Information and Telecommunication Sciences

OPTIMIZING DISTRIBUTED DATA STORAGE IN MULTI-CLOUD ENVIRONMENTS: ALGORITHMIC APPROACH

Larysa Globa — 2024-12-23

Background. Multi-cloud environments present complex challenges in optimal resource allocation and provider selection. Previous research has established a comprehensive ontological model and evaluation criteria for distributed data storage, however efficient provider selection remains a significant challenge due to the dynamic nature of cloud services and the multitude of interdependent factors affecting performance and cost-effectiveness.

Objective. The purpose of the paper is to develop and validate a sophisticated optimization function for cloud provider selection in multi-cloud environments, incorporating both Reinforcement Learning (RL) and Multi-Objective Evolutionary Algorithms (MOEAs) to address the complexity of provider selection while considering multiple competing objectives and constraints.

Methods. The research employs an ontological approach to formalize domain concepts, relationships, and properties in multi-cloud environments. Additionally, an optimization function is developed incorporating multiple weighted criteria derived from the established ontological model. The study focuses on the implementation of the RL algorithm to adapt to dynamic changes in cloud provider characteristics and integration of MOEAs to handle multiple competing objectives as well as providing a comparative analysis with traditional selection methods and alternative optimization approaches for multi-cloud storage settings.

Results. The proposed ontological model successfully formalizes the domain's concepts, relationships, and properties in multi-cloud environments. The optimization function demonstrates effectiveness in selecting the most suitable public cloud provider based on the proposed features, enhancing data management practices automation and decision-making processes.

Conclusions. The developed optimization function and suggested methodology significantly advance the state-of-the-art in distributed multi-cloud data storage. The integration of RL and MOEAs provides a robust framework for addressing the complexity of multi-cloud environments while offering superior performance compared to existing approaches. The methodology successfully balances multiple objectives while adapting to dynamic changes in cloud provider characteristics.

METHOD FOR IMPROVING SECURITY OF IOT DEVICES PAIRING

Stanislav Pedan — 2024-12-23

Background. The usage of IoT technologies leads to the social, technological and financial development of society. While complex systems play an important role in the IoT, the design, integration and use of simple devices really drive the technology's widespread adoption. At the same time, ensuring a high level of security for simple IoT devices is a difficult task. The reasons for this are device limited computing resources and low power consumption requirements. It prevents the implementation of most modern cryptographic protocols for simple IoT devices. From a security point of view, the most critical communication stage is device pairing, when shared encryption keys are formed to establish a secure communication channel.

Objective. The purpose of the paper is to analyse the main vulnerabilities of a simple IoT device pairing process and develop a method for improving security of this process. The method should provide proximity-based device authentication and pairing process protection against known attacks, such as man-in-the-middle attack.

Methods. The method of pairing process security improvement includes proximity-based device authentication using analysis of the wireless signal strength. The security of the authentication method is proven analytically and by results of practical experiments with measurement of wireless signal strength change with distance and obstacles between devices.

Results. Performed research demonstrated that the proposed method guarantees secure user authentication at a close distance between devices and protection against attacker located at least 10 meters from the paired device. Provided theoretical calculations and experimental results show that the level of attacker's wireless signal power increase required for a successful attack exceeds technical capabilities of existing communication devices.

Conclusions. The article solves an important issue of improving the security of simple device pairing. The proposed method of proximity-based IoT device authentication provides pairing process protection against man-in-the-middle attacks. Mathematical calculations were confirmed by conducting a number of experiments to research wireless signal power change depending on the distance and types of obstacles between devices. The proposed authentication method can be integrated into the existing JustWorks protocol for connecting simple IoT devices using the BLE communication channel.

AUTOMATED LECTURE NOTE-TAKING SYSTEM

Svitlana Sulima — 2024-12-23

Background. In the modern world, information technologies evolve rapidly, constantly altering our approaches to learning, work, and daily life. One significant aspect of this evolution is the automation of various processes, including education. Students and teachers are faced with large volumes of information that need to be processed, stored, and used in the educational process. Taking lecture notes is still an important task that requires a lot of time and effort, thus automating this process is both relevant and necessary. Automated lecture note-taking based on video and audio materials greatly facilitates the lives of students and teachers by providing quick access to structured information. The use of speech recognition and artificial intelligence technologies to create notes from lecture materials opens up new opportunities for effective learning. These systems can significantly save time, improve the quality and accuracy of notes, and ensure their accessibility to all participants in the educational process. These systems can not only create notes but also structure them by highlighting key points and providing easy access to information. This allows students to focus on understanding and comprehending the material rather than writing it down, thereby improving the quality of learning and knowledge acquisition.

Objective. The purpose of the paper is to simplify the note-taking process and improve its quality by developing a system for automated lecture note-taking based on video and audio materials, ensuring the efficient and rapid creation of structured notes from lecture materials.

Methods. Analysis of Literature and Contemporary Studies: Studying scientific articles, monographs, and dissertations related to the topic of automated lecture note-taking, speech recognition, and artificial intelligence. System Analysis: Defining system requirements, analysing possible approaches and tools for implementation. Experimental Method: Developing, implementing, and testing the system. Comparative Analysis: Evaluating the effectiveness of different speech recognition tools and AI models for creating notes. Modelling and Prototyping: Creating a system prototype, testing it, and improving it based on the obtained results.

Results. During the implementation of the automated lecture note-taking system, an effective Telegram bot was created, which uses "whisper-1" and "gpt-4" models to provide high-quality speech recognition and the generation of structured notes from video and audio materials.

Conclusions. The developed system of automated note-taking of lectures based on video and audio materials significantly simplifies the preparation of materials for students and teachers. Integration with Telegram and implementation of the system through a Telegram bot ensure cross-platform, accessibility and ease of use and at the same time provide an opportunity to avoid creating additional web or mobile applications for a wide range of users. The use of OpenAI's "whisper-1" model demonstrates high accuracy of speech recognition, which allowed improving the quality of transcriptions compared to other tools such as Vosk or FasterWhisper.

METOD FOR INCREASING THE SPECTRAL EFFICIENCY OF TROPOSCATTER COMMUNICATION BASED ON THE USE OF COMPOSITE SIGNALS IN THE WALSH BASIS

Sergii Kapshtyk — 2024-12-23

Background. In modern telecommunications, troposcatter communication systems organize long-distance communication. These systems allow communication beyond the line of sight. An important factor that must be considered in these systems is multipath, due to the physical principle underlying the functioning of troposcatter systems. Diversity reception and broadband signals are used to overcome this factor's negative impact. However, broadband signals use an excessive frequency band and are characterized by a low spectral efficiency.

Objective. The purpose of the paper is to develop a method for overcoming the negative impact of multipath by using composite signals on the Walsh basis.

Methods. Parallel composite signals provide simultaneous packet transmission of a group of signals built based on a complete system of mutually orthogonal Walsh-Hadamard functions. Each signal transmits one bit of information, but the parallel transmission of a packet of mutually orthogonal signals avoids decreasing the system's information transmission rate. To counteract the effect of multipath, pilot signals are added to the composite signal, as individual Walsh-Hadamard functions with better auto- and cross-correlation properties are selected. The advantages of composite signals in the Walsh-Hadamard basis include their spectral efficiency, which significantly exceeds the spectral efficiency of broadband signals. The paper describes a method for forming a composite signal on a Walsh-Hadamard basis with pilot signals and a functional diagram of a receiving device that provides optimal pre-detector addition of signals from four independent diversity reception channels.

Results. The method of forming the composite signal with pilot signals based on the Walsh-Hadamard basis is presented as a functional diagram of a reception device that will ensure optimal detection of composite signals from several independent channels of a separated receiver. The spectral efficiency of the composite signals is shown on the size of the Walsh-Hadamard vicor basis. The introduction of the pilot signals makes it possible to ensure the synchronous composition of signals received from several independent receiving channels.

Conclusions. The proposed technical solutions using composite signals in the Walsh-Hadamar basis make it possible to create troposcatter communication systems that provide operation in multi-path conditions, and the spectral efficiency of which significantly exceeds this indicator for systems using M-sequence signals, which allows increasing in the information transmission rate at the same frequency bandwidth or increasing their noise immunity by using additional noise-resistant coding at a fixed information transmission rate.

EVALUATING THE FUNCTIONING EFFECTIVENESS OF SENSOR GROUND-TO-AIR NETWORK USING MULTIPLE UAVS LAYERS AND DIRECTIONAL ANTENNAS

Ihor Sushyn — 2024-12-23

Background. Based on the theoretical and practical (using Atoll) calculation of radio communication lines and antenna devices were estimated the main network parameters (throughput, length of the data transmission route, delays, number of network elements) of proposed ground to air network (GAN) architecture.

Objective. The purpose of the work is to evaluate the effectiveness of mobile networks with directed action sensors using UAVs at different levels.

Methods. Simulation modelling of two mathematical models and their comparison using MATLAB software.

Results. It is shown that the throughput decreases with the increase of the data transmission route, while the delay and the number of network elements increase in accordance with the previous study. Changing the location of the nodes also affects the parameters evaluated, so 10,000 measurements were made to obtain the required amount of statistical data. Two mathematical models were created. The first model is based on an existing mobile omnidirectional sensor network using a single UAV layer while the second one is based on a mobile network of directional sensors using two levels of UAVs. In both models, the data was transmitted from the nodes to the pseudo-satellite. In the proposed model, the following average values were achieved: throughput - 852071 bits/s, number of network elements - 4.4, route length - 33673 meters.

