The article is devoted to the development and implementation of quadrature amplitude modulation algorithms based on an analog complex band-pass filter with Butterworth low-frequency prototypes. The use of complex Butterworth band pass filters makes it possible to obtain carrier signals with practically non-overlapping spectra. But the analog complex Butterworth filter has a non-linear phase-frequency response and, accordingly, the impulse responses of which are infinite and asymmetric. An overview of the development and implementation of a serial QAM modem based on an analog Butterworth complex band-pass filter and an inverse digital FIR filter. The procedure for obtaining the expression for the impulse response of analog complex band-pass Butterworth filters is considered. With the help of circuit simulation, the frequency response and impulse response of such a filter are determined. The choice of the center frequency is carried out by setting two coefficients. A block diagram of a serial data transmission system with quadrature amplitude modulation based on an analog complex Butterworth bandpass filter and an inverse digital FIR filter is proposed. The results of its circuit simulation in the Micro-Cap environment are presented.

The purpose of this work is to analyze the energy saving schemes of user equipment in the first releases (Release 15) of the fifth generation (5G NR) cellular mobile communication systems, as well as to identify possible ways to improve the energy efficiency of these systems. The paper describes the identified drawbacks of the existing discontinuous reception scheme (DRX-scheme) used for user equipment energy saving in 5G NR. The effectiveness of discontinuous reception scheme in reducing user equipment energy consumption was analyzed in detail by simulation study for various traffic models and a key scenario for the deployment of 5G wireless cellular mobile communication systems. Analysis of the simulation results shows that the discontinuous reception scheme does not reach the upper limit of possible energy saving for all the traffic models studied for a number of reasons described in this paper.

to increase the efficiency of the trunking communication systems design process, an original algorithm for the automatic placement of base stations is proposed, taking into account the real conditions of radio wave propagation. The analysis showed that the existing methods allow you to place base stations manually, with a given step or automatically, but without taking into account the propagation of radio waves, which leads to poor-quality coverage of the required area with communication. The aim of the work is to reduce the complexity of designing a trunking communication system that is guaranteed to cover a given service area. It is proposed to calculate the service areas of base stations using a statistical model, as well as taking into account additional diffraction losses on the radio signal propagation path. The solution to the problem of automatic placement of base stations is based on the use of the proposed modified Hut model, which takes into account the terrain at the locations of the base and portable stations, as well as on the international recommendation for predicting signal propagation on a specific route for ground services. With automatic placement, the optimality criterion is fulfilled, which consists in placing the minimum number of base stations necessary to cover the required territory. An element of the novelty of the presented solution is that at the first stage of the calculation, the service area of the base station is determined by the statistical method, at the second stage, an updated calculation of the service area takes place taking into account the actual conditions of radio wave propagation at the binding site, and at the third stage, the zone of guaranteed customer service is determined. The use of the proposed algorithm makes it possible to reduce the complexity of the system design process and determine the sufficient number of base stations needed to cover a given area with communication. Appropriate software has been developed to apply the algorithm in real practice. To confirm the effectiveness of the algorithm, the paper presents comparative calculations of the time spent on designing a trunking communication system using the developed software and using the widely used RadioMobile program.

The article describes the results of research on the development and testing of an automatic speech recognition system (SAR) in Arabic numerals using artificial neural networks. Sound recordings (speech signals) of the Arabic Yemeni dialect recorded in the Republic of Yemen were used for the research. SAR is an isolated system of recognition of whole words, it is implemented in two modes: "speaker-dependent system" (the same speakers are used for training and testing the system) and "speaker-independent system" (the speakers used for training the system differ from those used for testing it). In the process of speech recognition, the speech signal is cleared of noise using filters, then the signal is pre-localized, processed and analyzed by the Hamming window (a time alignment algorithm is used to compensate for differences in pronunciation). Informative features are extracted from the speech signal using mel-frequency cepstral coefficients. The developed SAR provides high accuracy of the recognition of Arabic numerals of the Yemeni dialect – 96.2 % (for a speaker-dependent system) and 98.8 % (for a speaker-independent system).

