Advances in satellite miniaturization and launch cost reduction have enabled the deployment of increasingly large nanosatellite swarms in Low Earth Orbit. However, the ground infrastructure supporting these missions has not evolved at the same pace: many operators rely on a single ground station that can serve only one satellite at a time and must observe a non-negligible reconfiguration delay between consecutive contacts. This creates a critical bottleneck for missions requiring rapid offloading of large observation datasets within a few orbital passes.

Broadcasting all CAMs and CPMs saturates the NR-V2X sidelink. We frame joint CAM/CPM scheduling as a cooperative POMDP and learn a single MAPPO policy whose reward (controlled by weights α,β) spans the information–bandwidth Pareto frontier. In a SUMO-based Toulouse simulation with LoS-aware propagation and probabilistic vision detection, the learned scheduler (α =3.0, β =2×10−4) reduces channel load by 43.2% while retaining 82.1% of baseline scene knowledge, yielding a 42.9% improvement in information efficiency. Emergent role specialisation and bursty, context-aware transmissions show the approach outperforms static heuristics. Code and datasets are publicly available.

Routing in nanosatellites swarms presents distinct challenges, including variable node availability, constrained bandwidth, and dynamic topology. Strategies like delay-tolerant networking (DTN) can be advantageous, as they adapt to intermittent connectivity by storing and forwarding data when connections are established. Moreover, geographic routing protocols that exploit satellite positions can improve efficiency, while machine learning approaches may optimize routing decisions based on changing network conditions. What about hybrid approaches that may combine some of these methods? Basically, the crucial question is where to begin. The primary challenge for nanosatellites network designers is to determine which routing strategies to test prior to deployment. Given the vast number of existing routing protocols, testing all of them is not possible. This problem motivates the present study, which share the authors' experiences on selecting the most suitable routing algorithms for a given nanosatellites swarm. In particular, the study reports how the use of graph theory metrics helps in restricting the set of routing algorithms to be considered for network characterization and protocol selection.

Low-frequency radio interferometry is crucial to understanding the universe and its very early days. Unfortunately, most of the current instruments are ground-based and thus impacted by the interferences massively produced by the Earth. To alleviate this issue, scientific missions aim at using Moon-orbiting nano-satellite swarms as distributed radio-telescopes in outer space, keeping them out of Earth interference range. However, swarms of nano-satellites are systems with complex dynamics and need to be appropriately characterized to achieve their scientific mission. This paper presents a methodology based on graph theory for characterizing the swarm network system by computing graph theory metrics around three properties: the node density, network connectivity and ISL availability. We show that these properties are well-suited for highlighting a possible heterogeneity in a network and adapt a routing strategy accordingly. This work is the first milestone in defining the best-suited routing strategy within the swarm from the derived network properties.

We address the problem of partitioning a network of nano-satellites to fairly distribute the network load under energy consumption constraints. The study takes place in a context where a swarm of nano-satellites orbits the Moon and works as, but not limited to, a distributed radio-telescope for low-frequency radio interferometry. During an interferometry mission, each nano-satellite collects observation data, then shares them with the other swarm members to compute a global image of space. However, the simultaneous transmission of large volumes of data can cause communication issues by overloading the radio channel, leading to potential packet loss. In this context, we investigate three division algorithms based on graph sampling techniques. We prove that random walk-based algorithms overall perform the best in terms of conservation of graph properties and fairness for group sizes down to 10% of the original graph.

This paper proposes a multi-RAT Software Defined Network (SDN) assisted collision detection system designed to protect Vulnerable Road Users (VRU) by predicting road hazards. The system benefits from the Network Function Virtualization (NFV) and Software Defined Network (SDN). It includes a collision detection service, which collects specific messages from road users and processes them to detect collision risks. We propose a solution that allows vehicles and VRUs (such as pedestrians, cyclists, etc.) to smartly adapt the rate of the awareness messages. The frequency adaptation is performed under a certain number of constraints related to the risk level with the aim to improve trajectory prediction accuracy while decreasing unnecessary signalization on the network side and optimizing the energy consumption for the VRU side. Our simulation results suggest that frequency adaptation helps improve energy consumption and network signalization without impacting trajectory prediction accuracy and collision detection reliability.

