Перегляд за Автор "Uryvsky, Leonid"

Зараз показуємо 1 - 2 з 2
  • Ескіз
    ДокументВідкритий доступ
    Analysis of differences in the characteristics of queuing systems with the dynamics of input streams self-similarity
    (National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 2022) Uryvsky, Leonid; Kryklyva, Anastasiia
    Background. Modern queuing theory is used in many fields and in telecommunications it plays an important role. Today, the modern way to implement queuing systems is a cloud environment. And the main problem of queuing system is to ensure the quality of service. Objective. The purpose of the paper is to study the indicators of service quality of queuing systems with different initial characteristics, to analyse the service quality characteristics when comparing quantitative characteristics of different parameters of queuing systems to identify features of queuing system with self-similarity. Methods. Analyse the theory of QoS, types of distribution, such as Poisson and Weibull, as well as the properties of self-similar traffic. Compare the values of the main parameters that provide the desired quality of service at different inputs and different Hearst parameters. Results. The importance of taking into account the self-similarity factor f or t he a ccuracy o f t he v alues o f t he parameters in the calculation that ensure the quality of service in the QMS. Conclusions. Research of the influence of self-similar traffic on the quality of service in queuing systems.
  • Ескіз
    ДокументВідкритий доступ
    Evaluation of the multipath effect on the quality of radio communication in the technological range IEEE 802.11xx
    (National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", 2022) Uryvsky, Leonid; Solianikova, Valeriia
    Background. As a result of the rays’ reflection from buildings, from the surface of the Earth or from horizontal boundaries between different layers of the atmosphere, occur multipath effects that cause fast fading, which degrades the quality of service. Objective. The purpose of the paper is to determine the multipath effect on the signal-to-noise ratio in a wireless communication channel. Compare the results obtained for a communication channel at operating frequencies of the IEEE 802.11xx standard: 5 GHz and 2.4 GHz. Methods. The useful signal powers and the total interference powers for a communication channel with multipath are calculated. The signal-to-noise ratio for such a channel is compared at operating frequencies of 5 GHz and 2.4 GHz. Results. The results of the study showed that the higher the frequency of the carrier of the wireless radio link, the less pronounced the effect of multipath is. The frequency rating significantly affects the quality of communication in multipath conditions. In this case, lowering the frequency significantly improves the reception condition outside of multipath effect. However, it deteriorates significantly due to the effects of rays reflected from the Earth's surface. In the considered case, the useful signal power in the 2.4 GHz band is 4.2 times higher; at the same time, the power of reflected interference is 19 times higher than in the 5 GHz band. Conclusions. Suggested model makes it possible to determine the effect of interference power in the ranges traditionally assigned in IEEE 802.11xx technology, specifically 2.4 GHz and 5 GHz.