Beaconing Approaches in Vehicular Ad Hoc Networks: A Survey

A vehicular ad hoc network (VANET) is a type of wireless ad hoc network that facilitates ubiquitous connectivity between vehicles in the absence of fixed infrastructure. Beaconing approaches is an important research challenge in high mobility vehicular networks with enabling safety applications. In this article, we perform a survey and a comparative study of state-of-the-art adaptive beaconing approaches in VANET, that explores the main advantages and drawbacks behind their design. The survey part of the paper presents a review of existing adaptive beaconing approaches such as adaptive beacon transmission power, beacon rate adaptation, contention window size adjustment and Hybrid adaptation beaconing techniques. The comparative study of the paper compares the representatives of adaptive beaconing approaches in terms of their objective of study, summary of their study, the utilized simulator and the type of vehicular scenario. After implementing the representatives of beaconing approaches, we analysed the simulation results and discussed the strengths and weaknesses of these beaconing approaches with regard to their suitability to vehicular networks. Finally, we discussed the open issues and research directions related to VANET adaptive beaconing approaches.     

VANET: A novel service for predicting and disseminating vehicle traffic information

The arrival of cloud computing technology promises innovative solutions to the problems inherent in existing vehicular ad hoc network (VANET) networks. Because of the highly dynamic nature of these networks in crowded conditions, some network performance improvements are needed to anticipate and disseminate reliable traffic information. Although several approaches have been proposed for the dissemination of data in the vehicular clouds, these approaches rely on the dissemination of data from conventional clouds to vehicles, or vice versa. However, anticipating and delivering data, in a proactive way, based on query message or an event driven has not been defined so far by these approaches. Therefore, in this paper, a VANET‐Cloud layer is proposed for traffic management and network performance improvements during congested conditions. For the traffic management, the proposed layer integrates the benefits of the connected sensor network (CSN) to collect traffic data and the cloud infrastructure to provide on‐demand and automatic cloud services. In this work, traffic services use a data exchange mechanism to propagate the predicted data using a fuzzy aggregation technique. In the evaluation phase, simulation results demonstrate the effectiveness of the proposed VANET‐Cloud layer to dramatically improve traffic safety and network performance as compared with recent works.     

Research on adaptive beacon message broadcasting cycle based on vehicle driving stability

Ensuring smooth communication by fixed-cycle message beaconing in vehicular environments is necessary to address vehicles safety. However, fixed-cycle beacon messages cannot accommodate the characteristics of fast vehicle speeds and variable network topologies and can cause problems such as channel congestion when traffic density is too high. Therefore, in order to realize safe and reliable information transmission between vehicles, this paper proposes a strategy for adaptive update of beacon message cycle based on vehicle driving stability. It is based on two rules: one is that the vehicle position prediction error is defined as an unstable vehicle, and the small error is defined as a stable vehicle; and the other is that the adaptive beacon message cycle is ranged, which is determined according to the channel load capacity. The experimental results show that the strategy can effectively avoid the channel congestion problem and improve the driving safety of the vehicle. Compared with the fixed-cycle beacon message, the communication delay is reduced by about 10%, the packet loss is reduced by about 22%, and the energy consumption is reduced.     

Adaptive Congestion Prediction in Vehicular Ad-hoc Networks (VANET) Using Type-2 Fuzzy Model to Establish Reliable Routes

Urban areas are more prone to accidents and traffic congestions due to ever-increasing vehicles and poor traffic management. The increase in the emission of harmful gases is another important issue associated with vehicular traffic. Attaining a level of QOS is often challenging as it has to meet the eco-friendly factors along with reliable and safe transportation. Smart and accurate congestion management systems in VANET can significantly reduce the risk of accidents and health issues. To fulfil the requirements of QOS the congestion control methods should consider the properties such as fairness, decentralization, network characteristics, and application demands in VANET. We proposed an Adaptive Congestion Aware Routing Protocol (ACARP) for VANET using the dynamic artificial intelligence (AI) technique. The ACARP presents the adaptive congestion detection algorithm using the type-2 fuzzy logic AI technique. The fuzzy model detects the congestion around each vehicle using three fuzzy inputs viz. bandwidth occupancy, link quality, and moving speed. This is followed by inference model to estimate congestion probability for each vehicle. Finally, defuzzification determines status of congestion detection using the pre-defined threshold value for each vehicle. The status of congestion and its probability values were utilized to establish safe and reliable routes for data transmission. It also saves significant communication overhead and hence congestions in the network. The simulation results provide the evidence that the proposed protocol improves the QOS and assist in reduction of traffic congestions significantly.