The main goal of this work is to set up a solution that allows the V2X system to optimize network resources selection under a certain number of constraints related to the quality of service and energy consumption. In this paper, we design a novel neighboring scheme to enhance the existent communication policies of awareness messages. Vehicles and Vulnerable Road Users (VRUs) (such as pedestrians, cyclists, motorized two wheels, etc) will be able to efficiently adapt the frequency of sending awareness messages based not only on the variation in location dynamics (e.g. velocity, position, direction) but also on the environment's context. Context-aware and dynamic adaptation of the transmission periodicity undoubtedly helps in reducing unnecessary network signalization and saving the energy of the VRUs' connected devices. To this end, we demonstrate how the proposed scheme can optimize the network load of message transmission and thus the energy consumption especially for VRUs. Further, we study the impact of the adaptation on the reliability and latency of VRU protection system. Simulation results suggest that there is an interesting gain in network and application related metrics with the best configurations of messages periodicity.

Unmanned Aerial Vehicle (UAV)-aided Wireless Sensor Network (WSN) has been received increasing attentions in recent years due to its tremendous applications in many fields. The high dynamic topology in such network brings new communication challenges. In this paper, we address on the dynamic parameters, including the velocity and flying height of the UAV, the sensors velocities, and its real-time location, which affect the topology and influence the communication performance of the system. We introduce the contact-duration to mathematically integrate these parameters and to measure the transmission opportunity between the mobile node and the UAV and formulate the data collection issue as an optimization problem with the objectives of jointly maximizing the number of collected packets and the number of nodes that participate the communications with the UAV. Furthermore, we propose an opportunity-optimal frame selection algorithm, named as OFS algorithm, to increase the communication opportunities of the nodes, thereby, the data collection performance of the network was enhanced. Through extensive simulations based on simulated movement and real experiments, we evaluate the effectiveness of the proposed mechanisms under different configurations. The results present that the proposed mechanisms perform well on enhancing the transmission opportunity of the mobile nodes and the data collection performance of the network.

This paper proposes novel MAC protocols for an unmanned aerial vehicle (UAV) aided mobile wireless sensor network. UAV and sensors are mobile, and UAV collect data from sensors. In such dynamic aerial network, both the physical contact duration time (CDT) and the data-rate (DR) between mobile nodes and the UAV impact the data collection deeply. We propose hybrid beacon based MAC schemes combing CSMA/CA with physical parameters based scheduling. The UAV broadcasts ‘Beacon’ evenly to its coverage, and the mobile nodes that receive the ‘Beacon’ will randomly access to the channel through CSMA/CA. We compare fixed inter-beacon duration combined with a proactive scheduling MAC to an beacon-based IEEE 802.15.4. Through extensive simulations, the proposed MAC protocols have high performance in average delivery ratio and fairness compared to beacon beacon-based IEEE 802.15.4.

Unmanned Aerial Vehicles (UAVs) can be a cost saving and easy to deploy solution to implement a temporary network infrastructure. They can act as access points in scenarios such as emergency situations, special events, or specific area monitoring. Two main deployment families can be found in the literature. The first one, the location-based family, is based on the fundamental assumption that the network user positions are known. We do believe that this could not suit the most general scenarios. On the other hand, the location-independent family can not be as efficient as the first one. The main idea in this paper is to introduce a new crowd-based family, based on a probabilistic knowledge of user positions. We then propose a self-deployment method built on a Coulomb's law analogy where users and UAVs act as electrical charges. Short range interactions are implemented through network sensing, while long range ones use a crowd-based approach. Some numerical results are depicted, showing the performance of this self-deploying mechanism as well as a comparison with a well-known clustering algorithm.

