The paper proposes steady state and transient state diffusion approximation models for the design... more The paper proposes steady state and transient state diffusion approximation models for the design and performance evaluation of multichannel communication networks. We concentrate on \(G/G/c/c+K\) queueing model and highlight some its applications together with numerical examples to illustrate how this models can be used.
... Tadeusz Czachórski*, Jean-Michel Fourneau**, Stanisław Jędruś*, Ferhan Pekergin*** * IITiS PA... more ... Tadeusz Czachórski*, Jean-Michel Fourneau**, Stanisław Jędruś*, Ferhan Pekergin*** * IITiS PAN œ Gliwice, ** PRiSM, Université de ... Metoda aproksymacji dyfuzyjnej, zastosowana przy rozwiązywaniu modelu, pozwala na analizę zacho-wania sieci przy zmiennym w czasie ...
IEEE 802.11 MAC protocol is the de facto standard for wireless local area networks (WLANs). In to... more IEEE 802.11 MAC protocol is the de facto standard for wireless local area networks (WLANs). In today’s Internet, the emerging widespread use of real-time voice, audio, and video applications makes QoS (Quality of Service) a key problem. This article tries to show that implementation of some mechanisms of traffic shaping causes some improvement of the level of QoS in WLANs.
The goal of this article was to reduce the time of dropping packed decisions for Active Queue Mec... more The goal of this article was to reduce the time of dropping packed decisions for Active Queue Mechanisms based on \(PI^{\alpha }D^\beta \). This article introduces a new way of performing calculations in a non-integer order controller using CUDA technology.
Bulletin of The Polish Academy of Sciences-technical Sciences, 2000
ABSTRACT The paper discusses the use of diffusion and fluid flow approximations in modeling the t... more ABSTRACT The paper discusses the use of diffusion and fluid flow approximations in modeling the time-varying flows of cells which belong to different connections but are routed through the same ATM network switch. When the cells are leaving the switch, their class should be known to define the next routing. In steady-state queueing models the probability that a customer belongs to a class k is obtained as the ratio of the class k throughput to the whole throughput passing the node. We are interested in transient analysis where the throughputs are changing and the composition of multiclass flow at the entrance of a queue is not the same as at the output: we should consider the delay introduced by the queue the distribution of which is also changing with time. Numerical examples, validated by simulation, testify that diffusion approximation approach gives satisfactory results in the solution of this problem. The fluid flow approximation is much simpler to implement and needs relatively less computation effort but gives worse results; the reason of it is that in the modelling the delay introduced by a switch queue, the distribution of the queue is important and the reasoning based only on its mean value is oversimplified.
HAL (Le Centre pour la Communication Scientifique Directe), 2005
ABSTRACT We analyze the performance of all optical packet networks. As optical storage of packets... more ABSTRACT We analyze the performance of all optical packet networks. As optical storage of packets is not available, we assume that the routing protocol is based on deflection. This routing strategy does not allow packets loss. However it keeps the packets inside the network, increases the delay and reduces the bandwidth. Thus the transport delay distribution is the key performance issue for these networks. Here, we consider a 2D torus the size of which is odd. The method is based on a fixed point system between two sub-models. The first subsystem describes the global network performance while the other one models the stochastic behavior of two types of packets.
The paper presents the results of modeling of selected modern computer networks scenarios. The st... more The paper presents the results of modeling of selected modern computer networks scenarios. The study used a mathematical model of fluid flow approximation, describing the effects of time varying packet traffic on the network switches and packet loss generation by the assumptions of the RED mechanism used in routers. The carried out experiments included the influence of the parameters initial settings on the behavior of a whole system.
