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Modelling of advanced 802.11e technology features in OPNET Modeler environment
Šeliga, Michal ; Reichert, Pavel (referee) ; Molnár, Karol (advisor)
This master thesis includes a short review of the structure of WLAN (Wireless Local Area Network) technologies 802.11a/b/g, the description of their physical interface and the description of the basic medium access control mechanisms implementing the PCF (Point Coordination Function) and DCF (Distributed Coordination Function) methods. I mainly focused on the detailed evaluation the new 802.11e standard which was designed to efficiently support real-time services in wireless environment. To provide QoS (Quality of Service) support, this standard specifies the EDCA (Ehanced Distributed Channel Access) and HCF (Hybrid Coordination Function) medium access control methods for the shared wireless environment. The next chapter of my work is devoted to the verification of the theoretical results in OPNET Modeler simulation environment. I studied in details the WLAN model available in OPNET Modeler, the effect of data-flow classification into separate categories and the configuration of several access method parameters. Next, I created my own WLAN model according to the 802.11e standard. This model contains four applications two of them with real-time requirements. The model is divided into several scenarios, each focusing on different aspects of wireless network technologies like QoS support and it´s dependency on the number of clients, mobility of wireless terminals and comparison of the 802.11a/b/g and the 802.11e technology.
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Graphical user interface for probabilistic modelling of WLAN wireles networks
Stecík, Július ; Molnár, Karol (referee) ; Rajmic, Pavel (advisor)
Course includes functions to access the shared medium, DCF, PCF and HCF. In detail, then describes the EDCA method for accessing the shared medium. The thesis focuses on the probabilistic model of competing stations to access the wireless medium and mathematics and algorithms needed to calculate these probabilities. The last part also design and description of user interface in the form of a Java applet to compute the probability that the station win the competition or on a shared medium collision occurs. The work also contains a brief commentary on the created program embedded in an HTML file.
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Simulation of advanced access control functions in wireless networks
Uher, Václav ; Hošek, Jiří (referee) ; Molnár, Karol (advisor)
The work deals with the verification of methods to ensure quality of service and mobili-ty in wireless networks using OPNET Modeler program. It examined the possibility of adjustment the link layer model in order to achieve a better service compared to the model according to IEEE 802.11e and without support implementation of the quality of service. The results of simulations show that quality of service support is one of the key characteristics of wireless network deployment for applications demanding low delay and jitter such as voice services. After modifying the algorithm for calculating the wait-ing times for slow-growing window with specific parameters for the transfer haven’t changed so much that wasn’t worth to enforce it for deployment in the real world. Fur-thermore, it is examined to support mobility and service stations on the network layer. Here I had to tackle the problem in the transition from one network to another. Station, although almost immediately switched from one BSS to the other he, but when examin-ing the chart of received data at the application layer were apparent failures of transmis-sion of orders in a few seconds, which for high-quality voice services is not acceptable time interval. Lowest values were achieved using wireless bridges, the shortest period of failure of income data was 3.5 s. Up to that lack of support for the model of service quality work without problems.
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QoS simulating of wireless network in OPNET
Rágula, Michal ; Molnár, Karol (referee) ; Vlach, Jan (advisor)
The aim of this bachelor work is project and simulation of wireless network with the Quality of Service (QoS) support. It is composed of two parts, the theoretical and the practical one. In the first part there are analyzed findings needed for understanding the existing problems. The second part describes project in detail and setup of network. The theoretical part presents division and format of wireless networks, especially Wi-Fi settings, which is defined by IEEE 802.11 standard. The biggest attention is paid to IEEE 802. 11e standard, which improves the so-called Media Access control MAC (sublayer of line layer) with extension of the QoS (Quality of Service) support in wireless local networks. This standard is important for delay sensitive applications like Voice over Wireless IP and current multimedia. The practical part describes design of wireless network in Opnet Modeler settings and configurations of particular components for the right utility. The required quality of service (QoS) support is achieved by authorization of HCF (Hybrid Coordination Function) protocol at all operating stations and AP access points. It was necessary to make two models. First of them supported the QoS service. On the other hand the same service was inaccessible for the second one. Statistics are made by comparison of final graphs of these two models.
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Optimalizace podmínek testování turbínových kol na plynových hořácích
Handl, Martin
The thesis describes the topic of turbine wheel testing in terms of high-cycle fatigue in general. It explains specifics of fatigue life testing on engine with real conditions and testing on gas stand with simulated conditions. The main part solves the optimization of conditions simulated by gas stand in relation to the real conditions on the engine.