As Internet usages expand quickly, access networks are modernized with new technologies like fiber-optic communications. However, upgrade costs are prohibitive in sparsely populated areas, the latter turning notably towards satellite connection. Indeed, this technology allows deploying a high-throughput Internet access quickly in these regions. Nevertheless, GEO satellites induce a long delay, not experienced on terrestrial infrastructures despite their low throughput. In this paper, we consider a heterogeneous network with both a satellite and a terrestrial path. This kind of architecture is known to be difficult to operate because of the important differences between used technologies. The emerging MP-TCP transport protocol, whose design enables to aggregate disparate paths properly, brought new hopes for heterogeneous networks. However, it does not take user Quality of Experience (QoE) into account as it focuses on maximizing the links occupancy. This paper propose an intelligent path selector using the content size to maximize users QoE in heterogeneous networks. Before detailing this method, we describe the architecture able to retrieve the size of delivered contents thanks to Content Delivery Network Interconnection (CDNI). Finally, we implement a testbed to evaluate the behavior of the proposed routing method. The results show a significant improvement of the delivery performance, outperforming MP-TCP.

The Internet Of Things (IoT) market is growing more and more every year. Today, the number of IoT devices is estimated around 8 billion but forecasts announce 20 billion devices for 2020. Terrestrial or satellite communications systems are already deployed to answer the connectivity need. These systems rely on a Random Access CHannel (RACH) used either to send resource allocation requests or directly the useful message. Because of the number of IoT devices, the overload on the RACH is an emerging issue since it may cause a service outage. This is especially the case for IoT satellite systems because of the wide area covered by a single satellite. The Access Class Barring (ACB) is the load control mechanism used within the Narrow Band IoT. Unfortunately, no method was specified to compute the load control parameters. In this paper, in the context of a satellite IoT system, we propose a method to compute dynamically ACB based load control parameters. Thanks to our method, the load control mechanism reach excellent results regarding transmission reliability and energy consumption for various traffic scenarios.

Unmanned Aerial Vehicles (UAVs) are becoming an attractive solution for road traffic monitoring because of their mobility, low cost, and broad view range. Up to now, existing traffic monitoring systems based on UAVs only use one UAV with fixed trajectory to extract information about vehicles. In this paper, we propose a road traffic monitoring system using multiple UAVs. We develop a method to generate adaptive UAVs trajectories, which is based on the tracking of moving points in the UAV field of view. Also we generate UAVs trajectories using mobility models that are usually used to model vehicles mobility. UAVs monitor the traffic on a city road, they are responsible for collecting and sending, in real time, vehicle information to a traffic processing center for traffic regulation purposes. We show that the performance of our system is better than the performance of the fixed UAV trajectory traffic monitoring system in terms of coverage rates and events detection rates.

This paper studies the opportunistic routing (OR) in unmanned aerial vehicle (UAV) assisted wireless sensor networks (WSNs). We consider the scenario where a UAV collects data from randomly deployed mobile sensors that are moving with different velocities along a predefined route. Due to the dynamic topology, mobile sensors have different opportunities to communicate with the UAV. This paper proposes the All Neighbors Opportunistic Routing (ANOR) and Highest Velocity Opportunistic Routing (HVOR) protocols. In essence, ANOR forwards packets to all neighbors and HVOR forwards them to one neighbor with highest velocity. HVOR is a new OR protocol which dynamically selects route on a pre-transmission basis in multi-hop network. HVOR helps the sensor which has little opportunity to communicate with the UAV to determine which sensor, among all the sensors that are within its range, is the forwarder. The selected node forwards the packet. As a result, in each hop, the packet moves to the sensor that has higher opportunity to communicate with the UAV. In addition, we focus on various performance metrics, including Packets Delivery Ratio (PDR), Routing Overhead Ratio (ROR), Average Latency (AL) and Average Hop Count (AHC), to evaluate the proposed algorithms and compare them with a Direct Communication (DC) protocol. Through extensive simulations, we have shown that both HVOR and ANOR algorithms work better than DC. Moreover, the HVOR algorithm outperforms the other two algorithms in terms of the average overhead.