     

DESCV—A Secure Wireless Communication Scheme for Vehicle ad hoc Networking

As an indispensable part of intelligent transportation system (ITS), inter-vehicle communication (IVC) emerges as an important research topic. The inter-vehicle communication works based on vehicular ad hoc networking (VANET), and provides communications among different vehicles. The wide applications of VANET helps to improve driving safety with the help of traffic information updates. To ensure that messages can be delivered effectively, the security in VANET becomes a critical issue. Conventional security systems rely heavily on centralized infrastructure to perform security operations such as key assignment and management, which may not suit well for VANET due to its high mobility and ad hoc links. Some works suggested that vehicles should be connected to fixed devices such as road side units (RSUs), but this requires deployment of a large number of costly RSUs in a specific area. This paper is focused on the issues on decentralized IVC without fixed infrastructure and proposes a method for Dynamic Establishment of Secure Communications in VANET (DESCV), which works in particular well for VANET communication key management when centralistic infrastructure or RSU is not available. We will demonstrate through synergy analysis and simulations that DESCV performs well in providing secure communications among vehicles traveling at a relative velocity as high as 240 km/h.     

Exploration of adaptive beaconing for efficient intervehicle safety communication

In the future intervehicle communication will make driving safer, easier, and more comfortable. As a cornerstone of the system, vehicles need to be aware of other vehicles in the vicinity. This cooperative awareness is achieved by beaconing, the exchange of periodic single-hop broadcast messages that include data on the status of a vehicle. While the concept of beaconing has been developed in the first phase of research on VANETs, recent studies have revealed limitations with respect to network performance. Obviously, the frequency of beacon messages directly translates into accuracy of cooperative awareness and thus traffic safety. There is an indisputable trade-off between required bandwidth and achieved accuracy. In this work we analyze this trade-off from different perspectives considering the consequences for safety applications. As a solution to the problem of overloading the channel, we propose to control the offered load by adjusting the beacon frequency dynamically to the current traffic situation while maintaining appropriate accuracy. To find an optimal adaptation, we elaborate on several options that arise when determining the beacon frequency. As a result, we propose situation-adaptive beaconing. It depends on the vehicle's own movement and the movement of surrounding vehicles, macroscopic aspects like the current vehicle density, or microscopic aspects.     

Localizing non‐line‐of‐sight nodes in Vehicluar Adhoc Networks using gray wolf methodology

Vehicular ad hoc networks (VANETs) evolved by adopting the principles of mobile ad hoc networks. This network has been designed to deploy safety related application in vehicular node in the less chaotic environment in road scenarios. Vehicles exchange emergency messages through direct communication. In a practical situation, a direct communication between the vehicles is not possible, and it is prohibited by either static or dynamic obstacles. These obstacles prevent the direct communication between the vehicles and can craft a situation like non‐line of sight (NLOS). This NLOS becomes a perennial problem to the researchers as it creates localization and integrity issues which are considered to be important for road safety applications. Handling the moving obstacles is found to be a challenging one in the VANET environment as obstacles like truck are found to have similar characteristics of the vehicular nodes. This paper utilizes the merits of the meta‐heuristic approach and makes use of the improved gray wolf optimization algorithm for improving the localization and integrity services of the VANET by overcoming the NLOS conditions. The proposed methodology is found to have improved neighborhood awareness, reduced latency, improved emergency message delivery rate, and reduced mean square error rate.     

