Massimiliano Lenardi

A survey and qualitative analysis of mac protocols for vehicular ad hoc networks

In order to avoid transmission collisions in mobile ad hoc networks (MANETs), a reliable and efficient medium access control (MAC) protocol is needed. Vehicular MANETs (VANETs) have vehicles as network nodes and their main characteristics are high mobility and speed. Active safety applications for VANETs need to establish reliable communications with minimal transmission collisions. Only few MAC protocols designed for MANETs can be adapted to efficiently work in VANETs. In this article we provide a short overview on some MANET MAC protocols, and then we summarize and qualitatively compare the ones suited for VANETs

Multi-Hop Vehicular Broadcast (MHVB)

Inter-vehicular communications (IVCs) are now considered as a way to realize active safety, for example, by providing the position information of each other or the potential danger warning by wireless communications. We have worked on a flooding protocol over vehicular ad hoc networks (VANETs) to efficiently disseminate the information for the sake of active safety applications, such as the positions and the velocities of the vehicles. We propose a flooding protocol with (i) congestion detection algorithm which suppresses unnecessary packets due to vehicular congested traffic and (ii) Backfire algorithm which efficiently forwards the packet through the network by selecting the adequate receiver node based on the distance from the original node. In this paper, we show simulation results over NS2 (network simulator 2). They show that the proposed flooding protocol significantly improves the performance of data dissemination over VANETs

Movement Prediction-Based Routing (MOPR) Concept for Position-Based Routing in Vehicular Networks

Nowadays, researchers show more and more interests to vehicular ad hoc networks (VANETs), which are a specific instance of mobile ad hoc networks (MANETs) where nodes are vehicles. In VANETs, vehicles have no energy resource constraint which could extend coverage and network lifetime, but have a high mobility patterns that cause frequent and fast topology changes. Consequently, VANETs have particular research interests, like dedicated MAC and routing optimization. In our previous work, we have proposed movement prediction-based routing (MOPR) concept for VANETs, which improves the routing process by selecting the most stable route in terms of lifetime with respect to the movement of vehicles. And in this paper, we present how this MOPR concept can be applied to position-based routing protocols, and how it improves their performances. Based on simulation results we compare MOPR with the position-based routing protocol GPSR and another movement-based routing protocol called MORA.

Improving Proactive Routing in VANETs with the MOPR Movement Prediction Framework

Wireless vehicular communications are attracting more and more interests for applied research in industries. Most of the efforts are spent in deploying Vehicular Mobile Ad-Hoc Networks (VANETs) for applications such as active safety and Internet services. This paper addresses routing problem in VANETs for applications related to comfort and infotainment for users where an unicast routing protocol optimized for fast topology changes is needed. In previous research work, we have proposed a new movement prediction-based routing concept for VANETs called MOPR which we have already applied to the reactive routing protocol AODV in order to improve its performances by exploiting vehicules movements patterns. In this work, we first propose a new design of this concept, then we apply it to the OLSR routing protocol by optimizing the procedure of selecting the MPR (Multipoint Relay) sets as well as that of determining the optimal path from each pair of vehicles. Basically, the connected MPR graph is composed of the most stable wireless links in the VANETs. We conduct several simulation scenarios to investigate the performance of the modified OLSR (OLSR-MOPR) by studying several metrics including the end-to-end average delay, the routing overhead, the packet delivery ratio, and the routing overhead ratio. The simulation results of the modified OLSR for various VANETs scenarios show great improvements comparing to the basic OLSR.

An adaptive forwarding mechanism for data dissemination in vehicular networks

Efficient dissemination of messages in a Vehicular Ad Hoc Network (VANET) still face many challenges in the current research scenario. This paper addresses the problem of redundant forwarding of messages that occur during broad- cast and proposes an adaptive forwarding mechanism which controls the amount of redundant messages thereby improving message dissemination over a VANET. The mechanism will enable a node to efficiently forward a message and at the same time refrain other potential forwarders of the same message in a chosen area to forward the message. The algorithm exploits the density of nodes on the network for its functionality and will make an adaptive sector under which the redundant nodes will be refrained from sending the same message. The area of the sector for a particular node will be proportional to the density of its neighbors that are within the nodes communication range. The proposal assumes that the nodes in the VANET are aware of their surroundings up to a certain area by periodic exchange of location information from each of the nodes. The mechanism will enable routing algorithms and/or beaconing systems to consume lesser bandwidth and thereby enhance the efficiency of the algorithm itself.

