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Nowadays vehicles on the roads can communicate using a special type of wireless network called Vehicular Ad-hoc Networks (VANETs). It has been demonstrated by the researchers that because of the unique features such as high density of vehicles and frequent change of network topology, VANETs are not supported by the traditional routing protocols. The routing consistency of such highly dynamic networks must be taken into account in VANETs as communication links are disintegrated in VANETs more often than Mobile ad-hoc Networks (MANETs). The nature of VANET communication can bring extreme routing overhead to the network, therefore to increase network performance, the overhead issue must be tackled. The proposed protocol is focused on reducing the overhead to get the improved PDR performance of the network. The improvement is achieved by permitting communication amongst only those nodes which are considered reliable in terms of availability and geographical position. The reliability factor simply reduces unnecessary nodes from the communication process and selects a set of reliable nodes that are discovered with the help of clustering technique throughout the routing process. Simulation experiments using the network simulator are presented to demonstrate the efficacy of the proposed protocol. The results show that the proposed protocol has enhanced network performance effectively compared to prior approaches.

Message forwarding schemes allow vehicles to exchange messages for various purposes such as safety, entertainment and traffic efficiency in vehicular ad hoc networks (VANETs). This paper addresses the problem of message dissemination under emergency situations in the context of vehicle-to-vehicle communication along the roads. The paper proposes a new forwarding scheme for both hazardous and normal traffic messages. The proposed scheme improves the irresponsible forwarding probability in case of both emergency and non-emergency situations. Furthermore, the scheme uses adaptive broadcast range rather than using static one and thus more appropriate for practical applications. In our work Veins-SUMO-OMNeT simulation platform has been used. The simulation results show that the proposed forwarding algorithm outperforms the other dissemination techniques in terms of message losses and data dissemination success for normal messages and emergency messages.

Localization is one of the main problems in Mobile Wireless Sensor Networks, since it provides the location of an event occurrence. This paper presents a performance evaluation of the localization algorithms: Multilateration Algorithm, Weighted Multilateration Algorithm and Probabilistic Multilateration Algorithm (PMA). In addition, we propose an Improved Probabilistic Multilateration Algorithm that decreases the localization error of the interest node by using an approach that computes iteratively the position of a node of interest until it reaches the solution that minimizes the localization error. The proposed approach regards the noisy environment by its impact on a correlation matrix that involves the variance of the separation distance between the node of interest and the respective reference nodes (RNs). Furthermore, we also introduce a constant parameter called damping factor; which enhances the convergence of the localization algorithm providing the solution that minimizes the localization error. In this study, we evaluate localization algorithms in a single-hop and multi-hop scenarios considering a distribution with solid geometry of the RNs and randomly distributed RNs in both scenarios. The results we obtained show that our proposed algorithm Improved PMA presents a better performance according to the Normalized Root Mean Squared Error varying the number of reference nodes and noise proportion.

REACT is a distributed resource allocation protocol used to negotiate a max–min allocation of airtime for multi-hop ad hoc wireless networks. Two approaches are proposed for a node to realize its REACT allocation in a contention-based MAC protocol. This is achieved by tuning its contention window to a value that corresponds to its allocation. Only a change in the allocation, due to a change in local traffic requirements or local network views, results in re-tuning. The approaches for tuning are implemented in commercial Wi-Fi devices and their stability and convergence are studied experimentally in the w-iLab.t wireless network testbed. These properties are also studied analytically to support the experimental results. In addition, REACT is extended to support airtime reservations for multi-hop flows. With a reservation in place, multi-hop TCP flows exhibit improved performance metrics when running over REACT than when running over 802.11 DCF in the w-iLab.t testbed.

International audience; In the 90s, Q-routing assisted by reinforcement learning was introduced by Boyan and Littman with interesting results in terms of quality of service. Some recent works continue to promote the idea through improvement of the algorithm or specialized extensions. In this paper, we propose a simple modification to workaround the greedy behaviour of Q-routing by considering epoch notion. In comparison with the original Q-routing and the standard OLSRv2 under Qualnet simulator, we show that our extension provides an interesting improvement in terms of packet delivery ratio on the original irregular grid of Boyan and Littman with wireless links.

This paper focus on developing a new practical classification for ad-hoc networks, were all the past classifications revolve upon three main categories respectively, mobile ad- hoc network (MANET), Vehicle ad-hoc network (VANET) and Flying ad-hoc network (FANET). My new classification will illustrate Underwater vehicle ad-hoc network (UWVANET) as the fourth category in ad-hoc main classification, showing the powerful and the weakness of each category defined.

A planar multifunctional four-port antenna system integrated on one substrate applied in the suburban mobile tablet is presented in this paper. The types of these antennas are selected based on different functions and the interactions between them are analyzed and reduced. Two identical T-shaped printed monopole antennas are designed for the MIMO mobile ad-hoc networks (MANET) application. The mutual coupling between the ports of these two MANET antennas is decreased by introducing a decoupling metal strip loaded with an inductor. Two horizontal printed dipoles with parasitic strips are developed to operate in the satellite navigation and communication frequency bands. Through the analysis of the interaction between the MANET antenna and satellite antennas, the satellite antennas with improved broadside radiation patterns are obtained. The performance stability of the proposed antenna system is verified by the investigation of the performances in different gestures. A prototype of the antenna system is fabricated and the measured results show that the proposed antenna system can cover the frequency bands of MANET communication, satellite navigation, and satellite communication with good performances. This proposed multifunctional antenna system is a good choice for the sub-urban mobile terminal systems.

Autonomous vehicles are becoming a reality in places with advanced infrastructure to support their operations. In crowded places, harsh environments, missions that require these vehicles to be aware of the context in which they are operating, and situations requiring continuous coordination with humans such as in disaster relief, advanced-vehicle systems (AVSs) need to be better contextually aware. The vast literature referring to “context-aware systems” is still sparse, focusing on very limited forms of contextual awareness. It requires a structured approach to bring it together to truly realize contextual awareness in AVSs. This paper uses a human-AVSs (HAVSs) lens to polarize the literature in a coherent form suitable for designing distributed HAVSs. We group the relevant literature into two categories: contextual-awareness related to the vehicle infrastructure itself that enables AVSs to operate, and contextual-awareness related to HAVSs. The former category focuses on the communication backbone for AVSs including ad-hoc networks, services, wireless communication, radio systems, and the cyber security and privacy challenges that arise in these contexts. The latter category covers recommender systems, which are used to coordinate the actions that sit at the interface of the human and AVSs, human-machine interaction issues, and the activity recognition systems as the enabling technology for recommender systems to operate autonomously. The structured analysis of the literature has identified a number of open research questions and opportunities for further research in this area.

