Abstract

It is noted that the complexity and constant variability of the ionosphere structure, the presence of many factors affecting the propagation of radio waves in such an environment, as well as the complex topology of communication networks lead to the need the computer modeling of data transmission in HF-band networks. The existing models of representation of ionospheric processes and digital radio channels are described. It is shown that to solve the problems of designing a radio data transmission network, complex modeling is necessary, taking into account the network topology, signal propagation losses in the radio channel, noise level, type of digital modulation, and radio forecast of communication conditions. In this paper, we consider a modeling complex for packet radio networks of HF-band data transmission with changing communication conditions. The complex consists of a set of interacting models implemented in the Matlab software environment. The software model for predicting communication conditions complies with ITU-R recommendation P. 533–13 of the International Telecommunication Union (ITU). The description of the model for the "Point-to-point" and "Area" modes is given and the results of its application for calculating extended radio lines are shown. The initial data and system parameters of the model are described. A model of the HF-band digital radio channel is presented. The communications System Toolbox package, which is part of the Matlab software environment, is used for this modeling. The model's input and output data are described. A model of Ionospheric Wave Frequency Dispatcher service of the radio network has been developed. This model is intended for building a wave schedule for stable operation of HF radio lines in the network. The rules for building a two-frequency and multi-frequency wave schedule are described. A scheme for modeling the operation of a packet radio network under changing communication conditions is proposed. The complex allows you to evaluate the probabilistic and temporal characteristics of radio lines and zonal radio coverage depending on geographical coordinates, time, month, solar activity and selected system parameters for a period of up to one year. Examples of using the modeling complex are given. The purpose of this work is to formulate the problem of simulation of HF radio networks under changing communication conditions.

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