We are facing a steady increase in Internet usages and bandwidth requirements. However, many terrestrial infrastructures remain unchanged due to exorbitant modernization costs, particularly in rural areas. In front of the aging of their infrastructures, concerned users are turning towards satellite internet access. Indeed, these solutions offer a high-throughput internet access at a moderate cost of deployment. Unfortunately, the long delay introduced by GEO satellite degrades significantly the user Quality of Experience (QoE) in many cases. In this paper, we consider a hybrid access, composed of a low data rate terrestrial path and a satellite path, within a Content Delivery Network (CDN) context. Thanks to the CDN, requested content size is known allowing to use this information in routing schemes to maximize the users' QoE. Then, we compare flow and packet based routing in this heterogeneous and size-aware context. We finally conclude on the limited interest in packet-based routing compared to flow-based routing, privileged by its simplicity and good performance from a QoE point of view.

In this paper, we present a solution for Unmanned Aerial Vehicle (UAV) energy saving problem while ensuring a continuous tracking of a mobile target. Our tracking algorithm is based on three zones, and according to the target placement in those zones, the UAV will do a specific type of actions. We proposed an additional zone called the authorized zone. In this zone, the UAV keeps a fixed velocity and a fixed altitude, and this contributes to the limitation of the energy consumption while also maintaining a minimal altitude. We also proposed an adapted criterion which considers the velocity, altitude and acceleration changes to evaluate the energy consumption. The idea here is to limit the number of the UAV adjustments to reduce the energy consumption and still keeping the target in its camera field of view.

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.

The software integration with new network architectures via SDN (Software Defined Network) axis appears to be a major evolution of networks. While this paradigm was primarily developed for easy network setup, its ability to integrate services has also to be considered. Thus, the mobility service for which solutions have been proposed in conventional architectures by defining standardized protocols should be rethought in terms of SDN service. Mobile devices might use or move in SDN network. In this paper, we have shown that SDN can be implemented without IP mobility protocol for providing mobility like as Proxy Mobile IPv6 (PMIPv6) that is the solution adopted by 3GPP, with some performance gain.

Satellite networks are easy-to-deploy solutions to connect rural un-served and underserved areas. But satellite latency has a significant negative impact on performance. Hybrid networks, combining high-throughput long-delay links (e.g. GEO satellites) and short-delay low-throughput links (e.g. poor ADSL), can improve user experience by the use of intelligent routing. Emerging solutions, such as MultiPath TCP (MPTCP), already optimize the throughput in these hybrid networks. However, this kind of solutions does not take into account QoE requirements by the lack of relevant flows information, leading to sub-optimal path selection. This paper proposes an architecture able to retrieve the content size through interconnection with Content Delivery Networks (CDNs). Then, we conduct an analytical study of a probabilistic and a size threshold based routing schemes with the Mean Value Analysis (MVA) method. This shows the great benefit brought by size information in terms of QoE. To solve the limitations due to the threshold configuration, we propose a third algorithm that takes into account the path delay and capacity. Finally, we develop a testbed in order to validate our model and to compare this third scheme to the previous ones. We obtain results equivalent to the size threshold scheme, without its disadvantages.

The rapid increase of portable devices providing a multitude of mobile applications have led to excessive cellular traffic demands and consequently to the overload of cellular networks. Recently, migrating this traffic by opportunistic vehicular networks has attracted a great interest and appeared as a promising solution. Indeed, only a limited set of vehicles (seeds) is selected to download objects from an Internet-content server through the cellular network and then propagate the content gradually by opportunistic communications (i.e. vehicle-to-vehicle V2V). This paper proposes SIEVE, an innovative seed selection scheme, that exploits two key criteria: users' interests and near-future contacts prediction. Based on these criteria, SIEVE allows to select the seeds in order to maximally satisfy the users' interests and, hence, achieve a maximum content utility (i.e. quantitative metric that determines how satisfied are the users). Simulations results show that SIEVE can improve the content utility when compared to other algorithms.

This paper studies the fault management in mobile ad hoc networks. We focus on schemes which provide the robustness in MANETs: service restoration and service protection. Firstly, we propose an analytical comparison of service restoration, in terms of restoration time, at the routing layer (reactive and proactive protocols). Service restoration with reactive protocol is the most suitable in MANETs. The second motivation of the paper is an analytical study of the service protection at the network layer (multipath routing protocols) and its interest in terms of restoration time and reliability. The advantage of route redundancy in terms of restoration depends on the probability that alternate route is running after the primary route failure. The value, of this probability is studied, according to the used link connectivity maintenance mechanisms: Link-Layer Feedback Acknowledgements (LLF), Hello messages and Network-Layer Acknowledgements [1]. In terms of reliability, the multipath protocols are always better than unipath protocols. Segment recovery is the best recovery policy in terms of reliability.