CubeSats, which are limited by size and mass, have limited functionality. These miniaturised satellites suffer from a low power budget, short radio range, low transmission speeds, and limited data storage capacity. Regardless of these limitations, CubeSats have been deployed to carry out many research missions, such as gravity mapping and the tracking of forest fires. One method of increasing their functionality and reducing their limitations is to form CubeSat networks, or swarms, where many CubeSats work together to carry out a mission. Nevertheless, the network might have intermittent connectivity and, accordingly, data communication becomes challenging in such a disjointed network where there is no contemporaneous path between source and destination due to satellites’ mobility pattern and given the limitations of range. In this survey, various inter-satellite routing protocols that are Delay Tolerant (DTN) and Non Delay Tolerant (Non-DTN) are considered. DTN routing protocols are considered for the scenarios where the network is disjointed with no contemporaneous path between a source and a destination. We qualitatively compare all of the above routing protocols to highlight the positive and negative points under different network constraints. We conclude that the performance of routing protocols used in aerospace communications is highly dependent on the evolving topology of the network over time. Additionally, the Non-DTN routing protocols will work efficiently if the network is dense enough to establish reliable links between CubeSats. Emphasis is also given to network capacity in terms of how buffer, energy, bandwidth, and contact duration influence the performance of DTN routing protocols, where, for example, flooding-based DTN protocols can provide superior performance in terms of maximizing delivery ratio and minimizing a delivery delay. However, such protocols are not suitable for CubeSat networks, as they harvest the limited resources of these tiny satellites and they are contrasted with forwarding-based DTN routing protocols, which are resource-friendly and produce minimum overheads on the cost of degraded delivery probability. From the literature, we found that quota-based DTN routing protocols can provide the necessary balance between delivery delay and overhead costs in many CubeSat missions.

Multi-agent systems (MAS) rely on positioning technologies to determine their physical location, and on wireless communication technologies to exchange information. Both positioning and communication are affected by uncertainties, which should be accounted for. This paper considers an agent placement problem to optimize end-to-end communication quality in a MAS, in the presence of uncertainties. Using Gaussian processes (GPs), operating on the input space of location distributions, we are able to model, learn, and predict the wireless channel. Predictions, in the form of distributions, are fed into the communication optimization problems. This approach inherently avoids regions of the workspace with high position uncertainty and leads to better average communication performance. We illustrate the benefits of our approach via extensive simulations, based on real wireless channel measurements. Finally, we demonstrate the improved channel learning and prediction performance, as well as the increased robustness in agent placement.

During the last years, researchers have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that integrates an incentive scheme and a reputation mechanism. Our proposal follows the principles of the Hidden Market Design approach, which allows users to specify the amount of resources they are willing to sacrifice when participating in the offloading system. The underlying algorithm, that users are not aware of, is based on a truthful auction strategy and a peer-to-peer reputation exchange scheme. Extensive simulations on real traces depict how our designed mechanism achieves higher offloading rate and produces less traffic compared to three benchmark algorithms. Finally, we show how collaborating devices get rewarded for their contribution, while selfish ones get sidelined by others.

This paper proposes a spectRum Aware cRoss-layEr (RARE) medium access control protocol for cognitive radio ad-hoc networks. The RARE protocol initially splits the network into clusters, where cluster formation is defined as maximum edge biclique problem. Besides, in order to maintain the integrity of the cluster-based network, super-frame structure, and topology maintenance protocols are also presented in this paper. Moreover, RARE also integrates a delay-aware routing protocol, where the routing protocol is defined as a weighted graph problem. It is anticipated that clusters in RARE adapt themselves dynamically with respect to spectrum availability and nodes mobility. Furthermore, the routing protocol in RARE is expected to select stable paths while ensuring faster data delivery from a source node to the destination. Simulation is conducted to evaluate the performance of the proposed RARE protocol, where it is found that RARE outperforms existing approaches by maintaining a lesser number of clusters and a steady number of common channels. The simulation results also show that route selection in RARE proves to be more stable with the lowest packet transmission delay compared with the other approaches.

From the radar and military research world’s, the Ultra-WideBand Impulse Radio (UWB-IR) was adopted in the telecommunications world in the 1990’. Currently, the UWB-IR technology is an interesting candidate for close range Wireless Sensors Networks (WSNs). It is particularly attractive for industrial sensor networks due to its resilience to multipath interference, simple transceiver circuitry, accurate ranging ability, and low transmission power. In order to secure data and communications in the Ad-Hoc UWB-IR networks, UWB-IR requires suitable encryption protocols. In this paper, we review and summarize the IEEE 802.15.4 security sub-layer protocol of UWB-IR based Symmetric Key Cryptography scheme. Then, we highlight the different vulnerabilities and weaknesses present in this type of scheme. Finally, we prove, after a deep examination of multiple Public Key Cryptography (PKC) schemes, that the certificateless one is the most suitable for Ad-Hoc UWB-IR networks characterized by nodes mobility. Indeed, we have also evaluated and analyzed the different public key cryptosystems (PKCS) and concluded that NTRU is the most optimum public key cryptosystem to be used with the certificateless scheme in order to secure data and communications in Ad-Hoc UWB-IR Networks. This is due to the fact that it is the fastest PKCS to provide different security levels at a high speed with very constrained resources.

The research explored the current scenario of crime in Botswana, and the current measures employed to help combat it, including usage of crime prevention clusters. Through usage of the quantitative approach, with the aid of questionnaire and interviews, the research found that, there is an increasingly growth of crime rate in Botswana, sustaining the literature findings. The research highlighted the presence of crime prevention clusters, but noted a disconnection between them and the police. The bleak state of communication between the two, and ineffectiveness of current measures, causes the disconnection. Cluster members have to use own limited resources to report crime to the police, and this disadvantages the crime prevention efforts. Ad-hoc networks with emphasizes on Wi-Fi networks were found to be a solution to the communication gap identified. In conclusion, the authors developed a Wi-Fi network facility model to enable cluster members to make voice calls with no costs.

