Measurements and Characterization for the Vehicle-to-Infrastructure Channel in Urban and Highway Scenarios at 5.92GHz

In the future smart transportation system, reliable vehicle-to-infrastructure(V2 I) communication is very important to ensure vehicle driving safety and to improve vehicle driving efficiency. In this paper, V2 I channel measurements at 5.92 GHz are conducted in typical urban and highway scenarios.The frequency and bandwidth of transmission, as well as the deployment of the RSU(roadside unit) and the OBU(on board unit), are selected by considering the recommendation proposed by 3 GPP TR 36.885. Then,based on the measured data, the key channel characteristic parameters of the V2 I channel are extracted,including path loss, root-mean-square delay spread,stationarity distance, and Doppler spread, etc. Also,the statistical characteristics of the parameters, including time-varying and Doppler characteristics, are investigated and characterized. The work in this paper helps researchers design technology and communication systems in similar scenarios.

Fairness Assurance through TXOP Tuning in IEEE 802.11p Vehicle-to-Infrastructure Networks for Drive-Thru Internet Applications

This paper addresses an unfairness problem that exists among vehicles of distinct velocities in IEEE 802.11p based vehicle-to-infrastructure (V2I) networks used for drive-thru Internet applications. The standard IEEE 802.11p does not take into account, the residence time of vehicles within the coverage of each road side unit (RSU), for granting channel access. Due to this, a vehicle moving with higher velocity has less chance to communicate with the RSU, as compared to vehicles with lower velocity, due to its shorter residence time in the coverage area of RSU. Accordingly, the data transfer performance of a higher velocity vehicle gets degraded significantly, as compared to that of the vehicle with lower velocity, resulting in unfairness among them. In this paper, our aim is to resolve this unfairness problem by assigning the transmission opportunity (TXOP) limits to vehicles according to their mean velocities. Using an analytical model, we prove that tuning TXOP limit proportional to mean velocity can ensure fairness among vehicles belonging to distinct classes of mean velocities, in the sense of equal chance of communicating with RSU. Analytical results are validated using extensive simulations.

How Do V2V and V2I Messages Affect the Performance of Driving Smart Vehicles?

Intelligent transportation systems(ITSs)are becoming increasingly popular as they support efficient coordinated transport.ITSs aim to improve the safety,efficiency and reliability of road transportation through integrated approaches to the exchange of relevant information.Mobile adhoc networks(MANETs)and vehicle ad-hoc networks(VANETs)are integral components of ITS.The VANET is composed of interconnected vehicles with sensitivity capabilities to exchange traffic,positioning,weather and emergency information.One of the main challenges in VANET is the reliable and timely dissemination of information between vehicular nodes to improve decision-making processes.This paper illustrates challenges in VANET and reviews possible solutions to improve road safety control and management using V2V and V2I communications.This paper also summarizes existing rules-based and optimized-based solutions,including reducing the effect of mixed environments,obstacles,malfunctions and short wireless ranges on transportation efficiency and reducing false messages that cause unintended vehicle actions and unreliable transportation systems.Additionally,an event simulation algorithm was designed to maximize the benefits of exchangeable messages among vehicles.Furthermore,simulated VANET environments were developed to demonstrate how the algorithm can be used for transformable messages.Experimental results show that coupling of both V2V and V2I messages yielded better results in terms of end-to-end delay and average time.Future research directions were highlighted to be taken into account in the development of ITS and intelligent routing mechanisms.

Identifying Smartphone Based Intelligent Messages for Worker’s Crossing in Work Zones

A smartphone warning system is a feasible option to notify motorists about a safety threat and/or pedestrian crossings ahead. In this paper, a smartphone-based warning system was proposed to enhance workers’ safety in work zones. Three different warning message systems, including sound, male voice and female voice, were designed to alert drivers. Twenty-four subjects were recruited for a total of ninety-six rounds driving simulator test in a work zone to investigate the impacts of smartphone-based warning messages on subjects’ driving performance, in terms of driving speed, speed variation, acceleration, and brake reaction distance. The outcome showed that, with the assistance of the sound and voice (either female or male) warning messages, drivers could effectively reduce their accelerations and speeds. Meanwhile, such a warning system can induce subjects to shorten their brake reaction distances for worker crossings. All participants found that this warning system is applicable to enhance their defensive driving behaviors while driving through a work zone.

