A Robust Approach for Reliable Dissemination of Critical Messages in Connected Vehicles

Vehicular Ad-hoc Networks (VANET) enable efficient communication between vehicles with the aim of improving road safety. However, the growing number of vehicles in dense regions and obstacle shadowing regions like Manhattan and other downtown areas leads to frequent disconnection problems resulting in disrupted radio wave propagation between vehicles. To address this issue and to transmit critical messages between vehicles and drones deployed from service vehicles to overcome road incidents and obstacles, we proposed a hybrid technique based on fog computing called Hybrid-Vehfog to disseminate messages in obstacle shadowing regions, and multi-hop technique to disseminate messages in non-obstacle shadowing regions. Our proposed algorithm dynamically adapts to changes in an environment and benefits in efficiency with robust drone deployment capability as needed. Performance of Hybrid-Vehfog is carried out in Network Simulator (NS-2) and Simulation of Urban Mobility (SUMO) simulators. The results showed that Hybrid-Vehfog outperformed Cloud-assisted Message Downlink Dissemination Scheme (CMDS), Cross-Layer Broadcast Protocol (CLBP), PEer-to-Peer protocol for Allocated REsource (PrEPARE), Fog-Named Data Networking (NDN) with mobility, and flooding schemes at all vehicle densities and simulation times

Vehicle-to-barrier communication during real-world vehicle crash tests

Vehicle-to-barrier (V2B) communication is expected to facilitate wireless interactions between vehicles and roadside barriers in next-generation intelligent transportation systems. V2B systems will help mitigate single-vehicle, run-off-road crashes, which account for more than 50% of roadside crash fatalities. In this work, the characteristics of the wireless channel prior to and during a crash are analyzed using orthogonal frequency division multiplexing (OFDM) techniques, which has been used in existing vehicular communication systems. More specifically, the performance of OFDM-based V2B links are measured in real-world crash tests for the first time. Three crash tests conducted at the Midwest Roadside Safety Facility, Lincoln, Nebraska, are reported: a bogie vehicle crashing into a soil-embedded post at 27 mph, a sedan crashing to a concrete curb at 15 mph, and a pickup crashing to a steel barrier at 62 mph. Metrics including signal to interference plus noise ratio received signal strength, error vector magnitude, phase error, channel coherence, and bit error rate, are used to illustrate the impacts of antenna type, antenna deployment, speed, and mobility during the crash tests. The empirical evidence shows that barrier-height (0.7–0.9 m) antennas at the barrier can improve V2B signal quality compared to higher deployments (≥1.5 m) due to the stronger reflection of electromagnetic waves at a larger angle of incidence. Moreover, compared to omni-directional barrier antennas, directional barrier antennas can increase signal quality, connectivity, and coherence time of V2B channel because of reduced multi-path effects, however, the antenna orientation needs to be carefully determined to maintain connectivity