Conclusions. According to the obtained results, it can be argued that the proposed two-level UAV location model using directional sensors can be effectively used to maintain the connectivity of a mobile sensor network with the achievement of a gain in the evaluated indicators.

OPTIMIZATION OF THE SCATTERING MATRIX OF FREQUENCY -DETUNED ADD/DROP FILTERS FOR MULTIPLEXERS BUILT ON SYSTEMS OF OPTICAL DIELECTRIC RESONATORS WITH WHISPERING GALLERY MODES

Alexander Trubin — 2024-12-23

Background. A significant increase in the speed of information transmission in fiber-optic communication networks is determined by the strict requirements imposed on the elemental base of receiving and transmitting devices. One of the important components of such devices is diplexers built on different notch and bandpass filters, which are often performed on dielectric resonators (DR) with whispering gallery mode (WGM) oscillations. Calculation and optimization of the parameters of multilink filters and diplexers built on DR is impossible without further development of the theory of their design. The development of the theory of diplexers today is often based on electrodynamic modelling, which is built on preliminary calculations of filter scattering parameters in various transmission lines with a complex topology of connections.

Objective. The aim of this study is to construct electrodynamics' models of wave scattering on complex multi-connected DR structures with degenerate types of WGM natural oscillations, which contain several frequency-detuned bandpass or notch filters located in one or several transmission lines. To solve the scattering problem, we proposed a system of equations derived from perturbation theory for Maxwell's equations [24], modified to describe the DR fields with whispering gallery oscillations in transmission lines. The construction of such solutions is complicated by the fact that each of the partial optical resonators of the filters, in the case of excitation of azimuthally inhomogeneous WGM in it, has, as a rule, two degenerate types of natural oscillations. Moreover, each such type of oscillation is characterized by different complex values of the coupling coefficients with the line, open space, and also with other resonators. The latter circumstance leads to the fact that the systems of equations for the amplitudes of natural and forced oscillations of resonators are doubled. The signs of the coefficients of mutual coupling are usually different, this leads to the fact that the behaviour of DRs in the system becomes more difficult to predict, therefore the second objective of this work is to study the patterns of the scattering characteristics of line waves on systems of frequency-detuned DRs with degenerate types of oscillations with the possibility of constructing multiplexers for modern optical communication systems.

Methods. The methods of technical electrodynamics are used for calculating and analysing scattering matrices. The end result is obtaining new analytical equations and formulas for new complex structures of coupled dielectric resonators with whispering gallery oscillations in the different transmission lines.

Results. Frequency dependences of scattering matrices on complex structures of frequency-detuned filters built on coupled optical DR with whispering gallery oscillations located in one or more transmission lines are considered. Electromagnetic models of bandstop and add/drop filters are built, consisting of various optical resonators with degenerate types of natural oscillations. General analytical expressions of vector coefficients and matrices for building systems of equations describing coupled oscillations, as well as forced oscillations of resonators in cases of their use in optical filters with serial and parallel arrangement, are given. General solutions for the scattering field on frequency-detuned resonators located in different optical transmission lines have been found. Examples of calculating frequency dependences of the scattering matrix for the most interesting structures consisting of two different frequency-detuned filters are given. The frequency scattering characteristics of several types of devices are calculated, which consist of two notch filters with different blocking bands, made on detuned DRs in one transmission line. The possibilities of the earlier proposed method are demonstrated in the example of calculating the scattering characteristics of known types of diplexers built on the basis of the use of two add/drop filters with different frequency bandwidths. The frequency dependences of the scattering matrices of the two most common types of devices, located in parallel between two or four regular transmission lines of add/drop filters with different numbers of resonators; laterally coupled add/drop filters; parallel-coupled add/drop filters; twisted double-channel side-coupled integrated space sequence of resonators (SCISSORs), were studied. New scattering models of diplexers consisting of optical resonators of different connection topologies were built: serial, parallel with the use of laterally coupled add/drop filters; parallel-coupled add/drop filters; twisted double-channel SCISSORs. The frequency dependences scattering matrix of the diplexers were also calculated. The characteristics of the designed diplexers obtained from the examined filters of different types were compared.

Conclusions. The theory of diplexer construction, which takes place on the simultaneous optimization of the scattering matrix of several filters built on complex systems of dielectric resonators with degenerate types of whispering gallery oscillations is expanded. A calculation method was developed and new analytical relations were found for the scattering matrix coefficients of optical diplexers of various types.

