Efficient Broadcasting in VANETs Using Dynamic Backbone and Network Coding

Vehicular Ad Hoc Networks (VANETs) have emerged as an exciting research and application area. The envisioned applications, as well as some inherent VANET characteristics such as highly dynamic topology, frequently disconnected network, and different and dynamic network density, make data dissemination a challenging task in these networks. Several approaches for data dissemination in VANETs have been recently proposed in the literature. However, more work needs to be done since most of the proposed solutions do not effectively address some or all of the main challenges in these scenarios such as the broadcast storm, network partition and temporal network fragmentation. In this paper, we provide a comprehensive and critical review of proposed techniques for data dissemination in VANETs and identify the main challenges in this area. For this, we first define suitable criteria to classify and organize some of the existing solutions. Next we identify and discuss some open issues and conclude with possible future research directions.

VANETs (vehicular ad hoc networks) are emerging as a new network environment for intelligent transportation systems. Many of the applications built for VANETs will depend on the data push communication model, where information is disseminated to a group of vehicles. In this paper, we present a formal model of data dissemination in VANETs and study how VANET characteristics, specifically the bidirectional mobility on well defined paths, affects the performance of data dissemination. We study the data push model in the context of TrafficView, a system we have implemented to disseminate information about the vehicles on the road. Traffic data could be disseminated using vehicles moving on the same direction, vehicles moving in the opposite direction, or vehicles moving in both directions. Our analysis as well as simulation results show that dissemination using only vehicles in the opposite direction increases the data dissemination performance significantly

With the growth of large urban centers, some problems arise and solutions must be sought to contain them. In this context, traffic congestion is one such problem, where road infrastructure does not follow the high growth in the number of vehicles. Traffic Management Systems (TMS) arise to mitigate traffic-related problems, with automatic detection of slow roadways and vehicle rerouting to avoid such routes. Such applications are supported by the Vehicular Ad hoc NETworks (VANETs), where traffic information are disseminated between the vehicles or central server, and thus the better decisions about traffic management can be made. However, the data dissemination in VANETs is a challenging task, due to the short-range communication and high node mobility. Thus, this paper introduces a protocol for Data Dissemination based on Metrics of Complex Networks, called CRONOS. It provides data dissemination of traffic data with low overhead and high coverage. Simulation results show that CRONOS reduced the number of transmissions by 95%, the congestion time by 48.95%, and travel time by 18.11% for a TMS application.

SFTD: A SMART forwarding technique based reliable data dissemination scheme for VANETs

Data dissemination is a challenging problem in vehicular ad hoc networks (VANETs) due to the characteristics of VANETs such as highly dynamic topology, intermittent connectivity, and the road-constrained mobility. Observed from the fact that on-street parking is a common phenomenon in the city, the parked vehicles at roadside can also contribute their resources to the communications in network. In this paper, an efficient data dissemination protocol (EDP) for VANETS is proposed. Different from the existing works which consider mainly mobile vehicles or some expensive roadside infrastructure, EDP leverages the resources of parked vehicles at roadside to help in forwarding data. EDP groups the parked vehicles at roadside into a cluster, which buffers and relays data from mobile vehicles and manages the duplicates of data. Simulation results based on a real city map show that EDP achieves a higher delivery ratio and lower delivery delay.

In vehicular ad hoc networks (VANETs), designing an efficient routing protocol is particularly challenging due to the vehicle movement and lossy wireless channel. A packet can be lost at a forwarder node even when a proper node is selected as the forwarder. In this paper, we propose a loss-tolerant scheme for unicast routing protocols in VANETs. The proposed scheme uses multiple forwarder nodes to improve the packet reception ratio at the forwarders. The scheme uses network coding to reduce the number of required transmissions, resulting in a significant improvement of end-to-end packet delivery ratio without increasing the message overhead. We show the effectiveness of the proposed scheme by using both theoretical analysis and computer simulations.

The vehicular adhoc networks (VANETs) is an integral part of the intelligent transportation system required for delivering safety and non-safety messages to vehicles in real-time via vehicle to vehicle and vehicle to everything communication modes. The purpose of VANETs is to provide efficient routing, message security, congestion-free traffic, and other services related to entertainment and comfortable journey. All these VANETs services, at the core, are related to efficient and secure data dissemination. In this paper, we have focused on clustering in VANETs for efficient data dissemination and resource sharing tasks. Considering the importance of fog computing for fast computing and processing, we have focused on clustering techniques in Fog-based VANET as well that can enhance the range of transmission and expand the number of available resources. This survey paper discusses the existing clustering techniques in VANETs scenario, cluster head selection parameters, the context-based techniques, and cluster performance parameters in VANETs.

Vehicular Ad-Hoc Networks (VANETs) are a fast growing technology that many governments and automobile manufacturers are investing in to provide not only safer and more secure roads, but also informational and entertainment-based applications for drivers. The applications developed for VANETs can be classified into multiple categories (safety, informational, entertainment). Most VANET applications, regardless of their category, depend on having certain vehicular data (vehicular speed, X position and Y position) available. Although these applications appear to use the same vehicular data, the characteristics of this data (i.e., amount, accuracy, and update rate) will vary based on the application category. For example, safety applications need an accurate version of the vehicular data with high frequency, but over short distances. Informational applications relax the data frequency constraint as they need the vehicular data to be reasonably accurate with less frequency, but over longer distances. If each of these applications shares the vehicular data with only its peers using its own mechanism, this behavior will not only introduce redundant functionalities (sending, receiving, processing, etc.) for handling the same data, but also wastefully consume the bandwidth by broadcasting the same data multiple times. Despite the differences in the data characteristics needed by each application, this data can be still shared. Vehicular networks introduce the potential for many co-existing applications. If we do not address the problem of data redundancy early, it may hinder the deployment and usefulness of many of these applications. Therefore, we developed a framework, cluster-based accurate syntactic compression of aggregated data in VANETs (CASCADE), for efficiently aggregating and disseminating commonly-used vehicular data. CASCADE is architccted as a layer that provides applications with a customized version of the vehicular data, based on parameters that each application registers with CASCADE. Additionally, the framework performs the common data handling functionalities (sending, receiving, aggregating, etc.) needed by the applications. This dissertation makes the following contributions: (1) a lossless data compression technique based on differential coding that is tailored for the characteristics of vehicular data; (2) a syntactic data aggregation mechanism that can represent the vehicular data in a 1.5 km area in one IEEE 802.11 frame; (3) a light-weight position verification technique that quickly detects false data with very low false positives; (4) a probabilistic data dissemination technique that alleviates the spatial broadcast storm problem and effectively uses the bandwidth to disseminate data to distant areas in a short amount of time in addition to having less redundancy and more coverage than other techniques. (5) a mechanism for recovering from the communication discontinuity problem in short time based on the traffic density in the opposite direction; (6) an investigation of the possible data structures for representing the vehicular data in a searchable format; (7) a parametric mechanism for matching the vehicular data and providing a customized version of the data that satisfies certain characteristics based on the parameter value. CASCADE through its four major components, local view, extended view, data security and data dissemination, provides an efficient solution for the problem of scalability for VANET applications.

Road safety applications envisaged for vehicular ad hoc networks (VANETs) depend largely on the exchange of messages to deliver information to concerned vehicles. Safety applications as well as inherent VANET characteristics make data dissemination an essential service and a challenging task. We are developing a decentralized efficient solution for broadcast data dissemination through two game-theoretical mechanisms. Besides, VANETs can also include autonomous vehicles (AVs). AVs might represent a revolutionary new paradigm that can be a reality in our cities in the next few years. AVs do not need a driver to work; instead, they should copy a proper human behavior to adapt the driving according to the current circumstances, such as speed limit, pedestrian crossing street or wheather conditions. We will develop an AV software module including artificial intelligence (AI) techniques so that AVs can interact with the dynamic scenario throughout time. Finally, we also will include electrical vehicles (EV) in the VANET, so that special services such as finding and reserving an EV charging station place will be welcome. In addition, we are developing a multimetric geographic routing protocol for VANETs to transmit H.265 video (traffic accident, traffic state, commercial….) over VANETs.

Vehicular Ad hoc Networks (VANETs) have become a cornerstone component of Intelligent Transportation Systems (ITS). VANET applications present a huge potential for improving road safety and travel comfort, hence the growing interest of both academia and industry. The main advantage of VANETs is its ad hoc nature which does not require fixed infrastructure or centralized administration. However, designing scalable information dissemination techniques for VANET applications remains a challenging task due to the inherent nature of such highly dynamic environments. Existing dissemination techniques often resort to simulation for performance evaluation and there are only few studies that offer mathematical modeling. In this paper we provide a comparative study of existing performance modeling approaches for data dissemination techniques designed for different VANET applications.

A Vehicular Ad Hoc Network (VANET) is a subclass of Mobile Ad Hoc Networks, which provides wireless communication among vehicles as well as between vehicles and roadside units. Providing safety, traffic efficiency and user comfort for drivers and passengers are promising goals of these networks. To reach these goals many envisaged applications for VANETs will rely on data dissemination, turning this task into an essential service. However, due to some inherent characteristics of VANETs, such as intermittent connectivity, highly dynamic topology, and diverse network densities, data dissemination is a challenging activity in this kind of network. Although data dissemination has been extensively studied in the literature, existing solutions do not effectively address the broadcast storm and network partition problems when considered together. To deal with both problems, we propose a network partition-aware geographical data dissemination protocol, which eliminates the broadcast storm and maximizes the data dissemination capability across network partitions with short delays and low overhead. The proposed algorithm is able to autonomically adjust message transmissions in the network. Simulation results show that our proposed approach provides good efficiency with respect to the coverage of event processing, delay and overhead.

The accuracy and the reactivity of link quality estimators are key concepts in Mobile Ad hoc networks (MANETs) and especially in Vehicular Ad hoc Networks (VANETs), since routing process uses link quality related metrics based on neighbour information for making routing decisions. The Expected Transmission Count (ETX) is the most salient metric that assesses the link quality for wireless ad hoc and mesh networks. Its estimation varies according to the link changes like disruption and bidirectional to unidirectional switching. Such changes occur more often in highly mobile networks like VANETs. In order to be efficient routing protocols have to deal with these events. It has been observed that current implementation of ETX leads to a limited accuracy and cannot be efficient in VANETs. In this paper is presented an algorithm which makes the ETX metric more adapted for VANETs. Our contribution significantly improves the reactivity and the accuracy of the metric. In addition, our metric is not limited to the link quality estimation but also brings a link stability information. This results a new metric called Fast-ETX (F-ETX). This metric has been tested under realistic physical layer and mobility patterns to evaluate its reactivity, accuracy and stability properties.

For improving the traffic safety in intelligent transportation systems, vehicles that are formed by Vehicular Ad-hoc Networks (VANETs) conventionally disseminate warning messages to their nearby vehicles as soon as a dangerous situation occurs. However, the major challenge in VANETs is to develop an efficient data dissemination protocol for tackling the broadcast storm and network partition problems. In this paper, we propose an Adaptive Beacon-based Data Dissemination (ABDDis) scheme to deal with these problems using only local one-hop neighbor information. The ABDDis scheme features a novel mechanism to adaptively adjust the beacon interval to reduce the channel load while maintaining the correct information about nearby vehicles. Additionally, a novel store-carry-forward (SCF) mechanism is proposed to overcome the network partition problem. The performance of the ABDDis scheme is evaluated in the Veins simulation framework that provides a bidirectional coupling between the network simulator OMNeT++ and the traffic simulator SUMO. The simulation result shows that the ABDDis scheme significantly mitigates the broadcast storm compared to other schemes and maintains a good coverage across various traffic densities. Moreover, the ABDDis scheme shows its robustness by being able to tolerate reasonable GPS drift.

OF DISSERTATION Secure and Authenticated Message Dissemination in Vehicular ad hoc Networks and an Incentive-based Architecture for Vehicular Cloud Vehicular ad hoc Networks (VANETs) allow vehicles to form a self-organized network. VANETs are likely to be widely deployed in the future, given the interest shown by industry in self-driving cars and satisfying their customers various interests. Problems related to Mobile ad hoc Networks (MANETs) such as routing, security, etc. have been extensively studied. Even though VANETs are special type of MANETs, solutions proposed for MANETs cannot be directly applied to VANETs because all problems related to MANETs have been studied for small networks. Moreover, in MANETs, nodes can move randomly. On the other hand, movement of nodes in VANETs are constrained to roads and the number of nodes in VANETs is large and covers typically large area. The following are the contributions of the thesis. Secure, authenticated, privacy preserving message dissemination in VANETs: When vehicles in VANET observe phenomena such as accidents, icy road condition, etc., they need to disseminate this information to vehicles in appropriate areas so the drivers of those vehicles can take appropriate action. When such messages are disseminated, the authenticity of the vehicles disseminating such messages should be verified while at the same time the anonymity of the vehicles should be preserved. Moreover, to punish the vehicles spreading malicious messages, authorities should be able to trace such messages to their senders when necessary. For this, we present an efficient protocol for the dissemination of authenticated messages. Incentive-based architecture for vehicular cloud: Due to the advantages such as flexibility and availability, interest in cloud computing has gained lot of attention in recent years. Allowing vehicles in VANETs to store the collected information in the cloud would facilitate other vehicles to retrieve this information when they need. In this thesis, we present a secure incentive-based architecture for vehicular cloud. Our architecture allows vehicles to collect and store information in the cloud; it also provides a mechanism for rewarding vehicles that contributing to the cloud. Privacy preserving message dissemination in VANETs: Sometimes, it is sufficient to ensure the anonymity of the vehicles disseminating messages in VANETs. We present a privacy preserving message dissemination protocol for VANETs.

In vehicular Ad Hoc Networks (VANETs), smart data dissemination is crucial for efficient exchange of traffic and road information. Given the dynamic nature of VANET, the challenge is to design an adaptive multi-hop broadcast scheme that achieves high reachability while efficiently utilizing the bandwidth by reducing the number of redundant transmissions. In this paper, we propose a novel intelligent fuzzy logic based density and distribution adaptive broadcast protocol for VANETs. The proposed protocol estimates the spatial distribution of vehicles in the network employing the Nearest Neighbor Distance method, and uses it to adapt the transmission range to enhance reachability. To reduce packet collisions, the protocol intelligently adapts the contention window size to the network density and spatial distribution. Bloom filter technique is used to reduce the overhead resulting from the inclusion of the neighbor IDs in the header of the broadcast message, which is needed in identifying the set of potential rebroadcasting vehicles. Our simulation results confirmed the effectiveness of the proposed scheme in enhancing reachability while efficiently utilizing bandwidth.