Evaluating the Impact of Transmission Power on Selecting Tall Vehicles as Best Next Communication Hop

The relatively low height of antennas on communicating vehicles in Vehicular Ad Hoc Networks (VANETs) makes one hop and as well multi-hop Vehicle-to-Vehicle (V2V) communication susceptible to obstruction by other vehicles on the road. When the transmitter or receiver (or both) is a Tall vehi- cle, (i.e., truck), the V2V communication suffer less from these obstructions. The transmission power control is an important feature in the design of (multi- hop) VANET communication algorithms. However, the benefits of choosing a Tall vehicle when transmission power is varied are not yet extensively re- searched. Therefore, the main contribution of this paper is to evaluate the im- pact of transmission power control on the improved V2V communication capa- bilities of tall vehicles. Based on simulations, it is shown that significant bene- fits are observed when a Tall vehicle is selected rather than a Short vehicle as a next V2V communication hop to relay packets. Moreover, the simulation exper- iments show that as the transmission power is increasing, the rate of Tall vehi- cles that are selected as best next V2V communication hop is significantly growing

Line-of-Sight Obstruction Analysis for Vehicle-to-Vehicle Network Simulations in a Two-Lane Highway Scenario

In vehicular ad-hoc networks (VANETs) the impact of vehicles as obstacles has largely been neglected in the past. Recent studies have reported that the vehicles that obstruct the line-of-sight (LOS) path may introduce 10-20 dB additional loss, and as a result reduce the communication range. Most of the traffic mobility models (TMMs) today do not treat other vehicles as obstacles and thus can not model the impact of LOS obstruction in VANET simulations. In this paper the LOS obstruction caused by other vehicles is studied in a highway scenario. First a car-following model is used to characterize the motion of the vehicles driving in the same direction on a two-lane highway. Vehicles are allowed to change lanes when necessary. The position of each vehicle is updated by using the car-following rules together with the lane-changing rules for the forward motion. Based on the simulated traffic a simple TMM is proposed for VANET simulations, which is capable to identify the vehicles that are in the shadow region of other vehicles. The presented traffic mobility model together with the shadow fading path loss model can take in to account the impact of LOS obstruction on the total received power in the multiple-lane highway scenarios.Comment: 8 pages, 11 figures, Accepted for publication in the International Journal of Antennas and Propagation, Special Issue on Radio Wave Propagation and Wireless Channel Modeling 201

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

GUI: GPS-Less Traffic Congestion Avoidance in Urban Areas with Inter-Vehicular Communication

Abstract—Driving in an urban canyon can be frustrating when your GPS teller keeps telling you to make a turn at the place that you just passed, because the information transmission is deferred by the wireless signal reflecting off of buildings and other interfering objects. In this paper, we provide a practical solution for turn-to-turn guidance with inter-vehicle communication in vehicle ad-hoc networks (VANETs). Vehicles collect information from neighbors and catch the snapshot to describe the global impact of traffic congestions, in the presence of unpredictable changes of topology and vehicle trajectory. Without any central-ized control, the information can be aggregated along the traffic flow and be disseminated in a minimal area, while sufficiently guiding each vehicle to achieve a global optimization on its path, and to remain on a non-blocked route. The information constitution is implemented in the proactive model, saving the delay of reconstruction in the reactive model (on-demand). Its substantial improvement on the elapsed time will be shown in the experimental results, compared with the best results known to date in both proactive and reactive information models. Keywords—Information model, inter-vehicular wireless commu-nication, traffic congestion, vehicular ad-hoc network (VANET). I