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

Politique d’austérité en Algérie : Décision appropriée ou précipitée ?

Ce papier tentera de traiter de la mise en place d’une politique économique, relativement et rarement appliquée par les économies nationales, à savoir la politique d’austérité dans le cas algérien, du fait que l’économie de ce pays connait quelques difficultés et complications suite à l’effondrement des prix du baril qui a causé des préjudices financiers assez importants et délicats du fait de la dépendance de cette économie à cette matière première et l’absence d’autres produits alternatifs pour compenser cette perte financière. Ainsi, et devant l’urgence de remédier à cela et éviter d’autres complications d’ordre sociales, économiques et financières, l’Etat algérien s’est vu contraint de recourir aux mécanismes et stratégies adoptées dans ce sens, entre-autres, cette politique d’austérité qu’on essayera d’analyser les contours, les fondements et les objectifs tracés.Mots-clés : Politiques-Austérité-Algérie-Rente-Budget-Etat-Population.JEL: F63, H11, H12, R38.AbstractThis paper will attempt to discuss the implementation of an economic policy, relatively and rarely applied by the national economies, namely the austerity policy in the Algerian case, because the economy of this country is experiencing some difficulties and complications due to the collapse of the price of a barrel, which caused fairly significant and delicate financial damage due to the dependence of this economy on this raw material and the absence of other alternative products to offset this financial loss. Thus, and faced with the urgent need to remedy this and avoid other social, economic and financial complications, the Algerian State was forced to resort to the mechanisms and strategies adopted in this direction, among others, this policy of austerity that we will try to analyze the main fundamentals and the aims and targets.Key-words: Politics-Austerity-Algeria-Rent-Budget-State-Population.JEL: F63, H11, H12, R38.ستحاول هذه الورقة مناقشة تنفيذ سياسة اقتصادية ، ونادراً ما تطبقها الاقتصادات الوطنية ، وهي سياسة التقشف في الحالة الجزائرية ، لأن اقتصاد هذا البلد يعاني من بعض الصعوبات. تعقيدات بسبب انهيار سعر البرميل الذي تسبب في أضرار مالية كبيرة ودقيقة بسبب اعتماد هذا الاقتصاد على هذه المادة الخام وغياب منتجات بديلة أخرى لتعويض هذه الخسارة المالية. وبالتالي ، وفي مواجهة الحاجة الملحة لعلاج هذا وتفادي التعقيدات الاجتماعية والاقتصادية والمالية الأخرى ، أُجبرت الدولة الجزائرية على اللجوء إلى الآليات والاستراتيجيات المعتمدة في هذا الاتجاه ، ضمن أمور أخرى ، سياسة التقشف هذه التي سنحاول تحليلها ، والأسس والأهداف المرسومة.الكلمات المفتاحية: سياسات-التقشف-الجزائر-الإيجار-الميزانية-الدولة-السكان

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

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

A Safety-Aware Location Privacy-Preserving IoV Scheme with Road Congestion-Estimation in Mobile Edge Computing

By leveraging the conventional Vehicular Ad-hoc Networks (VANETs), the Internet of Vehicles (IoV) paradigm has attracted the attention of different research and development bodies. However, IoV deployment is still at stake as many security and privacy issues are looming; location tracking using overheard safety messages is a good example of such issues. In the context of location privacy, many schemes have been deployed to mitigate the adversary’s exploiting abilities. The most appealing schemes are those using the silent period feature, since they provide an acceptable level of privacy. Unfortunately, the cost of silent periods in most schemes is the trade-off between privacy and safety, as these schemes do not consider the timing of silent periods from the perspective of safety. In this paper, and by exploiting the nature of public transport and role vehicles (overseers), we propose a novel location privacy scheme, called OVR, that uses the silent period feature by letting the overseers ensure safety and allowing other vehicles to enter into silence mode, thus enhancing their location privacy. This scheme is inspired by the well-known war strategy “Give up a Pawn to Save a Chariot”. Additionally, the scheme does support road congestion estimation in real time by enabling the estimation locally on their On-Board Units that act as mobile edge servers and deliver these data to a static edge server that is implemented at the cell tower or road-side unit level, which boosts the connectivity and reduces network latencies. When OVR is compared with other schemes in urban and highway models, the overall results show its beneficial use