Performance Analysis with Traffic Accident for Cooperative Active Safety Driving in VANET/ITS

Recently, by using vehicle-to-vehicle and vehicle-to-infrastructure communications for VANET/ITS, the cooperative active safety driving (ASD) providing vehicular traffic information sharing among vehicles significantly prevents accidents. Clearly, the performance analysis of ASD becomes difficult because of high vehicle mobility, diverse road topologies, and high wireless interference. An inaccurate analysis of packet connectivity probability significantly affects and degrades the VANET/ITS performance. Especially, most of related studies seldom concern the impact factors of vehicular accidents for the performance analyses of VANET/ITS. Thus, this paper proposes a two-phase approach to model a distributed VANET/ITS network with considering accidents happening on roads and to analyze the connectivity probability. Phase 1 proposes a reliable packet routing and then analyzes an analytical model of packet connectivity. Moreover, the analysis is extended to the cases with and without exhibiting transportation accidents. In phase 2, by applying the analysis results of phase 1 to phase 2, an adaptive vehicle routing, namely adaptive vehicle routing (AVR), is proposed for accomplishing dynamic vehicular navigation, in which the cost of a road link is defined in terms of several critical factors: traffic density, vehicle velocity, road class, etc. Finally, the path with the least path cost is selected as the optimal vehicle routing path. Numerical results demonstrate that the analytical packet connectivity probability and packet delay are close to that of simulations. The yielded supreme features justify the analytical model. In evaluations, the proposed approach outperforms the compared approaches in packet connectivity probability, average travel time, average exhausted gasoline. However, the proposed approach may lead to a longer travel distance because it enables the navigated vehicle to avoid traversing via the roads with a higher traffic density.     

AMOEBA: Robust Location Privacy Scheme for VANET

Communication messages in vehicular ad hoc networks (VANET) can be used to locate and track vehicles. While tracking can be beneficial for vehicle navigation, it can also lead to threats on location privacy of vehicle user. In this paper, we address the problem of mitigating unauthorized tracking of vehicles based on their broadcast communications, to enhance the user location privacy in VANET. Compared to other mobile networks, VANET exhibits unique characteristics in terms of vehicular mobility constraints, application requirements such as a safety message broadcast period, and vehicular network connectivity. Based on the observed characteristics, we propose a scheme called AMOEBA, that provides location privacy by utilizing the group navigation of vehicles. By simulating vehicular mobility in freeways and streets, the performance of the proposed scheme is evaluated under VANET application constraints and two passive adversary models. We make use of vehicular groups for anonymous access to location based service applications in VANET, for user privacy protection. The robustness of the user privacy provided is considered under various attacks.     

A Dual Ring Connectivity Model for VANET Under Heterogeneous Traffic Flow

Vehicular ad-hoc network (VANET) is characterized as a highly dynamic wireless network due to the dynamic connectivity of the network nodes. To achieve better connectivity under such dynamic conditions, an optimal transmission strategy is required to direct the information flow between the nodes. Earlier studies on VANET’s overlook the characteristics of heterogeneity in vehicle types, traffic structure, flow for density estimation, and connectivity observation. In this paper, we have proposed a heterogeneous traffic flow based dual ring connectivity model to enhance both the message disseminations and network connectivity. In our proposed model the availability of different types of vehicles on the road, such as, cars, buses, etc., are introduced in an attempt to propose a new communication structure for moving vehicles in VANETl under cooperative transmission in heterogeneous traffic flow. The model is based on the dual-ring structure that forms the primary and secondary rings of vehicular communication. During message disseminations, Slow speed vehicles (buses) on the secondary ring provide a backup path of communication for high speed vehicles (cars) moving on the primary ring. The Slow speed vehicles act as the intermediate nodes in the aforementioned connectivity model that helps improve the network coverage and end-to-end data delivery. For the evaluation and the implementation of dual-ring model a clustering routing scheme warning energy aware cluster-head is adopted that also caters for the energy optimization. The implemented dual-ring message delivery scheme under the cluster-head based routing technique does show improved network coverage and connectivity dynamics even under the multi-hop communication system.     