Vehicle Positioning Based on Optical Camera Communication in V2I Environments

Demand for precise vehicle positioning(VP)increases as autonomous vehicles have recently been drawing attention.This paper proposes a scheme for positioning vehicles on the move based on optical camera communication(OCC)technology in the vehicle-to-infrastructure(V2I)environment.Light-emitting diode(LED)streetlights and vehicle cameras are used as transmitters and receivers respectively.Regions of streetlights are detected and traced by examining images that are obtained from cameras of vehicles.Then,a scheme for analyzing visible light data extracted from the images is proposed.The proposed vehicle positioning scheme uses information on angles between vectors that are formed under the collinearity conditions between the absolute coordinates of at least three received streetlights,and the coordinates of an image sensor.The experiments are performed under stationary state and moving state at a speed of 5 and 20 km/h.To verify the reliability of the proposed scheme,a comparison is made between the actual and estimated location of the camera in the stationary state.In addition,the path of a moving vehicle and the estimated path of the vehicle are compared to check the performance of the scheme.The performance of the proposed technique is analyzed and experimental demonstration confirms that the proposed OCC-based VP scheme achieves positioning accuracy of under 1 m.

Review of the Security Issues in Vehicular Ad Hoc Networks (VANET)

There is a significant increase in the rates of vehicle accidents in countries around the world and also the casualties involved ever year. New technologies have been explored relating to the Vehicular Ad Hoc Network (VANET) due to the increase in vehicular traffic/congestions around us. Vehicular communication is very important as technology has evolved. The research of VANET and development of proposed systems and implementation would increase safety among road users and improve the comfort for the corresponding passengers, drivers and also other road users, and a great improvement in the traffic efficiency would be achieved. This research paper investigates the current and existing security issues associated with the VANET and exposes any slack amongst them in order to lighten possible problem domains in this field.

Advances in Vehicular Ad-hoc Networks(VANETs):Challenges and Road-map for Future Development

Recent advances in wireless communication technologies and auto-mobile industry have triggered a significant research interest in the field of vehicular ad-hoc networks （VANETs） over the past few years. A vehicular network consists of vehicle-to-vehicle （V2V） and vehicle-to-infrastructure （V2I） communications supported by wireless access technologies such as IEEE 802.11p. This innovation in wireless communication has been envisaged to improve road safety and motor traffic efficiency in near future through the development of intelligent transportation system （ITS）. Hence, governments, auto-mobile industries and academia are heavily partnering through several ongoing research projects to establish standards for VANETs. The typical set of VANET application areas, such as vehicle collision warning and traffic information dissemination have made VANET an interesting field of mobile wireless communication. This paper provides an overview on current research state, challenges, potentials of VANETs as well as the ways forward to achieving the long awaited ITS.

A V2I communication-based pipeline model for adaptive urban traffic light scheduling

Adaptive traffic light scheduling based on realtime traffic information processing has proven effective for urban traffic congestion management. However, fine-grained information regarding individual vehicles is difficult to acquire through traditional data collection techniques and its accuracy cannot be guaranteed because of congestion and harsh environments. In this study, we first build a pipeline model based on vehicle-to-infrastructure communication, which is a salient technique in vehicular adhoc networks. This model enables the acquisition of fine-grained and accurate traffic information in real time via message exchange between vehicles and roadside units. We then propose an intelligent traffic light scheduling method (ITLM) based on a “demand assignment” principle by considering the types and turning intentions of vehicles. In the context of this principle, a signal phase with more vehicles will be assigned a longer green time. Furthermore, a green-way traffic light scheduling method (GTLM) is investigated for special vehicles (e.g., ambulances and fire engines) in emergency scenarios. Signal states will be adjusted or maintained by the traffic light control system to keep special vehicles moving along smoothly. Comparative experiments demonstrate that the ITLM reduces average wait time by 34%-78% and average stop frequency by 12%-34% in the context of traffic management. The GTLM reduces travel time by 22%^44% and 30%-55% under two types of traffic conditions and achieves optimal performance in congested scenarios.