Проблематика. Задача побудови мережі з безперервним режимом передачі даних для рухомих вузлів зводиться до побудови безпроводової мережі та підтримання стану втрати мінімальної кількості пакетів під час обміну інформацією. Однією з головних проблем управління мережами MANET (Mobile Ad hoc Networks) є їх динаміка та те, що мобільні пристрої обмежені у своїх обчислювальних можливостях. Існує проблема маршрутизації трафіка всередині мереж MANET і внутрішньої ієрархії передавачів, залучених до системи. До того ж ці мережі мають проблеми оптимізації пропускної спроможності та управління потужністю. Брак фіксованої топології вводить нові наукові проблеми, зокрема мережеву конфігурацію, пошук пристроїв і підтримки такої топології, а також спеціальну адресацію та саморуйнування мережі. Ця задача є актуальною для передачі даних між рухомими пристроями в умовах розвідувальних операцій. Мета дослідження. Дослідити зменшення затримок пакетів у вузлах під час динамічної маршрутизації, зменшення службового трафіка та програмну оптимізацію передачі даних у мережах MANET відносно наявних методів. Методика реалізації. Для досягнення цієї мети використовуються методи комп’ютерного моделювання, статистичні та емпіричні методи. На основі оптимізації динамічної маршрутизації з використанням Ad hoc On-Demand Distance Vector алгоритму виділено чотири основні показники: швидкість встановлення шляху, затримка повідомлення в одному вузлі, виникнення зациклень, обсяг службового трафіка. Для тестування запропонованого методу моделюється граф із дванадцяти вершин, що імітує безпроводову однорангову мережу MANET. Тестування проводиться в кількості понад сто ітерацій. За кожної ітерації випадковим чином вибираються вершини графа мережі та моделюється передача даних між кожною вершиною графа. Результати дослідження. За використання створеного програмного забезпечення було проведено аналіз показників якості безперервної передачі даних і маршрутизації мережі запропонованим методом. Запропонований метод показав зменшення обсягу службового трафіка на 15 % і на 5–10 % кращі результати зменшення часу затримки в межах вузла та при обробці повідомлення. Висновки. Запропонований метод дає змогу зменшити час затримки в межах вузла, який змінює своє положення при обробці повідомлення, а також зменшити об’єм службового трафіка при передачі даних між вузлами в мережі MANET. Для дослідження запропонованого методу використано комп’ютерне моделювання. Background. The task of building a network with a continuous mode of data transmission for mobile nodes is to build a wireless network and maintain a state of loss of the minimum number of packets during the exchange of information. One of the main problems of MANET (Mobile Ad hoc Networks) network management is their dynamics and the fact that mobile devices are limited in their computing capabilities. There is a problem of traffic routing within MANET networks and the internal hierarchy of transmitters involved in the system. These networks also have problems with bandwidth optimization and power management. Lack of fixed topology introduces new scientific problems, such as network configuration, device search and topology support, as well as special addressing and self-destruction of the network. This task is relevant for data transmission between mobile devices in terms of reconnaissance operations. Objective. The goal of the article is the research of reducing packet delays in nodes during dynamic routing, reducing service traffic and software optimization of data transmission in MANET relative to existing methods. Methods. To achieve this goal, we use computer simulation, statistical and empirical methods. Based on the optimization of dynamic routing using the Ad hoc On-Demand Distance Vector algorithm, four main indicators are identified: speed of path establishment, message delay in one node, occurrence of loops, the amount of service traffic. To test the proposed method, a graph of twelve vertices simulating a wireless peer-to-peer MANET network is simulated. Testing is performed in more than a hundred iterations. At each iteration, the vertices of the network graph are randomly selected and the data transfer between each vertex of the graph is modeled. Results. The use of the created software provides the analysis of the indicators of the quality of continuous data transmission and network routing by the proposed method. The proposed method shows reducing the amount of office traffic by 15 % and the best results by 5–10 % reduction of delay time within the node and when processing messages. Conclusions. A method is proposed to reduce the delay time within a node that changes its position when processing a message, to reduce the amount of service traffic when transmitting data between nodes in the MANET network. Computer simulation is used to study the proposed method. Проблематика. Задача построения сети с непрерывным режимом передачи данных для подвижных узлов сводится к построению беспроводной сети и поддержания состояния потери минимального количества пакетов при обмене информацией. Одной из главных проблем управления сетями MANET (Mobile Ad hoc Networks) является их динамика и то, что мобильные устройства ограничены в своих вычислительных возможностях. Существует проблема маршрутизации трафика внутри сетей MANET и внутренней иерархии передатчиков, вовлеченных в систему. Также эти сети имеют проблемы оптимизации пропускной способности и управления мощностью. Отсутствие фиксированной топологии вводит новые научные проблемы, такие, как сетевая конфигурация, поиск устройств и поддержка такой топологии, а также специальная адресация и саморазрушения сети. Эта задача актуальна для передачи данных между подвижными устройствами в условиях разведывательных операций. Цель исследования. Исследовать уменьшение задержек пакетов в узлах при динамической маршрутизации, а также уменьшение служебного трафика и программную оптимизацию передачи данных в сетях MANET относительно существующих методов. Методика реализации. Для достижения этой цели используются методы компьютерного моделирования, статистические и эмпирические методы. На основе оптимизации динамической маршрутизации с использованием Ad hoc On-Demand Distance Vector алгоритма выделено четыре основных показателя: скорость установления пути, задержка сообщения в одном узле, возникновение зацикленности, объем служебного трафика. Для тестирования предложенного метода моделируется граф из двенадцати вершин, имитирующий беспроводную одноранговую сеть MANET. Тестирование проводится в количестве более ста итераций. При каждой итерации случайным образом выбираются вершины графа сети и моделируется передача данных между каждой вершиной графа. Результаты исследования. Благодаря использованию созданного программного обеспечения проведен анализ показателей качества непрерывной передачи данных и маршрутизации сети предложенным методом. Предложенный метод показал уменьшение объема служебного трафика на 15 % и лучшие на 5–10 % результаты уменьшения времени задержки в рамках узла и при обработке сообщения. Выводы. Предложенный метод позволяет уменьшить время задержки в рамках узла, который меняет свое положение при обработке сообщения, а также уменьшить объем служебного трафика при передаче данных между узлами в сети MANET. Для исследования предложенного метода использовалось компьютерное моделирование.

This paper focuses on how the probability can affect on the ad hoc routing protocols and especially on AODV regarding energy consumption. The evaluation of the performance of AODV with different message forwarding probability based on the mechanism that AODV protocol uses in order to forward the message in all nodes of the network. The evaluation of AODV protocol was carried out using network simulator-2 (NS-2), on 10 scales of probability. The outcome of this evaluation showed that using smaller probability than that of the original AODV protocol has, we can have better results on power consumption.

In this paper, we evaluate available bandwidth as a routing metric for IEEE 802.15.4-based ad-hoc networks. The available bandwidth on a data forwarding path is an approximation of the forwarding path’s residual data relaying capacity. High available bandwidth on a data forwarding path implies low data traffic load on the path, therefore data flows may experience low delay and high packet delivery ratio (PDR). Our aim is to evaluate available bandwidth as a routing metric. We present different available-bandwidth-based routing protocols for IEEE 802.15.40-based networks, namely: end-to-end available-bandwidth-based routing protocol (ABR), available bandwidth and contention-aware routing protocol (ABCR), and shortest hop-count and available-bandwidth-based opportunistic routing protocol (ABOR). Moreover, we also present variants of ABR and ABCR capable of distributing a flow’s data packets on multiple paths by maintaining the top K downstream nodes (the downstream nodes that advertised best data forwarding paths towards a sink node) corresponding to each sink node in a routing table. We focus on both single-sink and multi-sink networks. We performed extensive simulations, and the simulation results demonstrate that the available bandwidth routing metric shows better results when combined with a routing metric that helps to limit a data forwarding path’s length, i.e., shortest hop-count or intra-flow contention count. For multi-path data forwarding towards the same sink node, and at high traffic volumes, the available bandwidth metric demonstrates best performance when combined with the shortest hop-count routing metric.

Time synchronization protocols assume a primary role in IoT era. Their design, implementation and test often follow separate paths and they are not ensured with the same level of accuracy. Simulation validation exhibits unpredictable gap with real performance levels. According to these statements and in order to answer to the proposed open issues, the paper present a fine-grained controlled environment to perform custom validation test of time synchronization algorithms. The set-up is built by adopting widely known Raspberry development boards, exploiting the ad-hoc fiber optic links provided by Unicas-Net, taking advantage of NetEm built-in emulator in Raspbian Operating Systems, and finally developing a tailored user-friendly software to adequately control network link quality. Accordingly, synchronizing nodes can connect to one of the open points (provided by Raspberry devices) of the network ring and run their algorithms with other nodes that access to the set-up at 50 km distance. Finally, time synchronization performance can easily be assessed by exploiting GPS time provided by the GPS receiver and antenna, which complete each board equipment. First functionality tests are also reported in the paper.

The ANTop (Adjacent Network Topology) is a distributed and decentralized protocol for ad-hoc networks. It is based on a hypercube address space where the nodes names are mapped to assure their adjacency, allowing greedy routing protocols to find the optimum route. A distributed mechanism, to match real names to the network address, is implemented by distributed hashing tables. In this work we address the partition and assimilation networks problems, to complete the functionalities of ANTop, and we also provide a complete implementation for Linux systems., ANTop (Adjacent Network Topology) es un protocolo distribuido y descentralizado para redes ad-hoc. Está basado en un hipercubo para el espacio de direccionamiento, donde se asegura la adyacencia de las direcciones de los nodos, lo cual permite que protocolos de ruteo glutones encuentren la ruta óptima. Un mecanismo distribuido, que establece una analogı́a entre los nombres reales y las direcciones de red, es implementado usando tablas distribuidas de hash. En este trabajo nosotros estudiamos los problemas de partición y mezcla, con el fin de completar las funcionalidades de ANTop, y proveer una implementación en sistemas Linux.

This article describes and evaluates the performance of DETIboot, a system conceived for securely deploying temporary Linux systems into countless receiving hosts close enough to a Wi-Fi DETIboot server. This system was created with the ultimate goal of installing, in numerous students’ laptops and just-in-time, special Linux distributions for being temporarily used in practical classes. In this document we present an overview of DETIboot, a comprehensive description of the coding used in the broadcast communication and a detailed performance evaluation in a spacious auditorium. This evaluation did not involve security features to reduce the amount of variables influencing the final results. However, previous experiments allow us to extrapolate a maximum of 5% increase in the download time due to security. On average, it took us 50.1 s to download a 225 MiB Slax Linux over 802.11g, taking on average 15% more time than the theoretical lower bound of our setup (43.4 s). The influence of the position of receivers in the auditorium was not prominent. published

International audience; —We review the research literature investigating systems in which mobile entities can carry data while they move. These entities can be either mobile by nature (e.g., human beings and animals) or mobile by design (e.g., trains, airplanes, and cars). The movements of such entities equipped with storage capabilities create a communication channel which can help overcome the limitations or the lack of conventional data networks. Common limitations include the mismatch between the capacity offered by these networks and the traffic demand or their limited deployment owing to environmental factors. Application scenarios include offloading traffic off legacy networks for capacity improvement, bridging connectivity gaps, or deploying ad hoc networks in challenging environments for coverage enhancement.

The rapid proliferation of the Internet of Things (IoT) has led to growth in the ad-hoc networking scenario. With the recent upcoming technologies of network programmability like SDN may be effectively integrated to create a communication platform. In this work, we present the details of our preliminary study of how to determine the effectiveness of an approach to build a cluster network using Software-Defined Networking (SDN). We will provide an overview of optimum path routing protocol with cluster interaction. Our proposed scheme is a starting point for some experiments providing perspective over SDN deployment in a cluster environment for IoT. With this aim in mind, we propose a routing protocol that manages routing tasks over Cluster-SDN. By using network virtualization and OpenFlow technologies to generate virtual nodes, we simulate a prototype system controlled by SDN. Our designed testbed, is a real openflow protocol evaluation environment comprising networks and applications, which provide flexible control of framework support for large scale experiments.

