Search results for "Computer Networks"
showing 10 items of 860 documents
Verification of JADE Agents Using ATL Model Checking
2015
It is widely accepted that the key to successfully developing a system is to produce a thorough system specification and design. This task requires an appropriate formal method and a suitable tool to determine whether or not an implementation conforms to the specifications. In this paper we present an advanced technique to analyse, design and debug JADE software agents, using Alternating-time Temporal Logic (ATL) which is interpreted over concurrent game structures, considered as natural models for compositions of open systems. In development of the proposed solution, we will use our original ATL model checker. In contrast to previous approaches, our tool permits an interactive or programma…
Learning From Errors: Detecting Cross-Technology Interference in WiFi Networks
2018
In this paper, we show that inter-technology interference can be recognized using commodity WiFi devices by monitoring the statistics of receiver errors. Indeed, while for WiFi standard frames the error probability varies during the frame reception in different frame fields (PHY, MAC headers, and payloads) protected with heterogeneous coding, errors may appear randomly at any point during the time the demodulator is trying to receive an exogenous interfering signal. We thus detect and identify cross-technology interference on off-the-shelf WiFi cards by monitoring the sequence of receiver errors (bad PLCP, bad FCS, invalid headers, etc.) and propose two methods to recognize the source of in…
What's New for QoS in IEEE 802.11?
2013
Two amendments to IEEE 802.11 have recently been published: 802.11aa and 802.11ae. Both enhance Quality of Service (QoS) provisioning in Wi-Fi networks by providing support for multicast transmission, enhanced audio video streaming, coping with inter-network interference, and improved prioritization of management frames. The proposed solutions either extend mechanisms already existing in the standard or introduce new ones. Therefore, it is important for researchers to understand the new functionalities. To this end we provide the first description of these latest mechanisms: we present the motivation behind them, explain their design principles, provide examples of usage, and comment on com…
Estimation techniques to measure subjective quality on live video streaming in Cloud Mobile Media services
2018
Abstract The adoption of smart phones, the increased access to mobile broadband networks and the availability of public cloud infrastructures are aligning to the next generation of truly ubiquitous multimedia services, known as Cloud Mobile Media (CMM) services offering mobile video. Nevertheless, due to an inherit higher and variable end to end delay mainly as a result of the virtualization process, new challenges appear. One challenge is given by live video streaming applications when trying to keep a good Quality of Experience of the delivered video, measured in terms of a subjective video quality metric, named Mean Opinion Score (MOS). Our goal is to estimate and predict this subjective…
Multimedia application to support distance learning and other social interactions in real-time
2000
Supporting social interactions, in distance learning situations for example, with modern technology is very difficult. Generally Internet, networked PC, document handling and communication services and applications are not designed from a multiple user perspective but to support a one-person-one-device (or tool) interaction. This approach creates problems for supporting awareness of, and communication with other people while simultaneously working on documents. Such simultaneous activities have been identified as essential by CSCW and CHI studies, where users are reported to move promiscuously between media and devices, and combine applications and media intuitively, while maintaining aware…
Applying a web-based training to foster self-regulated learning — Effects of an intervention for large numbers of participants
2016
Trainings on self-regulated learning (SRL) have been shown to be effective in improving both competence of self-regulated learning and objective measures of performance. However, human trainers can reach only a limited number of people at a time. Web-based trainings (WBT) could improve efficiency, as they can be distributed to potentially unlimited numbers of participants. We developed a WBT based on the process model of SRL by Schmitz and Wiese (2006) and tested it with 211 university students in a randomized control evaluation study including additional process analyses of learning diaries. Results showed that the training had significant effects on SRL knowledge, SRL behavior measured by…
Scalable Virtual Network Video-Optimizer for Adaptive Real-Time Video Transmission in 5G Networks
2020
The increasing popularity of video applications and ever-growing high-quality video transmissions (e.g., 4K resolutions), has encouraged other sectors to explore the growth of opportunities. In the case of health sector, mobile Health services are becoming increasingly relevant in real-time emergency video communication scenarios where a remote medical experts’ support is paramount to a successful and early disease diagnosis. To minimize the negative effects that could affect critical services in a heavily loaded network, it is essential for 5G video providers to deploy highly scalable and priorizable in-network video optimization schemes to meet the expectations of a large quantity of vide…
Effect of size and deformation on polarizabilities of carbon nanotubes from atomic increments
2004
The interacting induced-dipole polarization model implemented in program POLAR is used for the calculation of the polarizability α. The method is tested with single-wall carbon nanotubes (SWNTs) as a function of radius and elliptical deformation. This work gives a partial success with the application of POLAR when compared with reference calculations performed with program PAPID. α follows a simple law. PAPID differentiates more effectively than POLAR among SWNTs with increasing radial deformation, a can be modified reversibly by external radial deformation. Different effective αeff are calculated for the atoms at the highest and lowest curvature sites. The difference between POLAR and PAPI…
LaCoDa: Layered connected topology for massive data centers
2017
One of the fundamental challenges of existing data centers is to design a network that interconnects massive number of servers, and therefore providing an efficient and fault-tolerant routing service to upper-layer applications. Several solutions have been proposed (e.g. FatTree, DCell and BCube), however they either scale too fast (i.e., double exponentially) or too slow. This paper proposes a new data center topology, called LaCoDa, that combines the advantages of previous topologies while avoiding their limitations. LaCoDa uses a small node degree that matches physical restriction for servers, and it also interconnects a large number of servers while reducing the wiring complexity and wi…
A new proposed cloud computing based architecture for space ground data systems
2018
International audience; Many companies decided to move towards the cloud computing technology in order to manage, monitor and explore huge space data amount in the space ground data systems. The corresponding transition adaptation needs a study to classify each space related service in the appropriate cloud computing service model layer; SaaS, PaaS and IaaS. In this paper, we specify a representation of proposed cloud computing based ground data system architecture for earth observation missions. The proposed architecture takes into consideration the collaboration aspect between multiple space agencies. We evaluate the time, storage and processing performance when using the cloud computing …