Visible light communication for intelligent transportation systems:A review of the latest technologies

In seeking to improve traffic congestion and safety on roads and highways,there has been an increased interest in intelligent transportation systems(ITS).The emerging visible light communication(VLC)technology is a new candidate to enable wireless access in ITS.The purpose of this study is to present a comprehensive review of the current studies related to VLC.Since VLC facilitates illumination and data communication simultaneously,it reduces energy consumption significantly.Additionally,VLC is immune to electromagnetic interference,provides high data security,and utilizes unregulated visible light spectrum,showing promise as a potentially cheaper alternative to existing radio frequency(RF)based technology.Moreover,recent advances in semiconductor materials and solid-state technologies have enabled the development of efficient light-emitting diodes(LEDs)and laser diodes(LDs)which are used as transmitters in a VLC system.Although 10 s of Gbits/s data rate has been demonstrated in indoor VLC links,successful implementation of it in outdoor environments requires further research to overcome the challenges presented by environmental factors,unwanted lights,non-line of sight communication,directional radiation pattern,frequent fragmentation,and so on.Besides,in recent years,semiconductor LDs have been garnering more attention since they can transmit more data over longer distances due to their high quantum efficiency and modulation bandwidth compared to LEDs.As a result,urban planners,policy-makers,transportation engineers,and vehicle manufacturers are considering LD-based VLC to facilitate vehicle-to-vehicle and vehicle-to-infrastructure communication.Thus,this paper reviews and compares the most recent developments in VLC technologies,identifies their benefits and potential use in ITS applications,discusses the probable barriers for their implementation in our existing transportation infrastructure,and suggests future research directions and recommendations to overcome these challenges.

Software defined Internet of vehicles:architecture,challenges and solutions

IoV(Internet of Vehicles)is a promising paradigm to the future of automobiles,which will undoubtedly boost the automobile market as well as accelerate innovation in Internet services and applications.The concept of SD-IoV(Software Defined IoV)is presented,which is capable of improving resource utilization,service quality,and network optimization in the harsh vehicular network environments.First,A generalized SD-IoV architecture as an intuitive big picture is presented.Then,the major functions realized by SD-IoV are elabrated on to illustrate how the current challenges are resolved.As the key enablers of SD-IoV,three possible implementation methods of the wireless control path are described and compared.Finally,the challenges and existing solutions of SD-IoV are disuessed and open issues are pointed out so as to shed light on future research.

A Ray Tracing and Joint Spectrum Based Clustering and Tracking Algorithm for Internet of Intelligent Vehicles

Driven by the rapid growth in information services provided by the Internet and the appearance of new multimedia applications,millimeter wave is foreseen as a key enabler towards the Internet of intelligent vehicles(IoIV)for urban traffic safety enhancement.In this regard,cluster-based channel modeling has become an important research topic in the realm of emergency communications.To fully understand the cluster-based channel model,a series of vehicle-to-infrastructure(V2I)channel simulations at 22.6 GHz are conducted by a three-dimensional ray tracing(RT)simulator.The clustering and tracking algorithm is proposed and analyzed from three aspects by the obtained simulation results.The multiple signal classification estimation spectrum is applied to restrain the influence of antenna sidelobes and identify targets at first.Based on the fundamentals,the clusters can be identified and subsequently tracked using the proposed approach.The impacts of antenna sidelobes,angle resolution of beam rotation,and non-line-of-sight propagation path on the performance of clustering and tracking are evaluated.The multi-component-level RT results are adopted as comparison benchmarks,which reflect the ground truth.This work aims to provide a full picture of the clustering characteristics for designing and analyzing emergency communication systems.

Safety effects of work zone advisory systems under the intelligent connected vehicle environment:a microsimulation approach

Purpose–This study aims to investigate the safety effects of work zone advisory systems.The traditional system includes a dynamic message sign(DMS),whereas the advanced system includes an in-vehicle work zone warning application under the connected vehicle(CV)environment.Design/methodology/approach–A comparative analysis was conducted based on the microsimulation experiments.Findings–The results indicate that the CV-based warning system outperforms the DMS.From this study,the optimal distances of placing a DMS varies according to different traffic conditions.Nevertheless,negative influence of excessive distance DMS placed from the work zone would be more obvious when there is heavier traffic volume.Thus,it is recommended that the optimal distance DMS placed from the work zone should be shortened if there is a traffic congestion.It was also revealed that higher market penetration rate of CVs will lead to safer network under good traffic conditions.Research limitations/implications–Because this study used only microsimulation,the results do not reflect the real-world drivers’reactions to DMS and CV warning messages.A series of driving simulator experiments need to be conducted to capture the real driving behaviors so as to investigate the unresolved-related issues.Human machine interface needs be used to simulate the process of in-vehicle warning information delivery.The validation of the simulation model was not conducted because of the data limitation.Practical implications–It suggests for the optimal DMS placement for improving the overall efficiency and safety under the CV environment.Originality/value–A traffic network evaluation method considering both efficiency and safety is proposed by applying traffic simulation.