In this paper, we study data collection in mobile wireless sensor networks (WSNs) assisted by unmanned aerial vehicle (UAV). We focus on randomly deployed mobile sensors along a predefined path with different but constant velocities, and a flying UAV in different heights to collect data from the mobile sensors. As the network topology is changing under the mobility of the UAV and the sensor nodes, the design of efficient data collection protocols is a major concern. In this paper, we propose four data collection algorithms taking into account the multi-data-rate transmissions (DR) and the contact duration time (CDT) between the sensors and the UAV. Besides, we propose a fairness metric to evaluate the algorithms. Through extensive simulations, we examine the effectiveness of the proposed algorithms under different configurations and show how the algorithm combining DR and CDT outperforms the others in terms of number of collected packets and weighted fairness.

Sensor Networks can be envisaged to monitor mobile systems. Nevertheless, new challenges appear from mobility such as delay and connectivity disruptions. These challenges can be tackled by the Delay/Disruption Tolerant Networking architecture. However, implementing DTN mechanisms on sensors require to select the schemes which propose an efficient use of the memory. Our scheme, FREAK, aims at providing high performance with low-memory usage. This scheme relies on the mean frequency of past encounter with the base station. Transmissions are driven by this metric. The FREAK solution is keen because we assume that future can be predicted from the past events. The acknowledgements effects on performance is analysed. We run simulations using mobility quota-based mainstreammodels and real traces. FREAK is compared to several replication and quota-based mainstream DTN solutions and achieves quite better performance in realistic scenarios.

The mobile context of Mobile Wireless Sensor Networks (MWSN) limits the existence of a direct route from source to destination. A Disruption Tolerant Networking (DTN) architecture fits the requirements for such a context where messages need to be stored, carried and forwarded. For this kind of DTN applications, the goal is to achieve a high delivery ratio at low transmission cost with the lowest latency. Some DTN routing protocols use this ACK information to decrease the number of useless transmissions. Nevertheless in memory-constrained environments, the proportion of memory allocated to ACKs is a problem to study. This paper focuses on the use of acknowledgements (ACKs). We model the network with a Markov chain, to study the effect of ACKs on buffer time occupancy. Finally, an extensive set of simulations is run to analyse the influence of the memory proportion allocated to ACKs, on the performance.

In this paper, we address the design of a cooperative protocol for a hybrid satellite/terrestrial emergency system. We want to perform energy savings compared to the case where all the terrestrial relay nodes are forwarding satellite messages to ground receivers. This is done via the selection of relevant relay nodes. The parameterization of the protocol phases has been done through simulations and takes into account the duration of the selection process, the number of selected nodes, and the signaling overhead. The selection process based on a node identifier (ID) appears to provide greater energy savings compared to the selection process based on the signal to interference and noise ratio (SINR). The solutions have been implemented in the real case scenario of forest fire that has been thoroughly documented by the US administration. According to the scenario parameters, 100% of the masked nodes are reached after cooperation.

Recent work has shown that content dissemination protocols in vehicular networks can achieve throughput and fan-out delay optimization by either simple network flooding or destination-driven dissemination. While those content dissemination schemes work well, they require all nodes in the network to forward every data packet, which has inherent inefficiencies for non-flooding traffic patterns, where not all nodes need to receive the data. Hence, they support adequately safety applications, being not efficient for non-safety applications, whereby the flow of information is interest-driven rather than destination-driven, e.g. restaurant recommendation and sale advertisement. In this work, the concept of “useful” forwarder is formalized aiming at maximizing content utility for end users. Further, it presents I-SEND, a forwarder selection approach, which enables nodes to choose the most appropriate forwarders. Incorporating I-SEND on trace-driven and synthetic simulation scenarios can produce higher content utility than other concurrent schemes.