Contributions à la résolution des processus décisionnels de Markov centralisés et décentralisés (Algorithmes et Théorie)

Cette thèse porte sur les aspects calculatoires des problèmes de prise de décisions sous diverses sources d'incertitude de systèmes munis d'un ou de plusieurs agents. En particulier, nous aborderons des problèmes pouvant être modélisés sous forme de processus décisionnels de Markov. De plus, nous étudions également les extensions des processus décisionnels de Markov, notamment ceux incorporant l'incertitude résultant soit des autres agents du système, soit des informations sur l'état du système. Nous présentons des stratégies permettant d'améliorer les performances des techniques de l'état de l'art de la résolution des processus décisionnels de Markov. Nous suggérons tout d abord une méthode générale, nommée programmation dynamique topologique, qui exploite les dépendances causales entre états du système afin de faire face à deux problématiques. D'une part, elle détecte la structure du problème, comme un moyen de surmonter à la fois la malédiction de la dimension et celle de l'historique. D'autre part, elle contourne le problème lié aux mises à jour redondantes et construit des solutions optimales ou approximatives suivant un ordre topologique induit par la structure sous-jacente du problème. En outre, nous introduisons la planification centralisée pour le contrôle distribué des processus décisionnels de Markov. Nous offrons les bases théoriques utiles pour des travaux futurs dans cette direction. Cette analyse formelle a débouché sur bon nombre d'algorithmes exacts et approximatifs pour la résolution centralisée des processus décisionnels de Markov décentralisés. Parmi tous ces algorithmes figure, l'algorithme d'élagage incrémental à base de croyances, qui s'est révélé le meilleur algorithme approximatif à ce jour. La planification centralisée pour le contrôle distribué ouvre un certain nombre de perspectives, y compris celle d'une statistique suffisante bornée pour le contrôle distribué des processus de Markov.This thesis addresses the computational issues in sequential decision-making under various sources of uncertainty for either single or multi-agent systems. In particular, we will be concerned in problems that can be modeled as Markov decision processes. In addition, we address extensions of Markov decision process, which involve uncertainty resulting from other agents in the world, and partial observability. We present several strategies that improve the performances of state-of-the-art techniques for solving Markov decision processes. We suggest a general method, namely topological dynamic programming, that exploits the causal relation between states to deal with two key issues. First, it detects the structure of the problem as a means of overcoming both dimensionality and history curses. Secondly, it circumvents the problem of unnecessary backups and builds optimal and approximate solutions based on a topological order induced by the underlying problem structure. Moreover, we introduce the centralized planning for distributed control of Markov decision processes. We provide theoretical basis for further work in that direction. This analysis results in a number of efficient exact as well as approximate algorithms for solving decentralized Markov decision processes. Among many, point-based incremental pruning algorithm turns out to be the most efficient so far. The centralized planning for distributed control opens a number avenues, including a bounded sufficient statistic for a general model of decentralized Markov decision processes.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

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

Enhancing QoS in privacy based vehicular communication

Smart vehicles constitute the heart of the Intelligent Transportation Systems (ITS), they exchange safety-related data continuously using bea-cons. This data comprise information about the vehicle movements and visited places. Unfortunately, eavesdroppers might exploit the collected information to build location profiles about the drivers and their pri-vate activities. Researchers have proposed a wide range of solutions to solve the issue. Most of them are based on pseudonyms that should be switched after silent periods. The aspect of QoS (Quality of Service) is either neglected or not optimized enough. In this paper, we provide our new solution PPC (Probabilistic Pseudonym Change) to make a trade-off between privacy and QoS. We have extended the Prext framework (a privacy framework for vehicular communication) to implement our approach and assess our work. The obtained results show that the proposed solution provides a good QoS while preserving the privacy aspect adequately according to the carried data application