A Turnover based Adaptive HELLO Protocol for Mobile Ad Hoc and Sensor Networks

International audienceWe present a turnover based adaptive HELLO protocol (TAP), which enables nodes in mobile networks to dynamically adjust their HELLO messages frequency depending on the current speed of nodes. To the best of our knowledge, all existing solutions are based on specific assumptions (\eg{} slotted networks) and/or require specific hardware (\eg{} GPS) for speed evaluation. One of the key aspects of our solution is that no additional hardware is required since it does not need this speed information. TAP may be used in any kind of mobile networks that rely on HELLO messages to maintain neighborhood tables and is thus highly relevant in the context of ad hoc and sensor networks. In our solution, each node has to monitor its neighborhood table to count new neighbors whenever a HELLO is sent. This \emph{turnover} is then used to adjust HELLO frequency. To evaluate our solution, we propose a theoretical analysis based on some given assumptions that provides the optimal turnover when these assumptions hold. Our experimental results demonstrate that when this optimal value is used as the targeted turnover in TAP, the HELLO frequency is correctly adjusted and provides a good accuracy with regards to the neighborhood tables

Data Gathering Solutions for Dense RFID Deployments

International audienceThe advent of RFID (Radio Frequency Identification) has allowed the development of numerous applications. Indeed, solutions such as tracking of goods in large areas or sensing in smart cities are now made possible. However, such solutions encounter two main issues, first is inherent to the technology itself which is readers collisions, the second one being the gathering of read data up to a base station, potentially in a multihop fashion. While the first one has been a main research subject in the late years, the next one has not been investigated for the sole purpose of RFID, but rather for wireless adhoc networks. This multihop tag information collection must be done in regards of the application requirements but it should also care for the deployment strategy of readers to take advantage of their relative positions, coverage, reading activity and deployment density to avoid interfering between tag reading and data forwarding. To the best of our knowledge, the issue for a joint scheduling between tag reading and forwarding has never been investigated so far in the literature, although important.In this paper, we propose two new distributed, crosslayer solutions meant for the reduction of collisions and better efficiency of the RFID system but also serve as a routing solution towards a base station. Simulations show high levels of throughput while not lowering on the fairness on medium access staying above 85% in the highest deployment density with up to 500 readers, also providing a 90% data rate

Smart communications via a tree-based overlay over multiple and heterogeneous (TOMH) spontaneous networks

The current networking scenario is characterized by widespread availability of ubiquitous devices with significant processing capabilities, e.g., smartphones, tablets, and laptops. In addition, the simultaneous availability of multiple connectivity interfaces, e.g., cellular, WiFi, and Ethernet, pushes towards spontaneous networking scenarios where devices create a multi-network environment based on collaborative and best-effort dispatching of packets. Connectivity in such novel scenarios is far less reliable than in traditional networks, e.g., links abruptly dis/appear simply due to node mobility, thus making hard to support quality-sensitive applications. In this paper, we present our framework for Tree-based Overlay over Multiple and Heterogeneous (TOMH) spontaneous networks for easily supporting smart network management features on top of heterogeneous multi-network environments. TOMH creates and maintains a dynamic and mobility-Aware tree-based overlay network to integrate different connectivity technologies while enabling a tradeoff between accuracy of the global network view and collection/monitoring overhead. The TOMH overlay construction mechanism has been thoroughly validated and evaluated via simulation studies: the reported experimental results reveal that our proposal significantly outperforms comparable solutions for MANET environments, especially when the size of the targeted multi-network increases

Transmission Power Adaptation Based Energy Efficient Neighborhood Discovery

International audienceAbstract--Neighborhood discovery - detection of the devices within communication range using HELLO messages - is a fundamental mechanism in wireless sensor networks (WSN) which enables usage of many di erent topology control and routing algorithms. Even though it is very important, most of the algorithms does not take into account parameters of the neighborhood discovery. We present two algorithms that adapt power of transmission of the sensors in a mobile WSN by still adapting frequency of HELLO messages in order to save energy and get accurate neighborhood tables. First solution is based on the knowledge of turnover - change in the number of neighbors in consecutive iterations of the neighborhood discovery - used in conjunction with adaptation of frequency and transmission range, minimizing general cost of transmission of the HELLO messages. Second solution is based on computing of optimal range. Both algorithms are based on theoretical analysis. Results show that they are energy e cient and outperform solutions of the literature

Alternative opportunistic alert diffusion to support infrastructure failure during disasters

