Performance evaluation of a TDMA-based multi-hop communication scheme for reliable delivery of warning messages in vehicular networks

International audienceVehicular Ad hoc NETworks, known as VANETs, are deployed to reduce the risk of road accidents as well as to improve passenger comfort by allowing vehicles to exchange different kinds of data, both between the vehicles themselves and potentially between the vehicles and the infrastructure. One of the major issues in VANETs is the need to improve safety information delivery over long distances. Hence, VANETs require efficient and stable routing protocols that can allow the safety information to be disseminated in a timely manner. We recently proposed TRPM, a TDMA-aware routing protocol for multi-hop communication based on a cross layer approach between the Medium Access Control (MAC) and the routing layers, in which the intermediate vehicles are selected according to their geographic position and the position of their time-slot in the TDMA scheduling frame. The main purpose of this paper is to analyze the efficiency of the TRPM protocol. To do so an analytical model is presented in which expressions are derived to calculate two performance metrics: the delivery delay and packet loss rate. In order to validate the mathematical model and the protocol, a comparison between simulation and analytical results is presented using the network simulator ns-2 and the realistic road traffic simulator MOVE/SUMO

TDMA scheduling strategies for vehicular ad hoc networks: from a distributed to a centralized approach

International audienceVehicular Ad hoc NETworks, known as VANETs, are deployed to reduce the risk of road accidents as well as to improve passenger comfort and safety by allowing vehicles to exchange different kinds of data. Medium Access Control protocols, namely those that are based on TDMA technique play a primary role in providing bounded transmission delay while minimizing data packet loss. However, due to mobility constraints and frequent changes in topology, slot scheduling is a more challenging task in VANETs than in other networks. Many MAC protocols based on TDMA for vehicular networks have been proposed to date. Among them, CTMAC is a centralized scheduling mechanism, while DTMAC, VeMAC and AD-HOCMAC are three distributed TDMA based MAC protocols. In this paper, we evaluate and analyze the performance these four protocols. The scenarios used in the simulation experiments take into account density variation factor that influences protocol performance. We use the MOVE and SUMO tools to generate realistic mobility scenarios. Performance metrics such as access collision, merging collision rate, packet loss and overhead are evaluated using NS-2.34

Performance Impact Analysis of Security Attacks on Cross-Layer Routing Protocols in Vehicular Ad hoc Networks

International audienceRecently, several cross-layer protocols have been designed for vehicular networks to optimize data dissemination by ensuring internal communications between routing and MAC layers. In this context, a cross-layer protocol, called TDMA-aware Routing Protocol for Multi-hop communications (TRPM), was proposed in order to efficiently select a relay node based on time slot scheduling information obtained from the MAC layer. However, due to the constant evolution of cyber-attacks on the routing and MAC layers, data dissemination in vehicular networks is vulnerable to several types of attack. In this paper, we identify the different attack models that can disrupt the cross-layer operation of the TRPM protocol and assess their impact on performance through simulation. Several new vulnerabilities related to the MAC slot scheduling process are identified. Exploiting of these vulnerabilities would lead to severe channel capacity wastage where up to half of the free slots could not be reserved

A game theory‐based route planning approach for automated vehicle collection

International audienceWe consider a shared transportation system in an urban environment where human drivers collect vehicles that are no longer being used. Each driver, also called a platoon leader, is in charge of driving collected vehicles as a platoon to bring them back to some given location (e.g. an airport, a railway station). Platoon allocation and route planning for picking up and returning automated vehicles is one of the major issues of shared transportation systems that need to be addressed. In this paper, we propose a coalition game approach to compute 1) the allocation of unused vehicles to a minimal number of platoons, 2) the optimized tour of each platoon and 3) the minimum energy consumed to collect all these vehicles. In this coalition game, the players are the parked vehicles, and the coalitions are the platoons that are formed. This game, where each player joins the coalition that maximizes its payoff, converges to a stable solution. The quality of the solution obtained is evaluated with regard to three optimization criteria and its complexity is measured by the computation time required. Simulation experiments are carried out in various configurations. They show that this approach is very efficient to solve the multi-objective optimization problem considered, since it provides the optimal number of platoons in less than a second for 300 vehicles to be collected, and considerably outperforms other well-known optimization approaches like MOPSO (Multi-Objective Particle Swarm Optimization) and NSGA-II (Non dominated Sorting Genetic Algorithm)