The second part of the study of beamforming issues, based on positioning in ultra-dense millimeter wave radio access networks, is devoted to the formalization and software implementation of a complex simulation model of the functioning of a set of directional radio links. Each directional radio link between a base station (gNodeB – gNB), equipped with an antenna array, and a user equipment (UE), operating in omnidirectional mode, is formed according to the location of the UE, known at the gNB. The set of gNB→UE directional radio links, simultaneously operating in a common frequency range, is studied as a set of traffic beams, that implement space division multiple access (SDMA). Spatial multiplexing is implemented through three-dimensional beamforming at the gNB and makes it possible to compensate for propagation losses and high levels of interference. In the first part of the study, it was shown that the problem of practical implementation of SDMA in ultra-dense radio access networks is a significant (tens of dB) spread in the signal to interference plus noise ratio (SINR), depending on the arrangement of two devices. The purpose of this study is to establish the dependence of SINR on 1) the beamwidth of the gNB sector in the direction of the user equipment in the radio link of the signal of interest (SOI); 2) uncertainty of the UE location; 3) interference from radio links of signal not of interest (SNOI): a) within its sector, b) other sectors of its cell and c) other cells in the network. The simulation model developed and implemented in software in this work for the first time made it possible to establish the interdependence of the UE positioning error factors and the required width of the traffic beam for its service. In particular, it was found, that as the positioning error decreases from 10 to 1 m, the required beam width in the horizontal and vertical planes narrows to 3 °, which makes it possible to increase the SINR to 25 dB. A simultaneous transmission multiplexing study showed that for 64 spatially multiplexed UEs, as the cell size increases from 20 to 300 m, the SINR increases by approximately 30 dB, subject to a beamwidth constraint of 3°. Unlike similar studies, in this model, the contribution from interference from simultaneously operating traffic beams within its sector, other sectors of its cell and other cells in the network is shown separately for the first time, which allows to differentiate the origin of interference and use scientifically based beamwidth control for their compensation.

Application classification is essential to improve network performance. However, with the constant growth in the number of users and applications, as well as the scaling of networks, traditional classification methods cannot fully cope with the identification and classification of network applications with the required level of delay. The use of deep learning technology together with the architecture features of software-defined networks (SDN) will allow the implementation of a new hybrid deep neural network for application classification, which can provide high classification accuracy without manual selection and feature extraction. The proposed structure proposes a classification of applications, taking into account the logical centralized management on the SDN controller. The processed data is used to train a hybrid deep neural network consisting of stacked autoencoder with a high dimensionality of the hidden layer and an output layer based on softmax regression. The necessary network flow parameters can be obtained by processing traffic with a stacked auto-encoder instead of manual processing. The softmax regression layer is used as the final application classifier. The article presents simulation results that demonstrate the advantages of the proposed classification method in comparison with the support vector machine.

The results of creating a unified methodology for reverse engineering the devices machine code are presented. The first part of the series of articles reviews scientific publications in this subject area. In the absence of satisfactory solutions, the author's process methodology is proposed, consisting of the following 4 stages: preparatory activities, static research, dynamic research and documentation. A detailed description of the steps of the first stage is provided, as well as examples of their application in practice using standard software. The scheme of the proposed methodology is presented in graphical form, and the steps given are formally written. The next part of the series of articles will describe the steps of the remaining stages and their systematization in tabular form, indicating the input and output objects, as well as the form of steps execution.

Methods of user identification based on digital fingerprints are considered. The main approaches for the browser fingerprints creation which is installed on the user's device and characterizes the device belonging to the user are presented. The methods used to identify a person (user) during the operation of the device are also described. Methods using both the dynamics of keystrokes and interactions with the touch screen, voice and geolocation data, as well as behavioral biometrics and behavioral profile are presented. The concept of continuous authentication is described as a development of the identification approach. A list of publicly available data sets mentioned in the studies reviewed in the review is provided, with links to download them.

The paper considers a method for estimating the fractal properties of traffic, and also evaluates the statistical parameters of the fractal dimension of IoT traffic. An analysis of real traffic with attacks from the Kitsune dump and an analysis of the fractal properties of traffic in normal mode and under the influence of attacks such as SSDP Flood, Mirai, OS Scan showed that jumps in the fractal dimension of traffic when attacks occur can be used to create algorithms for detecting computer attacks in IoT networks. Studies have shown that in the case of online analysis of network traffic, when assessing the RF, preference should be given to the modified algorithm for estimating the Hurst exponent in a sliding analysis window.

A method of paper certificate protection against a cloning attack is investigated, that was proposed recently theoretically in a paper of the same author. This method is based on the use of digital watermarks. In order to extend watermark approach to a protection against cloning attacks, it has been suggested to execute estimation of the noise power which appear during the image scanning and printing. Algorithms of embedding and extraction of watermarks out of the images are presented along with a method of detecting of the cloning attack after scanning and printing by an attacker. Numerical results of the experiments for the error probabilities of a cloning missing and a false alarm are also presented and are in agreement with theoretical results obtained before.