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Wyszukujesz frazę "data networks" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
End-to-end service survivability under attacks on networks
Autorzy:
Molisz, W.
Rak, J.
Powiązania:
https://bibliotekanauki.pl/articles/308000.pdf
Data publikacji:
2006
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
survivable data networks
attacks on networks
scale-free networks
routing
resource allocation
Opis:
Network survivability is a capability of a networked system to provide its services despite failures or attacks. Attacks, e.g., due to acts of war, being potentially damaging events, were basically considered in the historical definitions of a survivability phenomenon. The meaning of the term: "network survivability" evolved in the last decade. Recently, attacks replayed the important role again. Their nature, however, including intrusions, probes, denials of service, differs from the old one. Survivability is strongly related to other fields of study. In particular, quality of service depends on network survivability. We investigate these dependencies in scale-free networks. Many networks are scale-free, i.e., their node degree distribution follows the power law. Nodes of the highest degrees, called centers, are highly vulnerable to attacks. Elimination of these nodes seriously degrades the overall performance of network services. In this paper we propose a model, which, based on traffic parameters of a demand, like delay or bit rate, allows to establish the survivable and attack proof end-to-end connections. The key idea of this model is that for the significant traffic, it establishes paths, which omit centers. The important connections become more resistant to attacks. We show that in the best case, obtained for the highest class of service, the number of broken connections is reduced even by factor 3. Example results are compared to those for the standard distance metrics. Our model is applicable to many network architectures and many classes of service.
Źródło:
Journal of Telecommunications and Information Technology; 2006, 3; 19-26
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the connections between optimal control, regulation and dynamic network routing
Autorzy:
Karbowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/307694.pdf
Data publikacji:
2003
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
stabilization
nonlinear control
optimal control
dynamic programming
data networks
routing algorithms
Opis:
The paper is devoted to studying general features of dynamic network routing problems. It is shown that these problems may be interpreted as receding horizon optimal control problems or simply regulation problems. In the basic formulation it is assumed, that the nodes have no dynamics and the only goal of the optimization mechanism is to find the shortest paths from the source to the destination nodes. In this problem the optimization mechanism (i.e. the Bellman-Ford algorithm) may be interpreted as a receding horizon optimal control routine. Moreover, there is one-toone correspondence between the Bellman optimal cost-to-go function in the shortest path problem and the Lyapunov function in the regulation problem. At the end some results of the application of the routing optimization algorithm to an inverted pendulum regulation problem are presented.
Źródło:
Journal of Telecommunications and Information Technology; 2003, 3; 67-72
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Developments on an IEEE 802.15.4-based wireless sensor network
Autorzy:
Scheers, B.
Mees, W.
Lauwens, B.
Powiązania:
https://bibliotekanauki.pl/articles/308225.pdf
Data publikacji:
2008
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
wireless sensor networks
IEEE 802.15.4
effective data capacity
positioning
Opis:
In this paper a summary is given of the ongoing research at the Belgian Royal Military Academy in the field of mobile ad hoc networks in general and wireless sensor networks (WSNs) in particular. In this study, all wireless sensor networks are based on the physical and the medium access layer of the IEEE 802.15.4 low rate wireless personal area networks standard. The paper gives a short overview of the IEEE 802.15.4 standard in the beaconless mode together with a description of the sensor nodes and the software used throughout this work. The paper also reports on the development of a packet sniffer for IEEE 802.15.4 integrated in wireshark. This packet sniffer turns out to be indispensable for debugging purposes. In view of future applications on the wireless network, we made a theoretical study of the effective data capacity and compared this with measurements performed on a real sensor network. The differences between measurements and theory are explained. In case of geograph- ically meaningful sensor data, it is important to have a knowledge of the relative position of each node. In the last part of the paper we present some experimental results of positioning based on the received signal strength indicators (RSSI). As one could expect, the accuracy of such a method is poor, even in a well controlled environment. But the method has some potential.
