U2RV: UAV-assisted reactive routing protocol for VANETs

When it comes to keeping the data routing robust and effective in Vehicular Ad hoc Networks (VANETs), stable and durable connectivity constitutes the keystone to ensure successful point-to-point communication. Since VANETs can comprise all kinds of mobile vehicles moving and changing direction frequently, this may result in frequent link failures and network partitions. Moreover, when VANETs are deployed in a city environment, another problem arises, that is, the existing obstructions (e.g., buildings, trees, hoppers, etc.) preventing the line-of-sight between vehicles, thus degrading wireless transmissions. Therefore, it is more complicated to design a routing technique that adapts to frequent changes in the topology. In order to settle all these problems, in this work, we design a flooding scheme that automatically reacts at each topology variation while overcoming the present obstacles while exchanging data in ad hoc mode with drones that are commonly called Unmanned Aerial Vehicles (UAVs). Also, the aim of this work is to explore well-regulated routing paths providing a long lifetime connectivity based on the amount of traffic and the expiration time of each discovered path, respectively. A set of experiments is carried out using simulation, and the outcomes are confronted with similar protocols based on a couple of metrics. The results clearly show that the assistance of UAVs to vehicles is capable to provide high delivery ratios and low delivery delays while efficiently extending the network connectivity

BRT: Bus-based Routing Technique in Urban Vehicular Networks

International audienceRouting data in Vehicular Ad hoc Networks is still a challenging topic. The unpredictable mobility of nodes renders routing of data packets over optimal paths not always possible. Therefore, there is a need to enhance the routing service. Bus Rapid Transit systems, consisting of buses characterized by a regular mobility pattern, can be a good candidate for building a backbone to tackle the problem of uncontrolled mobility of nodes and to select appropriate routing paths for data delivery. For this purpose, we propose a new routing scheme called Bus-based Routing Technique (BRT) which exploits the periodic and predictable movement of buses to learn the required time (the temporal distance) for each data transmission to RoadSide Units (RSUs) through a dedicated bus-based backbone. Indeed, BRT comprises two phases: (i) Learning process which should be carried out, basically, one time to allow buses to build routing tables entries and expect the delay for routing data packets over buses, (ii) Data delivery process which exploits the pre-learned temporal distances to route data packets through the bus backbone towards an RSU (backbone mode). BRT uses other types of vehicles to boost the routing of data packets and also provides a maintenance procedure to deal with unexpected situations like a missing nexthop bus, which allows BRT to continue routing data packets. Simulation results show that BRT provides good performance results in terms of delivery ratio and end-to-end delay

On-Demand Routing for Urban VANETs using Cooperating UAVs

Vehicular ad hoc networks (VANETs) are characterized by frequent routing path failures due to the high mobility caused by the sudden changes of the direction of vehicles. The routing paths between two different vehicles should be established with this challenge in mind. Stability and connectedness are a mandatory condition to ensure a robust and reliable data delivery. The idea behind this work is to exploit a new reactive routing technique to provide regulated and well-connected routing paths. Unmanned Aerial Vehicles (UAVs) or what are referred to as drones can be both involved in the discovery process and be full members in these discovered paths in order to avoid possible disconnections on the ground when the network is sparsely connected. The different tests of this technique are performed based on NS-2 simulator and the outcomes are compared with those of related on-demand routing protocols dedicated for VANETs. Interesting results are distinguished showing a reduced end-to-end delay and a high delivery ratio, which proving that this heterogeneous communication between vehicles and UAVs is able to extend the network connectivity.Comment: 6 pages, 7 figures, conferenc

Leveraging Communicating UAVs for Emergency Vehicle Guidance in Urban Areas

International audienceThe response time to emergency situations in urban areas is considered as a crucial key in limiting material damage or even saving human lives. Thanks to their "bird's eye view" and their flexible mobility, Unmanned Aerial Vehicles (UAVs) can be a promising candidate for several vital applications. Under these perspectives, we investigate the use of communicating UAVs to detect any incident on the road, provide rescue teams with their exact locations, and plot the fastest path to intervene, while considering the constraints of the roads. To efficiently inform the rescue services, a robust routing scheme is introduced to ensure a high level of communication stability based on an efficient backbone, while considering both the high mobility and the restricted energy capacity of UAVs. This allows both predicting any routing path breakage prior to its occurrence, and carrying out a balanced energy consumption among UAVs. To ensure a rapid intervention by rescue teams, UAVs communicate in an ad hoc fashion with existing vehicles on the ground to estimate the fluidity of the roads. Our system is implemented and evaluated through a series of experiments. The reported results show that each part of the system reliably succeeds in achieving its planned objective