A Novel Angle-based Clustering Algorithm for Vehicular Ad Hoc Networks

International audienceA 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

Coexistence of IEEE 802.11p and the TDMA-based AS-DTMAC Protocol

International audienceAdvanced vehicular applications such as autonomous driving are leading to a new evolution in vehicular radio access technologies. The Task Group BD on the Next-Generation V2X (NGV) have defined IEEE 802.11bd as the new standard for the Dedicated Short Range Communications (DSRC). Notwithstanding its the promising performances in terms of high reliability, low latency and high throughput, the design must also respect certain specifications, such as coexistence, interoperability, and compatibility with the previous standard. In this article, we study how the IEEE 802.11p protocol could coexist with a TDMA-based protocol named AS-DTMAC, which has recently been proposed to control access in Vehicular Ad Hoc Networks (VANETs). We carry out several analyses to show that the two protocols can coexist by several analysis when both are operating simultaneously on the same network. We also propose a modification of AS-DTMAC to handle the situation where both IEEE 802.11p and AS-DTMAC have to send urgent packets

Optimized trajectories of multi-robot deploying wireless sensor nodes

International audienceA main reason to the growth of wireless sensor networks deployed worldwide is their easy and fast deployment. In this paper we consider deployments assisted by mobile robots where static sensor nodes are deployed by mobile robots in a given area. Each robot must make a tour to place its sensor nodes. All sensor nodes must be placed at their precomputed positions. The Multi-Robot Deploying wireless Sensor nodes problem, called the MRDS problem, consists in minimizing the longest tour duration (i.e. the total deployment duration), the number of robots used and the standard deviation between duration of robots tours. After a formal definition of the MRDS problem, we show how to use a multi-objective version of genetic algorithms, more precisely the NSGA-II algorithm, to solve this multi-objective optimization problem. The solutions belonging to the best Pareto front are given to the designer in charge of selecting the best trade-off taking into account various criteria. We then show how to extend this method to take obstacles into account, which is more representative of real situations

A secure trust-aware cross-layer routing protocol for Vehicular Ad hoc Networks

International audienceVANETs currently represent one of the most prominent solutions that aim to reduce the number of road accident victims and congestion problems while improving the quality of driving. VANETs form a very dynamic open network in which vehicles exchange information and warnings about road situations and other traffic information through several routing protocols, without any intermediate control. However, the absence of a central control makes such a network vulnerable to several types of attack, not only from the outside but also, and mostly, from the interior. This makes their detection by classical security techniques more difficult and requires the development of new techniques to control the information circulating in the network. In this context, a proposed routing protocol called TDMA-aware Routing Protocol for Multi hop communication in Vehicular networks, is vulnerable to security threats, such as Black Hole and Gray Hole attacks, as well as MAC attacks such as Denial of Service (DoS), which lead to a considerable deterioration in the network's performance in terms of packet delivery ratio, end-to-end delays, channel access rate, etc. To mitigate the effect of those attacks, we propose a trust-based model in which each node will establish a trust relationship with its neighbors based on their behaviors during the channel access and packet forwarding process. The simulation results show a significant decrease in the effect of attacks on the performance of the TRPM protocol

An Analytical Model for Performance Analysis of an Active Signaling-based TDMA MAC Protocol for Vehicular Networks

International audienceIn Vehicular Ad hoc NETworks (VANETs) the vehicles moving along roads communicate with each other through ad hoc wireless devices. VANETs have attracted a great deal of attention in the research community in recent years, with the main focus being on their support of safety applications. Time Division Multiple Access (TDMA)-based protocols are advantageous in many aspects of VANETs. They can cope with the hidden-terminal problem, and guarantee a strict Quality-of-Service (QoS) to satisfy real-time applications. However, the initial assignment of time-slots to the vehicles can suffer from the access collision problem, which can frequently occur between vehicles trying to access the same time slots. Moreover, a low latency access is not usually possible. That is why we have developed an Active Signaling system (AS-DTMAC : Active Signaling Decentralized Tdma MAC protocol) which operates above the existing DTMAC protocol : a Medium Access Control (MAC) protocol specially devoted to VANETs. AS-DTMAC can drastically reduce the number of access collisions and also offer low latency access. The aim of this article is to provide a complete mathematical analysis of the performance of this scheme, to show its high performances and to validate these results using simulations

Platoon Route Optimization for Picking up Automated Vehicles in an Urban Network

International audienceIn this paper, we consider the problem of vehicle collection assisted by a fleet manager where parked vehicles are collected and guided by fleet managers. Each platoon follows a calculated and optimized route to collect and guide the parked vehicles to their final destinations. The Platoon Route Optimization for Picking up Automated Vehicles problem, called PROPAV, consists in minimizing the collection duration, the number of platoons and the total energy required by the platoon leaders. We propose a formal definition of PROPAV as an integer linear programming problem, and then we show how to use the Non-dominated Sorting Genetic Algorithm II (NSGA-II), to deal with this multi-criteria optimization problem. Results in various configurations are presented to demonstrate the capabilities of NSGA-II to provide well-distributed Pareto-front solutions