Herald of SPbSUT

The purpose: derivation of the balanced duplex equation and development of the calculation method of the downlink and uplink channel budgets in the cell of the GSM-2G mobile communication system. Research methods: circuit analysis of the duplex radio communication conditions for typical structures of the downlink and uplink channels of the cell. The novelty: according to the proposed method, the maximum radio communication range in a GSM-2G cell, due to the limited power of the subscriber station, is calculated based on the parameters of the uplink channel, and the required transmitter power of the base station is determined using the balanced duplex equation based on the parameters of the receiving and transmitting equipment of the base and subscriber stations, as well as the characteristics of the downlink and uplink radio channels. Result: a new balanced duplex equation was obtained and a method for calculating the downlink and uplink channel budgets of the GSM-2G cellular system was proposed. Practical / Theoretical significance: the results of the work can be useful for developers of receiving and transmitting equipment of various radio systems.

Purpose. Financial bubbles and crises are complex phenomena related to the deviation of asset prices from their fundamental value, which requires the development of new approaches to their analysis. The aim of the paper is to investigate financial bubbles through fractal analysis techniques, including fractal dimension calculation, to identify anomalies and predict market crashes. Methods. The methods used include RS analysis (Hurst method) to assess the persistence of time series, Box-count method to determine the fractal dimension and multifractal analysis to study the local features of market dynamics. Novelty. The novelty of the study lies in the comprehensive application of fractal analysis for early detection of financial bubbles, as well as in comparing the effectiveness of different methods. Results. The results show that the increase in fractal dimension correlates with the periods of bubble formation, and its sharp changes can serve as indicators of crises, which is confirmed by the examples of the dot-com crisis (2000) and the financial crisis (2008). Practical relevance. The significance of the work lies in the possibility of using the proposed approach to create systems of early warning of crises, algorithmic trading and risk management.

Problem statement. The growing number of devices in heterogeneous Internet of Things networks creates an additional load on limited radio resources, which complicates ensuring stability and quality of data transmission. Heterogeneous communication subchannels have different characteristics that require effective load balancing mechanisms. The development of methods to minimize data transmission delay and reduce the likelihood of packet loss is especially relevant for high-density Internet of Things networks, where resource management becomes critical. The aim of the work is to improve the efficiency of data transmission in a high-density heterogeneous Internet of Things network. Methods used. The work uses optimization methods, the gray wolf pack algorithm, queuing theory and probabilistic analysis. Novelty. The method proposed in the article takes into account the individual characteristics of subchannels and provides dynamic load distribution. This allows adapting the solution to different types of heterogeneous networks, reducing delay and data loss. Result. A mathematical model describing data transmission through several communication subchannels and an objective function combining the average data transmission delay and the probability of packet loss have been developed. Analytical expressions for key network characteristics, such as the probability of loss and average delay, have been derived. Practical significance. The developed model and method can be used in the design of devices and networks of high-density heterogeneous Internet of Things networks in order to improve their efficiency.