UAV-Assisted Reactive Routing for Urban VANETs

International audienceVehicular ad hoc networks (VANETs) are characterized by frequent path failures due to the high mobility caused by the sudden changes of vehicles direction. The routing paths between two different vehicles should be established with this challenge in mind. It must be stable and well connected in order to guarantee a reliable and safe delivery of packets. The aim of this work is to present a new reactive routing technique providing effective and well-regulated communication paths. These discovered paths are created based on a robust flooding discovery process involving UAVs (Un-manned Aerial Vehicles) to ensure the connectivity when the network is sparsely connected. The evaluation of this technique is performed using NS-2 simulator and its performances are compared with on-demand protocols dedicated for VANET. Simulation results show clearly that our approach gives interesting outcomes ensuring a high delivery ratio with a minimum delay. This hybrid communication between the vehicles and UAVs is attractive to initiate more smart connected nodes in the near future

ECaD: Energy‐efficient routing in flying ad hoc networks

Much progress can be expected in the domain of unmanned aerial vehicle (UAV) communication by the next decade. The cooperation between multiple UAVs in the air exchanging data among themselves can naturally form a flying ad hoc network (FANET). Such networks can be the key support to accomplish several kinds of missions while providing the required assistance to terrestrial networks. However, they are confronted with many challenges and difficulties, which are due to the high mobility of UAVs, the frequent packet losses, and the weak links between UAVs, all affecting the reliability of the data delivery. Furthermore, the unbalanced energy consumption may result in earlier UAV failure and consequently accelerate the decrease of the network lifetime, thus disrupting the overall network. This paper supports the use of the movement information and the residual energy level of each UAV to guarantee a high level of communication stability while predicting a sudden link breakage prior to its occurrence. A robust route discovery process is used to explore routing paths where the balanced energy consumption, the link breakage prediction, and the connectivity degree of the discovered paths are all considered. The performance of the scheme is evaluated through a series of simulations. The outcomes demonstrate the benefits of the proposed scheme in terms of increasing the lifetime of the network, minimizing the number of path failures, and decreasing the packet losses.Much progress can be expected in the domain of unmanned aerial vehicle (UAV) communication by the next decade. The cooperation between multiple UAVs in the air exchanging data among themselves can naturally form a flying ad hoc network (FANET). Such networks can be the key support to accomplish several kinds of missions while providing the required assistance to terrestrial networks. However, they are confronted with many challenges and difficulties, which are due to the high mobility of UAVs, the frequent packet losses, and the weak links between UAVs, all affecting the reliability of the data delivery. Furthermore, the unbalanced energy consumption may result in earlier UAV failure and consequently accelerate the decrease of the network lifetime, thus disrupting the overall network. This paper supports the use of the movement information and the residual energy level of each UAV to guarantee a high level of communication stability while predicting a sudden link breakage prior to its occurrence. A robust route discovery process is used to explore routing paths where the balanced energy consumption, the link breakage prediction, and the connectivity degree of the discovered paths are all considered. The performance of the scheme is evaluated through a series of simulations. The outcomes demonstrate the benefits of the proposed scheme in terms of increasing the lifetime of the network, minimizing the number of path failures, and decreasing the packet losses

