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International audience; When a disaster occurs, during a long period of time people suffer to have no means to communicate with their relatives. The presented work aims at proposing a solution composed of a ground station located nearby the damaged area coupled with a swarm of drones. The ground station plays the role of a gateway between cellular networks, that are still up but out of reach of people, with drones that carry messages from and to people located in the disastered region. We analyze the possibility of deploying drones with fixed positions and a more flexible solution allowing drones to move but at the cost of intermittent communications, allowing only sms-like messages. We show that using the same number of drones, allowing drones to move improves dramatically the coverage of people with respect to a FANET in which drones stay at a fixed position. We also show that even for a very restricted number of drones, for reasonable communication ranges, almost all the people benefit from an important average connected time.

International audience; Monitoring some sites using a wireless sensor network (WSN) may be hampered by the di culty of recharging or renewing the batteries of the sensing devices. Mechanisms aiming at improving the energy usage at any moment while ful lling the application requirements are thus key for maximizing the lifetime of such networks. Among the di erent methods for achieving such a goal, we focus on energy management methods based on duty-cycling allowing the sensors to switch between two modes: a high-energy mode (active) and a low- energy mode (sleep). In this paper we propose two new sched- uling heuristics for addressing the problem of maximizing the lifetime of a WSN under the constraint of coverage of a subset of xed targets. The rst one is a stochastic greedy algorithm and the second one is based on applying Simulated Annealing (SA). Both heuristics use a speci c knowledge about the problem. Experimental results show that while both algorithms perform well, greedy algorithm is preferable for small and medium sizes networks, and SA algorithm has competitive advantages for larger networks.

Open access: https://www.sciencedirect.com/science/article/pii/S1571066106001010; International audience; Mobile Ad hoc NETworks (MANETs) are dynamic networks populated by mobile stations. Stations in MANETs are usually laptops, PDAs or mobile phones. These devices feature Bluetooth and/or IEEE 802.11 (WiFi) network interfaces and communicate in a decentralized manner. Mobility is a key feature of MANETs. Because of their high cost and their lack of flexibility of such networks, experimentation is mostly achievable through simulation. Numerous tools exist for MANETs simulation, including ns-2 and GloMoSim which are the two most popular ones. This paper provides a State of the Art of MANETs simulators and associated simulation techniques. First it gives an overview of the domain. Then it provides a map of the main characteristics that MANETs simulation tools should feature and the current support of these. Finally, a description for each simulator is provided, including an explanation of what make them appealing solutions.

Unmanned Aerial Vehicle (UAV) networks can be consid- ered as a kind of mobile ad hoc network. One of the most important goals in UAV networks is to achieve a powerful collaborative fleet. For that, efficient communication pro- tocols are needed. In this paper, we are proposing a new energy efficient broadcasting algorithm, CEDBBT, that is making use of community knowledge to enhance the perfor- mance of the dissemination process. Additionally, a hybrid multi-objective algorithm, CellDE, is used to optimize the configuration parameters of this broadcasting protocol. The optimization is done by maximizing the coverage achieved and minimizing at the same time both, energy consumption and the broadcast time. Results show the improvement ob- tained in the performance of the broadcasting process, as well as, a wide range of solutions for the configuration of CEDBBT that outperforms the original setting.

Many algorithms and protocols in Ad-Hoc Networks are based on the use of neighborhood information. It is usually accepted that one-hop neighbors in static networks are stable. However, based on intensive sets of experiments, it appears that wireless links both in indoors or outdoors contexts are very sensitive to conditions. During two years we have recorded sets of measures and draw today some conclusions about the stability of links between wireless-enable small communicating objects like smartphones and PDAs.

We consider the problem of finding and maintaining communication paths in wireless mobile ad hoc networks (MANET). We consider this problem as a bi-objective problem when trying to minimize both the length of the constructed paths and the number link reconnections. We propose two centralized algorithms that help analyse the problem from a dynamic graph point of view. These algorithms give lower bounds for our proposed decentralized ant-based algorithm that constructs and maintains such paths in a MANET.

International audience; What is the impact of obstacles on the graphs of connections between stations in Mobile Ad hoc Networks? In order to answer, at least partially, this question, the first step is to define both an environment with obstacles and a mobility model for the stations in such an environment. The present paper focuses on a new way of considering the mobility within environments with obstacles, while keeping the core ideas of the well-known Random WayPoint mobility model (a.k.a RWP). Based on a mesh-partitioning of the space, we propose a new model called RSP-O-G for which we compute the spatial distribution of stations and analyse how the presence of obstacles impacts this distribution compared to the distribution when no obstacles are present. Coupled with a simple model of radio propagation, and according to the density of stations in the environment, we study the mean degree of the connection graphs corresponding to such mobile ad hoc networks.

