Telekomunikacja Cyfrowa : technologie i usługi
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ISSN 1505-9405
Call number
Volume
T. 9
Date
2008/2009
Description
Journal
Telekomunikacja Cyfrowa : technologie i usługi
Wydawnictwa AGH (2007-2011)
ISSN: 1505-9405
ISSN: 1505-9405
journal.volume.project
Contains
Journal Issues
Articles
Wykorzystanie informacji pomiarowych pochodzących z protokołu BGP do oceny struktury sieci Internet
(Wydawnictwa AGH, 2008/2009) Malinowski, Marcin; Pacyna, Piotr; Nowak, Jacek
The paper presents methods for investigating topology of the contemporary Internet which jointly allow to learn its structure, discover operators and interconnections. The focus is on methods based on information available in BGP protocol which allows to learn dynamic properties of the Internet. Usability of the methods is presented in a case study of ACK CYFRONET AGH network.
Architektura QoS integrująca sieci ad-hoc z sieciami stałymi
(Wydawnictwa AGH, 2008/2009) Natkaniec, Marek; Gozdecki, Janusz; Kosek, Katarzyna; Szott, Szymon; Pach, Andrzej R.
This paper proposes a complete QoS architecture for integration of ad-hoc networks with infrastructure networks. The technology, service differentiation mechanisms, and signalling protocols are discussed. The modules required in the network elements and its integration to provide end-to-end QoS in mobile ad-hoc networks are also presented. The proposed solution is based on the SWAN model with several extensions to provide L2 traffic differentiation for four classes and supports integration with infrastructure networks. The deployed hierarchical architecture guarantees scalability and allows per-flow resource management in wireless access where scarce radio resources should be managed effectively.
Analiza zagadnienia sprawiedliwego dostępu do kanału radiowego realizowanego za pomocą modyfikacji parametrów okna współzawodnictwa w sieciach ad-hoc standardu IEEE 802.11e
(Wydawnictwa AGH, 2008/2009) Natkaniec, Marek; Szott, Szymon; Pach, Andrzej R.
This paper is related to the problem of node misbehaviour. The presented work determines how contention window cheating can influence the performance of ad-hoc networks based on the new IEEE 802.11e standard. It is explained why such networks are more prone to misbehaviour than previous 802.11 (other WiFi) standards. A simulation analysis has been carried out for several distinct scenarios. The presented results show that a misbehaving node can significantly decrease the network performance. Therefore, countermeasures to this problem need to be developed.
Analiza symulacyjna sieci IEEE 802.11e o topologii gwiazdy w przypadku występowania stacji ukrytych
(Wydawnictwa AGH, 2008/2009) Kosek, Katarzyna; Natkaniec, Marek; Pach, Andrzej R.
The article presents results derived from a simulation analysis of IEEE 802.11e networks in the presence of hidden nodes. In order to show how meaningful the degrading impact of hidden nodes on ad-hoc networks performance is, two different star topologies were analyzed. There were three- and four-node ones. Additionally, in the presence of hidden nodes, the inability of the EDCA mechanism to assure a desired quality of service for different services (most of all video and voice) was shown. Furthermore, the usefulness of the RTS/CTS mechanism was also verified.
Otwarty system przechowywania i udostępniania zbiorów przez Internet - projekty OASIS Archive i GAMA w Katedrze Telekomunikacji AGH
(Wydawnictwa AGH, 2008/2009) Głowacz, Andrzej; Grega, Michał; Leszczuk, Mikołaj; Romaniak, Piotr
This paper presents OASIS Archive project (with its extension plans in the framework of the GAMA project), which goal was to develop a system for the universal presentation of art works independent of their location. The main focus was on establishing a user-friendly search system in order to ensure the preservation and availability (sustainability) of cultural heritage in the field of Media Art. Databases of several participating institutions were integrated on basis of interlinking metadata system. The archive can be easily accessed by individual users (both researchers and general public) through an on-line interface, by multimedia archive servers engaged in exchange within a distributed system and by various play-out media. Scalability of the archive has been addressed during the project as well.