Wyniki wyszukiwania - BazTech

1

Multi criterion multicast routing algorithm comparison for large networks

Stachowiak K.

Image Processing & Communications

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2017

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Vol. 22, no. 1

49--55

EN

QoS enabled multicast routing is known to be of non-polynominal complexity, which leads to the necessity of using heuristic algorithms to ﬁnd sub-optimal solutions to the problems of this class. The evaluation of such algorithms requires the use of the simulation techniques as the heuristics’ results are of stochastic nature. Because of the problem complexity the simulation times increase signiﬁcantly in the function of the network size, therefore the results presented in the literature are often limited to only small models. In this article the results of the evaluation of different multicast QoS routing algorithms (further referred to as the Multi-Constrained Minimum Steiner Tree Problem-MCMST)have been presented for a wide range of network sizes reaching thousands of nodes.

2

Multicast Connections in Wireless Sensor Networks with Topology Control

Piechowiak M., Stachowiak K., Bartczak T.

Journal of Telecommunications and Information Technology

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2016

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nr 1

61--67

EN

The article explores the quality of multicast trees constructed by heuristic routing algorithms in wireless sensor networks where topology control protocols operate. Network topology planning and performance analysis are crucial challenges for wire and wireless network designers. They are also involved in the research on routing algorithms, and protocols for these networks. In addition, it is worth to emphasize that the generation of realistic network topologies makes it possible to construct and study routing algorithms, protocols and traffic characteristics for WSN networks.

3

Architektura i implementacja wielokryterialnego algorytmu routingu dla ruchu rozgałęźnego

Stachowiak K., Zwierzykowski P.

Studia Informatica

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2013

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Vol. 34, nr 3

7--20

PL

Ze względu na złożoność problemu, dla wielokryterialnej optymalizacji trasowania rozgałęźnego zaproponowano szeroką gamę rozwiązań heurystycznych, które cechują się zróżnicowaną złożonością i dokładnością. W artykule przedstawiono propozycję nowego algorytmu, jak również rozważania na temat jego implementacji. Zaproponowany algorytm, zdaniem autorów, pozwala na osiągnięcie dobrego kompromisu pomiędzy wydajnością i jakością wyników.

EN

The multicriterial multicast routing has been given a lot of attention. Algorithms of different precision and complexity have been proposed to solve the problem. In the article a novel algorithm for this class of the problems have been presented, which allows for reaching the compromise between the efficiency and the quality of the results.

4

Innovative Method of the Evaluation of Multicriterial Multicast Routing Algorithms

Stachowiak K., Zwierzykowski P.

Journal of Telecommunications and Information Technology

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2013

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nr 1

49-55

EN

Theoretical considerations of the multicast Quality of Service (QoS) routing have been a rapidly developing and dynamic research area for years. Several algorithms derived from different approaches have been proposed, while the pool of valid solutions to the problem is steadily growing. When new solutions are compared with their predecessors, as much information as possible about their characteristics and differences is needed. Both the graph theory and the optimization theory provide robust and objective means of comparing not only algorithms, but also the results they produce. However, any possible extension to the comparison methods is vital and can bring interesting new information that would eventually lead to innovative conclusions. This article presents a method, derived from practice and experience, that simulates the drainage of resources accumulated by consecutive communication allocations. The nature of this comparison is an extension to the classical measurement of the success ratio and this creates a context of the continuous measure of a success rather than a simple binary value. In this article such a method with regard to algorithms optimizing multicast problems for more than two criteria is used for the first time and leads to an interesting conclusion about the influence of the number of the criteria on the result.

5

Lagrangian Relaxation and Linear Intersection Based QoS Routing Algorithm

Stachowiak K., Zwierzykowski P.

International Journal of Electronics and Telecommunications

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2012

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Vol. 58, No. 4

307-314

EN

Due to the process of network convergence, the variety of types of traffic transmitted over a single medium increases steeply. This phenomenon can be handled by the existing networking structure although the protocols that are used and, especially, the underlying routing protocols need to be improved. The problem of finding the shortest path on the Internet can no longer be easily defined as there is an increasing number of different characteristics to describe a point-to-point link. The definition of the shortest path may differ for different traffic types. Therefore, in the mathematical models used to solve the modern routing problems multiple criteria must be taken into account. One of the interesting classes of the optimization problem is the problem of finding the solution that is minimized against one of the criteria under certain constraints with regard to the others. In this paper, two algorithms solving this kind of problems are presented and compared with a new solution proposed by the authors.

6

Performance evaluation of multicast overlay routing protocols

Stachowiak K., Pawlak T., Piechowiak M.

Image Processing & Communications

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2012

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Vol. 17, no. 1-2

19--31

EN

For almost three decades the multicast communication has been a subject of a dynamic research. It came to the world of the packet switching networks rather late and still has not becorne a fist class citizen of the Internet, yet the demand for such services is growing and thus the relevant technologies evolve persistently providing increasing quality and availability of the means of the group communication. The overlay approach to the multicast is an application layer realization which came to life due to certain deficiencies at the lower layers. In general the gain from using multicast for group communication instead of duplicated unicast links is that we avoid sending the same data many times through a single link. Such gain may he achieved with the use of the router level mulitcast solution. The overlay solutions tend to approach his level of efficiency with a different degree of success. Therefore one of the main characteristics that is interesting when evaluating a particular overlay protocol- is how well does it achieve the aforementioned gain. There are several metrics that allow for objective comparison of protocols in this regard. However this is not the only point of view to provide a valuable evaluation of the multicast overlay solutions. One of the important as aspects of the modem group communication such as the IPTV or teleconferencing is the dynamic nature of the users' participation. A particular group may be joined and left by multiple users at a very frequent rate which is critical to the resources management as well as to maintaining the integrity of the abstract communication structure, e.g. a tree spanning all the participants. In such case two major classes of the evaluation criteria emerge: the statical and the dynamical ones. They're both very important and interdependent, however the means to measure them may differ significantly. In this article a wide variety of the multicast overlay protocols have been analysed and two of them have been chosen to be compared. The stress of the evaluation has heen put on the dynamic aspects of the multicast overlay protocols operation.

7

Metody prognozowania wielkości sprzedaży w przedsiębiorstwie teleinformatycznym (na przykładzie firmy MEDICOMP sp. z o.o.)

Urbańczyk E., Stachowiak K.

Zeszyty Naukowe. Prace Instytutu Ekonomiki i Organizacji Przedsiębiorstw / Uniwersytet Szczeciński

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2001

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Nr 39

157-190

EN

In management with firm especially important part plays build strategy of development. Is this process consisting from analysis's all of spheres of activity of firm. Prognosis to determines important element of all process of management and is one from basic elements of construction strategic plan. Need prognosis in firm results from two of principle reasons: uncertainties of future and delays during between moment of undertaking of decision and resulting with her with results. One from most important prognosis's prepared in firm is sale prognosing, which to state point of departure to realisations of most of economic analysis's consisting on strategy of firm. Serves it to construction of business plan, to fixing sizes {magnitude} of production and of wrestling, to planning of flows of cash and of capital expenses. Uses oneself it to qualifying of future needs financial firms, what is indispensable to maintenance's and of enlarging of future production of firm.