In this paper, a new cooperative MAC protocol with distributed relay selection and rate adaptation is proposed in the context of multi-rate ad hoc networks. When the wireless link between a source and a destination nodes experiences poor channel conditions, a relay station is selected in the vicinity of both nodes so that the low data rate direct link is replaced by a two-hop path with a higher data rate. The relay station is selected through a distributed contention process. The procedure requires no topology knowledge and no communication among potential relays. A data rate adaptation is also performed without any additional signaling. The best-relay selection and the rate adaptation are based on instantaneous channel measurements to adapt to dynamic channel conditions. Results show that cooperative transmissions significantly outperform conventional non-cooperative transmissions in terms of throughput, delay and energy consumption.

Energy efficiency has emerged as a defining scientific and engineering challenge of our time. Ethernet, as the dominant wireline technology, has been a focus of intense research and development efforts with the goal of significantly decreasing its energy consumption. In 2010 the IEEE Std 802.3az, which uses a Low Power Idle (LPI) mode to reduce the energy consumption of a link when there is no data traffic, was approved. Recently, the major manufacturers have brought to market the first switches the implement the new energy efficient standard. In this paper, we make use of the first generation of hardware that support the IEEE 802.3az to get a better understanding of the behavior of energy efficient mechanisms for ethernet. Based on measurement on DLINK switches that are IEEE 802.3az compliant, we build a power model that reflects more accurately the power used by real hardware in practice. We use the measurement-driven power model to analyze the behavior of Lazy Start, the state of the art algorithm for energy efficient ethernet, in the ns-3 simulator. Based on our analysis, we provide recommendations for improvements and potential directions for future work.

In this paper, a new Medium Access Control (MAC) protocol combining Transmit Power Control (TPC), Rate Adaptation (RA) and Cooperative Transmission (CT) is proposed, in the context of multi-rate ad hoc networks. The protocol aims to achieve energy efficiency of data transmission while increasing the overall network throughput. The key idea of the protocol is to allow each wireless node to create a table with the optimal power-rate combinations based only on the network interface card specifications. In the presence of low data-rate nodes the network throughput is greatly degraded. To mitigate this well-known “rate anomaly” problem we use CT to replace the direct low-rate links by relayed high-rate links. By exchanging control frames and looking up the power-rate table, the wireless node chooses the most suitable transmission strategy (which consists of selecting the most optimal power-rate combination) for each data-frame as well as the transmission scheme (direct or relayed). Results reveal an important improvement in the overall network throughput as well as in the energy consumption with the new protocol compared to the scheme without TPC and without cooperation. Furthermore, simulation results show that our scheme deliver more data per unit of energy consumption than the IEEE 802.11 scheme.

Both WSNs (Wireless Sensor Networks) and observation satellites are able to get measurements from a geographic area. To interconnect these technologies, we propose to use a store-carry-and-forward architecture relying on the DTN (Disruption and Delay Tolerant Networking) Bundle Protocol. This architecture aims at being generic, so it is application-agnostic and suits a wide range of scenarios. WSN may collect sporadically large data volume while terrestrial stations communicating with Low Earth Orbit (LEO) satellites have to endure long link disruptions when the satellite is not in the line of sight. These sporadic growths within the WSN coupled with the large latency on satellite links require to schedule data to provide quality of service to several flows. We propose a scheduling policy based on deadline of Bundles and compare it with classical DTN solutions.

To improve the robustness and adaptation to node mobility, ad hoc routing protocol uses as route selection criterion, the route reliability metric between end points. In the first part of this paper, we derive an analytical closed form expression for the computation of route reliability metric, that takes into account dependencies between adjacent links. Based on our analytical formulation, the route reliability metric computation does not introduce any complexity. Simulations show that our model can obtain more accurate results than the traditional methods. However, the route reliability metric increases network resources used in terms of intermediate nodes between source and destination. It may also increase packet delay. Moreover, the interference and collision probability between packet increase when the number of relays in the same range increases. In order to overcome these inconveniences, in the second part of this paper, we propose a new routing metric which combines reliability and hop count criteria. Simulations results show that the introduced metric allows better results.

