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.

Simulation Based Evaluation of Highway Road Scenario between DSRC/802.11p MAC Protocol and STDMA for Vehicle-to-Vehicle Communication

In this paper the DSRC/IEEE 802.11p Medium Access Control (MAC) method of the vehicular communication has been simulated on highway road scenario with periodic broadcast of packets in a vehicle-to-vehicle situation. IEEE 802.11p MAC method is basically based on carrier sense multiple accesses (CSMA) where nodes listen to the wireless channel before sending the packets. If the channel is busy, the vehicle node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets/messages because no channel access was possible before the next message/packet was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad- hoc vehicular networks.

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.

An Improved Non-Geometrical Stochastic Model for Non-WSSUS Vehicle-to-Vehicle Channels

A novel non-geometrical stochastic model(NGSM)for non-wide sense station ary uncorrelated scattering(non-WSSUS)vehicle-to-vehicle(V2V)channels is proposed.This model is based on a conventional NGSM and employs a more accurate method to reproduce the realistic characteristics of V2V channels,which successfully extends the existing NGSM to include the line-of-sight(LoS)component.Moreover,the statistical properties of the proposed model in different scenarios,including Doppler power spectral density(PSD),power delay profile(PDP),and the tap correlation coefficient matrix are simulated and compared with those of the existing NGSM.Furthermore,the simulation results dem onstrate not only the utility of the proposed model,but also the correctness of our theoreti cal derivations.

Resilient and Safe Platooning Control of Connected Automated Vehicles Against Intermittent Denial-of-Service Attacks

Connected automated vehicles(CAVs)serve as a promising enabler for future intelligent transportation systems because of their capabilities in improving traffic efficiency and driving safety,and reducing fuel consumption and vehicle emissions.A fundamental issue in CAVs is platooning control that empowers a convoy of CAVs to be cooperatively maneuvered with desired longitudinal spacings and identical velocities on roads.This paper addresses the issue of resilient and safe platooning control of CAVs subject to intermittent denial-of-service(DoS)attacks that disrupt vehicle-to-vehicle communications.First,a heterogeneous and uncertain vehicle longitudinal dynamic model is presented to accommodate a variety of uncertainties,including diverse vehicle masses and engine inertial delays,unknown and nonlinear resistance forces,and a dynamic platoon leader.Then,a resilient and safe distributed longitudinal platooning control law is constructed with an aim to preserve simultaneous individual vehicle stability,attack resilience,platoon safety and scalability.Furthermore,a numerically efficient offline design algorithm for determining the desired platoon control law is developed,under which the platoon resilience against DoS attacks can be maximized but the anticipated stability,safety and scalability requirements remain preserved.Finally,extensive numerical experiments are provided to substantiate the efficacy of the proposed platooning method.

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.

Coalitional game based resource allocation in D2D-enabled V2V communication

The joint resource block(RB)allocation and power optimization problem is studied to maximize the sum-rate of the vehicle-to-vehicle(V2V)links in the device-to-device(D2D)-enabled V2V communication system,where one feasible cellular user(FCU)can share its RB with multiple V2V pairs.The problem is first formulated as a nonconvex mixed-integer nonlinear programming(MINLP)problem with constraint of the maximum interference power in the FCU links.Using the game theory,two coalition formation algorithms are proposed to accomplish V2V link partitioning and FCU selection,where the transferable utility functions are introduced to minimize the interference among the V2V links and the FCU links for the optimal RB allocation.The successive convex approximation(SCA)is used to transform the original problem into a convex one and the Lagrangian dual method is further applied to obtain the optimal transmit power of the V2V links.Finally,numerical results demonstrate the efficiency of the proposed resource allocation algorithm in terms of the system sum-rate.

Performance analysis of different coding schemes for wideband vehicle-to-vehicle MIMO systems

The signal is subjected to lots of interferences in vehicle-to-vehicle(V2V)channel propagation,resulting in receiving error codes.Two-dimensional(2D)and three-dimensional(3D)geometrical channel models are used to depict the wideband V2V multiple-input multiple-output(MIMO)channels.Using the channel model,Turbo code and low-density parity-check(LDPC)code are investigated for wideband V2V MIMO system,and the encoding and the decoding schemes are investigated.The bit error rate(BER),channel capacity and outage probability of wideband V2V MIMO system using Turbo code and LDPC code are analyzed at different typical speeds.The results show that the performance of wideband V2V MIMO system using Turbo code outperform that using LDPC code.The performance is affected by transmitting and receiving speeds with the same coding scheme.And the channel capacity of the 3D channel is larger than that of 2D channel.