Position-Based Adaptive Clustering Model (PACM) for Efficient Data Caching in Vehicular Named Data Networks (VNDN)

The seamless data delivery is essential in VANET for application such as autonomous vehicle, intelligent traffic management and for the road safety and emergency applications. The incorporation of named data networking (NDN) with VANET, intended to frame intelligent traffic flow and seamless data delivery. Such integration of vehicular ad hoc networks (VANET) with NDN is termed as vehicular named data networks (VNDN). Because of the continuous node/vehicle mobility, it is a tedious process to build constant and consistent communication between vehicles. With that concern, for enhancing the performance of VNDN and solving the issues such as frequent cluster formation on heavy loaded data transmissions, position-based adaptive clustering model (PACM) is developed. The major intention of PACM is to form clusters based on trajectory. Besides, PACM performs efficient data caching by collecting significant data from vehicles to establish consistent data communication with all nodes in the network. Efficient data caching is done with the elected cluster heads among the framed clusters based on its positions and mobility models. For handling the vehicles at higher mobility speed, mutual data caching process is also designed that makes vehicles to perform on-demand data gathering from cluster heads. Further, the model is simulated and the obtained results are compared with the existing models based on the metrics such as packet delivery ratio, mean delay, cache hit rate and mean hop distance. The comparative analysis shows that the proposed model outperforms the available techniques.

     

Reducing saturation and congestion in VANET networks: Alliance‐based approach and comparisons

A vehicular ad hoc network (VANET) is composed mainly of fixed roadside entities (RSUs) and mobile entities (vehicles). In order to exchange information and data relating to the safety and comfort of road users, these different entities must establish communications between them. In these communications, one of the main problems is related to congestion and saturation of RSUs. In this paper, we first study the main protocols that involve RSUs in their strategy of routing by classifying them according to four levels. Furthermore, to deal with the problem of saturation of RSUs, we present a new approach of cooperation between the RSUs of a VANET in order to reduce its congestion and avoid as much as possible the saturation of these entities. This approach, called “D2A2RS” (defensive alliance–based approach for reducing RSUs saturation), is based on the concept of defensive alliances in graphs that ensures effective collaboration between RSUs. To evaluate the performance of the proposed approach, we conduct a comparative analysis by using both analytical models and simulations. The obtained comparison results have shown the efficiency and the performance of our approach compared with other concurrent approaches in the literature in terms of packet loss/success rate, end‐to‐end transmission delay, and network scalability.     

Minimizing transmission delays in vehicular ad hoc networks by optimized placement of road-side unit

Wireless Networks - In a vehicular ad hoc network (VANET), a road side unit (RSU) is a network traffic transmitter statically placed along the route to facilitate communication between vehicles and...     

Fuzzy Logic Ticket Rate Predictor for Congestion Control in Vehicular Networks

Cooperative vehicular systems are currently being investigated to design innovative intelligent transportation systems (ITS) solutions for road traffic management and safety. This paper proposes a preventive congestion control mechanism applied at highway entrances and devised for ITS systems. Our mechanism integrates different types of vehicles and copes with vehicular traffic fluctuations due to an innovative fuzzy logic ticket rate predictor. The proposed mechanism efficiently detects road traffic congestion and provides valuable information for the vehicular admission control. When we apply an authentic enhanced mobility model, the results demonstrate the mechanism capability to accurately characterize road traffic congestion conditions, shape vehicular traffic and reduce travel time.     

A Novel Mobility Management Scheme for Integration of Vehicular Ad Hoc Networks and Fixed IP Networks

Integration of vehicular ad hoc network and fixed IP network is important to provide Internet connection and mobile data service for vehicles. However, the unique characteristics of vehicular networks, such as linear topology and constrained movements of vehicles, are not considered in the conventional mobility management schemes. Using conventional schemes, unnecessary management messages are generated and the connections to roadside-installed base stations are not fully utilized. As the results, bandwidth is wasted and data delivery ratio is not maximized. In this paper, we propose a novel mobility management scheme to integrate vehicular ad hoc network and fixed IP networks more efficiently. The proposed scheme manages mobility of vehicles based on street layout as well as the distance between vehicles and base stations. Utilizing the unique characteristics of vehicular networks, the proposed scheme has substantially less mobility management overhead and higher data delivery ratio. The proposed scheme is simulated by SUMO (a vehicular traffic simulator) and QualNet (a data network simulator). The simulation results show that the proposed scheme reduced the mobility management overhead up to 63% and improved the data delivery ratio up to 90%.     