Due to the unreliability characteristics of wireless communications, and nodes mobility, mobile ad hoc networks demand robust protocol design. Hence, routing protocol choosing the most reliable route between two terminals have been proposed in order to minimize the path failure occurrence. The interest of this approach has been shown, in research literature, mainly by simulation in terms of delay or packet delivery ratio. Meanwhile, there is a problem to put in practice the route reliability paradigm. The route reliability depends on links reliability. The motivation of this paper is to determine a measure of the link reliability. In this paper, we study the link reliability formulation in order to propose a realistic wireless link parameters modeling. The modeling takes into account the mobility, the transmission quality, and the communication load. Reliability can be computed without extra signaling by each node.

Long Term Evolution (LTE) prevails as the next 4thgeneration of mobile communications. Hybrid satellite and terrestrial LTE network takes advantages from the large satellite coverage for several emergency applications, such as providing civil security communications. In this paper we propose a LTE architecture partly composed of an integrated component with satellite backhaul on the LTE-S1 interface. Since ensuring seamless communications is essential in LTE, we describe an optimization of the handover mechanism adapted to this specific architecture. This paper focuses on the handover between an eNB with a satellite S1 interface and an eNB with a standard terrestrial S1 interface.

The lifetime of Wireless Sensor Networks (WSN) is crucial. The goal of all WSN application scenarios is to have sensor nodes deployed, unattended, for months or years. In this work, we investigate the problem of energy consumption and lifetime maximizing in a many-to-one sensor network. In such network pattern, all sensor nodes generate and send data to a single sink via multihop transmissions. In our previous experimental studies, we noticed that, since all the sensor data has to be forwarded to a base station via multihop routing, the traffic pattern is highly nonuniform, putting a high burden on the sensor nodes close to the base station. In this paper, we analyze and propose some strategies that balance the energy consumption of these nodes and ensure maximum network lifetime by balancing the load as equally as possible.

Temperature control is a major concern in cold chain monitoring and traceability services for the largest cause of food poisoning. Considerable work has examined the use of wireless solutions in warehouses. However, the maintaining of the chain during the transportation phase remains very crucial. In this paper, we present new wireless sensor network (WSN) solution for cold chain monitoring. This solution is based on self-organizing protocols and aims at saving energy in order to increase the sensor lifetime and as a result the global network longevity within the given context. Furthermore, this solution does not need any base station or central equipment. To save energy, periodical active/sleep schedule is adopted in the design of our protocols which were dimensioned and validated by an analytical model described in this paper.

Wireless sensor networks (WSN) have received much attention during the last few years especially with regard to energy consumption and scalability. In this paper, we will focus on mechanisms which may be implemented for small WSNs. So, in the present work, we design energy-aware self-organization algorithms for WSNs in such a context. These algorithms can be used to design effective and adaptive protocols. The first protocol concerns the initialization or the setting up of the network topology under a chain form. The second one (steady-state protocol) implements the communication part or the information exchange between the different nodes of the chain. Our algorithms were dimensioned and validated by an analytical model. We also perform a detailed study of these algorithms by using TOSSIM, a simulation environment for TinyOS, the operating system for the Berkeley sensor nodes. Finally, we achieve an experimental test using Tmote Sky nodes, a popular commercial hardware platform for wireless sensor systems. The results emphasize the interest of the proposed algorithms.

Next generation networks will be characterized by variable and high data rates, QoS, and seamless mobility, within a network and between heterogeneous networks with different technologies and service providers. In this paper, we consider a model of mobility for WiMAX network users introducing horizontal handover mechanism with channel reservation. We take into account several approaches in order to carry out the reservation. We evaluate the performance of the proposed model. The results show, by means of simulation, that channel reservation mechanism improves horizontal handover without reducing the performance of the system.

Mobility issue and service continuity represent important challenges for next generation networks. The integration of a satellite segment within a terrestrial network (especially WiMAX) has several advantages in a 4G context. In this paper, we focus on channel reservation mechanisms to ensure quality of service. Primary results show, by means of simulation, the gains and limitations of each mechanism. It is shown that the best results are obtained when the mechanisms are performed by the base stations when the density of users is low. Otherwise, cooperative solutions for which reservations are done by neighboring nodes may improve the performance of the system.