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1
Content available Traffic Modeling in Industrial Ethernet Networks
Głąbowski M., Hanczewski S., Stasiak M., Weissenberg M., Zwierzykowski P., Bai V.
International Journal of Electronics and Telecommunications
|
2020
|
Vol. 66, No. 1
145--153
EN
This article discusses the traffic types typically used in industrial networks. The authors propose a number of methods of generating traffic that can be used in modeling traffic sources in the networks under consideration. The proposed traffic models have been developed on the basis of the ON/OFF model. The proposed solutions can be applied to model typical traffic types that are used in industrial systems, such as Time-Triggered (TT) traffic, Audio-Video Bridging (AVB) traffic or Best Effort traffic. The article discusses four traffic models with modifications and shows how the proposed models can be used in modeling different traffic types used in industrial networks.
2
Content available An analytical model of a system with priorities servicing a mixture of different elastic traffic streams
Nowak B., Piechowiak M., Stasiak M., Zwierzykowski P.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2020
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Vol. 68, nr 2
263--270
EN
This article proposes an analytical model of a system with priorities servicing a mixture of different elastic traffic streams. The model presented in the article was developed as the extension of earlier works published by the authors. It utilizes the concept of equivalent bandwidth and then, following bandwidth discretization, uses the dependencies introduced on the basis of the assumptions adopted for the generalized Kaufman-Roberts formula and for the model of a full-availability group with traffic compression. The article presents a possibility of using the proposed model to model the radio interface in a multi-service mobile network and provides an example of the above with the interface of an LTE network. Since the proposed model is an approximate one, the results of the calculations are compared with the results of simulations. A comparison of the results confirms an acceptable level of accuracy of the model. The model can be successfully used in the analysis and design of links and nodes of telecommunication and computer networks.
3
Ewolucja technik dostarczania sygnału telewizyjnego na przykładzie Winogradzkiej Telewizji Kablowej
Owczarzak B., Zwierzykowski P.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
2018
|
nr 1
8--15
PL
W ciągu kilku ostatnich lat nastąpiła duża zmiana w sposobie dostarczania sygnału telewizyjnego do sieci operatorów telewizji kablowych oraz w metodach dystrybucji tego sygnału wewnątrz sieci. Do niedawna dominującym sposobem dostarczania sygnału telewizyjnego była transmisja satelitarna, ale dynamiczny rozwój sieci, który nastąpił w ostatnich latach, umożliwił nadawcom wykorzystanie przewodowych sieci teleinformatycznych. Ten sposób dostarczania treści jest obecnie również podstawową metodą dystrybucji sygnału telewizyjnego. W artykule omówiono podstawowe różnice dotyczące metod przesyłu sygnału telewizyjnego pomiędzy nadawcami a operatorami sieci telewizji kablowych. Ewolucję metod przesyłu i dystrybucji sygnału telewizyjnego przedstawiono na przykładzie Winogradzkiej Telewizji Kablowej – WTvK).
EN
Over the past years there has been a significant change in the way that television signal is delivered to cable television providers as well as in the methods for signal distribution within a network infrastructure. Until quite recently, the dominant method for television signal delivery was satellite transmission, but the dynamic development of the network, that has been witnessed over the past few years, has allowed senders to take advantage of wired telecommunications and computer networks. Nowadays, broadband fiber technology for distribution of both analog and digital content is also the basic method for distribution of television signal. The present article provides an overview of the basic differences between the methods for television signal transmission between senders and cable television operators. The evolution of the methods for transmission and distribution of the television signal is presented with an example based on Winogradzka Telewizja Kablowa (a Poznań-based cable operator).
4
Content available remote The impact of selected parameters on the performance of routing protocols in wireless sensor networks
Piechowiak M., Zwierzykowski P., Kotlarz P., Żmudziński P.
Image Processing & Communications
|
2017
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Vol. 22, no. 1
57--62
EN
The aim of the article was to compare the effectiveness of the selected routing protocols for wireless sensor networks taking In to account a number of specific parameters as network troughput, packet error rate and message buffer capacity for different network topologies. The simulation research was conducted in open source OMNeT++ environment. In order to achieve the assumed requirements, four different-sized network topologies were established and AODV and DYMO routing protocols were adapted.
5
Zastosowanie systemu czasu rzeczywistego w urządzeniach działających w Internecie Rzeczy
Kaliszan A., Zwierzykowski P.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
2016
|
nr 8-9
801--806, CD
PL
W artykule zaproponowano zastosowanie minimalistycznego systemu czasu rzeczywistego do budowy urządzenia działającego w Internecie Rzeczy. W artykule przedstawiono projekt serwera dostępowego, który umożliwia zdalnąobsługę 16 portów szeregowych oraz steruje 16 liniami zasilania za pośrednictwemsieci Ethernet.W urządzeniu wykorzystano system operacyjny, dzięki temu oprogramowanie można było podzielić na wiele równoległych, komunikujących się między sobą, zadań .
EN
In the article application of minimalistic Real Time Operating System (RTOS) for construction devices that are working in Internet of Things was proposed. The paper presents the design of the access server, which allows for remote operation 16 serial ports and controls 16 power lines via Ethernet. By using operating system the software consists of a number of tasks running in parallel and being in close communication with one another.
6
Content available Review of Simulators for Wireless Mesh Networks
Owczarek P., Zwierzykowski P.
Journal of Telecommunications and Information Technology
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2014
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nr 3
82--89
EN
The research of computer networks construction of models that reflect the current audited environment to carry out practical research is extremely dicult and often involves signicant costs. Hence, the popularity of simulation tools that help developers to determine as early as at the stage of the simulation whether a given solution can be deployed in a real network. However, over time many dierent simulation tools have been developed, each with dierent characteristics, dierent uses, dierent strengths and weaknesses. It is the task of the researcher then to select, before starting the actual research, one of the available simulators in accordance with the needs and adopted criteria of evaluation. In the article the authors present issues related to the simulation tools and the main advantages of simulation as well as their drawbacks. To help researchers select an appropriate simulation environment, the authors present statistical information gathered during a literature survey of a number of research articles from the most popular publishers in which the selected simulators were used in initial system design.
7
Architektura i implementacja wielokryterialnego algorytmu routingu dla ruchu rozgałęźnego
Stachowiak K., Zwierzykowski P.
Studia Informatica
|
2013
|
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.
8
Content available Single hysteresis model for limited-availability group with BPP traffic
Sobieraj M., Stasiak M., Weissenberg J., Zwierzykowski P.
Journal of Telecommunications and Information Technology
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2013
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nr 3
89--96
EN
This 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.
9
Content available Innovative Method of the Evaluation of Multicriterial Multicast Routing Algorithms
Stachowiak K., Zwierzykowski P.
Journal of Telecommunications and Information Technology
|
2013
|
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.
10
Content available remote Metrics in routing protocol for wireless mesh networks
Owczarek P., Zwierzykowski P.
Image Processing & Communications
|
2013
|
Vol. 18, no. 4
7--20
EN
The interest in services offered by wireless network has been growing for many years. It has encouraged the development of wireless technologies. New solutions are able to satisfy the ever-increasing demands concerning wireless services. It is also evident in the diversification of quality assessment methods employed with reference to connections used in such networks. One of the basic elements used in connection quality assessment are metrics. The use of metrics is directly linked to the type of the routing protocol applied in a given network. The selection of a given routing protocol is often determined by its specific properties that might be advantageous in a certain network type, or that are important in terms of the type or scope of services provided. Therefore, it is easy to identify a relationship between metrics and the area of application of a given routing protocol. The significance and diversity of metrics is also reflected inWireless Mesh Networks (WMNs). The proposed paper presents a review of the current state-of-the-art routing metrics for Ad-hoc and WMN networks.
11
Content available Lagrangian Relaxation and Linear Intersection Based QoS Routing Algorithm
Stachowiak K., Zwierzykowski P.
International Journal of Electronics and Telecommunications
|
2012
|
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.
12
Content available remote Shortest path problem solving based on ant colony optimization metaheuristic
Głąbowski M., Musznicki B, Nowak P., Zwierzykowski P.
Image Processing & Communications
|
2012
|
Vol. 17, no. 1-2
7--17
EN
The Ant Colony Optimization (ACO) metaheuristic is a versatile algorithmic optimization approach based on the observation of the behaviour of ants. As a result of numerous analyses, ACO has been applied to solving various combinatorial problems. The ant colony metaheuristic proves itsel I' to be efficient in solving NP-hard problems, often generating the best solution in the shortest amount of time. However, not enough attention has been paid to ACO as a means of solving problems that have optimal solutions which can be found using other methods. The shortest path problem is undoubtedly one of the aspects of great significance to navigation and telecommunications. It is used, amongst others, for determining the shortest route between two geographical locations, for routing in packet networks, and to balance and optimize network utilization. Thus, this article introduces ShortestPathACO, an Ant Colony Optimization based algorithm designed to find the shortest path in a graph. The algorithm consists of several subproblems that are presented successively. Each subproblem is discussed from many points of view to enable researchers to find the most suitable solutions to the problems they investigate.
13
Content available remote Geographic Dijkstra-Based Multicast Algorithm for Wireless Sensor Networks
Musznicki B, Tomczak M., Zwierzykowski P.
Image Processing & Communications
|
2012
|
Vol. 17, no. 1-2
33--46
EN
Limited resources in Wireless Sensor Networks (WSNs) are the key concern that needs to be given a careful consideration when studying virtually any aspect of a sensor network. Therefore, energy demands and radio bandwidth utilization should be addressed, especially in one-to-many communication. It is evident that a need for centralized networkwide topology knowledge can jeopardize scarce energy resources of a sensor network. Thus, localized geographic multicast relies solely on locally available information about the position of current node, other nodes within the radio range and the location of destination group members. Greedy multicast routing procedures often transport messages along paths that may be far from being optimal. Therefore, Dijkstrabased Localized Energy-Efficient Multicast Algorithm (DLEMA) is presented, described with pseudocode, and discussed. DLEMA focuses on discovering energy shortest paths leading through nodes that provide the maximum geographical advance towards desired destinations. Local routes are followed owing to the use of a source routing technique. Additionally, the algorithm takes advantage of the broadcast nature of omnidirectional radio communication and utilizes perimeter routing to find a solution for local optimum situations. The analysis of the simulation results confirms interesting characteristics of the proposed algorithm.
14
Content available remote Multi-service switching networks with overflow links
Stasiak M., Zwierzykowski P.
Image Processing & Communications
|
2010
|
Vol. 15, no 2
61-71
EN
The article presents the results of a simulation study on multirate three-stage Clos switching networks with additional inter-section links. Switching networks in which a system of overflow links was provided for the first, second and the third stage are investigated. Additionally, different structures of connections between inter-section links are discussed. The investigation has proved that an application of overflow systems is followed by a substantial decrease in the internal blocking probability in the switching network. An appropriate capacity of overflow links can even result in a virtually complete elimination of internal blocking. The article proves that the best results are obtained with the introduction of overflow links to the first stage of the network, both in the case of point-to-point and point-to-group selection.
15
Content available remote The Application of K–Shortest Path Algorithm in Multicast Routing
Stasiak M., Piechowiak M., Zwierzykowski P.
Theoretical and Applied Informatics
|
2009
|
Vol. 21, No. 2
69-82
EN
There have been many heuristic algorithms finding multicast trees proposed over the past few years. The necessity for finding a better and more suitable algorithm is still a current and important challenge. The article presents a new multicast routing algorithm for finding a multicast tree in packet networks. The objective of the K-Shortest Path Multicast Algorithm (KSPMA) is to minimize the cost of paths between the source and each destination node using a generalized Dijkstra’s algorithm that would comply with maximum delay bound along each path. A wide range of simulation research carried out by the authors for many network topologies and parameters has confirmed the effectiveness of the proposed algorithm.
PL
W artykule zaproponowano nowy algorytm routingu dla połączeń rozgałęzionych. Prezentowany algorytm stosuje algorytm K–najkrótszych ścieżek do wyznaczenia ścieżek o minimalnych kosztach pomiędzy węzłem źródłowym, a każdym z węzłów docelowych, z uwzględnieniem maksymalnej dopuszczalnej wartości opóźnienia (c) wzdłuż każdej ścieżki. Algorytm KSPMA został przebadany symulacyjnie biorąc pod uwagę parametry określające zarówno struktura, jak i właściwości sieci. Badania przeprowadzono wykorzystując topologie sieci wygenerowane metodami Waxmana [2] oraz Barabasi-Alberta [24]. W symulacjach zbadano również efektywność algorytmu w funkcji podstawowych parametrów sieci tj. liczba węzłów sieci, liczność grupy odbiorców, średni stopień grafu (węzła) oraz maksymalne opóźnienie wzdłuż ścieżki. W badaniach uwzględniono także średnie koszty ścieżek uzyskane po zastosowaniu algorytmów CSPT, KPP oraz LDC. Liczne doświadczenia symulacyjne przeprowadzone przez autorów potwierdziły efektywność proponowanego algorytmu KSPMA.
16
Content available Analytical Modeling of the WCDMA Interface with Packet Scheduling
Stasiak M., Zwierzykowski P., Wiewióra J.
Journal of Telecommunications and Information Technology
|
2009
|
nr 3
103-110
EN
The article presents the application of a new analytical model of the full-availability group carrying a mixture of different multi-rate traffic classes with compression property for modeling the WCDMA radio interface with packet scheduling. The proposed model can be directly used for modeling of theWCDMA interface in the UMTS network servicing different traffic classes. The described model can be applied for a validation of the efficiency of the WCDMA interface measured by the blocking probability and the average carried traffic for particular traffic classes.
17
Content available remote New genetic multicast routing algorithm for ad-hoc networks
Szymaniak P., Piechowiak M., Zwierzykowski P.
Image Processing & Communications
|
2008
|
Vol. 13, no 1-2
3-11
EN
Real-time multimedia applications in computer networks require techniques of providing data to a group of users at the same time. Building efficient multicast trees is a challenge for multicast routing protocols and algorithms. The article focuses on the implementation of genetic multicast algorithms in ad-hoc networks. It also proposes a new approach in ad-hoc networks modelling. Tests were carried out for a wide range of parameters defining properties and characteristics of test networks topologies.
18
Content available remote Genetic routing algorithm for multicast connections in packet networks
Chojnacki A., Piechowiak M., Zwierzykowski P.
Image Processing & Communications
|
2008
|
Vol. 13, no 1-2
13-20
EN
The article analyzes and explores the influence of different genetical solutions on the efficiency and effectiveness of the performance of genetic algorithms for multicast routing. The results of the simulation studies were compared with the results obtained with the application of classic heuristics, i.e. (KPP [12], CSPT [5] and LD). The tests were carried out for a wide range of parameters defining properties and characteristics of test networks topologies. The simulation study takes into consideration topology generation methods in line with the Waxman model and the Barabasi-Albert model.
19
Content available remote Analytical method of calculating blocking probability in 3G networks with spreading spectrum and a finite number of traffic sources
Stasiak M., Wiśniewski A., Zwierzykowski P.
Theoretical and Applied Informatics
|
2007
|
Vol. 19, No. 4
297-314
EN
Admission control in wireless networks with the WCDMA radio interface admits or blocks new calls depending on a current load situation both in the access celi and in neighboring cells. A new cali is rejected if the predicted load exceeds particular thresholds set by radio network planning. This article presents a new blocking probability calculation method in cellular systems with the WCDMA radio interface for the uplink and the downlink directions. The model considers a finite and an infinite source population of users. In the model we use the load factor to estimate whether a new cali can be admitted or blocked. In the proposed calculation method the corresponding value of the load factor in the neighboring celi is based on the Okumura-Hata propagation model. The results of the analytical calculations arę com-pared with the results of the simulation experiments, confirming the accuracy of the proposed method. The proposed scheme can be applicable for a cost-effective radio resource management in 3G mobile networks and can be easily applied to network capacity calculations.
PL
W artykule zaproponowano nową metodę wyznaczania prawdodobieństwa blokady w sieciach komórkowych z interfejsem radiowym WCDMA. Prezentowana metoda jest rozszerzeniem modelu analitycznego omawianego przez autorów w wielu wcześniejszych pracach tj. [5, 6, 21, 22, 23]. W modelu po raz pierwszy rozważono możliwość obsługi skończonej i nieskończonej liczby użytkowników rozmieszczonych w grupie komórek oraz założono, że użytkownicy mogą wykorzystywać interfejs radiowy sieci 3G w obu kierunkach. W celu określenia poziomu interferencji wnoszonych do komórek sąsiednich przez zgłoszenia pojawiające w komórce dostepowej zastosowano model propagacyjny Okumura-Hatty [14, 15].W metodzie analitycznej założono, że modelem interfejsu radiowego WCDMA w obu kierunkach będzie wiązka pełnodostępną obsługującą mieszaninę ruchu zintegrowanego typu PCT l i PCT 2. Przyjęto również, że zjawisko ograniczenia szumowego pojemności łącza "w górę", wynikające z interferencji towarzyszących obsłudze zgłoszeń w sąsiednich komórkach, można uwzględnić stosując metodę ustalonego punktu [12]. Metodę tę wykorzystano również do określenia wzajemnej zależności procesów obsługi zgłoszeń poszczególnych klas ruchu oferowanych łączom w kierunkach "w górę" i "w dół". Porównanie wyników analitycznych z rezultatami symulacji potwierdziło dokładność proponowanej metody obliczeniowej. Uzyskane wyniki uzasadniają możliwość zastosowania metody do szacowania pojemności sieci 3G na etapie projektu.
20
Evaluation of uplink and downlink blocking probability for cellular systems with WCDMA radio interface
Syroczyński K., Wiśniewski A., Zwierzykowski P.
Poznan University of Technology Academic Journals. Electrical Engineering
|
2007
|
No 54
197-204
EN
The admission control in wireless networks with WCDMA radio interface admits or blocks new calls depending on a current load situation both in the access cell and in neighboring cells. A new call is rejected if the predicted load exceeds particular thresholds set by the radio network planning. This article presents a method for uplink and downlink blocking probability determination in cellular systems with WCDMA radio interface and finite and infinite source population. In our model, we use the load factor to estimate whether a new call of classy service can be admitted or blocked. The proposed scheme is applicable for cost-effective radio resource management in 3G mobile networks and can be easily applied to network capacity calculations.
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