International audienceOpportunistic communications present a promising solution for disaster network recovery in emergency situations such as hurricanes, earthquakes, and floods, where infrastructure might be destroyed. Some recent works in the literature have proposed opportunistic-based disaster recovery solutions, but they have omitted the consideration of mobile devices that come with different network technologies and various initial energy levels. This work presents COPE, an energy-aware Cooperative OPportunistic alErt diffusion scheme for trapped survivors to use during disaster scenarios to report their position and ease their rescue operation. It aims to maintain mobile devices functional for as long as possible for maximum network coverage until reaching proximate rescuers. COPE deals with mobile devices that come with an assortment of networks and aims to perform systematic network interface selection. Furthermore, it considers mobile devices with various energy levels and allows low-energy nodes to hold their charge for longer time with the support of high-energy nodes. A proof-of-concept implementation has been performed to study the doability and efficiency of COPE, and to highlight the lessons learned

GSAR: Greedy Stand-Alone Position-Based Routing protocol to avoid hole problem occurance in Mobile Ad Hoc Networks

The routing process in a Mobile Ad Hoc Network (MANET) poses critical challenges because of its features such as frequent topology changes and resource limitations. Hence, designing a reliable and dynamic routing protocol that satisfies MANET requirements is highly demanded. The Greedy Forwarding Strategy (GFS) has been the most used strategy in position-based routing protocols. The GFS algorithm was designed as a high-performance protocol that adopts hop count in soliciting shortest path. However, the GFS does not consider MANET needs and is therefore insufficient in computing reliable routes. Hence, this study aims to improve the existing GFS by transforming it into a dynamic stand-alone routing protocol that responds swiftly to MANET needs, and provides reliable routes among the communicating nodes. To achieve the aim, two mechanisms were proposed as extensions to the current GFS, namely the Dynamic Beaconing Updates Mechanism (DBUM) and the Dynamic and Reactive Reliability Estimation with Selective Metrics Mechanism (DRESM). The DBUM algorithm is mainly responsible for providing a node with up-to-date status information about its neighbours. The DRESM algorithm is responsible for making forwarding decisions based on multiple routing metrics. Both mechanisms were integrated into the conventional GFS to form Greedy Stand-Alone Routing (GSAR) protocol. Evaluations of GSAR were performed using network simulator Ns2 based upon a defined set of performance metrics, scenarios and topologies. The results demonstrate that GSAR eliminates recovery mode mechanism in GFS and consequently improve overall network performance. Under various mobility conditions, GSAR avoids hole problem by about 87% and 79% over Greedy Perimeter Stateless Routing and Position-based Opportunistic Routing Protocol respectively. Therefore, the GSAR protocol is a reasonable alternative to position-based unicast routing protocol in MANET

Link failure detection, network recovery, and network reliability in multi-hop wireless networks

In this thesis, we study Wireless Mesh Network (WMN) and Mobile Ad hoc NETwork (MANET), which are two kinds of wireless multi-hop communication networks. WMNs and MANETs are promising technologies that have the ability to provide effective solutions to many applications in the technological, social, military, disaster recovery, and economic fields. Some of these applications are the extension of the cellular network's coverage, broadband internet access, and community and neighborhood networks. The big challenge in these kinds of networks is the frequent link failures, which make them less reliable compared to other kinds of networks. Implementing a fast mechanism to detect link failures, effective and reliable routing protocols and metrics, and a powerful reconfiguration scheme to recover from the link failures greatly enhance the WMNs and MANETs performance, and increase their reliability and availability. Our research has three directions. In the first direction, we study link failure detection approaches and link failure recovery techniques. In this direction, we mathematically analyze Hello based link failure detection approach implemented in routing protocols that use two routes, one as a primary route, and the other one as a backup route that is immediately used upon link failures. The objectives behind the above analysis are to mathematically calculate the packet delivery ratio, and to find how much gain we could achieve by using two routes instead of one. Our results show that the packet delivery is increased by 1.5 times by using two routes instead of one. It also shows that applying two routes is essential to cover high link failure rate values, and the need using two routes instead of one is more urgent in WMNs and MANETs with higher link failure rate values, i.e. less reliable networks. In addition to that, we propose a novel framework that dynamically assigns the values of Hello based link failure detection scheme parameters based on the communication types and the QoS requirements. Besides that, we propose a novel protocol to enhance the Hello based link failure detection scheme performance. In the second direction, we study the reliable routing protocols and metrics. This thesis proposes a novel adaptive routing protocol to increase the network connectivity and reliability, while minimizing the hop count, reducing the network nodes' spatial distribution and memory, and simplifying the routing process. The network reliability and connectivity are investigated in the last direction. Based in our study, the only ways to provide reliable and stable communications, virtually decrease the packet loss to zero, and to support multimedia communications in MANETs and WMNs are by using multi-route instead of one, and letting the routing protocols select the most stable routes among the available routes. The network node density specifies the probability that a route exists between any randomly chosen source and destination pair. Thus, to ensure the existence of two routes between any source and destination pairs, the node density must be above a certain threshold. In this thesis, we propose a mathematical model to find the above threshold. Our results show that the probability to have two routes exponentially increases with the number of nodes until it reaches the saturation region where the increase of the number of nodes has negligible improvements in terms of network availability. In addition to that, we study the effects of nodes mobility on the network connectivity. Our work is evaluated by MATLAB