Źródło:
Journal of Telecommunications and Information Technology; 2008, 2; 46-53
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Modeling of Database Systems: a Survey
Autorzy:
Krajewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/309263.pdf
Data publikacji:
2018
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
database systems
NoSQL data stores
performance evaluation
queueing networks
queueing Petri nets
Opis:
This paper presents a systematic survey of the existing database system performance evaluation models based on the queueing theory. The continuous evolution of the methodologies developed is classified according to the mathematical modeling language used. This survey covers formal models – from queueing systems and queueing networks to queueing Petri nets. Some fundamentals of the queueing system theory are presented and queueing system models are classified according to service time distribution. The paper introduces queueing networks and considers several classification criteria applicable to such models. This survey distinguishes methodologies, which evaluate database performance at the integrated system level. Finally, queueing Petri nets are introduced, which combine modeling power of queueing networks and Petri nets. Two performance models within this formalism are investigated. We find that an insufficient amount of research effort is directed into the area of NoSQL data stores. Vast majority of models developed focus on traditional relational models. These models should be adapted to evaluate performance of non-relational data stores.
Źródło:
Journal of Telecommunications and Information Technology; 2018, 4; 37-45
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Novel Graph-modification Technique for User Privacy-preserving on Social Networks
Autorzy:
Hamideh Erfani, Seyedeh
Mortazavi, Reza
Powiązania:
https://bibliotekanauki.pl/articles/958060.pdf
Data publikacji:
2019
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
graph-modification
social networks
privacypreserving publication of data
graph anonymization
database security
Opis:
The growing popularity of social networks and the increasing need for publishing related data mean that protection of privacy becomes an important and challenging problem in social networks. This paper describes the (k,l k,l k,l)-anonymity model used for social network graph anonymization. The method is based on edge addition and is utility-aware, i.e. it is designed to generate a graph that is similar to the original one. Different strategies are evaluated to this end and the results are compared based on common utility metrics. The outputs confirm that the na¨ıve idea of adding some random or even minimum number of possible edges does not always produce useful anonymized social network graphs, thus creating some interesting alternatives for graph anonymization techniques.
Źródło:
Journal of Telecommunications and Information Technology; 2019, 3; 27-38
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wireless communication for medical applications: the HEARTS experience
Autorzy:
Kropp, A.
Powiązania:
https://bibliotekanauki.pl/articles/309511.pdf
Data publikacji:
2005
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
Bluetooth
wearable 802.11b
wireless networks
sensor data
DSP
medical devices
dehospitalization
Opis:
Wireless networks provide all the functionality of wire-line networks without the physical constraints of the wire itself giving an interesting alternative to phone-line and powerline wiring systems. With a wireless network, physicians can actively monitor a patient's vital signs from anywhere in a hospital. HEARTS (health early alarm recognition and telemonitoring system) is a research project having the major aim to provide support for prevention and monitoring heart disease, based on advanced technology. The HEARTS idea is to gather biometric and environmental data coming from patients during both hospitalization phase and in their normal lifetime activities, using wireless networks. The wireless network and its composing devices are called personal health network (PHN). WPAN and WLAN technologies have been investigated, each with its pros and cons, for use in health monitoring activities inside hospitals and at home, for improving patient mobility, and to provide patients for "last interconnection hop" to the infrastructure network. Technological and operational problems have been addressed concerning bluetooth, IEEE 802.11b (WiFi), GSM/GPRS/UMTS wireless transports, all of them tested and some of them concretely adopted inside the HEARTS framework.
Źródło:
Journal of Telecommunications and Information Technology; 2005, 4; 40-41
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolutionary paths in wireless communication systems
Autorzy:
Michalski, W.
Powiązania:
https://bibliotekanauki.pl/articles/309042.pdf
Data publikacji:
2005
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cellular mobile radio systems
wireless local area networks
wireless personal networks
wide area wireless packet data systems
satellite-based mobile systems
paging/messaging systems
cordless telephones
access points
switches
GPRS
Mobile IP
WLAN cellular integration
Opis:
The paper contains a review and analysis of evolutionary paths of seven most important, from network development strategy point of view, wireless communication systems, especially the WLAN operating according to the IEEE 802.11 standard. With respect to WLAN, trends related to evolution toward mobile network and self organizing network as well as toward integration of WLAN and GSM using GPRS are presented. Concerning WLAN architecture development, evolution paths toward distributed controlled network as well as centrally coordinated and controlled network are described. Moreover, analysis includes cellular mobile radio systems, wireless personal networks, wide area wireless packet data systems, satellite-based mobile systems, paging/messaging systems and cordless telephones. With respect to these systems, general evolution process and trends associated with this process are described.
Źródło:
Journal of Telecommunications and Information Technology; 2005, 3; 105-111
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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