Streszczenie. Zmienne natezenie ruchu generowanego przez aplikacje internetowe, np. multimedialne... more Streszczenie. Zmienne natezenie ruchu generowanego przez aplikacje internetowe, np. multimedialne, a takze przyjeta przez protokol TCP zasada regulacji natezenia transmisji w funkcji wykrytego obciązenia sieci, określanego na podstawie strat lub czasu transmisji, powodują, ze natezenie transmisji internetowych jest permanentnie zmienne w czasie, a zmiany natezenia i dynamika tych zmian muszą byc uwzglednione w ocenie algorytmow sterowania ruchem i unikania przeciązen. Modelowanie struktur w Internecie wymaga z kolei dostosowania istniejących metod i modeli do analizy bardzo duzych konfiguracji sieciowych. Niniejsza praca bada pod kątem obliczen numerycznych znany model matematyczny, umozliwiający analize stanow nieustalonych w stanowisku obslugi i ich sieci, wykorzystujący metode aproksymacji dyfuzyjnej. Zbadano wplyw poszczegolnych parametrow modelu i rozmiaru sieci na calkowity czas obliczen, a wiec na skalowalnośc metody. Slowa kluczowe: aproksymacja dyfuzyjna
Communications in computer and information science, 2016
This paper examines the impact of the degree of self-similarity on the selected AQM mechanisms. D... more This paper examines the impact of the degree of self-similarity on the selected AQM mechanisms. During the tests we analyzed the length of the queue, the number of rejected packets and waiting times in queues. We use fractional Gaussian noise as a self-similar traffic source. The quantitative analysis is based on simulation.
Communications in computer and information science, 2018
The high demand for more bandwidth and high speed networks stimulates research in the design, opt... more The high demand for more bandwidth and high speed networks stimulates research in the design, optimization and performance evaluation of IP over all-optical networks. In this paper we study optical packet filling algorithm applied at ingress nodes of an all-optical network. Arriving electronic packets of variable sizes are stored at a buffer the volume of which is equal to the fixed size of optical packet. When the available space in the buffer is less than the size of an arriving packet, the stored already content of the buffer is sent inside the optical packet and the electronic packet is rescheduled for the next filling cycle. To avoid excessive delays, the optical packet is dispatched also after a specified deadline whatever is the (non-null) content of the buffer. The performance metrics we consider comprises the filling of optical packets (that means the ratio of blocks in the packet to the actual constant size of the packet) and the distribution of optical packets interdeparture times. The paper demonstrates that the variability of the size of arriving packets and the self-similarity of the input traffic have a visible impact on the both parameters.
The paper proposes steady state and transient state diffusion approximation models for the design... more The paper proposes steady state and transient state diffusion approximation models for the design and performance evaluation of multichannel communication networks. We concentrate on \(G/G/c/c+K\) queueing model and highlight some its applications together with numerical examples to illustrate how this models can be used.
... Tadeusz Czachórski*, Jean-Michel Fourneau**, Stanisław Jędruś*, Ferhan Pekergin*** * IITiS PA... more ... Tadeusz Czachórski*, Jean-Michel Fourneau**, Stanisław Jędruś*, Ferhan Pekergin*** * IITiS PAN œ Gliwice, ** PRiSM, Université de ... Metoda aproksymacji dyfuzyjnej, zastosowana przy rozwiązywaniu modelu, pozwala na analizę zacho-wania sieci przy zmiennym w czasie ...
IEEE 802.11 MAC protocol is the de facto standard for wireless local area networks (WLANs). In to... more IEEE 802.11 MAC protocol is the de facto standard for wireless local area networks (WLANs). In today’s Internet, the emerging widespread use of real-time voice, audio, and video applications makes QoS (Quality of Service) a key problem. This article tries to show that implementation of some mechanisms of traffic shaping causes some improvement of the level of QoS in WLANs.
The goal of this article was to reduce the time of dropping packed decisions for Active Queue Mec... more The goal of this article was to reduce the time of dropping packed decisions for Active Queue Mechanisms based on \(PI^{\alpha }D^\beta \). This article introduces a new way of performing calculations in a non-integer order controller using CUDA technology.