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Graphical user interface for probabilistic modelling of WLAN wireles networks
Stecík, Július ; Molnár, Karol (referee) ; Rajmic, Pavel (advisor)
Course includes functions to access the shared medium, DCF, PCF and HCF. In detail, then describes the EDCA method for accessing the shared medium. The thesis focuses on the probabilistic model of competing stations to access the wireless medium and mathematics and algorithms needed to calculate these probabilities. The last part also design and description of user interface in the form of a Java applet to compute the probability that the station win the competition or on a shared medium collision occurs. The work also contains a brief commentary on the created program embedded in an HTML file.
|
|
|
Simulation of advanced access control functions in wireless networks
Uher, Václav ; Hošek, Jiří (referee) ; Molnár, Karol (advisor)
The work deals with the verification of methods to ensure quality of service and mobili-ty in wireless networks using OPNET Modeler program. It examined the possibility of adjustment the link layer model in order to achieve a better service compared to the model according to IEEE 802.11e and without support implementation of the quality of service. The results of simulations show that quality of service support is one of the key characteristics of wireless network deployment for applications demanding low delay and jitter such as voice services. After modifying the algorithm for calculating the wait-ing times for slow-growing window with specific parameters for the transfer haven’t changed so much that wasn’t worth to enforce it for deployment in the real world. Fur-thermore, it is examined to support mobility and service stations on the network layer. Here I had to tackle the problem in the transition from one network to another. Station, although almost immediately switched from one BSS to the other he, but when examin-ing the chart of received data at the application layer were apparent failures of transmis-sion of orders in a few seconds, which for high-quality voice services is not acceptable time interval. Lowest values were achieved using wireless bridges, the shortest period of failure of income data was 3.5 s. Up to that lack of support for the model of service quality work without problems.
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QoS simulating of wireless network in OPNET
Rágula, Michal ; Molnár, Karol (referee) ; Vlach, Jan (advisor)
The aim of this bachelor work is project and simulation of wireless network with the Quality of Service (QoS) support. It is composed of two parts, the theoretical and the practical one. In the first part there are analyzed findings needed for understanding the existing problems. The second part describes project in detail and setup of network. The theoretical part presents division and format of wireless networks, especially Wi-Fi settings, which is defined by IEEE 802.11 standard. The biggest attention is paid to IEEE 802. 11e standard, which improves the so-called Media Access control MAC (sublayer of line layer) with extension of the QoS (Quality of Service) support in wireless local networks. This standard is important for delay sensitive applications like Voice over Wireless IP and current multimedia. The practical part describes design of wireless network in Opnet Modeler settings and configurations of particular components for the right utility. The required quality of service (QoS) support is achieved by authorization of HCF (Hybrid Coordination Function) protocol at all operating stations and AP access points. It was necessary to make two models. First of them supported the QoS service. On the other hand the same service was inaccessible for the second one. Statistics are made by comparison of final graphs of these two models.
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Modelling of advanced 802.11e technology features in OPNET Modeler environment
Šeliga, Michal ; Reichert, Pavel (referee) ; Molnár, Karol (advisor)
This master thesis includes a short review of the structure of WLAN (Wireless Local Area Network) technologies 802.11a/b/g, the description of their physical interface and the description of the basic medium access control mechanisms implementing the PCF (Point Coordination Function) and DCF (Distributed Coordination Function) methods. I mainly focused on the detailed evaluation the new 802.11e standard which was designed to efficiently support real-time services in wireless environment. To provide QoS (Quality of Service) support, this standard specifies the EDCA (Ehanced Distributed Channel Access) and HCF (Hybrid Coordination Function) medium access control methods for the shared wireless environment. The next chapter of my work is devoted to the verification of the theoretical results in OPNET Modeler simulation environment. I studied in details the WLAN model available in OPNET Modeler, the effect of data-flow classification into separate categories and the configuration of several access method parameters. Next, I created my own WLAN model according to the 802.11e standard. This model contains four applications two of them with real-time requirements. The model is divided into several scenarios, each focusing on different aspects of wireless network technologies like QoS support and it´s dependency on the number of clients, mobility of wireless terminals and comparison of the 802.11a/b/g and the 802.11e technology.
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