Relevance. Modern requirements for specialized automated control systems and advances in communication technology are reviving interest in the HF band as a promising means of controlling ground, sea, and air-based robotic complexes (RCs). Existing adaptation algorithms for HF communication systems, by national and international standards are reactive and do not take into account the frequency dependence of ionospheric parameters, which limits their effectiveness for reliable RC control. Objective. To develop an algorithm for selecting the optimal operating frequency and transmission parameters (bandwidth, data rate, power, interleaving depth) based on prediction of frequency-dependent characteristics of a diffuse HF channel using passive GNSS monitoring data. Methods. A structural multipath model for correlation intervals, the ITU-R method for the mean signal-to-interference ratio, and analytical expressions for the Nakagami parameter and the permissible signal-to-interference ratio taking into account diversity reception are used. Results. An algorithm has been developed that includes estimating ionospheric parameters from GNSS data, calculating the frequency-dependent characteristics of the channel, and selecting the optimal operating mode that maximizes the energy margin and communication reliability. Numerical simulation for a typical path confirmed its efficiency. Conclusions. The proposed algorithm provides proactive selection of communication parameters taking into account the real state of the ionosphere, increasing reliability and data rate, which is critically important for RC control tasks. It is a step towards the creation of cognitive HF systems.
The aim of the research work was to study and select the existing adaptation options for transmission parameters, in order to reduce the influence of shortcomings of the short-wave radio line, it is advisable to use the methods of digital signal processing as efficiently as possible. According to the results of the characteristics of analog-to-digital converters (ADCs), it became a study of the available hardware for constructing extended radio links, it was concluded that with an increase in the performance of FPGAs on which digital signal processing is implemented, it is possible to implement the technology of creating an active antenna array (AAR), consisting of the Nth number of independent antenna modules, which is a conceptual task in solving the issue of adapting information and technical characteristics to constantly changing parameters of ionospheric transmission, for a more energy-efficient approach to designing an ionospheric radio communication system. Improving the performance of the radio system by improving communication protocols, solving the problem of optimal channel load from the time of formation and reception of signals. The main idea of such an AAR is to digitize or generate a high-frequency signal in the immediate vicinity of the antenna, as part of the antenna modules. The indicated results make it possible to replace separately tuned radios and transceivers built according to a complex superheterodyne circuit with a limited number of available hardware units operating under software model of a software-configurable radio channel. In the next work, it is planned to conduct studies to assess the passage of OFDM signals through multipath communication channels with fading of Rayleigh and Rice. The resulting model will allow us to evaluate the noise immunity at different lengths of the cyclic prefix of the OFDM symbol and to observe the behavior of the signal constellation under the influence of various instabilities.
