Nasreddine Lagraa

Intelligent UAV-assisted routing protocol for urban VANETs

The process of routing in Vehicular Ad hoc Networks (VANET) is a challenging task in city environments. Finding the shortest end-to-end connected path satisfying delay restriction and minimal overhead is confronted with many constraints and difficulties. Such difficulties are due to the high mobility of vehicles, the frequent path failures, and the various obstructions, which may affect the reliability of the data transmission and routing. Commercial Unmanned Aerial Vehicles (UAVs) or what are commonly referred to as drones can come in handy in dealing with these constraints. In this paper, we study how UAVs operating in ad hoc mode can cooperate with VANET on the ground so as to assist in the routing process and improve the reliability of the data delivery by bridging the communication gap whenever it is possible. In a previous work, we have proposed UVAR a UAV-Assisted VANETs routing protocol, which improves data routing and connectivity of the vehicles on the ground through the use of UAVs. However, UVAR does not fully exploit UAVs in the sky for data forwarding because it uses UAVs only when the network is poorly dense. In this paper, we propose an extension of this protocol by supporting two different ways of routing data: (i) delivering data packets exclusively on the ground using UVAR-G; and (ii) transmitting data packets in the sky using a reactive routing based on UVAR-S. Simulation results demonstrate that the hybrid communication between vehicles and UAVs is ideally suited for VANETs compared to traditional vehicle-to-vehicle (V2V) communications.

Trust Management for Vehicular Networks: An Adversary-Oriented Overview

Cooperative Intelligent Transportation Systems, mainly represented by vehicular ad hoc networks (VANETs), are among the key components contributing to the Smart City and Smart World paradigms. Based on the continuous exchange of both periodic and event triggered messages, smart vehicles can enhance road safety, while also providing support for comfort applications. In addition to the different communication protocols, securing such communications and establishing a certain trustiness among vehicles are among the main challenges to address, since the presence of dishonest peers can lead to unwanted situations. To this end, existing security solutions are typically divided into two main categories, cryptography and trust, where trust appeared as a complement to cryptography on some specific adversary models and environments where the latter was not enough to mitigate all possible attacks. In this paper, we provide an adversary-oriented survey of the existing trust models for VANETs. We also show when trust is preferable to cryptography, and the opposite. In addition, we show how trust models are usually evaluated in VANET contexts, and finally, we point out some critical scenarios that existing trust models cannot handle, together with some possible solutions.

UVAR: An intersection UAV-assisted VANET routing protocol

It is a challenging task to develop an efficient routing solution for a reliable data delivery in urban vehicular environments. Indeed, it is difficult to find a shortest end-to-end connected path especially in urban city given the mobility pattern of the vehicles and the various obstructions to a clear transmission such as buildings. To overcome these difficulties, we investigate how unmanned aerial vehicles (UAVs) can assist vehicles on the ground in relaying in urban areas. In this paper, we propose UVAR (UAV-Assisted VANET Routing Protocol), a new routing technique for Vehicular Ad hoc Networks (VANets). This protocol is based on the use of the traffic density and the knowledge of vehicular connectivity in the streets. With this approach UAVs collect information about the traffic density on the ground and the state of vehicles connectivity, and exchange them with vehicles through Hello messages. These information allow UAV to place themselves so as to allow relaying data when connectivity between sole vehicles on the ground is not possible. Through vehicle-to-UAV (V2U) communication, the overall connectivity between vehicles is improved and therefore the routing process is efficiently improved. The performance of the proposed protocol is evaluated and the results to different scenarios are discussed.

Trust model with delayed verification for message relay in VANETs.

Trust management is one of the major issues for secure communication in vehicular network. Most of the existing trust models are identity-based and use excessive periodic exchange between vehicles to build a decision about trustiness of participating vehicles. Malicious data can be minimized in such models using identities reputation. In general, the nature and the quality of the data are not taken into account, despite some models which may revoke messages based on their nature and their type. In this work, we propose a new trust model for VANETs, which based on the early detection of attacks by relying on the opinion of the last forwarder and delayed verification of the exchanged messages. In our scheme, we developed an intrusion detection module which perform such operation and evaluate the trustiness of received messages. We introduce a new concept of companion vehicles which is used to filter out and select the most trusted nodes among neighboring vehicles, to be used as relays in the forwarding procedure. The deployment of this mechanism allow us to prevent vehicles identified as probable dishonest nodes from participating in the network. In this study, we simulation results show the effectiveness of our trust model in detecting dishonest nodes as well as malicious messages that are sent by honest or dishonest nodes, after a very low number of messages exchange. We also show that in the worst case scenario, our trust model offers equally good results.

Token-based Clustered Data Gathering Protocol(TCDGP) in vehicular networks

By adopting different detection technologies, vehicles in Vehicular Ad-hoc Networks (VANets) are able to collect various kinds of information, like road traffic and environmental information, then, to transmit them to interested entities. Data collection in VANets is considered as an interesting application which aims at providing a safer, more efficient and more comfortable driving. In a previous study [8] we have proposed a Robust Clustered Data Gathering Protocol (CDGP), by using a Dynamic Space Division Multiple Access (D-SDMA) technique with a retransmission mechanism. However, CDGP provides a low collection efficiency given the large number of unused slots, which are wasted in a vehicle-to-vehicle communication (V2V). In this paper, we propose a new data collection protocol, which improves the data collection efficiency by using an enhanced Dynamic SDMA technique. Through simulation results we show that our new protocol enhances data collection efficiency and provides a reliable data collection.