International audience; Tree-based backbone establishment and maintenance in Mobile ad hoc Delay Tolerant Networks is often operated throught the use of traversing tokens. A study and framework are proposed here for various token traversal strategies on tree-based backbones. The proposed strategies execute in a distributed and purely decentralized manner, and require only 1-hop knowledge. Aiming at providing the highest robustness and quality of services, these token-traversal strategies are studied in particular with an algorithm for merging and maintaining the different trees based on the quality of the nodes. For the robustness aspect, the use of a trust-based evaluation framework is assumed and the weights of the different nodes are based on their quality of cooperation. Three cost functions are implemented in order to evaluate the trust based framework proposed, including another function for evaluating tree-convergence time. Results and comparison charts are provided to illustrate the trade-off between the various strategies in terms of performances, cost (memory and communication) and robustness.

With the common availability of mobile communicating devices like PDA or smartphones, mobile ad hoc networks (a.k.a MANET) are rising as an interesting domain of research. They are now ready for a wide development. These infrastructureless networks are composed of wireless-enable communicating devices, which moves entail frequent changes in their own neighborhood. Consequently, obtaining real data on this kind of networks in order to observe the dynamic of their topology is rather complicated. Thus, it is critical to be able to simulate human mobility in various environments for the purpose of recreating, in a global way, a dynamic network close to reality. Many mobility models have already been used for analyzing the viability of new protocols for routing, communicating or broadcasting. The purpose of this demonstration is present a simulation plateform for mobility models within urban environments. A new type of mobility model implementing the planification of moves will illustrate the way of using such simulator.

Quality of service (QoS) is an important issue in delay tolerant mobile ad-hoc networks (DTMs). This work attempts to improve the QoS in DTMs by relying on spanning forests algorithms. The existing algorithms are improved by introducing the notion of trust and choosing the most robust (trustable) spanning trees among existing opportunities. The robustness/quality of the tree can be assessed based on two cost functions. In order to improve QoS in a DTM, a greedy-based heuristic is proposed to the existing algorithms and becomes G-TRUST. To aid efficient break away of low-trust node, another heuristic, BREAK heuristic, is further incorporated to G-TRUST (G-TRUST BREAK). Simulation on realistic mobility models were carried out on both G-TRUST and G-TRUST BREAK. Their results verified the advantages of incorporating these heuristics.

Delay tolerant networks (DTNs) are an extension of mobile ad-hoc networks (MANETs). Global knowledge in DTNs cannot be obtained or guaranteed due to their dynamicity, decentralized nature and non-permanent structure. Managing such networks optimally is very difficult, if not impossible. Trust management in such networks receives much attention recently due to their potential application. One solution for managing information within DTNs lies in constructing and maintaining spanning forests. DA-GRS is a local computation based model for the description of decentralized algorithms designed for dynamically distributed environments like delay-tolerant MANETs (DTMs). DA-GRS proposes a framework for constructing and maintaining a spanning forest in such an environment. This work introduces the notion of trust into DA-GRS resulting in T-DA-GRS algorithm. The goal of the proposed algorithms is to construct and maintain robust trusted spanning tree where less trustable nodes are leaves. Three cost functions are suggested as means to assess the robustness of trusted spanning trees. T-DA-GRS is also further improved by incorporating greedy algorithm to become T-GDA-GRS. These algorithms were tested with four different networks generated by a DTM simulator known as Madhoc. Efficiency of these algorithms is compared with optimal values.

This paper presents a new broadcasting protocol called Delayed Flooding with Cumulative Neighborhood (DFCN) designed for wireless ad hoc networks. DFCN enables bandwidth-efficient broadcasting in wide area network composed of large number of mobile devices. The protocol was validated trough simulation which proved its efficiency and cost-effectiveness. Comparison with other well known protocols has shown that the proposed protocol outperforms them in such terms as a number of emissions and redundant receptions.

The recent rise of wireless networking technologies let us envision the metropolitan ad hoc network (MAHN). MAHNs are built on-the- fly by user’s mobile stations which communicate in a peer-to-peer mode. Communications within the network hence do not rely on any fixed infrastructure. This paper tackles the message broadcasting problem in such networks. Unlike most of the studies on this issue, we do consider that the network is very likely to be split in several partitions and that the steady mobility of the nodes allows the broadcasting process to reach previously inaccessible partitions. This article presents the Delayed Flooding with Cumulative Neighbourhood (DFCN) algorithm as an algorithm for message broadcasting on metropolitan ad hoc networks and, through experiments, analyses its performance.

Topology management for mobile ad hoc networks is usually based on the notion of virtual backbones. We address the notion of quality of such backbones as a multi-objective problem addressing quality of the mobiles composing the backbone and of the connection links. We validate the approach using extensive simulation based on different mobility models and using backbones composed of spanning forests. We provide ways to address the global behaviour of the algorithms by fine-tuning the greedy local decision policy and compare it to the solution quality that could be achieved using global knowledge and metaheuristics.