Browsing by Author "Гаркуша, С. В."

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Модель превентивного обмеження швидкості передачі низхідного каналу зв’язку технології WIMAX в умовах перевантажень
(Видавництво Львівської політехніки, 2013) Лемешко, О. В.; Гаркуша, С. В.
To meet the put forward contradictory technical and economic demands to the structure of transmission networks it is necessary to use multi-criteria optimization methods when planning them. During our planning of a transmission network we design such a topology that has to provide high quality and sufficient reserve capacity at least costs. In practice it means that the designer must balance three transmission network quality factors, which characterize the cost, the quality and the capacity. In this paper we are going to discuss mostly the features of performing the nominal stage of the transmission network planning with the aid of multi-criteria optimization methods. We substantiate our choice of the set of quality factors which can be used to find the optimal topology of a transmission network with respect to them. The optimization procedure includes the next steps: 1) forming a set of valid network topology variants; 2) extracting from the obtained set the Pareto-optimal variants followed by selection of a single variant. The main method to protect against unavailability factor increase is to build a ring topology. However this strategy requires the use of additional equipment and trunks which will lead to a considerable increase in the cost of our network. The cost of the network should be calculated in accordance with the required number of connections and of cross-connectors. That is why it is advisable to carry out the optimization of a mobile communications transmission network with respect to these two conflicting parameters, namely, unavailability factor and cost. Analysis of stages and tasks of mobile communication transmission networks has been done. Initial data, technical characteristics and quality factors that are taken into account during transmission networks planning have been determined. A feature of such networks is that their quality factors are not only related and contradictory to each other, but the values of them depend on the selected specific network topology. That is why to select optimal topologies of a transmission network taking into account the set of quality factors we have to use general provisions of multi-criteria optimization. The paper presents results of solution to the problem of discrete choice of transmission network optimal topologies. The choice takes into account the set of quality factors, namely, unavailability factor and network cost. The set of valid topologies is constructed. The values of contradictory quality factors are estimated and the subset of Paretooptimal variants of network topology over the criterion space of estimates of quality factors is found. By using the conditional preference criterion we extracted a single variant of transmission network topology from the Pareto subset. Рассмотрены особенности оптимизации транспортной сети и приведены результаты решения задачи выбора оптимальной топологии транспортной сети с учетом совокупности показателей качества на основе методов многокритериальной оптимизации.
Разработка и анализ модели распределения подканалов в беспроводной сети стандарта IEEE 802.16
(Видавництво Львівської політехніки, 2012) Гаркуша, С. В.
Представлена математическая модель распределения подканалов в широко-полосных беспроводных сетях стандарта IEEE 802.16. Сформулированы требования, выдвигаемые к математическим моделям распределения подканалов. Проведен анализ получаемых решений при использовании различных критериев оптимальности. The article presents a mathematical model of the distribution of sub-channels in the broadband wireless standard IEEE 802.16. Formulated the requirements for mathematical models of the distribution of subchannels. The analysis of the solutions obtained by using different optimality criteria.
Розробка математичної моделі управління пропускною здатністю низхідного каналу зв’язку технології LTE, що використовує перший вид розподілу ресурсів
(Видавництво Львівської політехніки, 2015) Гаркуша, С. В.; Гаркуша, О. В.
Наведено результати розроблення математичної моделі розподілу частотно-часового ресурсу низхідного каналу зв’язку технології LTE, що використовує перший вид розподілу ресурсів. Запропонована модель спрямована на забезпечення гарантованої якості обслуговування користувачів безпроводової мережі виділенням станціям користувачів необхідної пропускної здатності в низхідному каналі зв’язку. Проаналізовано запропоновану модель розподілу частотно-часового ресурсу технології LTE з погляду забезпечення необхідних пропускних здатностей різних станцій користувачів у низхідному каналі зв’язку. It was established that one of the main problems in the wireless network that operates using LTE, is the task of ensuring the required quality of service, which includes the need for the user equipment network bandwidth required in the downlink. Providing the required bandwidth can be achieved by solving the problems of distribution of a time-frequency resource in a downlink, which acts as resource blocks. As shown by the analysis known solutions for bandwidth allocation in the downlink LTE are oriented on the use of Resources Allocation Type 0, which has a low flexibility due to combination in the resource blocks group. The analysis decision on the need to develop a mathematical model of bandwidth management downlink LTE, using the first type of resource allocation is formulated as a problem of resource allocation sides, to provide the required bandwidth of each user equipment. As a result of this article proposed a mathematical model of the distribution bandwidth downlink LTE which novelty is the use of the Recourse Allocation Type 1. The calculation of the unknown variables in the model proposed in accordance with the conditions, it is advisable to carry out the limitations in solving optimization problems using an optimality criterion aimed at maximizing the overall performance of the downlink. The formulated problem from a mathematical point of view is a task Integer Linear Programming (ILP). In the model the desired variables are boolean, and restrictions on the unknown variables are linear. Using the proposed model has allowed to produce records of technological features downlink LTE (partition resource blocks into subsets assigned to the subscriber station RB only one subset), as well as the territorial remoteness of user equipment (the type of modulation and coding). As an example, a solution was obtained in the formulated optimization problem using c system MatLab R2014a. This has been enabled bintprog package optimization Optimization Toolbox. Graphically it shows how dependent bandwidth allocation and resource blocks of the downlink between the user equipment required when changing the value of one of them. The analysis found that the use of the proposed model aims to provide each user equipment the quality of service in terms of bandwidth in the downlink with the possibility of access to additional (non-guaranteed) bandwidth.