An efficient and robust clustered data gathering protocol (CDGP) for vehicular networks

Data collection in Vehicular Ad-hoc Networks (VANets) is considered as an interesting application which aims at delivering road traffic, environmental information and other kinds of data to interested entities. The protocols developed for the wireless mobile networks and particularly for WSN cannot be applied directly to vehicular networks due to the high mobility and the frequent disconnection especially in the highway. Therefore, the design of an efficient protocol is depending firstly on the use of an efficient technique for medium access and secondly on a correct data delivery. In this paper, we propose a data collection protocol based on clustering and on he use of a dynamic medium access technique. This protocol is based on acknowledged delivery and allows retransmission of data in the case of loss or errors. We present simulation results which show the feasibility, the effectiveness and the robustness of our proposed protocol.

TFDD: A trust-based framework for reliable data delivery and DoS defense in VANETs

Abstract A trust establishment scheme for enhancing inter-vehicular communication and preventing DoS attacks ‘TFDD’ is proposed in this paper. Based on a developed intrusion detection module (IDM) and data centric verification, our framework allows preventing DDoS attacks and eliminating misbehaving nodes in a distributed, collaborative and instantaneous manner. In addition, a trusted routing protocol is proposed that, using context-based information such as link stability and trust information, delivers data through the most reliable way. In this study, the simulation results obtained demonstrate the effectiveness of our trust framework at detecting dishonest nodes, as well as malicious messages that are sent by honest or dishonest nodes, after a very low number of message exchanges. Furthermore, colluding attacks are detected in a small period of time, which results in network resources being released immediately after an overload period. We also show that, in a worst-case scenario, our trust-based framework is able to sustain performance levels, and outperforming existing solutions such as T-CLAIDS and AECFV.

IRTIV: Intelligent Routing Protocol Using Real Time Traffic Information in Urban Vehicular Environment

Routing in vehicular Ad hoc networks is a challenging task due to the high mobility of nodes and the network fragmentations. The challenge is most important in urban environment where many constraints are added like multipath and the presence of obstacles. In this way, many protocols are proposed. In this paper, we introduce a new position-based routing scheme called IRTIV, conceived exclusively for inter-vehicle communication in a city environment, the proposed protocol aims to find the shortest connected path to the destination by taking into account the real time traffic variation which is estimated by a completely distributed manner based on the periodic exchange of Hello messages. Simulation results show that the proposed protocol increases the packet delivery ratio and reduces the end to end delay.

RITA: RIsk-aware Trust-based Architecture for collaborative multi-hop vehicular communications

Trust establishment over vehicular networks can enhance the security against probable insider attackers. Regrettably, existing solutions assume that the attackers have always a dishonest behavior that remains stable over time. This assumption may be misleading, as the attacker can behave intelligently to avoid being detected. In this paper, we propose a novel solution that combines trust establishment and a risk estimation concerning behavior changes. Our proposal, called risk-aware trust-based architecture, evaluates the trust among vehicles for independent time periods, while the risk estimation computes the behavior variation between smaller, consecutive time periods in order to prevent risks like an intelligent attacker attempting to bypass the security measures deployed. In addition, our proposal works over a collaborative multi-hop broadcast communication technique for both vehicle-to-vehicle and vehicle-to-roadside unit messages in order to ensure an efficient dissemination of both safety and infotainment messages. Simulation results evidence the high efficiency of risk-aware trust-based architecture at enhancing the detection ratios by more than 7% compared with existing solutions, such as T-CLAIDS and AECFV, even in the presence of high ratios of attackers, while offering short end-to-end delays and low packet loss ratios. Copyright

ETAR: Efficient Traffic Light Aware Routing Protocol for Vehicular Networks

Routing in Vehicular Ad hoc Networks (VANETs) is an important factor to ensure a reliable and efficient delivery of data packets. In urban environments, routing protocols must efficiently handle the constantly changing network topology and frequent disconnections due to the high mobility and direction changes of vehicles. The challenge is greater when there are traffic lights fixed along intersections which affect directly the mobility and therefore can greatly impact routing in urban areas. In our previous work [1] we have proposed IRTIV (Intelligent Routing protocol using real time Traffic Information in urban Vehicular environment) that takes into account the real time traffic variation without any use of pre-installed infrastructures or additional messages. However, IRTIV does not take into consideration the traffic lights impact. In this paper, we propose ETAR (Efficient Traffic Light Aware Routing Protocol for Vehicular Networks). This protocols objective is to find the most stable path for delivering data packets based on traffic lights and traffic density of vehicles using the periodical exchange of Hello messages. We present simulation-based performance results, which show that the proposed protocol increases the packet delivery ratio and reduces the end-to-end delay.