Floating car data system enforcement through vehicle to vehicle communications

The paper presents a new application enabled by vehicle-to-vehicle (V2V) communication systems; our target is to combine V2V with floating car data (FCD) systems and merge advantages of both: the V2V application warnings to enhance the FCD traffic information precision as well as the information availability; inversely, V2V communication can also benefit from the FCD system and offer some large-scale road network traffic information. We present some architecture modifications which are needed to realize this new application, both in terms of in-vehicle components as well as the networking requirements. The proposed approach is to be built upon the existing infrastructure of FCD system to lower the implementation cost

Securing Multihop Vehicular Message Broadcast using Trust Sensors

The ad hoc wireless exchange of position and velocity information between vehicles enables a plethora of new applications that can increase the safety and efficiency of driving. Efficient and reliable flooding mechanisms for vehicular applications mandate correct and timely received positions, vehicular safety applications even more so. This work first assesses the impact of different position faking attackers on the “goodput” of Multi-Hop Vehicular Beacon Broadcast (MHVB-B), a dissemination mechanism for vehicular networks. Then we use a set of known and simple heuristics to improve the detection of fake positions within MHVB-B data and briefly assess their impact on the goodput. At the core of this work, we define a framework for integrating arbitrary trust sensors using Bayesian reasoning and describe a way to determine their contribution to the overall assessment of message trustworthiness, that we model as a conditional probability.

RSVconf: Node Autoconfiguration for MANETs

A mobile ad-hoc network (MANET) is a self-configuring network of mobile nodes connected by wireless links, which can form an arbitrary topology. We have worked on a new protocol, RSVconf, to ensure the IP address self-configuration of MANETs, with a special focus on the ITS (intelligent transportation system) context which is indeed the most mobile scenario. The RSVconf protocol manages the creation, merger and remerger (merger after part of the network temporarily separated) of networks at IP layer. It is stateful, distributed and routing independent. The simulation results show its capability to react fast and correctly to the rapid topology changes of mobile networks without a waste of bandwidth. In this paper we present the current status of our research, open aspects and future directions

A test architecture for V-2-X cooperative systems field operational tests

In recent years, several research projects have discovered the potential of Intelligent Transport Systems (ITS) and have developed corresponding demonstrators for Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communication, which act as proof of concepts. This paper provides the required test infrastructure to go beyond a pure proof of concept by enabling the validation of a complete V2X communication system that covers V2V and V2I communications plus the interconnection of vehicles and backend systems known as Vehicle-to-Business (V2B) communication. We present an integrated test architecture that allows not only the evaluation of vehicular communications on test tracks but moreover paves the way for conducting real life Field Operational Tests (FOT) with thousands of vehicles based on state-of-the-art broadband wireless access technologies. In addition, this paper presents the selection procedure applied for the identification of hardware and software components required for realizing the V2X system based on a predefined set of Use Cases (UCs).

Integrated networking simulation environment for vehicular networks

Vehicular communication is regarded as a key technology in improving road safety. The most promising approach is the creation of Vehicular Ad Hoc Networks (VANETs), autonomous networks managed without any fixed infrastructure. Because of their specific properties and range of applications, VANETs require the development of new wireless communication standards and protocols, and routing in VANETs is still a challenging issue. We present here a realistic networking simulator for VANETs, in which two existing protocols are combined for increased routing efficiency. We first present the state of the art regarding VANETs and the concerned protocols. Then we focus on the implementation of the project, before analyzing the simulation results. We conclude that this combination of protocols is promising enough to bring future research in this direction and perhaps lead to an effective implementation.