Protocoles de routage sans connaissance de voisinage pour réseaux radio multi-sauts

L'efficacité énergétique constitue l'objectif clef pour la conception des protocoles de communication pour des réseaux de capteurs radio multi-sauts. Beaucoup d'efforts ont été réalisés à différents niveaux de la pile protocolaire à travers des algorithmes d'agrégation spatiale et temporelle des données, des protocoles de routage efficaces en énergie, et des couches d'accès au médium avec des mécanismes d'ordonnancement permettant de mettre la radio en état d'endormissement afin d'économiser l'énergie. Pour autant, ces protocoles utilisent de façon importante des paquets de contrôle et de découverte du voisinage qui sont coûteux en énergie. En outre, cela se fait très souvent sans aucune interaction entre les différentes couches de la pile. Ces travaux de thèse s'intéressent donc particulièrement à la problématique de l'énergie des réseaux de capteurs à travers des protocoles de routage et d'accès au médium. Les contributions de cette thèse se résument de la manière suivante : Nous nous sommes tout d'abord intéressés à la problématique de l'énergie au niveau routage. Dans cette partie, les contributions se subdivisent en deux parties. Dans un premier temps, nous avons proposé une analyse théorique de la consommation d'énergie des protocoles de routage des réseaux radio multi-sauts d'appréhender au mieux les avantages et les inconvénients des uns et des autres en présence des modèles de trafic variables, un diamètre du réseau variable également et un modèle radio qui permet de modéliser les erreurs de réception des paquets. À l'issue de cette première étude, nous sommes parvenus à la conclusion que pour être économe en énergie, un protocole de routage doit avoir des approches similaires à celle des protocoles de routage géographique sans message hello. Puis, dans un second temps, nous introduisons une étude de l'influence des stratégies de relayage dans un voisinage à 1 saut sur les métriques de performance comme le taux de livraison, le nombre de messages dupliqués et la consommation d'énergie. Cette étude est suivie par une première proposition de protocole de routage géographique sans message hello (Pizza-Forwarding (PF)) exploitant des zones de relayage optimisées et sans aucune hypothèse sur les propriétés du canal radio. Dans le but de réduire considérablement la consommation de PF, nous proposons de le combiner avec une adaptation d'un protocole MAC asynchrone efficace en énergie à travers une approche transversale. La combinaison de ces deux approches montre un gain significatif en terme d'économie d'énergie avec des très bon taux de livraison et cela quels que soient les scénarios et la nature de la topologique.Energy-efficient communication protocol is a primary design goal for Wireless Sensor Networks (WSNs). Many efforts have been done to save energy anywhere in the protocol stack through temporal and spatial data aggregation schemes, energy-aware routing protocols, activity scheduling and energy-efficient MAC protocols with duty cycle. However both control packets and beacons remain which induces a huge waste energy. Moreover, their design follows the classical layered approach with the principle of modularity in system development, which can lead to a poor performance in WSNs. This thesis focuses on the issues of energy in WSNs through energy-efficient routing and medium access control protocols. The constributions of this thesis can be summarized as follows: First, we are interested on the energy issues at the routing layer for multihop wireless sensor networks (WSNs). We propose a mathematical framework to model and analyze the energy consumption of routing protocols in multihop WSNs by taking into account the protocol parameters, the traffic pattern and the network characteristics defined by the medium channel properties, the dynamic topology behavior, the network diameter and the node density. In this study, we show that Beacon-less routing protocol should be a best candidate to save energy in WSNs. We investigate the performance of some existing relay selection schemes which are used by Beacon-less routing protocols. Extensive simulations are proposed to evaluate their performance locally in terms of packet delivery ratio, duplicated packet and delay. Then, we extend the work in multihop wiriless networks and develop an optimal solution, Enhanced Nearest Forwarding within Radius, which tries to minimize the per-hop expected number of retranmissions in order to save energy. We present a new beaconless routing protocol called Pizza-Forwarding (PF) without any assumption on the radio environment: neither the radio range nor symmetric radio links nor radio properties (shadowing, etc.) are assumed or restricted. A classical greedy mode is proposed. To overcome the hole problem, packets are forwarded to an optimal node in the two hop neighbor following a reactive and optimized neighborhood discovery. In order to save energy due to idle listening and overhearing, we propose to combine PF's main concepts with an energy-efficient MAC protocol to provide a joint MAC/routing protocol suitable for a real radio environment. Performance results lead to conclude to the powerful behavior of PFMAC.VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF