Digital-to-analog converters are widely and effectively used in radio-electronic equipment for various purposes, when it is necessary to convert a digital control code into an analog parameter - current or voltage. They are used, among other things, in digital-to-analog frequency synthesizers to obtain the required envelope shape of the synthesized signal. At present, the main problems in the construction of precision and (or) high-speed digital-to-analog converters are technological limitations of production, namely, the final accuracy of the implementation of analog elements. Therefore, a structural method for overcoming technological limitations is relevant.

The purpose of this paper is to conduct a comparative analysis of classical digital-to-analog conversion methods based on the R-2R matrix and to substantiate a new approach to the ideology of digital-to-analog conversion and the construction of digital-to-analog converters of increased accuracy and (or) speed.

The solution to the problem lies in increasing the number of reference signals at the inputs of partial digital-to-analog converters while unconditionally ensuring their strict fractional-multiple (vernier) ratio. In this case, the conjugation of the vernier scales must be performed at one point and on direct current. The accuracy of the conjugation of the scales must correspond to the final accuracy of the digital-to-analog conversion.

The novelty and originality of the proposed method are confirmed by theoretical calculations, structural and circuit modeling, full-scale modeling, as well as Russian and US patents.

The possibility of practical implementation of the new structure of the digital-to-analog converter is confirmed by circuit modeling using the Microcap12 package and full-scale prototyping, which confirmed the correctness of the proposed method.

The proposed solution allows to bypass technological limitations on the potentially achievable conversion accuracy in the production of DAC microcircuits and provides qualitatively new capabilities of digital-to-analog conversion technology.

Relevance. This article addresses the problem of Joint Service Migration and Resource Allocation (SMRA) optimization in a Multi-access Edge Computing (MEC) environment, aiming to reduce latency in telepresence systems. MEC enhances cloud computing capabilities by relocating services to the network edge, as close as possible to users, thus resolving access latency issues. However, the high mobility of devices and the limited resources of edge servers complicate the maintenance of Quality of Service. The service migration process itself introduces additional latency, and different servers and user devices have their own unique requirements and resource allocation policies, necessitating a balanced approach to solving this problem. Despite advancements in the field of telepresence, such as high-quality video and spatial audio, virtual reality, and augmented reality, the effective operation of these systems requires a robust infrastructure and minimal interaction delays.

Problem statement. In this work, we propose a joint SMRA+MEC algorithm that considers the specific characteristics of telepresence systems and addresses the problem of optimal resource allocation and the necessity of service migration.

Purpose of the work. Development and evaluation of the effectiveness of a joint SMRA+MEC algorithm adapted for telepresence systems.

Methods used. To achieve the stated goal, mathematical models will be used in this work to formalize the SMRA+MEC problem, taking into account the parameters of telepresence systems.

The results show that the proposed algorithm achieves a significant latency reduction of 50 %.

Scientific novelty. A novel method for calculating latency is presented, which allows for minimizing latency and allocating resources more optimally. It is shown that combining SMRA+MEC methods is the most effective approach to latency minimization.

Practical significance. The developed SMRA+MEC algorithm can be used by mobile operators to optimize the deployment and management of MEC infrastructure, providing high-quality service for telepresence applications.

Relevance of the Study. Modern next-generation mobile networks impose extremely high requirements on spectral efficiency, reliability, and robustness in urban environments with high user density. The MIMO-NOMA technology, despite its proven potential, requires a revision of existing models due to the need to account for users' spatial dynamics, polarization distortions, hardware nonlinearity, and channel state information (CSI) estimation errors. The lack of comprehensive models capable of simultaneously addressing these factors significantly limits the ability to effectively optimize systems in practical scenarios.

Research Objective. The study aims to develop a comprehensive mathematical model of the MIMO-NOMA segment between the precoder and the summation scheme in the complex baseband domain, accounting for terminal mobility and orientation, antenna polarization, amplifier nonlinearities, and CSI errors, to analyze and optimize precoding and successive interference cancellation (SIC) algorithms.

Research Methods. The modeling incorporates: stochastic processes (including the Ornstein–Uhlenbeck model and social force models) to describe user mobility; analytical geometry to represent the spatial orientation of antennas; electromagnetic propagation theory methods to model cross-polarization effects; and Saleh and Volterra models to describe power amplifier nonlinearities in the FR1 and FR2 frequency ranges.

Research Results. A vector signal model was derived, incorporating the effects of terminal orientation, interference, polarization and nonlinear distortions, and CSI errors. Analytical expressions were obtained for evaluating SINR, SER, throughput, and energy efficiency, considering all distortions. A comparative analysis of the proposed model against existing standards (3GPP, ITU-R) and academic approaches (DL-based, IRS-assisted) demonstrated its superiority in terms of realism and analytical completeness.

Scientific Novelty. For the first time, a mathematical model of the MIMO-NOMA system is proposed that simultaneously accounts for terminal dynamics, dual polarization, nonlinearities with memory effects, and multipath scenarios, providing an analytical description within a unified parameter space.

Theoretical and Practical Significance. The model refines the description of the MIMO-NOMA channel and supports the optimization of precoders, summation schemes in the complex baseband domain, and SIC algorithms in next-generation mobile networks, particularly in conditions of high mobility and dense urban environments.

The relevance of the topic is to develop cellular networks, which, on the one hand, requires the development of antenna devices that provide the required communication range, and on the other hand, imposes restrictions on the linear dimensions of emitters while maintaining the requirements for ease of manufacture and reliability of operation, taking into account adverse weather conditions. With the transition to next-generation communication standards, there is an increasing demand for antenna systems capable of operating over a wide frequency range and providing a stable signal level under high subscriber density. Of particular importance is the development of antenna arrays that allow the formation of specified radiation patterns and ensure uniform coverage of the serviced area.

The goal is to develop a small-sized antenna array with the required electrical characteristics. Antenna elements should be distinguished by manufacturability. The finite element method (FEM) and the finite difference method in the time domain (FDTD) are used as numerical methods for calculating the electrical characteristics of the antenna. The gradient optimization method is used to solve the problem of reducing the linear dimensions of the antenna element while maintaining directional and range properties.

The result of the study is a full-size experimental sample of a linear antenna array of a cellular base station. Its design and characteristics are substantiated in this work.

Novelty: description of the method of a new approach to the manufacture of an antenna element, which differs from existing ones by using a special underlying insert under each element of the antenna array.

The practical significance of the results of scientific research lies in the development of an antenna array with a distortion-free directional diagram in the frequency range of 1710‒2700 MHz and a gain of at least 15 dB.

Relevance. Trunk radio communication systems have become widespread in Russia and other countries. In this regard, radio intelligence and radio monitoring services must regularly search for and identify functioning radio stations, as well as their direction finding and location assessment. Trunk systems have many frequency channels, and they are dynamically allocated to subscribers for the duration of communication sessions. Since subscribers can use different radio channels at different time intervals, to determine the location of the signal source it is necessary to select its bearings in all radio channels of the system. To solve this problem, address direction finding must be used, which includes detection of signals from trunk network sources, their identification and formation of bearings of identified sources.

The aim of the work is to develop algorithms for address direction finding of signal sources of trunk networks DMR, dPMR, NXDN, APCO P25, TETRA. The paper uses methods of computer and full-scale modeling of the developed algorithms. The instrumental base used is a two-channel receiver, an antenna array, trunk systems analyzers and test radio stations.

Novelty. The paper presents an algorithm for address direction finding of signal sources of trunk communication systems DMR, dPMR, P25, NXDN, TETRA, which performs detection, identification of signal sources and formation of an estimate of the direction to these sources. An algorithm for the preliminary detection of active radio channels of trunk networks has been developed, which allows for a significant reduction in the number of analyzed carrier frequencies and an increase the speed of the analyzer.

Decision. The implementation of the presented algorithm of address direction finding is based on the use of trunk system analyzers and a two-channel radio receiver with an antenna array and navigation equipment. The analyzers implement “addressability”, and the two-channel receiver and antenna array implement direction finding of identified sources. Based on spectral analysis, an algorithm for the preliminary detection of active radio channels of trunk networks has been developed.

Practical significance. The implementation of address direction finding of signal sources of trunk communication systems allows determining their location and expands the functionality of existing signal analyzers. The use of the developed algorithm for preliminary detection of active radio channels significantly reduces the analysis time. The developed algorithms for address direction finding have been implemented and successfully tested in the analyzer of signal sources of trunk communication systems based on the direction finder ARTIKUL-M1.

Unmanned Aerial Vehicles (UAVs) are currently undergoing active development. Their radio equipment is also advancing, presenting new challenges for designers. From the antenna perspective, a straightforward solution for ensuring communication is the use of omnidirectional antenna systems, which allow establishing a communication link with the UAV from any direction. However, such systems have a limited communication range. A relevant task is to increase the operational range of communication links for unmanned aerial vehicles while maintaining the capability to establish a link from any direction. Primarily, increasing the range can be achieved by employing directional antenna systems; however, this is limited by the specific operational features of UAVs. Although numerous studies focus on creating antenna arrays with a wide scanning angle range, such systems require complex beamforming networks, which complicates their implementation on commercial products due to the additional weight burden on the UAV.

Aim. Development a switchable antenna system for unmanned aerial vehicles with the capability to select the radiation / reception direction in any azimuth plane direction to enhance the communication range compared to omnidirectional onboard antenna systems.

Materials and methods. As part of this research, models of a radiating element, a switchable circular antenna array, and a cylindrical antenna array were developed using the Ansys HFSS electromagnetic simulation package, which is based on the finite element method for calculating electromagnetic fields.

Results. The radiation patterns of an 8-element and a 6-element circular antenna array are presented, specifically the values of the directivity coefficient and azimuthal plane radiation patterns. Similar characteristics and parameters for a 6×2 element cylindrical antenna array are also provided.

Scientific novelty. The developed models increase the communication link budget of the UAV by 4.4‒7.2 dB compared to omnidirectional systems, which proportionally extends the range of the communication link. Particular emphasis is placed on the shape of the radiation pattern envelope when switching to an adjacent element of the antenna system, as well as on the feasibility of implementing not only circular but also cylindrical array geometries.

Practical significance. This research proposes design solutions for use on UAVs, enabling operation from any direction in the azimuth plane, as well as with an inclination in the elevation plane for the cylindrical antenna system.

Relevance. At the current stage, methods for improving the reconnaissance and interference immunity of HF radio communication systems are based on packet data transmission technologies in the adaptive pseudorandom frequency hopping mode. To support frequency hopping, service functions should be organized, such as route probing, transmission of operating frequencies to radio stations, and synchronization of radio stations, which usually use the frequency hopping range. Using the frequency resource of the radio communication systems for service purposes limits the possibility of exchanging operational information and increases the probability of suppression. The article presents a solution to the urgent problem of ensuring the stability of the radio communication systems through the use of meteor radio channels for frequency provision of radio stations and their synchronization and collecting current data on the interference situation at corresponding radio stations.

The purpose of the work is to increase the stability of the radio communication systems operation through the use of a promising ionospheric-wave and frequency dispatch service equipped with meteor radio communication tools. The methods used: imitation modeling of the conflict of complex systems: radio communication systems and electronic warfare systems.

The result consists in achieving high noise immunity of the radio communication systems.

The novelty consists in the use of meteor radio communication facilities for frequency provision and synchronization of radio stations.

Practical significance is ensuring the continuity of the radio communication systems operation under conditions of active radio suppression.

Relevance. The development of the Internet of Things networks, being one of the priority areas of telecommunications development, leads to the formation of networks with a high concentration of devices - high-density and ultra-high-density networks. To ensure the functioning of such networks, various communication technologies can be used, which leads to the formation of heterogeneous networks of the Internet of Things. These can be data collection networks, machine-to-machine (M2M) communication networks, telecontrol and others. The use of many technologies requires the application of methods that ensure the efficiency of their use for data transmission. In this paper, one of such methods is proposed that ensures an increase in the efficiency of a heterogeneous Internet of Things network.

Problem statement. Development of a model and method for distributing power between subchannels in nodes of a heterogeneous high-density Internet of Things network, taking into account the features of such networks, allowing to obtain a description of their functioning and ensure an increase in the efficiency of functioning due to the redistribution of transmission power across subchannels.

Purpose of the work. Improving the efficiency of a heterogeneous high-density Internet of Things network. To solve the problem, methods of mathematical modeling, information theory, optimization and numerical modeling were used.

Result. A modeling and methodological apparatus has been developed that ensures increased efficiency of a high-density heterogeneous Internet of Things network due to optimal power redistribution between data transmission subchannels, which makes it possible to increase the data transmission rate at a fixed transmission power.

Novelty. The efficiency of the proposed method is ensured by solving the problem of optimal power distribution between subchannels taking into account the amount of interference and the serviced traffic (usage). The efficiency of the method depends on the parameters of the subchannels. It is minimal for identical subchannels and increases with increasing differences between the parameters of the subchannels used. The proposed method takes into account the traffic transmitted via subchannels (subchannel load) and their features in terms of achievable transmission speed, which makes it possible to adapt this method to specific conditions.

Practical significance. The developed model and method can be used in the construction of devices and heterogeneous networks of the Internet of Things of high density in order to increase their efficiency. The method of power distribution by subchannels can be used in the implementation of the transmission control system (protocol) for devices using various technologies for organizing transmission channels.

Relevance. In modern attack detection systems (ADSs), signature analysis algorithms are key components in the process of analyzing network traffic. Their widespread use in implementation of attack detection rules is due not only to the ease of their configuration and search speed, but also to the ability to detect attacks with zero false positives. This is achieved by specifying such sets of special rules (signature rules) that uniquely identify a specific type of attack. The development and optimization of models and algorithms for constructing such rules is an urgent task, since its solution allows increasing the level of protection of network resources from attacks.

The purpose of the research is to improve the operating efficiency of ADSs built on the basis of signature analysis. Methods used. The research is based on the application of provisions from the theories of sets and information retrieval, as well as parallel and network programming techniques. The subject is models and algorithms for signature search of attacks in network traffic, the object is signature ADSs.

Novelty. The paper presents a mathematical model of signature analysis of network traffic, which differs from known analogs in the universality of the representation of signature rules and support for multi-level processing of both individual packets and network data flows; an assessment of the effectiveness of the software implementation of this model is performed. The universality of the representation of signature rules is achieved due to the possibility of their expansion with new rules regardless of their internal implementation and without the need to reconstruct the original model. Multi-level processing of packets and network data flows by signature rules is ensured by the IP defragmentation and TCP reassembly algorithms developed and integrated into the model.

Practical significance. The result of the experiment shows that the developed network traffic analyzer demonstrates performance that is 1,5 times superior in terms of promptness and resource consumption to other open source ADSs. Thus, the developed model can be used in constructing an effective ADS.

The relevance of the study is determined by the need to identify production management solutions that ensure the required efficiency of its functioning under the influence of various disturbing factors.

Research objective: to identify ways to improve production efficiency by upgrading the automated production management system. During the study, simulation modeling of the production process and processing of its results using Rosenblatt ‒ Parzen methods and numerical n-fold integration were used to determine the probabilities of achieving a set of objectives. These probabilities made it possible to form a range of acceptable solutions for managing production operations and, using the centroid method, to select the optimal solution in terms of robustness.

Results. A methodology has been developed for justifying robust solutions for managing the production of a chemical industry holding company.

Novelty. The proposed methodology differs from existing ones in that it uses the criterion of maximizing robustness to find the optimal solution, which helps to find solutions that ensure the achievement of a set of production objectives even in the event of unforeseen circumstances or external disturbances in the future.

Practical significance. Implementing the proposed methodology as part of the existing mathematical support for the automated production management system of the chemical industry holding company will enable the introduction of a proactive approach to production management practices and significantly improve the efficiency of this process.

Introduction: software vulnerabilities is one of the leading causes of threats to information security. Such vulnerabilities can be countered by directly searching for them in the program code and correcting it. This requires converting the executable code to a higher-level representation that's more suitable for searching and fixes; however, for a number of reasons, existing solutions cannot be considered satisfactory. One of these solutions – an exhaustive search of all possible variants of the source code, converted to a given machine code – is extremely costly in every way.

Purpose: developing a less costly and more efficient method of exhaustive searching through source code variants.

Methods: quantitative and qualitative comparison of different source code generators, as well as the formalization of this method by writing it in an analytical form.

Results: a 7-step scheme for selecting an instance of the source code according to a given machine code is proposed; the authors refer to this method as «smart» because of its optimal combinations of syntactic constructions of the programming language. This method of code generation is based on iterating through paths along the graph of syntactic rules that represent the formal syntax of a programming language in a given space. The syntax is presented as a parameter, which makes its steps completely invariant from the programming language of the source code. After multiple instances of the source code are generated, they are compiled into machine code and compared with the specified instance; if they match, the task of decompilation by smart exhaustive search is considered solved.

Practical significance: despite the time cost of using exhaustive searching in solving such tasks, the smart iteration method has shown expert efficiency in a number of application scenarios; thus, it can be directly applied to reverse engineering.

Discussion: the qualitative optimization of the "smart" exhaustive search can significantly improve it by genetic algorithms used.