A New Buffer and Energy Based Scheduling Scheme for Supporting QoS in MANETs

Today, the original IEEE 802.11 standard has several problems in providing Quality of Service in MANETs. A single FIFO queue is used in best effort manner and it does not support QoS. The upcoming IEEE 802.11e was drafted to overcome these drawbacks. In this paper we describe a new multiple queuing system with an adaptive scheduling taking into account the states of buffers and energy consumption in a mobile ad hoc network. The proposed scheduling scheme uses dynamic weights for each queue. We study the performance of this scheme and compare it with the original IEEE 802.11b and the upcoming IEEE 802.11e. We show through simulations that the proposed buffer and energy based scheduling scheme improves overall end-to-end throughput, and gives better results than the original 802.11b and the Enhanced Distributed Coordination Function (EDCF), in terms of delay and total received and lost packets, as well as support service differentiation over multi-hop ad hoc networks

Helper, Sharer or Seeker? - A Concept to Determine Knowledge Worker Roles in Enterprise Social Networks

In order to manage knowledge work, companies need to understand how knowledge is shared, integrated, translated and transformed in organisa-tional practice. However, knowledge work often happens in informal organisa-tional structures, thus, making it difficult to identify and understand the occurring knowledge practices and participating actors. Enterprise Social Networks (ESN), i.e. internally accessible social networking services, have evolved as important platforms for knowledge work. Facilitating knowledge interactions between us-ers, the analysis of ESN data might be well suited for characterising and identi-fying knowledge actions and different knowledge worker roles. Drawing on an existing knowledge worker role typology as well as findings from social media research, this paper develops a conceptual basis that serves as starting point for determining knowledge worker roles using ESN data. The next steps of this re-search involve the empirical testing of the typology using data obtained from a real case scenario

Autonomous Energy Management system achieving piezoelectric energy harvesting in Wireless Sensors

International audienceWireless Sensor Networks (WSNs) are extensively used in monitoring applications such as humidity and temperature sensing in smart buildings, industrial automation, and predicting crop health. Sensor nodes are deployed in remote places to sense the data information from the environment and to transmit the sensing data to the Base Station (BS). When a sensor is drained of energy, it can no longer achieve its role without a substituted source of energy. However, limited energy in a sensor's battery prevents the long-term process in such applications. In addition, replacing the sensors' batteries and redeploying the sensors is very expensive in terms of time and budget. To overcome the energy limitation without changing the size of sensors, researchers have proposed the use of energy harvesting to reload the rechargeable battery by power. Therefore, efficient power management is required to increase the benefits of having additional environmental energy. This paper presents a new self-management of energy based on Proportional Integral Derivative controller (PID) to tune the energy harvesting and Microprocessor Controller Unit (MCU) to control the sensor modes

S-ROGUE: Routing protocol for Unmanned Systems on the Surface

International audienceThe cooperation of heterogeneous unmanned systems , for instance, between aerial engines and terrestrial engines, relies on reliable communication. Data delivery is ensured by routing protocols, but traditional routing approaches, MANET and DTN, are not efficient in such networks. In this paper, we propose the S-ROGUE routing protocol combining the paradigms MANET and DTN and switching between them according to the network connectivity. On the one hand, the S-ROGUE MANET algorithm relies on a proactive approach and a novel metric to anticipate link disruptions and detect unidirectional links. On the other hand, the S-ROGUE DTN algorithm uses on a reinforcement learning technique to select the best routing action. It implements also a replication control and packet prioritization to improve routing performances. We lead a performance evaluation of S-ROGUE with similar routing protocols in realistic simulated environments and conclude that S-ROGUE has the best routing performance regardless the scenarios

Leveraging Communicating UAVs for Emergency Vehicle Guidance in Urban Areas

International audienceThe response time to emergency situations in urban areas is considered as a crucial key in limiting material damage or even saving human lives. Thanks to their "bird's eye view" and their flexible mobility, Unmanned Aerial Vehicles (UAVs) can be a promising candidate for several vital applications. Under these perspectives, we investigate the use of communicating UAVs to detect any incident on the road, provide rescue teams with their exact locations, and plot the fastest path to intervene, while considering the constraints of the roads. To efficiently inform the rescue services, a robust routing scheme is introduced to ensure a high level of communication stability based on an efficient backbone, while considering both the high mobility and the restricted energy capacity of UAVs. This allows both predicting any routing path breakage prior to its occurrence, and carrying out a balanced energy consumption among UAVs. To ensure a rapid intervention by rescue teams, UAVs communicate in an ad hoc fashion with existing vehicles on the ground to estimate the fluidity of the roads. Our system is implemented and evaluated through a series of experiments. The reported results show that each part of the system reliably succeeds in achieving its planned objective

LAR Image transmission over fading channels: a hierarchical protection solution

International audienceThe aim of this paper is to present an efficient scheme to transmit a compressed digital image over a non frequency selective Rayleigh fading channel. The proposed scheme is based on the Locally Adaptive Resolution (LAR) algorithm, and the Reed-Solomon error correcting code is used to protect the data against the channel errors. In order to optimize the protection rate and ensure better protection we introduce an Unequal Error Protection (UEP) strategy, where we take the hierarchy of the information into account. The digital communication system also includes appropriate interleaving and differential modulation. Simulation results clearly show that our scheme presents an efficient solution for image transmission over wireless channels, and provides a high quality of service, outperforming the JPWL scheme in high bit error rate conditions

A survey of V2V channel modeling for VANET simulations

International audienceMost Vehicle to Vehicle (V2V) network protocols are evaluated by simulation. However in most network simulators, the physical layer suffers from a lack of realism. Therefore, realistic V2V channel modeling has become a crucial issue in Intelligent Transportation Systems (ITS) networks. V2V channels are known to exhibit specific features which imply the design of new simulation models. In this survey paper, we first recall the main physical features of such wireless time and frequency dispersive channels. Next, three "simulation-ready" V2V channel models found in the literature are reviewed. Finally, two complete VANET simulation frameworks are presented. They illustrate the importance of a realistic channel and physical layer modeling in vehicular networking

ECaD: Energy‐efficient routing in flying ad hoc networks

Much progress can be expected in the domain of unmanned aerial vehicle (UAV) communication by the next decade. The cooperation between multiple UAVs in the air exchanging data among themselves can naturally form a flying ad hoc network (FANET). Such networks can be the key support to accomplish several kinds of missions while providing the required assistance to terrestrial networks. However, they are confronted with many challenges and difficulties, which are due to the high mobility of UAVs, the frequent packet losses, and the weak links between UAVs, all affecting the reliability of the data delivery. Furthermore, the unbalanced energy consumption may result in earlier UAV failure and consequently accelerate the decrease of the network lifetime, thus disrupting the overall network. This paper supports the use of the movement information and the residual energy level of each UAV to guarantee a high level of communication stability while predicting a sudden link breakage prior to its occurrence. A robust route discovery process is used to explore routing paths where the balanced energy consumption, the link breakage prediction, and the connectivity degree of the discovered paths are all considered. The performance of the scheme is evaluated through a series of simulations. The outcomes demonstrate the benefits of the proposed scheme in terms of increasing the lifetime of the network, minimizing the number of path failures, and decreasing the packet losses.Much progress can be expected in the domain of unmanned aerial vehicle (UAV) communication by the next decade. The cooperation between multiple UAVs in the air exchanging data among themselves can naturally form a flying ad hoc network (FANET). Such networks can be the key support to accomplish several kinds of missions while providing the required assistance to terrestrial networks. However, they are confronted with many challenges and difficulties, which are due to the high mobility of UAVs, the frequent packet losses, and the weak links between UAVs, all affecting the reliability of the data delivery. Furthermore, the unbalanced energy consumption may result in earlier UAV failure and consequently accelerate the decrease of the network lifetime, thus disrupting the overall network. This paper supports the use of the movement information and the residual energy level of each UAV to guarantee a high level of communication stability while predicting a sudden link breakage prior to its occurrence. A robust route discovery process is used to explore routing paths where the balanced energy consumption, the link breakage prediction, and the connectivity degree of the discovered paths are all considered. The performance of the scheme is evaluated through a series of simulations. The outcomes demonstrate the benefits of the proposed scheme in terms of increasing the lifetime of the network, minimizing the number of path failures, and decreasing the packet losses