АДАПТИВНОЕ УПРАВЛЕНИЕ ПРЕДЕЛЬНОЙ ПОЛОСОЙ ЧАСТОТ СИСТЕМ СПУТНИКОВОЙ СВЯЗИ В ТРАНСИОНОСФЕРНЫХ РАДИОКАНАЛАХ В УСЛОВИЯХ ЧАСТОТНОЙ ДИСПЕРСИИ СРЕДЫ
Authors: Иванов Д.В. , Иванов В.А. , Кислицын А.А. , Рябова М.И. 
Published: February 2025

Для учёта и компенсации частотной дисперсии среды в широкополосных системах спутниковой связи предложены методы адаптивного управления их полосой частот. В методах используются экспериментальные оценки текущих значений полосы когерентности трансионосферного канала и принцип обратной фильтрации его частотной характеристики. Разработан алгоритм решения задачи сетевого управления предельной полосой частот. Экспериментально показано, что адаптивное управление предельной полосой частот систем спутниковой связи обеспечивает возможность увеличения используемой полосы частот (выигрыш) сверх минимального значения до 2,5 раза, а компенсация дисперсии – дополнительно к этому до 2,5 – 7 раз.

Introduction. Recently, the authors have been carrying out research into the influence of frequency dispersion of the ionospheric channel on the distortions of wideband signals and the feasibility of creating a method of correction for distortions based on the inverse filtering. There is a topical problem of studying the solutions for increasing the maximum bandwidth. This is urgent for two reasons: 1) without correction for dispersion, the maximum bandwidth has to be decreased to its minimum value (coherence bandwidth) that is important for solving the network problem of remote adaptive control of bandwidth; 2) experimental estimation of coherence bandwidth by means of navigation satellite signals allows to adapt the system on coherence bandwidth and compensation for dispersion by channel diagnosing will allow to use the maximum bandwidth beyond coherence bandwidth. The aim of the research is the development of adaptive method for controlling maximum bandwidth of satellite communication systems and estimation of the processing gain after overcoming dispersion of the transionospheric channel. Model and complex for research. Due to the fact that the parameters of the transionospheric radio channel change over time, the developed method is based on the use of a hybrid model (physical + channel), which allows to establish relations between the parameters of the channel characteristics and the TEC of the ionosphere. Within the framework of the channel model, the propagation problem is described in terms of a frequency response (FR) that is equivalent to a radio channel environment. In this case, the frequency response of the channel has a dynamic character, slow time is taken into account, and the amplitude-frequency and phase-frequency characteristics are experimentally obtained with the use of a physical model based on the wave equation. The complex of adaptive control of the maximum bandwidth in the presence of frequency dispersion, depending on the capabilities, requires the implementation of two operation modes: adaptive control of the bandwidth of satellite communication systems and adaptive compensation for frequency dispersion at the reception. Based on the analysis of a large amount of data from the network of navigation receivers and machine learning, at the beginning there is performed the sounding of the radio channel over the set of links. To get the robust estimates, there are plotted maps, performed averaging over tracks trapped in a radius of 300 km and used training of the system with variable coefficients. Conclusions.For satellite communication systems, there were proposed methods of adaptive control of the bandwidth of a transionospheric radio channel to compensate for the frequency dispersion of the medium during the propagation of wideband signals. The methods use experimental estimates of the current values of the coherence bandwidth of the transionospheric channel and the inverse filtering of its frequency response. The network problem of controlling the maximum bandwidth for different regions at the reference frequency has been solved. The verification of the methods showed that the adaptive control of the maximum bandwidth of satellite communication systems allows to increase the bandwidth (gain) beyond the minimum value of up to 2.5 times, and the compensation for dispersion with an error - in addition to this, up to 2.5–7 times.