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• DEVELOPMENT AND RESEARCH OF THE EQUALIZER CONFIGURATION TO INCREASE NOISE IMMUNITY IN DECAMETER RADIO LINES

  А. I. Rybakov

  212-227

  2025-10-01

  Abstract ▼

  The problem of increasing the noise immunity of decameter radio lines (DRL) in modern domestic radio communication systems, including short-wave (SW) communication, remains significant and in demand, despite the existence of numerous classical studies. The decameter radio communication systems have been chosen as the object of our analysis. Specifically, the R-016 system, which is used as a prototype, faces limitations such as its frequency range, which affects its effectiveness in conditions of variable ionospheric characteristics that negatively impact the signal level. Signal processing issues in prototypes can lead to bit errors reaching a bit error rate (BER) of 10^-3, even in the absence of significant interference. The main objective of the study is to evaluate the impact of various factors, such as changing the length of the preamble and implementing adaptive filters, on the noise immunity of systems. The analysis of the results indicates that increasing the length of the preamble improves the noise immunity of decameter radio lines. The practical significance of the results is that they can be used to improve the noise immunity of existing DFM radio communication systems that operate in variable ionospheric conditions. This paper also discusses the scientific basis for selecting an equalizer configuration for decameter radio lines to increase communication range and improve noise immunity. The developed methods provide a scientific basis for selecting effective equalizer settings, which can lead to improved communication range. To test different equalizer configurations in a Rayleigh channel, Simulink simulation is used, which confirms the correctness of the selected parameters. Experimental validation of the decameter radio line model includes the study of various preamble lengths, and the analysis of signal-to-noise ratios (SNR) at the receiver input allows for the adaptation of these parameters. Thus, the research results show that increasing the preamble length has a positive impact on the system's noise immunity. The work focuses on the modeling and operation of DFM radio lines, and the obtained results have practical significance for the active adaptation of existing radio systems in a changing ionosphere

• DEVELOPMENT OF ADAPTIVE OFDM-BASED COMMUNICATION SYSTEM FOR TROPOSPHERE AND RADIO RELAY CHANNEL

  P.V. Luferchik, А.А. Komarov, P.V. Shtro, А.N. Konev

  2022-11-01

  Abstract ▼

  It is known that inter-symbol interference may occur during data transmission in radio relay
  and tropospheric communication systems. The presence of multipath propagation, frequencyselective
  fading and extreme instability in the tropospheric and radio relay channel significantlyreduces the energy efficiency of the communication system. The aim of the work was to increase
  the efficiency of using the channel for radio relay and tropospheric communication by using
  OFDM (orthogonal frequency-division multiplexing) signals in the system using adaptive coding
  and modulation. In the course of execution, the modulator and demodulator models of the OFDM
  signal are implemented. When using various signal code structures in various reception/
  transmission conditions, it is possible to achieve optimal use of the frequency and energy
  resources, to create systems that adapt to the conditions of signal propagation. To implement this
  mechanism, a service field was introduced into the transmitted service data, which contains information
  about the code rate used, the modulation type, and the interleaving depth. This approach
  allows optimizing the use of energy and frequency resources. Together with the use of channel
  quality estimation algorithms, it becomes possible to dynamically change the signal-code structure
  when the reception conditions change. By adjusting the interleaving depth, it is possible to optimize
  the S/N threshold or the amount of information delay in the channel, depending on the system
  requirements. The use of adaptive choice of code rate and modulation will allow more efficient use
  of the channel resource with a constant change in its state. The obtained results will significantly
  increase the energy efficiency of the OFDM system, lead to stable communication in nonstationary
  channels and increase the throughput.