Energy constraints on wireless nodes represent a current field of research. Such restrictions are particularly significant because of the great amount of features and applications currently available on devices, which contribute to dramatically increase energy consumption. However, when transmitting delay-sensitive data, such as multimedia streaming, a balance between energy optimization and quality of service is required. In this sense, there are many works that address this issue from different layers of network architecture separately; however, a more efficient solution could be achieved by combining the management capabilities of the different layers and the joint use of such information, which is called a crosslayer mechanism. Moreover, despite the fact that the IEEE 802.11 standard defines an energy management mechanism at MAC level, it is envisaged only for structured networks, leaving just general guidelines for other kind of networks, such as Ad- Hoc networks. Therefore, as a first step towards the design of a cross-layer scheme, this paper analyzes the flaws of IEEE 802.11 standard as regards the infrastructureless mode and proposes an optimization mechanism for energy management in Ad-Hoc networks. The proposed approach is based on a buffering mechanism, which is able to increase power-saving periods of time in Ad-Hoc nodes. Simulations using NS3 indicate that it is possible to obtain higher levels of residual energy at the end of a transmission using the proposed scheme.

International audience; Unmanned Aerial Vehicles (UAVs) can be a solution for deploying temporary networks by serving as Access Points to users on the ground. The aim is to provide multiple communication services (voice, data, video, etc.) over a specific area. The network must be deployed quickly for a relatively short period (emergency situations, sporting events, etc.), in the case of cellular network overload or blackout. A Flying Ad-Hoc Network will be deployed to cover all the potential users. The objective of this paper is to investigate the impact of drone replacement due to the limitation of battery lifetime. A constraint for this kind of network is service continuity. For this purpose, an adaptation for the routing mechanism is proposed, to overcome the loss of connectivity observed in the simulations. In the beginning, a state of the art on use cases employing drones is given, followed by a description of our scenario. Thenceforth, the system is described as well as the deployment mechanism and the induced connectivity loss. In the end, we present a way to adapt the routing scheme so that the network remains connected when a node is replaced due to energy level reasons.

This paper analyzes the problem of modeling the collisions in a distributed and heterogeneous fixed wireless network in which spatial reuse enables multi-packet communication (MPC), thus allowing the coexistence of multiple peer to peer communications. The objective is to present a completely theoretical model that provides closed form expressions for the capture probability, and for the statistics of the interference power and of the signal-to-interference ratio (SIR) experienced by a receiving node. The presented theory aims in particular to investigate the impact on the capture probability of the heterogeneity introduced by the network topology and by the use of different antenna systems. All theoretical results are validated by independent Monte Carlo simulations. Finally, this study discusses the possible analogies between the developed and the existing frameworks for homogeneous scenarios, and presents a preliminary application of the developed capture analysis by evaluating the throughput-delay behavior of a homogeneous 802.11 MPC network.

Interest in the cognitive radio sensor network (CRSN) paradigm has gradually grown among researchers. This concept seeks to fuse the benefits of dynamic spectrum access into the sensor network, making it a potential player in the next generation (NextGen) network, which is characterized by ubiquity. Notwithstanding its massive potential, little research activity has been dedicated to the network layer. By contrast, we find recent research trends focusing on the physical layer, the link layer and the transport layers. The fact that the cross-layer approach is imperative, due to the resource-constrained nature of CRSNs, can make the design of unique solutions non-trivial in this respect. This paper seeks to explore possible design opportunities with wireless sensor networks (WSNs), cognitive radio ad-hoc networks (CRAHNs) and cross-layer considerations for implementing viable CRSN routing solutions. Additionally, a detailed performance evaluation of WSN routing strategies in a cognitive radio environment is performed to expose research gaps. With this work, we intend to lay a foundation for developing CRSN routing solutions and to establish a basis for future work in this area.

In mobile ad hoc network, nodes co-operatively form a network independent of any fixed base station infrastructure. Every node in a mobile ad-hoc network can function as a router and forwards the data packets to the other nodes. Multicasting plays an important role whenever group communications are required. Most of the existing multicast routing protocols in mobile ad hoc networks consider only one source in a multicast group and become inefficient when the protocol is extended to multi-source multicasting. In this paper, we propose a unicast forwarded multi-source multicast routing protocol, for ad hoc networks which is having more than one source in a group. Here, the sources of the group also act as a receiver for other sources in that group. The proposed routing method is a cluster based one and avoids the flooding or broadcasting of control packets to form routing structure. On executing source joining and receiver joining procedures, a complete path for multicast data transfer was established. As the join request control packets are forwarded only through cluster-heads and junction nodes, lower amount of control overhead is incurred. Simulation result shows that the proposed protocol maintains the delivery ratio with reduced control overhead and utilizes the bandwidth efficiently.

The strengthening of security solutions for computer networks increases the interests in new methods for the transfer of hidden information. In this paper, we considered the use of routing protocols for transmission of steganographic messages. We evaluated such approach using proactive and reactive routing protocols by analyzing the amount of sent data, the number of generated routing packets, the average size of routing packets, and the packet delivery ratio using the NS-3 simulator. Simulations included random network topologies with a various number of nodes and mobility settings. The obtained results showed that reactive routing protocols exchange a large amount of routing packets which can be suitable for steganographic purposes due to network flooding mechanism.

Resource discovery is one of the most important infrastructure-level facilities enabling the success of modern ad-hoc mobile communication networks, integrating services and capabilities provided by heterogeneous objects into the Future Internet environment. However, the highly dynamic and infrastructure-less nature of these organizations, where nodes continuously join and leave the network or change their attachment connections by moving between different coverage areas, makes resource discovery an extremely challenging tasks. In lack of specific knowledge about the availability of resources and their location over the network, flooding-based or pure probabilistic exploration approaches are the only feasible options to support search/discovery operations. By considering the high communication cost and the incomplete coverage problems respectively characterizing the aforementioned approaches we propose a novel adaptive random-walk search strategy, for resource discovery in ad-hoc networks, structured according to a selective stochastic query/response scheme where the exploration process is driven by posterior probability, using Bayesian inference and relying on the history of past discovery operations. This strategy, by also taking advantage of the scale-free properties characterizing the aforementioned ad-hoc organizations, is able to significantly contain the broadcast traffic without compromising the overall success of search operations by seamlessly accommodating to dynamic changes in resource location and network topology.

