Vol 9, No 1 (2023)

An approach to the substantiation of the empirical formula for calculating the bit error probability of quadrature modulation signals in terms of the average signal energy and the minimum Euclidean distance is considered. An analytical description of quadrature synthesis signals in the time and frequency continuum is presented. An approach to assessing the noise immunity of quadrature modulation signals from the standpoint of the indicator of the average signal energy and the Euclidean distance is considered. The equivalence of various well-known approaches to the analytical calculation of the bit error probability is shown. Graphic materials are presented, as well as simulation results. Empirically substantiated is a universal expression for assessing the noise immunity of receiving quadrature modulation signals, based on the differences in the average energy value and the value of the minimum Euclidean distance. Its generality with known expressions is shown.

The paper proposes a method for separate calculation of the reactive component of the input impedance, radiation resistance and loss resistance small, in comparison with the wavelength of normally open antennas. A detailed equivalent circuit of of the Unbalanced Monopole with Shunt Feed (UMSF). Integral relations are obtained that determine the radiation resistance and the electromotive force of an equivalent generator. The decomposition of the active part of the input resistance into two components, one of which characterizes the radiated power, and the other - thermal losses, allows us to successfully solve both the problem of determining the resistance matching coefficient and the antenna efficiency. The results obtained can be useful in the design of antennas and energy calculations of radio links.

When solving the problem of channel planning of IEEE 802.11 wireless access networks, it is necessary to allocate channels for access points so that the selected channel configuration provides minimum negative mutual influence. We will consider the covering of the plane “tessellation”, i.e. the densest filling, by coverage areas of access points groups, which in the spectral sense correspond to channel clusters. By assigning a channel to each of the access points, we obtain a set of possible configurations, each of which corresponds to a possible solution of the channel planning problem. When solving actual design problems in the 5 GHz band, it is often necessary to take into account channel plans that include 8 or more channels. Based on the previously proposed model and method, in this paper, solutions to the problem of finding the best channel configuration for clusters consisting of 8 access points are obtained, and their characteristics are shown in relation to their geometry.

The article deals with the testing of popular domestic and foreign cloud videoconferencing systems. A methodology for testing and comparing qualitative parameters of videoconferencing applications based on international experience is proposed. Assessment and comparison of videoconferencing services is based on the calculation of Hurst data flows, formed by the investigated cloud videoconferencing systems. Various applications of foreign and domestic videoconferencing systems have been tested in different operation modes with different channel quality parameters.

The paper considers the ability to describe malicious bots using their characteristics, which can be the basis for building models for recognising bot parameters and qualitatively analysing attack characteristics in social networks. The following metrics are proposed using the characteristics of VKontakte social network bots as an example: trust, survivability, price, seller type, speed, and expert quality. To extract these metrics, an approach is proposed that is based on the methods of test purchases and the Turing test. The main advantage of this approach is that it proposes to extract features from the data obtained experimentally, thereby obtaining a more reasonable estimation than the expert approach. Also, an experiment on extracting metrics from malicious bots of the VKontakte social network using the proposed approach is described, and an analysis of the metrics' dependence is carried out. The experiment demonstrates the possibility of metrics extracting and analysis. In general, the proposed metrics and the approach to their extraction can become the basis for the transition from binary attack detection in social networks to a qualitative description of the attacker and his capabilities, as well as an analysis of the evolution of bots.