Protocoles de routage intelligents dans les réseaux véhiculaires sans fils

Vehicular ad hoc networks (VANETs) are considered as a fundamental technology to manage the intelligent transportation systems (ITS), which are a set of innovative technologies enabling a wide range of road traffic management and safety services. VANETs have gone from a simple curiosity stage to a true interest from both the point of view of the automotive industry and the operators of networks and services. Indeed, these networks are an emerging class of wireless networks, allowing data exchange between vehicles or between vehicles and infrastructures placed along the roads and provide new technologies to improve the safety and efficiency of road transport. Following this same vision, commercial Unmanned Aerial Vehicles (UAVs) or what are commonly referred to as drones, have been increased significantly over urban areas because of their affordable prices and the multiplication of different useful applications in which the UAVs can be the suitable support during their functioning. Consequently, we can consider vehicles and UAVs as two different entities, with different properties, belonging to the same area, and can form a single network dealing with various common constraints over this kind of environment. In this context, in this thesis, we are interested in the process of inter-vehicle communications in urban areas. Our aim is to propose a set of routing solutions meeting the constraints and difficulties of such environments based on the cooperation of UAVs with VANETs. Firstly, we propose a routing scheme which relies on selecting, at each moment and ahead of time, the most connected road segments towards the target destinations based on the Hello packets exchanged periodically between vehicles with the assistance of UAVs acting as supervisors. Secondly, we propose a routing scheme which consists of two routing components, the first supports the wireless communications on the ground exclusively between vehicles, while the second operates in the sky in order to support the communications exclusively between UAVs. Finally, we introduce a reactive-based routing approach based on a prediction technique to calculate the expiration time of each discovered routing path between communicating entities. Our proposed approaches are promising candidates for routing in VANETs, which can realize reliable and efficient end-to-end communications between nodes in urban areas. On the other hand, the performances of our approaches are evaluated based on a series of simulations, and its merits and pitfalls are well discussed.Les réseaux véhiculaires (VANETs) sont considérés comme une technologie fondamentale pour gérer les systèmes de transport intelligents (ITS), qui sont un ensemble de technologies innovantes permettant une large gamme de services de gestion de la circulation routière et de sécurité. Les VANETs sont passés d’une simple étape de curiosité à un véritable intérêt tant du point de vue de l’industrie automobile que des opérateurs de réseaux et de services. En effet, ces réseaux constituent une classe émergente des réseaux sans fil, permettant l’échange de données entre les entités communicantes de la route et fournissent de nouvelles technologies afin d’améliorer la sécurité et l’efficacité du transport routier. Suivant cette même vision, les véhicules aériens sans pilote commerciaux (UAVs) ou ce que l’on appelle communément des drones ont été largement déployés dans les zones urbaines en raison de leurs prix abordables et de la multiplication des applications utiles dans lesquelles les drones peuvent être le support approprié pour leur fonctionnement correct. Par conséquent, les véhicules et les UAVs sont considérés comme deux entités différentes, ayant des propriétés différentes, appartenant à un même environnement, et pouvant former un seul réseau traitant de diverses contraintes communes sur ce type d’environnement. Dans cette thèse, notre objectif est de proposer un ensemble de solutions de routage dans les VANETs répondant aux contraintes et aux difficultés des environnements urbains. Dans un premier temps, nous proposons un protocole de routage qui consiste à sélectionner préalablement et de façon permanente les segments de route les plus connectés vers les destinations cibles à l’aide des paquets Hello échangés périodiquement entre véhicules où les drones peuvent agir comme des superviseurs. Ensuite, nous proposons un protocole de routage qui intègre deux composants de routage différents, le premier supporte les communications sans fil au sol exclusivement entre les véhicules et le second opère dans le ciel afin de supporter les communications exclusivement entre les drones. Pour finir, nous introduisons une approche de routage réactive basée sur une technique de prédiction pour calculer le temps d’expiration de chaque chemin de routage découvert entre les entités communicantes. Nos protocoles proposés peuvent être considérés comme efficace qui permettent de réaliser des communications de bout en bout fiables et efficaces entre les noeuds. En revanche, les performances de nos approches sont évaluées sur la base d’une série de simulations, dont les avantages et les inconvénients sont bien discutés

Multi-Agent Deep Reinforcement Learning for Wireless-Powered UAV Networks

International audienceUnmanned Aerial Vehicles (UAVs) have attracted much attention lately and are being used in a multitude of applications. But the duration of being in the sky remains to be an issue due to their energy limitation. In particular, this represents a major challenge when UAVs are used as base stations (BSs) to complement the wireless network. Therefore, as UAVs execute their missions in the sky, it becomes beneficial to wirelessly harvest energy from external and adjustable flying energy sources (FESs) to power their onboard batteries and avoid disrupting their trajectories. For this purpose, wireless power transfer (WPT) is seen as a promising charging technology to keep UAVs in flight and allow them to complete their missions. In this work, we leverage a multi-agent deep reinforcement learning (MADRL) method to optimize the task of energy transfer between FESs and UAVs. The optimization is performed by carrying out three essential tasks: (i) maximizing the sum-energy received by all UAVs based on FESs using WPT, (ii) optimizing the energy loading process of FESs from a ground BS, and (iii) computing the most energy-efficient trajectories of the FESs while carrying out their charging duties. Furthermore, to ensure highlevel reliability of energy transmission, we use directional energy transfer for charging both FESs and UAVs by using laser beams and energy beam-forming technologies, respectively. In this study, the simulation results show that the proposed MADRL method has efficiently optimized the trajectories and energy consumption of FESs, which translates into a significant energy transfer gain compared to the baseline strategies

UAV-assisted supporting services connectivity in urban VANETs

International audienceTo keep the services and applications of Intelligent Transportation System (ITS) stable and active, Vehicular Ad hoc Networks (VANETs) are considered as an essential building block to maintain and manage its features. A wide deployment of VANETs is possible only after addressing numerous research challenges. One of the most complicated issues consists in designing a routing strategy, taking into consideration several serious constraints, and especially in a network such as VANET. The severity of these issues would be increased significantly when a VANET is deployed over an urban area, where we distinguish the high mobility of nodes and existing obstructions (e.g., buildings, bridges, tunnels, etc.). In this paper, an efficient routing solution based on a flooding technique is conceived to make the data delivery more reliable and to guarantee robust paths. Vehicles can cooperate in ad hoc fashion with existing Unmanned Aerial Vehicles (UAVs). This kind of collaboration provides reliable routing paths and ensures alternative solutions in the case of path failures. Furthermore, a prediction technique is used to expect the expiration time of each discovered path. To limit the overhead over the network, all control packets are characterized by their static size making the originality of this work. Based on the simulation outputs, we discuss the performances of the proposed approach as compared with other dedicated previous schemes in terms of several metrics. The obtained results demonstrate that the hybrid communication between vehicles and UAVs based on the proposed flooding technique is perfectly suited to improve the data delivery process