Information and Control Systems

Fundamentals of the formal theory of real-time systems

Alexandr A. Zelenskii — 2025-10-28

Introduction: The importance and expressed specificity of real-time computing systems determines the demand for the construction of a strictly formalized system abstracted from the outside world, including a necessary and sufficient set of determining parameters. Purpose: To create a formal theory of computing systems operating under time constraints. Results: We propose a new formal theory of real-time systems, which allows formalizing the representation of real-time control systems. We expect it will expand the possibilities of the analysis and synthesis of these systems. The object of the proposed formal theory is the cycle of a real-time system. The cycle is defined on the basis of a given composition of functions which ensure the fulfillment of the system's functional purpose, and is represented as a configuration formed of actors which are distributed by groups, execution threads and the order of execution in each thread. The formal theory of real-time systems includes a set of standard and special symbols and formulas. These symbols and formulas are used to determine the configuration options that meet the specified requirements for a given actor composition; in addition, for each of these configurations, the achievable cycle times, required resources, and the number of input and output ports for actor communication are determined.In conclusion, we define the place and role of the formal theory of real-time systems in a feasibility study and state the possibility of two configuration options: static and dynamic. The latter may be necessary to redetermine a cycle configuration during its execution.

WI-FI node location based on FTM technology

Ivan Michailovich Protsenko — 2025-10-28

Introduction: The application of IEEE 802.11mc FTM technology for measuring distances and determining the location of network nodes is an active research area. The accuracy of distance estimation using FTM is limited by several factors related to signal propagation in real conditions and the hardware and software features of the nodes. Purpose: To develop and test practical positioning solutions for objects in buildings and structures based on FTM technology and to estimate the achievable accuracy of distance measurements. Results: With the experimental setup created, we have performed a series of measurements and estimated errors under various conditions. In addition, we have considered some methods for the compensation of the main error sources. The latter can be divided into two groups: multipath propagation, which leads to time scattering and a distortion of the round-trip time estimate; and hardware limitations, including the differences in clock frequency, timer drift, packet processing delays and timestamp quantization due to the discrete nature of timers. The frequency channel bandwidth affects the time resolution and does not allow achieving subnanosecond accuracy required to ensure distance estimation errors of the order of centimeters. One of the main conclusions made is that for the 2.4 GHz range the accuracy of distance determination is limited, with an error of up to 1 m. We furthermore consider the mathematical methods for processing the obtained data to reduce errors. Practical relevance: The presented implementation of hardware and software for measuring distances using IEEE 802.11mc technology has proven effective and can be used in indoor positioning systems.

A formal framework for the OSINT attacker and defender

Vitaliy Vladimirivich Gryzunov — 2025-10-28

Introduction: The proliferation of OSINT in cybersecurity revealed a gap between practical tools and their theoretical conceptualization. Existing approaches lack a comprehensive model of the OSINT analysis process, which hinders formal automation, verification, and threat analysis. Purpose: To develop a formal model of an OSINT attacker, conceptualized as an abstract machine that describes the intelligence process through graph-based knowledge representation, inference logic, and resource constraints. Results: We propose a model of an OSINT attacker as an abstract machine that operates on an iteratively expanding knowledge graph. The OSINT task is formalized as a pathfinding problem from public properties to confidential ones. We formulate the necessary and sufficient condition for disclosing a confidential property and define the concept of triangulation through the search for independent (non-intersecting) paths within the graph. The analysis shows that OSINT attacks exploite an “inference covert channel”, thereby violating the principles of classical security models, such as the Bell – LaPadula mandatory access control model. In addition, we introduce a formal stopping function that integrates practical criteria for analysis termination: goal achievement, resource depletion, diminishing returns, and detection risk. The study formalizes the concept of “independent sources”. Practical relevance: We translate the theoretical model into two applied frameworks. First, the OSINT Kill Chain provides a step-by-step methodology for attackers (Red Team). Second, the Blue Team Playbook offers a mirror framework for defenders, describing how to audit a digital footprint and minimize risks. Discussion: For future research, the study proposes using the framework of formal grammars to model not only static relationships but also the dynamic tactics, techniques, and procedures of an attacker.

Performance analysis of two-stage channel coding with noncoherent transmission over multipath fading channel with Doppler scattering

