Search results for "Information and communication Technology"
showing 10 items of 345 documents
Performance Analysis of Cooperative Communication Systems with Imperfect Channel Estimation
2009
This paper investigates the effects of channel estimation errors on the symbol-error-rate (SER) performance of a cooperative communication system operating in an amplify-and- forward (AF) mode. A pilot symbol assisted modulation scheme with linear minimum mean square estimation (LMMSE) is used for the channel estimation. An accurate and easy-to-evaluate SER expression is presented for uncoded cooperative communication systems with quadrature amplitude modulation (QAM) and phase-shift keying (PSK) constellations. Numerical simulations are conducted to verify the correctness of the proposed analytical formulation. It is shown that the performance loss caused by channel estimation errors incre…
Some organizational changes from the incorporation of ICT. A study of cases in two centers of elementary education
2007
In this communication we try to show the conclusions of an investigation which aim was to analyse the changes experienced by the organization of the centers of primary with the progressive incorporation of the computer technologies. At the moment of introducing the above mentioned technologies tensions and confusion are generated but also innovation and change expectancy, of wich it follows finally a series of actions in the shape of modifications or variations in your organization. For it, we investigate in this study about questions as what role does play the commission of pedagogic coordination? What do the teams of teachers say in this process? What paper does the coordinator of compute…
Delivering Services to Residential Appliances by Utilizing Remote Resource Awareness
2008
Service providers are nowadays offering a variety of services, and in particular multimedia content delivery. Besides, consumer appliances are increasingly becoming digitalized including support for communication networks. However, it is difficult, and in many cases impossible, to use these services with standard consumer appliances, such as TV and media player devices. Rather, usage is often restricted so that they can only be accessed through web browsers from PCs, mobile phones and similar terminals. This is unfortunate, because dedicated consumer appliances are often better suited to handle the content and thereby give consumers a better experience. Within this paper, three design appro…
Broadband Internet Access via Multi-Hop Wireless Mesh Networks: Design, Protocol and Experiments
2010
Published version of an article from the journal: Wireless Personal Communications. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11277-009-9907-9 While bandwidth for Internet access in urban areas is steadily increasing in recent years, many rural areas are still suffering from the effect of the digital divide. This paper presents a broadband Internet access paradigm developed in the context of the ADHOCSYS project, which was financed by the European Commission under the 6th Framework Program Information and Society Technologies, within the strategic objective of Broadband for All. Aiming at providing reliable Internet access in rural and mountainous regi…
A Learning Automata Based Solution to Service Selection in Stochastic Environments
2010
Published version of a paper published in the book: Trends in Applied Intelligent Systems. Also available on SpringerLink: http://dx.doi.org/10.1007/978-3-642-13033-5_22 With the abundance of services available in today’s world, identifying those of high quality is becoming increasingly difficult. Reputation systems can offer generic recommendations by aggregating user provided opinions about service quality, however, are prone to ballot stuffing and badmouthing . In general, unfair ratings may degrade the trustworthiness of reputation systems, and changes in service quality over time render previous ratings unreliable. In this paper, we provide a novel solution to the above problems based …
Discretized Bayesian Pursuit – A New Scheme for Reinforcement Learning
2012
Published version of a chapter in the book: Advanced Research in Applied Artificial Intelligence. Also available from the publisher at: http://dx.doi.org/10.1007/978-3-642-31087-4_79 The success of Learning Automata (LA)-based estimator algorithms over the classical, Linear Reward-Inaction ( L RI )-like schemes, can be explained by their ability to pursue the actions with the highest reward probability estimates. Without access to reward probability estimates, it makes sense for schemes like the L RI to first make large exploring steps, and then to gradually turn exploration into exploitation by making progressively smaller learning steps. However, this behavior becomes counter-intuitive wh…
Solving Non-Stationary Bandit Problems by Random Sampling from Sibling Kalman Filters
2010
Published version of an article from Lecture Notes in Computer Science. Also available at SpringerLink: http://dx.doi.org/10.1007/978-3-642-13033-5_21 The multi-armed bandit problem is a classical optimization problem where an agent sequentially pulls one of multiple arms attached to a gambling machine, with each pull resulting in a random reward. The reward distributions are unknown, and thus, one must balance between exploiting existing knowledge about the arms, and obtaining new information. Dynamically changing (non-stationary) bandit problems are particularly challenging because each change of the reward distributions may progressively degrade the performance of any fixed strategy. Alt…
Secure and efficient data storage in unattended wireless sensor networks
2009
©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Article also available from publisher: http://dx.doi.org/10.1109/NTMS.2009.5384753 Providing forward and backward secrecy is still a big challenge in Unattended Wireless Sensor Networks (UWSNs), though some storage schemes have been proposed. Additionally, high storage requirement needs efficient storage techniques. In this paper, we propose a novel homomorphic…
Didactics of ICT in Secondary Education: Conceptual Issues and Practical Perspectives
2009
Article published in the journal: Issues in Informing Science and Information Technology. Also available from the publisher: http://iisit.org/Vol6/IISITv6p153-178Hadjerrouit605.pdf While there is a huge research literature on the field of ICT (Information and Communication Technology) as a tool in teaching and learning, there is much less research on the area of ICT as a subject or similar designations such as school informatics. As a result, there is a lack of theoretical grounding of the didactics of ICT and associated teaching and learning processes. One of the main reasons for the lack of theoretical underpinnings of the didactics of ICT is that there have been in the past and there per…
PMG-Pro: A Model-Driven Development Method of Service-Based Applications
2011
Published version of a chapter published in the book: SDL 2011: Integrating System and Software Modeling. Also available from the publisher at: http://dx.doi.org/10.1007/978-3-642-25264-8_12 In the Internet of Things, billions of networked and software-driven devices will be connected to the Internet. They can communicate and cooperate with each other to form a composite system. In this paper, we propose PMG-pro (present, model, generate and provide), a language independent, bottom-up and model-driven method for the development of such composite system. We envision that all devices in the Internet of Things provide their functionalities as services. From a service description, a service pre…