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Документ Factor synergy analysis and merger strategy models in investigation of telecommunication operators' performance(Національний технічний університет "Харківський політехнічний інститут", 2020) Malyeyeva, Olga; Kosenko, Viktor; Davydovskyi, Yurii; Boiev, DmitriyThe subject of the study is the process of choosing a strategy to improve the effectiveness of telecom operators, given the trend of growth in multitraffic in data networks. The purpose of the work is to analyze the synergy of factors and develop models of traffic of data networks in the implementation of the strategy of merger of telecommunication operators. The following tasks are solved in the article: analysis of telecommunication development strategies; building a network model of synergistic effect in the implementation of development strategies; development of a model of data flow intensity in the integrated networks. The following research methods are used: statistical and system analysis, cause and effect models, mathematical programming models, and vector matrix models. The following resultsare obtained: The tendencies of development of multiservice services in the sphere of infocommunications are considered. Here are some basic strategies for developing a communications company. It is shown that merger and acquisition strategies are nowadays a means of integrating the necessary resources, contributing to competitive advantage. A mathematical model of linear programming is used to make the decision to invest in development strategies. The task of evaluating the effectiveness of development towards expanding the number of service users is considered. A network model in the form of a cause and effect diagram to investigate the mutual influence of sales factorswas formed. The economic manifestation of the synergistic effect of companies in the implementation of the merger strategy is considered. A multilevel data flow model is used to study the intensities of data flows in a unified network. Conclusions: Due to the increasing volume and heterogeneity of infocommunication network traffic, telecom operators are using merger strategies to pool network management resources. Thus there is a synergistic effect of factors affecting sales of services. The changes in traffic and performance of the consolidated network structure are investigated on the basis of a three-tier hierarchical model. The direction of further research is to simulate network load with different technical structure characteristics to evaluate the effectiveness of a reengineering strategy.Документ Application of the sliding window mechanism in simulation of computer network loading parameters(Національний технічний університет "Харківський політехнічний інститут", 2020) Davydovskyi, Yu.; Reva, O.; Malyeyeva, O.; Kosenko, V.The subject of the study in the article is the data transfer processes in computer networks from the point of view of the network performance indicators, in particular, overload parameters. The purpose of the work is to create a simulation model of the behavior of a computer network, taking into account the mechanism of the "sliding window" and to demonstrate its work using a test example in combination with the previously proposed algorithms. The following tasks are solved in the article: analysis of the network as a complex multilevel system and isolation of the problems related to the transport layer of the OSI model; consideration of tasks that are solved by the transport layer of the data network; creation of the mechanism of modeling of functions of "sliding window"; demonstration of model work. The following research methods are used: basics of system analysis, models of network functioning, simulation modeling method. The following results were obtained: Based on the results of previous studies, the article proposes a new model of computer network behavior over a period of time. This model is based on the principles of simulation modeling, which became possible because of the certain fractal properties of incoming traffic, that is one of the initial data for the simulation. In the process of development, the seven-level OSI model was taken as the basic network model and its four lower levels were selected. Ensuring reliable information transmission at all protocol levels is based on the mechanisms of acknowledgement and "sliding window". The proposed model can reduce the amount of user data directly for each of the directions in a proportion directly proportional to their utilization of the specified congested channel. It is proposed to use a correction vector for each direction of information transmission in the model. Conclusions: The adequacy of the developed model is confirmed on the basis of practical calculations of the test case. The practical value of this model is the ability to predict bottlenecks when creating a computer network, or vice versa, to point out the redundancy of certain solutions in order to save significant funds in the future for providers and operators of communication services.Документ Mathematical model of optimal distribution of applied problems of safety-critical systemsover the nodes of the information and telecommunication network(NTU "KhPI", 2017) Kosenko, V. V.The subject matter of the article is the processes of synthesis of the information and telecommunication network (ITN) for solving applied problems of safety-critical systems (SCS). The goalis to develop a mathematical model for the optimal distribution of applied tasks of safety-critical systems over the ITN nodes. The tasks to be solved are: to formalize the procedure of distribution of applied tasks and SCS software over the ITN nodes; to develop a mathematical model of optimal distribution in order to minimize the cost of network resources; to select an effective algorithm for solving it. The methods used are: alternative-graph approach, mathematical optimization models, methods for solving nonlinear integer programming problems with Boolean variables. The following results were obtained: the task of selecting the ITN optimal structure was formulated according to the alternative-graph model of information processing; in addition to structural characteristics, the requirements for the parameters necessary for performing applied tasks were taken into account while constructing a mathematical model; when minimizing the cost of a computing resource, constraints related to the capabilities for financing the development and operation of the network are taken into account; the costs for organizing additional connections among the network nodes are considered as well. As a result, a mathematical model of distributing SCS applied problems over the ITN environment was obtained in order to minimize the total costs of computing resource, data transmission, network setting and maintenance. This model is a non-linear integer programming problem with Boolean variables. Taking into account the specific nature of the objective function and model constraints with the use of pseudo-Boolean functions, the original task is reduced to a linear form. The obtained model represents the canonical form of the linear optimizing problem of large-dimensional Boolean programming, for which the method of the recession vector is effective. Conclusions. The scientific novelty of the results obtained is as follows: 1) the optimization model of distributing applied tasks over the nodes of the computer network was improved by defining the objective function in order to minimize the costs of both computational and data transmission and the constraints caused by the requirements for the technical and information struct ure of the network; 2) methods for solving the problems of optimizing the ITN structure on the basis of models of nonlinear Boolean programming by transforming the initial task into a linear form and applying the recession vector method was further developed, which makes obtaining a quasi-optimal solution of the problem in the context of large dimension possible.