Felix Aleksandrovich Taubin — 2025-10-28

Introduction: In high mobility communication systems noncoherent transmission schemes with relatively simple channel coding are considered to be a promising alternative to traditional coherent transmission methods where the accurate estimation of the channel parameters (for example, using periodic transmission of pilot signals) consumes a disproportionately large share of resources. The absence of estimates of current channel parameters in the receiver of a high mobility communication system is accompanied by the emergence of certain restrictions on the joint selection of effective methods of channel coding and modulation, as well as the need to develop procedures for a sufficiently accurate analysis of noise immunity. Purpose: To carry out a noise immunity analysis of two-stage coded transmission in a multipath channel with Doppler scattering using amplitude-phase modulation and non-coherent reception at the inner decoding stage. Results: For a multipath channel with Doppler scattering, we present a scenario of noncoherent transmission based on two-stage channel coding with interleaving between stages and an inner code with amplitude-phase modulation. We provide a description of the general decoding scheme of the two-stage design for a general channel model with an arbitrary multipath profile and Doppler scattering, which includes an explicit indication of significantly reducing the decoding complexity at the inner stage in cases of slow and fast fading in the channel. We present the analysis of the performance of the two-stage channel coding based on the developed method for the accurate calculation of the union bound on the decoding error probability for the considered scenario of transmission in a multipath channel with Doppler scattering. Practical relevance: The combination of a two-stage channel coding scheme with the amplitude-phase modulation significantly expands the set of rational options for the transmission scenario under consideration, and allows an acceptable level of reliable communication in a wide range of Doppler scattering and multipath profile. The proposed method for accurate calculating the pairwise error probability increases the efficiency of selecting specific coding schemes in a multipath channel with Doppler scattering.

Parametric identification of subsystems of radio-telescopes under the external loading

Andrey Yurievich Kuchmin — 2025-10-28

Introduction: Radio-telescopes are complex non-stationary dynamic objects. They are subject to the influence of various external loadings, such as gravity, wind and temperature. All this significantly reduces the control accuracy of the elements of radio-telescope dish systems. To improve the accuracy of radio-telescope control systems, it is necessary to create the models with the impact of external factors on them using the results of identification. Purpose: To develop methods for identifying radio-telescope subsystems based on intelligent electromechanical systems under the influence of external loadings of various natures. Results: Modifications of statistical MSE-identifier s have been obtained, which allows solving the problem of estimation of parameters of dynamic quasi-stationary systems under slowly changing external influences. We propose a simple and effective method for synthesizing such identifiers for the case of vector and scalar types of external influences, with certain restrictions taken into account. For the case of scalar external loadings, we develop a new two-cascade observer, that makes it possible to obtain estimates of different types of external influences, which is shown by the example of typical influences, such as the constant influence, the influence with a constant speed, the influence with a constant acceleration, the sinusoidal influence and the random one. We create a method for constructing program movements for dynamic systems under the influence of external loadings based on a full-order observer. Practical relevance: Taking into account external influences is the main factor in increasing the accuracy of radio-telescope control systems. The methods of estimation of parameters and external influences will allow building radio-telescope control systems with high accuracy.

Assessment of psycho-emotional state of a person using AI-based EEG analysis

Vladimir Ruslanovich Romaniuk — 2025-10-28

Introduction: Determining emotional valence based on electroencephalographic (EEG) data is an urgent issue. Nonetheless, traditional multi-electrode EEG systems are unsuitable for everyday use. In addition, signals from portable, low-channel devices exhibit high noise levels and significant variability across users, complicating their analysis and interpretation. Purpose: To develop a deep-learning-based approach for EEG data analysis suitable for a reliable assessment of emotional valence using low-channel wearable devices. Results: We propose a comprehensive approach combining signal processing with classification via convolutional and recurrent neural networks. Neural network models were trained on a publicly available multi-channel dataset, with the subsequent transfer to our recordings obtained with the use of a wearable four-electrode headband BrainBit. The experimental results demonstrate an emotion valence recognition accuracy (positive, negative, and neutral emotions) of 70–75% during cross-subject validation on public data, reaching 85–91% accuracy as compared to computer vision methods using our own data. Practical relevance: The findings confirm the feasibility of applying these models in wearable systems for monitoring human emotional and cognitive states. Discussion: There is a recognized need for further model adaptation to reduce inter-subject variability and noise, as well as for the refinement of signal synchronization methods and data labeling approaches.

Wavelet-based coherence analysis of interbrain synchronization in collaborative game solving

Vadim Evgenievich Titov — 2025-10-28

Introduction: Inter-brain synchrony during a joint cognitive activity is a relevant subject for understanding the neurophysiological mechanisms of social interaction. Purpose: To identify the features of in-phase, phase-lag, and anti-phase synchronization of EEG signals between two participants performing a cognitive game task. Methods: Wavelet transform coherence method is used for the analysis of simultaneous EEG recording from two participants, with the classification into in-phase, phase-lag, and anti-phase synchronization. Statistical significance is assessed with one-way ANOVA and surrogate data testing using the Monte Carlo method. Results: We report statistically significant effects of inter-brain synchronization in the alpha, beta, and gamma ranges. The in-phase synchronization is observed mainly in symmetrical occipital and parietal lobule leads, covering up to 75% of the recording interval. The phase-lag synchronization is detected in occipital, temporal, and occipito-parietal regions, with temporal coverage up to 54%. The anti-phase interactions occur predominantly in high-frequency ranges. Additionally, significant differences in synchronization duration across electrode pairs and frequency ranges are revealed. Practical relevance: The findings may be applied in the development of brain-computer interface technologies and in different studies of cognitive interaction, including education and training. Discussion: The relatively small sample size (five subjects) limits the generalization of the results, but repeated trials and statistical validation confirm the reliability of the observed effects. A promising direction for further research is the analysis of spatial sources of synchronized activity and the study of inter-individual variability.

Information about the authors

Unknown — 2025-10-28