Institute of Electron Technology
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2189 research outputs found
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Spectrum Management. Part 1. Telekomunikacja i Techniki Informacyjne, 2013, nr 3
Get PDFAs preparations for the Year 2000 World Radiocommunication Conference continue in earnest, ITU News will bring you in-depth analyses of what is at stake in the complex radio world. Indeed, how the spectrum/orbit resources are used and managed has a profound impact on society, its prosperity, security, culture, and education. This article takes you back in history on the use, management and regulation of the radio frequency spectrum resources. It then discusses current trends
Application of High-Performance Techniques for Solving Linear Systems of Algebraic Equations, Journal of Telecommunications and Information Technology, 2013, nr 4
Get PDFSolving many problems in mechanics, engineering, medicine and other (e.g., diffusion tensor magnetic resonance imaging or finite element modeling) requires the efficient solving of algebraic equations. In many cases, such systems are very complex with a large number of linear equations, which are symmetric positive-defined (SPD). This paper is focused on improving the computational efficiency of the solvers dedicated for the linear systems based on incomplete and noisy SPD matrices by using preconditioning technique – Incomplete Cholesky Factorization, and modern set of processor instructions – Advanced Vector Extension. Application of these techniques allows to fairly reduce the computational time, number of iterations of conventional algorithms and improve the speed of calculation
Performance Tests of Xen-based Node for Future Internet IIP Initiative, Journal of Telecommunications and Information Technology, 2013, nr 3
Get PDFIn this paper the authors intend to report results for performance evaluation of Xen-based node providing both transport and computational functionalities. This node design is proposed as the implementation platform developed for the Polish Initiative of Future Internet called System IIP. In particular, we search for mutual dependence among transport and computational performance parameters of the node. Our investigations show that there is significant dependence among performance indices, such as virtual link bandwidth and node’s processing power, strongly depending on frame size. The tests and measurements were done according to fundamental methodology designed for network devices, described in RFC 2544. The goal of those investigations is to design a provisioning module allocating both transport and computational resources
Single Hysteresis Model for Limited-availability Group with BPP Traffic, Journal of Telecommunications and Information Technology, 2013, nr 3
Get PDFThis paper presents a single hysteresis model for limited-availability group that are offered Erlang, Engset and Pascal traffic streams. The occupancy distribution in the system is approximated by a weighted sum of occupancy distributions in multi-threshold systems. Distribution weights are obtained on the basis of a specially constructed Markovian switching process. The results of the calculations of radio interfaces in which the single hysteresis mechanism has been implemented are compared with the results of the simulation experiments. The study demonstrates high accuracy of the proposed model
Approximation of Message Inter-Arrival and Inter-Departure Time Distributions in IMS/NGN Architecture Using Phase-Type Distributions, Journal of Telecommunications and Information Technology, 2013, nr 3
Get PDFCurrently it is assumed that requirements of the information society for delivering multimedia services will be satisfied by the Next Generation Network (NGN) architecture, which includes elements of the IP Multimedia Subsystem (IMS) solution. In order to guarantee Quality of Service (QoS), NGN has to be appropriately designed and dimensioned. Therefore, proper traffic models should be proposed and applied. This requires determination of queuing models adequate to message inter-arrival and inter-departure time distributions in the network. In the paper the above mentioned distributions in different points of a single domain of NGN are investigated, using a simulation model developed according to the latest standards and research. Relations between network parameters and obtained message inter-arrival as well as inter-departure time distributions are indicated. Moreover, possibility of approximating the above mentioned distributions using phase-type distributions is investigated, which can be helpful in identifying proper queuing models and constructing an analytical model suitable for NGN
On the Optimal Design of a Broadcast Data Dissemination System over VANET Providing V2V and V2I Communications “The Vision of Rome as a Smart City”, Journal of Telecommunications and Information Technology, 2013, nr 1
Get PDFIn different this paper we present the performance evaluation study of a simple broadcast data dissemination technique in new emerging Vehicular Ad hoc Networks (VANETs). Differently from the traditional Mobile Ad hoc NETworks (MANETs), VANETs require particular routing protocols, due to the high dynamism of the network topology, and to different traffic and mobility patterns. For safety and emergency message applications, broadcast data dissemination is an important key factor in VANETs. However, the design of optimal deployment of relay nodes in different network scenarios allows to enhance system performance. At this aim, this work analyzes vehicular network performances in terms of throughput and delays, for different traffic scenarios, exploiting both inter-vehicular communications, as well as the availability of fixed network infrastructure
Diversity of Temporal and Territorial Social Penetration Rates of Information Technology in Europe, Journal of Telecommunications and Information Technology, 2013, nr 1
Get PDFThis paper presents the diversity of social penetration rates of information and communication technologies (ICT) among selected European countries according to European statistics on diverse ICT indicators. The data considered cover the 2006–2010 time range and was obtained from the Eurostat portal. The scope of the study selected EU countries – Belgium, Germany, France, Finland, Sweden, Bulgaria, Czech Republic, Poland, Slovenia, Spain. The following ICT indicators were analyzed: percentage of households or corporations with broadband access to the Internet (HHBAI), percentage of individuals who are regularly using the Internet (IRUI), percentage of individuals who ordered goods or services over the Internet (IOGSI). These indicators of ICT penetration rate in the countries examined were analyzed in terms of the following aspects: forecasting (estimates until the year 2035), maximum speed of change of these indicators (the pace of social penetration of information technology), delays or advances (in years) as compared to the averages in EU. The results are presented in tables and graphs. General conclusions and directions of future research are indicated at the end of the paper
Quality Aware Virtual Service Delivery System, Journal of Telecommunications and Information Technology, 2013, nr 3
Get PDFThe problem of providing support for quality of service (QoS) guarantees is studied in many areas of information technologies. In recent years the evolution of software architectures led to the rising prominence of the Service Oriented Architecture (SOA) concept. For Web-based systems there are three attributes that directly relate to everyday perception of the QoS for the end user: availability, usability, and performance. The paper focuses on performance issues of service delivery. The architecture of Virtual Service Delivery System (VSDS), a tool to serve requests for synchronized services is presented. It is proposed suitable monitoring technique used for estimation of values of service parameters and allocation of communication and execution resources by means of service distribution. The paper also presents results of experiments performed in real environment that show effectiveness of proposed solutions