Vehicular Ad-Hoc Networks for Smart Cities

Various ongoing research efforts in Vehicular Ad hoc Network (VANET) related to safety and non-safety applications have been published in academia and industry. One of the main areas in VANET that is still lacking of significant research contributions is toward designing reliable Medium Access Control (MAC) protocols. Existing surveys on MAC protocols in VANET mostly discuss general MAC methods, that include contention-based and contention-free MAC protocols. A hybrid MAC protocol that adopts both contention-based and contention-free MAC, proposed to enhance the network performance in VANET, is fruitful to be explored further. Hence, a survey of hybrid MAC protocols for VANET is presented in this paper. The benefits and limitations of the existing hybrid MAC protocols are discussed based on their classification to provide some insights into the recent advancement of high-performance MAC protocols for vehicular networks. Finally, some open research issues are highlighted as part of future research directions that need further investigations.

Receiver-based data forwarding schemes are well suited for vehicular environment due to their ability of making routing decision on the fly. However, existing receiver-based schemes still face the challenges of unwanted multiple paths formation especially when contending nodes are out of transmission range of each other. In this paper, we propose an approach of the receiver-based forwarding scheme where receiving nodes decide whether to participate in contention for forwarding right based on signal-to-interference-plus-noise ratio (SINR) and forwarding zone. Upon qualifying to contend for forwarding right, the contending nodes set their waiting time based on geographical progress toward destination. We present the proposed scheme and then highlight some possible issues that require further investigation. The proposed scheme tends to minimize unnecessary formation of multiple paths toward the destination while also favors the selection of a forwarding node closer to destination.

A vehicular ad hoc network (VANET) is a mobile network in which vehicles acting as moving nodes communicate with each other through an ad hoc wireless network. VANETs have become the core component of Intelligent Transportation Systems (ITS) which aim to improve the road safety and efficiency. Only if the communication scheme used in a VANET is stable can these aims be achieved. Frequent changes in network topology and breaks in communication raise challenging issues in the design of communication protocols for such networks. Currently, clustering algorithms are being used as the control schemes to reduce changes in VANET topologies. However, the design of a clustering algorithm becomes a difficult task in VANETs when there are many road segments and intersections. In this work, we propose an Angle-based Clustering Algorithm (ACA), which exploits the angular position and the direction of the vehicles to select the most stable vehicles that can act as cluster heads for a long period of time. The simulation results reveal that ACA significantly outperforms other clustering protocols in terms of cluster stability.

An ad hoc network consisting of vehicles has emerged as an interesting but challenging domain where a lot of new application may find their place. Though research in this field is on since last two decades, large-scale practical implementation still require some time. In this paper, a survey of current challenges and potential applications, incorporating medium access control schemes, routing approaches, hardware and spectrum issues, and security and privacy issues for VANETs, is presented.

The Intelligent Transportation System (ITS) addresses issues regarding traffic management and road safety in the domain of Vehicular Ad hoc Networks (VANETs). With the evaluation of new applications, new goals regarding efficiency and security are added for logistics and general user application, which demand time bounded and reliable services. In this paper, we discuss VANET with regards to its suitability in logistics scenarios, challenges to cope with high mobile vehicles and their short contact duration to meet the goal of efficiency. Although VANET helps to provide efficient solutions for logistics and transportation, there are still number of issues to be solved to obtain an appropriate solution. In the context of increasing number of vehicles, high bandwidth requirements for applications, and highly dynamic topology, route optimization and efficient security mechanisms requires special attention. To this regards, a number of routing protocols have been proposed, yet each routing protocol focuses on traditional topological based routing protocols. The selection of the routing methods depends upon the nature of the networks. Number of researchers argued that the most of the routing protocols focus on the particular scenario and consider particular factors for evaluation such as type of network, mobility pattern, and Quality of Service (QoS) requirements for applications. Thus, the performance of the routing protocols depends upon the particular scenario. In this paper, we focus on designing a routing protocol framework, which can provide a reliable and efficient solution for the path selection by considering different factors from application scenarios like logistics and transportation using varying parameters such as speed, number of wireless nodes, traffic loads and bit error rate. Furthermore, we consider channel parameters for the routing protocols to render the communication to be reliable. For proof of concept, we provide and discuss basic simulation results of our proposed framework.

In this paper, we consider a Trust Model with Group Leader (GL)-based communication in VANET. This model is used to classify vehicles based on their trustworthiness and elect potential GLs. We propose a security risk assessment methodology and we apply it to our Trust Model. This methodology is used for identifying threats, assessing the risk involved, and defining approaches to mitigate them. The risk assessment includes assessment of the impact and likelihood of occurrence of attacks relevant to the identified threats, evaluation of the Trust Model design principles, validation of the built-in security, and the mitigation actions of attacks. Based on this assessment, we demonstrated the resiliency of the Trust Model to resist to many security attacks.

Vehicular networks are the building blocks of the intelligent transportation systems (ITS). Several applications are built to provide more safety and efficiency to users of the roads. Particularly, safety applications are the most critical and vital. This kind of application is very challenging as it is highly demanding in terms of reliability and latency. On the other hand, safety-related data should be delivered intact and in a secure manner. Vehicular technologies should therefore provide these requirements for an effective operation of these applications. In this paper, we propose an efficient receiver-based routing protocol that considers on the one hand the dynamicity and the characteristics of the vehicular environment and on the other hand the trustworthiness of the potential relays of safety data in order to secure the dissemination process. Simulations results showed that our trust-BZB reduces the delay of delivery of the information in a non-secure environment.