A blockchain-based trustworthy collaborative power trading scheme for 5G-enabled social internet of vehicles

Social Internet of Vehicles(SIoV)falls under the umbrella of social Internet of Things(IoT),where vehicles are socially connected to other vehicles and roadside units that can reliably share information and services with other social entities by leveraging the capabilities of 5G technology,which brings new opportunities and challenges,e.g.,collaborative power trading can address the mileage anxiety of electric vehicles.However,it relies on a trusted central party for scheduling,which introduces performance bottlenecks and cannot be set up in a distributed network,in addition,the lack of transparency in state-of-the-art Vehicle-to-Vehicle(V2V)power trading schemes can introduce further trust issues.In this paper,we propose a blockchain-based trustworthy collaborative power trading scheme for 5G-enabled social vehicular networks that uses a distributed market mechanism to introduce trusted power trading and avoids the dependence on a centralized dispatch center.Based on the game theory,we design the pricing and trading matching mechanism for V2V power trading to obtain maximum social welfare.We use blockchain to record power trading data for trusted pricing and use smart contracts for transaction matching.The simulation results verify the effectiveness of the proposed scheme in improving social welfare and reducing the load on the grid.

Secure Performance Analysis and Optimization for FD-NOMA Vehicular Communications

Vehicle-to-vehicle(V2V)communication appeals to increasing research interest as a result of its applications to provide safety information as well as infotainment services.The increasing demand of transmit rates and various requirements of quality of services(QoS)in vehicular communication scenarios call for the integration of V2V communication systems and potential techniques in the future wireless communications,such as full duplex(FD)and non-orthogonal multiple access(NOMA)which enhance spectral efficiency and provide massive connectivity.However,the large amount of data transmission and user connectivity give rise to the concern of security issues and personal privacy.In order to analyze the security performance of V2V communications,we introduce a cooperative NOMA V2V system model with an FD relay.This paper focuses on the security performance of the FD-NOMA based V2V system on the physical layer perspective.We first derive several analytical results of the ergodic secrecy capacity.Then,we propose a secrecy sum rate optimization scheme utilizing the instantaneous channel state information(CSI),which is formulated as a non-convex optimization problem.Based on the differential structure of the non-convex constraints,the original problem is approximated and solved by a series of convex optimization problems.Simulation results validate the analytical results and the effectiveness of the secrecy sum rate optimization algorithm.

A 3D Geometry-Based Scattering Model for Vehicleto-Vehicle Wideband MIMO Relay-Based Cooperative Channels

In this paper, a three-dimensional(3D) geometry- based stochastic scattering model(GBSSM) for wideband multi-input multi-output(MIMO) vehicle-to-vehicle(V2V) relay-based cooperative fading channel based on geometrical three-cylinder is proposed. Non-line-of-sight(NLOS) propagation condition is assumed in amplify-and-forward(AF) cooperative networks from the source mobile station(S) to the destination mobile station(D) via the mobile relay station(R). We extend the proposed narrowband model to wideband and also introduce the carrier frequency and bandwidth into the model. To avoid complicated procedure in deriving the analytical expressions of the channel parameters and functions, the channel is realized first. By using the realized channel matrix, the channel properties are further investigated.

Secure Model to Generate Path Map for Vehicles in Unusual Road Incidents Using Association Rule Based Mining in VANET

Logical behavioral arrangements are a class of conventional arrangements to illustrate the happening of incidents in an appropriate and structured approach in vehicular ad hoc network （VANET）. These incidents are characterized as a list of path segments that are passed through by the vehicles for the duration of their journeys from a pre-decided local source to a local destination in a structured manner. A set of proper description illustrating the paths traversed by the vehicles as logical behavioral arrangements is describedin this paper. The data gathering scheme based on secure authentication to gather the data from the vehicles is proposed in this paper. This proposed data gathering scheme based on secure authentication is compared with the existing data gathering schemes by using veins framework and the results of analysis reflect that the proposed scheme outperforms among others. The data collected from the vehicles by the proposed data gathering scheme is stored at distributed road side units （RSUs）. From these collected paths, the common and frequent paths opted by the vehicles in a certain region are determined by using frequent arrangement mining approach. An estimation model is used to decidethe next path and the whole path map opted by the vehicles in unusual situations like accident, jams, or a particular time of day. The proposed scheme will helpthe society in reducing the waiting time in vent of emergency or normal working days.

