Institute of Electron Technology
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An Experiment on Multi-Video Transmission with Multipoint Tiled Display Wall, Journal of Telecommunications and Information Technology, 2012, nr 1
Get PDFIn order to realize realistic remote communication between multipoint remote places via the Internet, displaying the appearance of remote participants by transmission of a video streaming with the large-sized display system is effective. However, the display of video streaming with sufficient quality is difficult because the specification of a commercial projector and large-sized display equipment is low-resolution. In order to these issues, we focus on the tiled display wall technology which configure effective wide-area screen system with two or more LCD panels and tried to display a high-resolution video streaming on the large-scale display environment. In this paper, we have constructed remote communication environment with tiled display wall in multipoint sites and have conducted experiment in order to study the possibility of realizing realistic remote communication with multi-video streaming. As these results, these video streaming from each site have been shown to display more high-quality than magnified view of video image by a single small camera. Moreover, we have measured the network throughput performance for each transmitted and received video streaming in this environment. From measurement results, the steady throughput performance has been gained at the case of each transmitted and received video streaming
Compact Broadband Rat-Race Coupler in Multilayer Technology Designed with the Use of Artificial Right- and Left-Handed Transmission Lines, Journal of Telecommunications and Information Technology, 2012, nr 2
Get PDFThe paper presents a compact broadband rat-race coupler for the first time designed and realized in a multilayer microstrip technology. To achieve both broad operational bandwidth and a compact size the 270◦ transmission line of a conventional rat-race, coupler has been replaced by a –90◦ left-handed transmission line realized with the use of a quasi-lumped element technique. Moreover, to achieve better compactness of the resulting coupler, all 90◦ right-handed transmission lines have been realized with the use of the same technique. It has been also proved that simple LC approximation of a left-handed transmission line can be successfully used for the design. Moreover, it has been shown that when appropriately chosen, the multilayer dielectric structure allows for realization of structures designed with the use of this simple approximation, for both right-handed and left-handed transmission lines, without loosing too much of a performance
How the Role-Based Trust Management Can Be Applied to Wireless Sensor Networks, Journal of Telecommunications and Information Technology, 2012, nr 4
Get PDFTrust plays an important role in human life environments. That is why the researchers has been focusing on it for a long time. It allows us to delegate tasks and decisions to an appropriate person. In social sciences trust between humans was studied, but it also was analyzed in economic transactions. A lot of computer scientists from different areas, like security, semantic web, electronic commerce, social networks tried to transfer this concept to their domains. Trust is an essential factor in any kind of network, whether social or computer. Wireless sensor networks (WSN) are characterized by severely constrained resources, they have limited power supplies, low transmission bandwidth, small memory sizes and limited energy, therefore security techniques used in traditional wired networks cannot be adopted directly. Some effort has been expended in this fields, but the concept of trust is defined in slightly different ways by different researchers. In this paper we will show how the family of Role-based Trust management languages (RT) can be used in WSN. RT is used for representing security policies and credentials in decentralized, distributed access control systems. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities
Optimizing the Structure of Vector Bend and Strain Sensor on the Base of Three-Core Microstructured Fiber, Journal of Telecommunications and Information Technology, 2012, nr 4
Get PDFIn the paper the optical sensor allowing measuring a direction, values and localization of bends and stresses in building structures is described. The sensitive element of the sensor is the microstructured fiber with three cores. The use of three-core fiber makes it possible to define the direction of deformation. Distribution of mode fields in fiber cores depending on fiber structure and bend value and direction is analyzed. The optimization of the sensitive element parameters depending on the application is proposed
On the Influence of Network Impairments on YouTube Video Streaming, Journal of Telecommunications and Information Technology, 2012, nr 3
Get PDFVideo sharing services like YouTube have become very popular which consequently results in a drastic shift of the Internet traffic statistic. When transmitting video content over packet based networks, stringent quality of service (QoS) constraints must be met in order to provide the comparable level of quality to a traditional broadcast television. However, the packet transmission is influenced by delays and losses of data packets which can have devastating influence on the perceived quality of the video. Therefore, we conducted an experimental evaluation of HTTP based video transmission focusing on how they react to packet delay and loss. Through this analysis we investigated how long video playback is stalled and how often re-buffering events take place. Our analysis revealed threshold levels for the packet delay, packet losses and network throughput which should not be exceeded in order to preserve smooth video transmission
On MILP Models for the OWA Optimization, Journal of Telecommunications and Information Technology, 2012, nr 2
Get PDFThe problem of aggregating multiple outcomes to form overall objective functions is of considerable importance in many applications. The ordered weighted averaging (OWA) aggregation uses the weights assigned to the ordered values (i.e., to the largest value, the second largest and so on) rather than to the specific coordinates. It allows to evaluate solutions impartially, when distribution of outcomes is more important than assignments these outcomes to the specific criteria. This applies to systems with multiple independent users or agents, whose objectives correspond to the criteria. The ordering operator causes that the OWA optimization problem is nonlinear. Several MILP models have been developed for the OWA optimization. They are built with different numbers of binary variables and auxiliary constraints. In this paper we analyze and compare computational performances of the different MILP model formulations
Zastosowanie norm pocztowych. Telekomunikacja i Techniki Informacyjne, 2012, nr 1-2
Get PDFW artykule przedstawiono normy definiujące badania jakości usług pocztowych. Przedstawiono także normy definiujące usługi pocztowe realizowane przez media elektroniczne oraz systemy informatyczne stosowane w realizacji procesów poczty tradycyjnej i nowych usług pocztowych
Competition and Diffusionof Telecommunication Services:The Multimedia CommunicationServices in Brazil, Journal of Telecommunications and Information Technology, 2012, nr 4
Get PDFThis paper aims to discuss the recent trends in the regulation of telecom services regarding the diffusion of broadband. To this matter, it compares the recent international competition regulation experiences to the Brazilian scenario. Considering that the telecom sector passed through huge technological and structural transformations in the last decades (from typical voice communications to convergent services based on broadband, and from voice services monopoly to multiple services oligopoly), its regulatory framework has also changed. Lately, several countries – such as the United States, the Netherlands, Korea and Chile – have established inter and intra-platform competition regulations in order to expand the access to the new forms of communications based on broadband. In Brazil, such mechanisms are not fully explored, and the country has lots of areas in which there is no competition in broadband services (known as multimedia communication services). As a result, Brazil has one of the highest prices of broadband services and one of the lowest levels of broadband penetration. In this way and considering international success in expanding services through competition, the paper defends that such mechanisms should be reinforced in the Brazilian broadband market