MODELING OF BANDPASS FILTERS WITH ATTENUATION POLES USING PARALLEL COUPLING CHANNELS

Kostiantyn Shevtsov — 2024-12-23

Background. Microwave filters are critical components in modern communication systems, playing a fundamental role in signal processing by allowing specific frequency bands to pass while attenuating unwanted frequencies. Over the years, significant advancements have been made in the design and development of various types of microwave filters, including directional, microstrip, and multi-resonator filters. These filters are widely used in radar, satellite communications, and wireless networks, where high performance and precise frequency control are essential.

Objective. This paper is dedicated to reviewing various microwave filters that were constructed developed or analysed by the team, including directional filters, microstrip filters with attenuation poles, and multi-resonator filters. The studies focus on investigating their unique properties, such as the formation of attenuation poles, metamaterial characteristics, and the effects of resonator coupling on filter performance. New Python-based software realization for modelling different filters six resonators, four resonators, and two resonators were developed and frequently used.

Methods. Electrodynamics simulations using software tools like CST Studio Suite, AWR Microwave Office, and LabVIEW, modelling filters using equivalent circuit models and bridge circuits. Use of microstrip lines, circular resonators, and dielectric resonators to construct and analyse different filter configurations. Analysis of energy propagation paths, resonator coupling, and transmission characteristics to optimize filter design.

Results: Various structures were researched like Microwave Directional Filters, Microstrip Resonator Filters with 2, 4, 6 resonator, their structures and characteristics were analysed, New python-based software that allows modelling resonance curves using corresponding parameters for filters with 2, 4, 6 resonators. The parameters of the scattering matrix of a bridge quadrupole were expressed in an analytical form and were used for Python based program.

Conclusions: the research presented across these publications contributes significantly to the development and understanding of advanced microwave filter designs. The article reveals various resonator-based filters, including directional, microstrip, and multi-resonator filters, these studies have highlighted key performance enhancements achievable through resonator coupling, metamaterial properties, and the introduction of attenuation poles. The use of advanced simulation tools, such as CST Studio Suite, AWR Microwave Office, and LabVIEW, allowed for accurate modelling and validation of theoretical designs. The introduction of Fano resonances and trapped modes in filters demonstrated improvements in selectivity and attenuation characteristics, which are critical for modern communication systems. Trapped modes manifest as attenuation poles, resulting from the interference of even and odd oscillations. This is evidenced by the presence of two independent energy pathways, along which these interfering oscillations propagate. With appropriate design parameters (such as resonator coupling coefficients and resonance frequencies), a complete energy exchange between resonators can occur at a certain frequency, in a direction perpendicular to the primary energy flow from input to output. The design and properties of directional filters based on circular resonators and dielectric resonators were described. These filters have "metamaterial" properties and are widely used in modern microwave technology. The characteristics of bandpass and rejector filters, as well as the characteristics of the filters formed by two microstrip resonators and resonators connected to each other, are given. It is important to emphasize the phenomena of "Fano resonances" observed in these filters, which arise as the interference of oscillations from individual resonators.

BASE STATION POWER BACKUP SCHEDULING FOR NETWORK PROVIDERS BY A THREE-PERSON DYADIC GAME

Vadim Romanuke — 2024-12-23

Background. Recently reliable telecommunication has been challenged due to power grid instability and temporary blackouts. There is a strong need for optimizing the base station power backup for telecommunication network providers.

Objective. The purpose of the paper is to substantiate a game model of optimizing the base station power backup for three major telecommunication network providers and determine the best strategy. The optimization is based on payoff symmetry, rather than equilibrium.

Methods. There are only two pure strategies at the provider — to apply the power backup or ignore applying, whenever needed. The latter means avoiding additional expenses for the provider while applying the power backup requires additional expenses. The cost of applying the power backup is set to a conditional unit. It is further assumed that, if only one provider does not apply the power backup, it does not affect the quality of service (QoS). When there is no backup at all, QoS worsens significantly, users subsequently seek for alternative telecommunication services, and shortly every provider loses the 3 units.

Results. The provider’s expected payoff, being treated as a loss, is minimized over the set of symmetric mixed situations, where the provider’s mixed strategy is the no-backup probability. The base station power backup best strategy is realized by turning the power backup off with an irrational probability whose value lies between 0.05904144 and 0.05904145. It is more likely that the backup state switch is possible at definite time intervals usually counted in hours or days.

Conclusions. The best strategy allows saving the power backup for 5.904 % of the temporarily-off-the-grid period by saving 2.9 % of expenses for the backup, which does not worsen the QoS. Whenever the amounts of providers’ expenses, costs, and losses are changed, the best strategy is determined in the same way it has been found.