Effective crowdsensing and routing algorithms for next generation vehicular networks

The vehicular ad hoc network (VANET) has recently emerged as a promising networking technique attracting both the vehicular manufacturing industry and the academic community. Therefore, the design of next generation VANET management schemes becomes an important issue to satisfy the new demands. However, it is difficult to adapt traditional control approaches, which have already proven reliable in ad-hoc wireless networks, directly. In this study, we focus on the development of vehicular crowdsensing and routing algorithms in VANETs. The proposed scheme, which is based on reinforcement learning and game theory, is designed as novel vertical and horizontal game models, and provides an effective dual-plane control mechanism. In a vertical game, network agent and vehicles work together toward an appropriate crowdsensing process. In a horizontal game, vehicles select their best routing route for the VANET routing. Based on the decentralized, distributed manner, our dual-plane game paradigm captures the dynamics of the VANET system. Simulations and performance analysis verify the efficiency of the proposed scheme, showing that our approach can outperform existing schemes in terms of RSU’s task success ratio, normalized routing throughput, and end-to-end packet delay.

     

SINR and throughput improvement for VANET using fuzzy power control

This paper proposes transmission power control for vehicular ad hoc network (VANET) using fuzzy system. Despite the potential advantages of VANET especially for safety and intelligent transportation system, some challenges are discovered during the implementation of VANET. Main challenges emerge because of the dynamic environment and high mobility of vehicle. Furthermore, the interference due to the shared‐spectrum usage can significantly decrease the quality of signal. Fuzzy system is implemented to control the transmission power based on the signal to interference and noise ratio (SINR) difference with the targeted value of the receiver vehicle and the interference inflicted by the transmitter vehicle. The algorithm of fuzzy power control for VANET is proposed, and the performance is evaluated through the simulations. The results of simulations show that the proposed algorithm can increase SINR of vehicles especially the vehicles with SINR value below the target. Thus, the average of SINR and the throughput of the system can be increased as well.     

Stochastic modeling and performance analysis in balancing load and traffic for vehicular ad hoc networks: A review

The rapid growth of vehicular applications has resulted in high demand for Internet technology, which demands an unprecedented network capacity and a high quality of service (QoS). In vehicular ad hoc networks (VANETs), since nodes (vehicles) are highly mobile. The dynamic nature of the network topology in the VANET system changes due to frequent changes in link connectivity. The vehicles-to-vehicles (V2V), vehicles-to-infrastructure (V2I), and QoS, as well as the heterogeneity of applications within the VANET. VANETs have been introduced to make driving comfortable by providing safety and support to drivers. Due to the flexibility and offloading schemes available in-vehicle applications, there are some limitations. However, there are many issues in providing optimum service provisioning and scheduling in the vehicular environment. In VANETs, BSs and roadside units (RSUs) improve QoS. However, Internet services transmit packets to vehicles using stochastic models, and it predicts the traffic on a VANET. We provide open challenges to drive stochastic models in this direction.     

基于票据的车联网安全和隐私保护方案

随着车联网的发展,车辆通信将在提高行车安全,驾驶效率和舒适度方面发挥重要作用。车辆将访问多种应用,考虑到现有行车安全应用面临的严峻威胁,加之对用户验证、授权和计费的需求,攻击防护安全对于车载自组网来说尤为重要。在车辆使用基于位置的服务或行车安全服务时,攻击者可能会窃听通信内容,获取用户身份信息和位置隐私。为了提高车载自组织网安全,提出了一种采用分布式车辆公钥基础设施(VPKI)对车辆通信安全、位置隐私和身份匿名进行保护的方案。该方案采用票据为应用服务提供匿名访问控制和认证,并且可以解析和撤销不法车辆身份。最后,通过实验分析方案的效率来证明VPKI的可实施性。     

VANET 中一种安全消息拥塞控制机制

针对车辆无线自组织网络在车流量密度大的情况下,周期性安全消息产生的Beacons可能占据整个信道带宽,从而导致信道拥塞的问题,提出了一种基于调整Beacon频率和车辆通信半径的拥塞控制机制。该机制首先为周期性安全消息和突发事件安全消息提出了一个信道分配算法,将周期性安全消息在信道中占用的带宽资源限定在一定的门限以下,保证有足够的信道资源传输突发事件安全消息。然后,在保证车辆用户安全的条件下,根据精确性要求和成功接收率,动态地调整Beacon频率和车辆通信半径,来控制信道中能够容纳的用户数,避免信道拥塞。