Fast and efficient recovery from node failure, with minimal disruption of routes and the consequent traffic loss is of the utmost importance for any routing protocol. Link-state protocols, albeit preferred to distance vector ones because of faster convergence, still suffer from a trade-off between control message overhead and performance. This work formalizes the routes' disruption following a node failure as an optimization problem depending on the nodes' centrality in the topology, constrained to a constant signaling overhead. Next, it shows that the solution can be found using Lagrange Multipliers. The solution complexity is low enough to be computed on-line on the network routers, thus obtaining the optimal setting of control message timers that minimize the traffic loss following a node failure. The gain obtained is quantified in power-law synthetic topologies, and it is also tested on real network topologies extending the OLSR protocol to use the modified timers, showing that the inevitable approximations introduced in the analysis do not hamper the very good results achievable through this novel approach. The technique can be applied to any link state protocol, including OSPF, and improves route convergence not only upon failures but on every topology modification.

MANET (Mobile Ad-hoc Network) is a mobile multi-hop wireless self-organized distributed ad-hoc network thatdoes not require the basic internal construction. Routing in MANET is a challenging problem which draws researcher's vision, due to nodes mobility, dynamic topology and lack of central point like base station or servers. Clustering of devices in MANET could reduce overhead, flooding and collision in communication and make the network topology more stable. The ABC (Artificial Bee Colony) algorithm is a new meta-heuristic population based optimization technique inspired by the intelligent foraging behavior of honeybee swarms. In this paper, a new general framework has been proposed for achieving QoS which provides a cluster based routing and applies Artificial Bee Colony optimization Technique for effective optimal route discovery in MANET. It works on the principle of collective intelligence and emergence of artificial honey bees. It's application in ad-hoc networks involves swarming agents (honey bees) hopping node to node, analyzing a set of variables exposed by the nodes and provide the optimal path and minimize the routing overhead and also provides QoS guarantees with an ability for minimal end-to-end delay and enhanced scalability.

This paper provides a review of antennas applied for indoor positioning or localization systems. The desired requirements of those antennas when integrated in anchor nodes (reference nodes) are discussed, according to different localization techniques and their performance. The described antennas will be subdivided into the following sections according to the nature of measurements: received signal strength (RSS), time of flight (ToF), and direction of arrival (DoA). This paper intends to provide a useful guide for antenna designers who are interested in developing suitable antennas for indoor localization systems.

This paper proposes a new Ad-Hoc network system which comprises the multiple relay access points (APs) with multi channels. Ad-Hoc network systems are recently proposed and incorporated for the communication infrastructure, which relays wireless transmission among access points (APs) in wireless LAN (WLAN) system. System throughput is decreased due to hidden terminal problem when only a single channel is used for the Ad-Hoc network. In order to solve this problem, a new system with multi channels is proposed. However, even if the multi channels are employed, the co- and/or adjacent-channel interference occurs due to hidden terminal problem and multiple APs in a limited space, when considering a simultaneous transmit and reception at the relay AP. In this paper, we develop an Ad-Hoc network testbed which can reduce and avoid co- and/or adjacent-channel interference by using vertically arranged antenna configuration and distributed channel allocation scheme. Moreover, the effectiveness of our testbed is clarified by applying actual WLAN signals.

CoopMAC has been recently proposed as a possible implementation of cooperation protocols in the medium access control (MAC) layer of a wireless network. However, some nodes may refrain from cooperation for selfish purposes, e.g. in order to save energy, in what is called selfish behavior or misbehavior. This protocol violation worsens other nodes' performance and can be avoided if other nodes detect and punish (e.g. banning from the network) misbehaving nodes. However, fading and interference may prevent nodes from cooperating even if they are willing, therefore it is not trivial to identify misbehaving nodes. In a fading scenario where an automatic repeat request (ARQ) protocol is used, we propose a mechanism that allows to detect misbehaving nodes. Two approaches, either based on the uniformly most powerful (UMP) test or on the sequential probability ratio test (SPRT) are considered. The two techniques are characterized and compared in terms of their average detection delay and resulting network performance.

This paper presents a unified mathematical performance analysis of the physical layer in orthogonal frequency division multiple access (OFDMA) wireless ad hoc networks, where several independent transmitter-receiver pairs share a common wideband channel in a local area environment. Multiuser interference (MUI) occurs when the signals from different users arrive at a given receiver with arbitrary timing misalignments, leading to the destruction of the orthogonality between subcarriers. Precise interference analysis in white Gaussian noise and Rayleigh multipath fading is developed in a partially loaded OFDMA network. New exact expressions of symbol and bit error rates are given in the case of interleaved subcarrier assignment schemes. On the other hand, tight upper bounds and accurate improved Gaussian approximations are developed for arbitrary subcarrier assignment schemes. Furthermore, expressions of the cutoff rates are derived and employed to estimate the spectral efficiency in bits/sec./Hz. These are used to quantify the improvement in the spectral efficiency that can be achieved by a common MUI mitigating technique based on the extension of guard intervals and dynamic positioning of FFT windows. © 2006 IEEE.

We propose a probabilistic system model for anonymous ad hoc routing protocols that takes into account the a priori knowledge of the adversary, and illustrate how the information theoretical entropy can be used for quantification of the anonymity offered by a routing protocol as the adversary captures an increasing number of nodes in the network. The proposed measurement schema is applied to ANODR and ARM routing protocols.