Bulletin of The Polish Academy of Sciences-technical Sciences, 2000
ABSTRACT The paper discusses the use of diffusion and fluid flow approximations in modeling the t... more ABSTRACT The paper discusses the use of diffusion and fluid flow approximations in modeling the time-varying flows of cells which belong to different connections but are routed through the same ATM network switch. When the cells are leaving the switch, their class should be known to define the next routing. In steady-state queueing models the probability that a customer belongs to a class k is obtained as the ratio of the class k throughput to the whole throughput passing the node. We are interested in transient analysis where the throughputs are changing and the composition of multiclass flow at the entrance of a queue is not the same as at the output: we should consider the delay introduced by the queue the distribution of which is also changing with time. Numerical examples, validated by simulation, testify that diffusion approximation approach gives satisfactory results in the solution of this problem. The fluid flow approximation is much simpler to implement and needs relatively less computation effort but gives worse results; the reason of it is that in the modelling the delay introduced by a switch queue, the distribution of the queue is important and the reasoning based only on its mean value is oversimplified.
HAL (Le Centre pour la Communication Scientifique Directe), 2005
ABSTRACT We analyze the performance of all optical packet networks. As optical storage of packets... more ABSTRACT We analyze the performance of all optical packet networks. As optical storage of packets is not available, we assume that the routing protocol is based on deflection. This routing strategy does not allow packets loss. However it keeps the packets inside the network, increases the delay and reduces the bandwidth. Thus the transport delay distribution is the key performance issue for these networks. Here, we consider a 2D torus the size of which is odd. The method is based on a fixed point system between two sub-models. The first subsystem describes the global network performance while the other one models the stochastic behavior of two types of packets.
The paper presents the results of modeling of selected modern computer networks scenarios. The st... more The paper presents the results of modeling of selected modern computer networks scenarios. The study used a mathematical model of fluid flow approximation, describing the effects of time varying packet traffic on the network switches and packet loss generation by the assumptions of the RED mechanism used in routers. The carried out experiments included the influence of the parameters initial settings on the behavior of a whole system.
Streszczenie. Zmienne natezenie ruchu generowanego przez aplikacje internetowe, np. multimedialne... more Streszczenie. Zmienne natezenie ruchu generowanego przez aplikacje internetowe, np. multimedialne, a takze przyjeta przez protokol TCP zasada regulacji natezenia transmisji w funkcji wykrytego obciązenia sieci, określanego na podstawie strat lub czasu transmisji, powodują, ze natezenie transmisji internetowych jest permanentnie zmienne w czasie, a zmiany natezenia i dynamika tych zmian muszą byc uwzglednione w ocenie algorytmow sterowania ruchem i unikania przeciązen. Modelowanie struktur w Internecie wymaga z kolei dostosowania istniejących metod i modeli do analizy bardzo duzych konfiguracji sieciowych. Niniejsza praca bada pod kątem obliczen numerycznych znany model matematyczny, umozliwiający analize stanow nieustalonych w stanowisku obslugi i ich sieci, wykorzystujący metode aproksymacji dyfuzyjnej. Zbadano wplyw poszczegolnych parametrow modelu i rozmiaru sieci na calkowity czas obliczen, a wiec na skalowalnośc metody. Slowa kluczowe: aproksymacja dyfuzyjna
Communications in computer and information science, 2016
This paper examines the impact of the degree of self-similarity on the selected AQM mechanisms. D... more This paper examines the impact of the degree of self-similarity on the selected AQM mechanisms. During the tests we analyzed the length of the queue, the number of rejected packets and waiting times in queues. We use fractional Gaussian noise as a self-similar traffic source. The quantitative analysis is based on simulation.
Communications in computer and information science, 2018
The high demand for more bandwidth and high speed networks stimulates research in the design, opt... more The high demand for more bandwidth and high speed networks stimulates research in the design, optimization and performance evaluation of IP over all-optical networks. In this paper we study optical packet filling algorithm applied at ingress nodes of an all-optical network. Arriving electronic packets of variable sizes are stored at a buffer the volume of which is equal to the fixed size of optical packet. When the available space in the buffer is less than the size of an arriving packet, the stored already content of the buffer is sent inside the optical packet and the electronic packet is rescheduled for the next filling cycle. To avoid excessive delays, the optical packet is dispatched also after a specified deadline whatever is the (non-null) content of the buffer. The performance metrics we consider comprises the filling of optical packets (that means the ratio of blocks in the packet to the actual constant size of the packet) and the distribution of optical packets interdeparture times. The paper demonstrates that the variability of the size of arriving packets and the self-similarity of the input traffic have a visible impact on the both parameters.
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