• DEVELOPMENT OF ENERGY EFFICIENT COMMUNICATION SYSTEM IN THE TROPOSPHERE RADIO CHANNEL BASED ON OFDM SIGNALS

  P.V. Luferchik, P.V. Shtro, А.N. Konev, А.А. Komarov

  2022-11-01

  Abstract ▼

  It is known that inter-symbol interference may occur during data transmission in radio relay
  and tropospheric communication systems. The presence of multipath propagation and frequencyselective
  fading in the tropospheric, radio relay channel significantly reduces the energy efficiency
  of the communication system as a whole. The aim of the work was to increase the efficiency of
  using the channel for radio relay and tropospheric communication by using OFDM (orthogonal
  frequency-division multiplexing using the methods of reducing the peak factor of the OFDM signal
  and increasing the linearity of the transmission path. To evaluate digital predistortion algorithms
  in the Matlab/Simulink environment, a model was developed for the LMS, NLMS, RLS, RPEM
  methods and a power amplifier model with real characteristics. Based on the results of modeling
  algorithms, RLS was chosen. In addition, in this work, a modified version of the adaptation algorithm
  based on the recursive least squares method (RLSm) was developed. The main result of the
  modification is: a decrease in the number of arithmetic operations per iteration (more than
  5 times), an increase in the stability of adaptation algorithms, due to the introduction of regularization
  methods, a decrease in the convergence time, due to the introduction of an exponential dependence.
  Various algorithms for reducing the peak factor of an OFDM signal were investigated,
  the best result was achieved by combining Tone reservation (TR) and Active constellation extension
  (ACE). Simulation in the Matlab/Simulink environment showed that the combination of TR
  and ACE algorithms reduces the peak factor of OFDM signals by ~5dB for BPSK data stream and
  ~4.5dB for 8-PSK, QAM-16, QAM-64, QAM-128 and QAM- 256. To increase the linearity of the
  transmission path, the RLSm digital pre-distortion algorithm was selected and upgraded, it made
  it possible to reduce the magnitude of the error vector modulus (EVM) by 13.5dB, and also increase
  the modulation/error ratio (MER) by 13.6dB.

• ADAPTATION OF INFORMATION AND TECHNICAL CHARACTERISTICS TO THE CONSTANTLY CHANGING PARAMETERS OF IONOSPHERIC PROPAGATION

  A.I. Rybakov, R.E. Krotov, S.A. Kokin

  2020-07-20

  Abstract ▼

  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.

• AUTOMATED CONTROL SYSTEM FOR THE ASSIGNMENT OF RADIO FREQUENCIES BASED ON A RISK-BASED APPROACH IN THE PLANNING OF RADIO COMMUNICATIONS IN THE UNITS OF MILITARY ROBOTIC COMPLEXES

  А. I. Nagovitsin, B.B. Molotkova, D.U. Azimov

  59-70

  2022-04-20

  Abstract ▼

  The use of a wide range of radio stations of various generations in the Armed Forces of the Russian
  Federation has led to the impossibility of fully taking into account all their features when planning
  radio communications. For example, it becomes an extremely difficult task to take into account the entire
  list of self-detected frequencies by the emissions of their own heterodynes of various radio stations,
  as well as frequencies prohibited for establishing and conducting radio communications. In this regard,
  the risks of lack of radio communication or violation of the rules for the use of the radio frequency range
  have increased many times, including in the units of military robotic complexes (RTK VN). The article
  notes that one of the biggest problems in creating a unified digital combat control system, the technical
  basis of which will be a wireless communication network - a radio communication network operating in
  various frequency ranges, today is meeting the requirements of electromagnetic compatibility (EMC)
  and, in particular, meeting the requirements for the correct use of the radio frequency spectrum.
  To optimize the process of radio communication planning in the formations of the RTK VN, to increase
  its efficiency and effectiveness, the article proposes to create and apply an automated system for monitoring
  the assignment of radio frequencies based on a risk-based approach. It is shown that the riskoriented
  approach when planning radio communications in the divisions of the RTK VN involves a
  comparative assessment of the nominal value of the assigned operating frequency with a list of selfdetected
  frequencies of each of the radio stations used, as well as with a list of prohibited frequencies for
  establishing radio communications (frequencies for transmitting distress signals, etc.). It is reasoned
  that this approach will reduce the risks of lack of radio communication or violation of the rules for using
  the radio frequency range. It will optimize the processes of automated planning of radio communications
  in the formations of the RTK VN and increase the efficiency and effectiveness of automated planning
  and management of radio communications during combat operations. The article describes the
  algorithm of the automated control system for the assignment of radio frequencies. The software implementation
  of this algorithm involves the creation and storage in the appropriate memory area of libraries
  (databases) of the main prohibited frequencies defined by the legislation of the Russian Federation.
  In addition, these libraries (databases) store lists of self-reflected frequencies by the emissions of their
  own heterodynes of all types of radio stations used, given in the technical description of each of the
  radio stations used.

• ALGORITHM FOR SELECTING THE OPTIMAL OPERATING FREQUENCY AND TRANSMISSION PARAMETERS IN THE HF CHANNEL BASED ON PREDICTION USING GNSS MONITORING DATA

  А. D. Skorik

  120-130

  2026-09-10

  Abstract ▼

  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.