We investigate the connectivity of fading wireless ad-hoc networks with a pair of novel connectivity metrics. Our first metric looks at the problem of connectivity relying on the outage capacity of MIMO channels. Our second metric relies on a probabilistic treatment of the symbol error rates for such channels. We relate both capacity and symbol error rates to the characteristics of the underlying communication system such as antenna configuration,modulation, coding, and signal strength measured in terms of Signal-to-Interference-Noise-Ratio (SINR). For each metric of connectivity, we also provide a simplified treatment in the case of ergodic fading channels. In each case, we assume a pair of nodes are connected if their bi-directional measure of connectivity is better than a given threshold. Our analysis relies on the central limit theorem to approximate the distribution of the combined undesired signal affecting each link of an ad-hoc network as Gaussian. Supported by our simulation results, our analysis shows that (1) a measure of connectivity purely based on signal strength is not capable of accurately capturing the connectivity phenomenon, and (2) employing multiple antenna mobile nodes improves the connectivity of fading ad-hoc networks.

In this work we focus on investigating the learning phase of an autonomous authentication mechanism. Through a series of simulation, an experimental best cutoff point and the aggression threshold values for different network size were calculated. In the test phase, those found values are proved by the average good accuracy.

We address the problem of a secure direct communication of two arbitrary peers in a P2P network without knowing each other's IP addresses. An efficient solution to this problem will provide a practically usable way of communication to privacy-sensitive P2P applications. Traditionally, P2P architectures view this problem as a problem of mutual anonymity of a message sender and receiver, but usual solutions suffer from various inefficiencies or complexities. By looking at the problem from a perspective of an ad-hoc network, we are able to apply a familiar approach of multihop communication and ad-hoc routing algorithms to a P2P overlay. Introduced usage of a public key as a node's identifier adds further security features, including data integrity through digital signatures, or end-to-end encryption. Proposed P2P overlay has been successfully used for building a decentralised cryptocurrency exchange Coincer.

Opportunistic traffic offloading has been proposed to tackle overload problems in cellular networks. However, existing proposals only address device-to-device-based offloading techniques with deadline-based data propagation, and neglect content injection procedures. In contrast, we tackle the offloading issue from another perspective: the base station interference coordination problem during content injection. In particular, we focus on dissemination of contents, and aim at the minimization of the total transmission time spent by base stations to inject the contents into the network. We leverage the almost blank subframe technique to keep under control the intercell interference in such a process. We formulate an optimization problem, prove that it is NP-hard and NP-complete, and propose a near-optimal heuristic to solve it. Our algorithm substantially outperforms classical intercell interference approaches, as we evaluate through the simulation of LTE-A networks. This work has been initially supported by the FP7 CROWD Project under Grant 318115 and later on followed up by the H2020 5G NORMA Project under Grant 671584. The work of V. Mancuso was supported by the Ramon y Cajal Grant from the Spanish Ministry of Economy and Competitiveness under Grant RYC-2014-01335.

One of the most present issues of computer wireless networks is the security. Comparing with their wired counterpart, the wireless networks not only accentuate some of the well-known security vulnerabilities but they are subject of new and specific ones. Among the existing wireless networks the ad hoc ones are the most exposed to attacks and collusions due to the absence of any centralized control. The most efficient way to ensure the communication secrecy, inclusively for ad hoc wireless networks, is the cryptography. From many reasons, following from specific operating conditions, the employment of asymmetric key techniques and Public Key Infrastructure is not a realistic choice. In the networks with a large number of nodes, as wireless sensor networks, a large number of secret keys are involved in order to ensure the communication secrecy. While dynamicity is one of the essential features of mobile wireless networks, when nodes may leave or join the network and in the absence of a centralized control entity, the management of secret keys is crucial. The paper presents the main aspects of mobile wireless networks security and focuses on the key management issue in ad-hoc wireless networks.

[EN] Intelligent Unmanned Aerial Vehicles (UAVs) on emergency rescue are widely used to detect injured mountaineers in inaccessible areas. These systems should satisfy several features. It is important to know the georeference of the injured mountaineers. It is also important to have real-time images of the area where people have suffered the accident. In this paper, we present the development of a UAV integrated within a wireless ad hoc network and the communication protocol that is able to transfer data between several UAV’s and the Smartphones carried by the mountaineers. This paper also shows how ad hoc networks extend the wireless coverage for emergency situations in critical areas without GSM cellular coverage. After developing our system, we have focused our effort on demonstrating the correct operation of our UAV and its network performance when the system is used to track someone within a zone. Experimental results show the big potential of this kind of networks working in hostile environments such as big mountains, ravines and river canyons without GSM signal communication., This work has been supported by the “Ministerio de Economía y Competitividad”, through the “Convocatoria 2014. Proyectos I+D - Programa Estatal de Investigación Científica y Técnica de Excelencia” in the “Subprograma Estatal de Generación de Conocimiento”, (Project Reference: TIN2014-57991-C3-1-P), by the postdoctoral grant “Contratos Postdoctorales UPV 2014 (PAID-10-14)” by the“Universitat Politècnica de València”, by the pre-doctoral student grant “Ayudas para contratos predoctorales de Formación del Profesorado Universitario FPU (Convocatoria 2014)” Reference: FPU14/02953 by the “Ministerio de Educación, Cultura y Deporte”.

Thanks to the widespread use of wireless systems with the Android operating system, the presence of intelligent devices that can access the network is increasingly high. Wireless Mesh Networks are proposed today as the enabling technology to increase even more the pervasiveness of the Internet access and as a alternative to overcome typical limitations of existing infrastructure, but there have not been so far substantial contributions about the integration of different technologies. Furthermore, nowadays heterogeneous networks are a promising reality; a seamless integration of different technologies would leverage them to a key element to increase pervasiveness of access and connectivity in the emerging view of the Internet of Things. In this perspective the present paper proposes an open source implementation of an ad-hoc network based on mobile devices running Android, along with its integration with the infrastructured network, in an IPv4/IPv6 dual stack environment. The use of commercial devices for the end-user terminals and the leverage of the infrastructured network on widely used routing protocols enable this solution to be easily deployable in the real world. The developed test bed provides a novel and flexible framework for validation of networking solutions in emerging scenarios with heterogeneous network components.