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.

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.

V2V Channel Modeling at 5.2 GHz for Highway Environment

To design and evaluate vehicle-to-vehicle(V2V)communication systems in intelligent transportation system(ITS),it is important to understand the propagation mechanisms and channel models of V2V channels.This paper aims to analyze the channel models at 5.2 GHz for the highway environment in obstructed line-of-sight(OLoS)and line-of-sight(LoS)scenarios,particularly the vehicle connectivity probability derivation based on the propagation model obtained from measurement.First,the path loss(PL),shadow fading(SF),narrowband K-factor,and small-scale amplitude fading are analyzed.Results showed that the received signal magnitude follows Rice and Weibull distribution in LoS and OLoS scenarios,respectively.Second,we develop simple and low-complexity tapped delay line(TDL)models with a 10 MHz bandwidth for LoS and OLoS scenarios;in addition,we investigate the wideband K-factor,the root mean square delay spread(RMS-DS),and delay-Doppler spectrum.Third,we derive the closed form connectivity probability between any two vehicles in the presence of Weibull fading channel,and analyze the effects of Weibull fading channel and traffic parameters on connectivity.It is found that Weibull fading parameter,transmit power and vehicle density have positive impact on connectivity probability,PL exponent has negative impact on connectivity probability.

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.

Evaluation of Effective Vehicle Probe Information Delivery with Multiple Communication Methods

Vehicle probe information delivery systems can be broadly divided into the center type and center-less type. Since conventional center-type information delivery systems generate a large load on the communications infrastructure and data center, research efforts have come to be focused on the centerless type. However, existing vehicle probe information delivery systems suffer from various problems including a limited service area, low delivery efficiency, and lack of immediacy in delivery. Our objective in this study is efficient delivery of vehicle probe information as needed. We propose a delivery scheme that uses vehicle-to-vehicle communication, infrastructure-to-vehicle communication, and mobile communication as well as Geo cast. This combined use of multiple communication methods achieves efficient information delivery by changing the communication method to fit the current situation. The results of an evaluation by simulation showed that the proposed scheme could deliver information efficiently in a variety of environments.

Simulation Evaluation of Filtering Method for Improving Pedestrian Positioning Accuracy Using Signal Strengths

In recent years, we have been able to use various services using the position information of smartphones and tablets. In addition, research on intelligent transport systems (ITS) has been actively conducted. To consider reducing traffic accidents by exchanging position information between pedestrians and vehicles by vehicle-to-pedestrian communication, we require accurate position information for pedestrians and vehicles. The GPS (global positioning system) is the most widely used method for acquiring position information. However, in urban areas, the GPS signal is affected by the surrounding buildings, which increases the positioning error. In this study, a method to improve the positioning accuracy of pedestrians using the signal strengths from vehicles and beacons was proposed. First, a Kalman filter was applied to the signal strength. Then, the path loss index was dynamically calculated using vehicle-to-vehicle communication. Finally, the position of a pedestrian was obtained using weighted centroid localization (WCL) after filtering the nodes. The positioning accuracy was evaluated using a simulator and demonstrated the superiority of the proposed method.

Fairness optimization and power allocation in cognitive NOMA/OMA V2V network with imperfect SIC

In order to improve the reliability and resource utilization efficiency of vehicle-to-vehicle(V2V)communication system,in this paper,the fairness optimization and power allocation for the cognitive V2V network that takes into account the realistic three-dimensional(3D)channel are investigated.Large-scale and small-scale fading are considered in the proposed channel model.An adaptive non-orthogonal multiple access(NOMA)/orthogonal multiple access(OMA)scheme is proposed to reduce the complexity of successive-interference-cancellation(SIC)in decoding and improve spectrum utilization.Also,a fairness index that takes into account each user's requirements is proposed to indicate the optimal point clearly.In the imperfect SIC,the optimization problem of maximizing user fairness is formulated.Then,a subgradient descent method is proposed to solve the optimization problem with customizable precision.And the computational complexity of the proposed method is analyzed.The achievable rate,outage probability and user fairness are analyzed.The results show that the proposed adaptive NOMA/OMA(A-NOMA/OMA)outperforms both NOMA and OMA.The simulation results are compared with validated analysis to confirm the theoretical analysis.

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.