—With the exponential growth of devices connected to the Internet, security networks as one of the hardest challenge for network managers. Maintaining and securing such large scale and heterogeneous network is a challenging task. In this context, the new networking paradigm, the Software Defined Networking (SDN), introduces many opportunities and provides the potential to overcome those challenges. In this article, we first present a new SDN based architecture for networking with or without infrastructure, that we call an SDN domain. A single domain includes wired network, wireless network and Ad-Hoc networks. Next, we propose a second architecture to include sensor networks in an SDN-based network and in a domain. Third, we interconnect multiple domains and we describe how we can enhanced the security of each domain and how to distribute the security rules in order not to compromise the security of one domain. Finally, we propose a new secure and distributed architecture for IoT (Internet of Things). —With the exponential growth of devices connected to the Internet, security networks as one of the hardest challenge for network managers. Maintaining and securing such large scale and heterogeneous network is a challenging task. In this context, the new networking paradigm, the Software Defined Networking (SDN), introduces many opportunities and provides the potential to overcome those challenges. In this article, we first present a new SDN based architecture for networking with or without infrastructure, that we call an SDN domain. A single domain includes wired network, wireless network and Ad-Hoc networks. Next, we propose a second architecture to include sensor networks in an SDN-based network and in a domain. Third, we interconnect multiple domains and we describe how we can enhanced the security of each domain and how to distribute the security rules in order not to compromise the security of one domain. Finally, we propose a new secure and distributed architecture for IoT (Internet of Things).

Topology control, wherein nodes adjust their transmission ranges to conserve energy and reduce interference, is an important feature in wireless ad hoc networks. Contrary to most of the literature on topology control which focuses on reducing energy consumption, in this paper we tackle the topology control problem with the goal of limiting interference as much as possible, while keeping the communication graph connected with high probability. Our approach is based on the principle of maintaining the number of physical neighbors of every node equal to or slightly below a specific value k. As we will discuss in this paper, having a nontrivially bounded physical node degree allows a network topology with bounded interference to be generated. The proposed approach enforces symmetry on the resulting communication graph, thereby easing the operation of higher layer protocols. To evaluate the performance of our approach, we estimate the value of k that guarantees connectivity of the communication graph with high probability both theoretically and through simulation. We then define k-NEIGH, a fully distributed, asynchronous, and localized protocol that uses distance estimation. k-NEIGH guarantees logarithmically bounded physical degree at every node, is the most efficient known protocol (requiring 2n messages in total, where n is the number of nodes in the network), and relies on simpler assumptions than existing protocols. Furthermore, we verify through simulation that the network topologies produced by k-NEIGH show good performance in terms of node energy consumption and expected interference

The throughput of wireless networks is known to scale poorly when the number of users grows. The rate at which an arbitrary pair of nodes can communicate must decrease to zero as the number of users tends to infinity, under various assumptions. One of them is the requirement that the network is fully connected: the computed rate must hold for any pair of nodes of the network. We show that this requirement can be responsible for the lack of throughput scalability. We consider a two-dimensional network of extending area with only one active source-destination pair at any given time, and all remaining nodes acting only as possible relays. Allowing an arbitrary small fraction of the nodes to be disconnected, we show that the per-node throughput remains constant as the network size increases. This result relies on percolation theory arguments and does not hold for one-dimensional networks, where a non-vanishing rate is impossible even if we allow an arbitrary large fraction of nodes to be disconnected. A converse bound is obtained using an ergodic property of shot noises. We show that communications occurring at a fixed non-zero rate imply some of the nodes to be disconnected. Our results are of information theoretic flavor, as they hold without assumptions on the communication strategies employed by the network nodes.

Network coding is a new research area that may have interesting applications in practical networking systems. With network coding, intermediate nodes may send out packets that are linear combinations of previously received information. There are two main benefits of this approach: potential throughput improvements and a high degree of robustness. Robustness translates into loss resilience and facilitates the design of simple distributed algorithms that perform well, even if decisions are based only on partial information. This paper is an instant primer on network coding: we explain what network coding does and how it does it. We also discuss the implications of theoretical results on network coding for realistic settings and show how network coding can be used in practice

In ad-hoc networks, autonomous wireless nodes can communicate by forwarding messages for each other. For routing protocols in this setting, it is known that a malicious node can perform a variety of attacks just by not behaving according to the specification. Whilst secure versions of routing protocols are under development, little effort has been made to formalise the scenario similarly to developments in the realm of traditional security protocols for secrecy and authentication. We present a broadcast process calculus suitable to describe the behaviour of protocols which require a local memory component for every node. By adding annotations for the origin of messages, we are able to formalise a vital security property in this context, called store authorisation. Furthermore, we describe a static analysis for the detection of violations of this property. For a model of the AODV protocol in our calculus, we are then able to deduce that an attacker may introduce a routing loop in certain networks.

The spread use of IEEE 802.11 networks in industrial automation raised the need to support multiple traffic classes with different requirements. This paper proposes a novel approach, called SchedWiFi, that provides flexible support to the scheduled traffic class, i.e., a high priority traffic class that is transmitted according to a fixed schedule, over IEEE 802.11 ad-hoc industrial networks. SchedWiFi operates on the IEEE 802.11n physical layer, thus providing high datarate, and supports multiple traffic classes with different priorities. SchedWiFi modifies the EDCA mechanism allowing to transmit scheduled traffic without requiring any predefined superframe structure, or timeslots, thus allowing for more flexible schedule of non-ST traffic.

The growing need for multimedia applications within wireless Local Area Networks (LAN) demands reliable and efficient broadcasting and multicasting transmission of throughput sensitive data, like audio and video. IEEE 802.11 standard which is the primary technology in wireless LANs was not initially designed to handle heavy broadcasting traffic. However, this raises a series of reliability problems mainly related to the lack of an effective feedback mechanism for multicasting and broadcasting transmission. This inherited drawback does not allow the standard to take full advantage of the bandwidth offered by its latest amendments. The main aim of this work is to offer an alternative congestion control mechanism especially for broadcasting. For this, the expanding use of the CTS-to-Self protection mechanism is proposed. The Medium Access Control (MAC) algorithm is appropriately modified and tested under various data traffic conditions. The simulation shows that the use of this amended MAC method in conjunction with the suitable data packet size can significantly improve throughput, in multimedia type data broadcasting over wireless ad-hoc networks.