Vol 21, No 1 (2023)

This article presents quality assessment results for the software generators of pseudo-random sequences (PRS) presented in [1; 2] for QS simulation, including second-order hyper-Erlang and hyper-exponential distributions of the second order, that flows organically from these works. These distribution laws are in demand in queuing theory as it provides a big range of changes in the variation coefficient which plays an important role in the average queue delay calculating. There is no data on such generators neither in scientific literature, no in the GPSS WORLD library. Software generator quality evaluation, regardless of the programming language, is usually made according to statistical tests. In this case, chi-squared and Kolmogorov-Smirnov’s tests are used. In addition, the comparison between theoretical and statistical aspects of the corresponding order is provided. Unlike simple distribution laws, for which the use of the above mentioned statistical tests is provided for in well-known software products and does not cause any difficulties, in our case automatic testing is impossible. The well-known packages STATISTICA, STATGAPHICS, Matlab/Simulink, etc. do not provide for the use of the hyper-Erlang and hyper-exponential distribution laws we consider. Therefore, the Pearson statistical test is calculated and checked manually. The presented results should be useful for professionals of discrete event modeling in the GPSS WORLD environment.

The article describes the problem of developing a mathematical model of data transmission channel in communication systems in the case when signals at the channel input channel are unknown at the channel output. Development of mathematical models directly from observed data constitutes an identification problem, and the case under consideration belongs to the blind identification problem. The work consistently examines the concept of linear dynamic system identifiability in state space and shows the connection of this concept with the observability and controllability concepts. A number of statements about identifiability of a linear dynamic system describing communication channel are proved. In particular, it is shown that if the system is identifiable, it is sufficient to use the input-output model for its description, while the input-state-output model is redundant. Further, based on the proven statements, blind identifiability conditions are formulated for the case of a discrete system with one input and multiple outputs, which are imposed on the components of the system’s transfer matrix.

This article describes the development of a real BAN (Body Area Network) network layout for human health monitoring. BAN networks can help improve life quality of people suffering from various diseases, such as diabetes, cardiovascular diseases and others. They are accessible to wide range of users, including people with disabilities and the elderly. They can also provide a high level of security, since they use data encryption and user authentication. These networks may be easily configured and adapted to the needs of a particular user. The article presents results of studies that show state of the human health under various conditions. Thanks to the developed BAN network layout, it is possible not only to study the condition of human health in practice, but also to use it for scientific research at universities.

The widespread use of unmanned aerial vehicles for various purposes, expanding scope of their application and ever-increasing requirements for the durability of communication channels urgently require the development of new effective antenna solutions for the equipment of command radio control lines and payloads. The article is devoted to a brief analysis of the available information about the radio lines of unmanned aerial vehicles, solutions in the field of antennas for the equipment of command control radio lines and payload and the study of perspective antennas for the repeaters placed on unmanned aerial vehicles. The review of the general types of antennas that may be installed on unmanned aerial vehicles, including pin, microstrip and spiral ones, as well as antenna arrays based on them, made it possible to substantiate the prospects of using low-profile and spiral antennas for repeaters installed on unmanned aerial vehicles. The studies conducted on the frequency and spatial characteristics of low-profile and spiral antennas have confirmed their sufficient effectiveness. Proposed solutions can be used as a basis for development of perspective antennas for repeaters installed on unmanned aerial vehicles.

The operation of uncertified broadcasting equipment located in 85 regions of Russia is the most important problem in the development of regional broadcasting networks in the absence of system requirements for network transmitters and earth stations of satellite repeaters in the «Digital Broadcasting Television. System of terrestrial terrestrial digital television broadcasting of the second generation DVB-T2. Second generation terrestrial digital television broadcasting system DVB-T2.» domestic standard. Standard system requirements are the basis for actualization of requirements to the equipment during its certification. Requirements for network transmitters and earth stations of satellite repeaters in single-frequency broadcasting networks based on the author's research, published in domestic and foreign articles, protected by patents of the Russian Federation, are presented. In particular, the system requirements to the equipment for regional multiplex formation, metrological support of SFN (Single Frequency Network) operation and distributed system of DVB-T2 standard broadcasting quality monitoring are formulated.  Requirements for assessing the efficiency of SFN networks, which will make it possible to further modernize existing regional networks to improve their reliability and the quality of television and radio broadcasting in all 85 regions of the Russian Federation, and to certify equipment in accordance with the resolution of the Government of the Russian Federation are also presented. The results of the author's research will make it possible to develop a system project for the creation of digital terrestrial television broadcasting in four new regions of Russia. The prospects for the development of DVB-T2 standard equipment at the program level are considered.

6G technology will create an intelligent, highly scalable, dynamic and programmable wireless network capable of serving a variety of heterogeneous wireless devices. Various 6G modules and devices will generate colossal amounts of distributed data, so post-NGN (New Generation Networks) will need to implement a number of machine learning methods that will solve significantly complicated network problems. To overcome these problems, distributed learning methods can be used, allowing devices to train models jointly, without exchanging raw data, which reduces communication costs, delays, and increases data privacy level as well. Distributed machine learning models will play an important role in 6G networks, since they have a number of advantages over centralized methods, however, the implementation of distributed algorithms in resource-constrained wireless environments can be challenging. It is important to take into account the wireless environment uncertainty associated with various disturbing factors and limited wireless (transmission power, radio frequency spectrum) and hardware resources (computing power). Consequently, it is important to choose the suitable machine learning algorithm based on the wireless environment characteristics and the resource requirements of the learning process. The article reviews the application of distributed artificial intelligence models in new generation communication networks for resource management and data processing purposes. The general algorithms and approaches of distributed machine learning, applications, methods and models are described. The article analyzes the ways in which distributed artificial intelligence models can solve various problems in communication networks, including optimizing resource use and ensuring high performance and availability of network services.

Secure data exchange over the network is ensured by the requirements of confidentiality, integrity and availability of information. To meet these requirements, sent data is encrypted on the sending side, and the received information is decrypted on the receiving side. Transmitted message is encrypted according to rules determined by the algorithm and key. Crypto security of encrypted information depends on the key length. Among the encryption algorithms, there are algorithms with a symmetric (private) key and with an asymmetric (public) key. Despite all the advantages of a private key, asymmetric keys are used to deliver it from one user to another (key distribution). However, high-performance quantum computers are capable to decrypt intercepted data. Therefore, modern cryptographic systems use quantum key distribution method. The idea of using quantum bits was proposed in 1970 by S. Wiesner. In 1984, Ch. Bennett and G. Brassard proposed the BB84 protocol. The use of «entangled» quanta for systems with quantum key distribution was offerred in 1991 by A. Eckert. All modern quantum cryptography systems are based on these above-mentioned protocols.

Spectrum sensor system performance and detection of spectrum band occupancy in cognitive radio are among of the main research aspects. When considering a system in which the primary user changes or there are multiple types of primary users, an energy detector is used. For energy detector operation, the main parameters that determine probabilistic characteristics of detection (probability of user detection, probability of a “false alarm” error and probability of a “missing target” error) will depend on the correct determination of the decision threshold. This article reviews an analytical approach to the normalized decision threshold determination. The purpose is to analyze and determine the optimal decision threshold value for an energy detector in a channel with Rayleigh fading. A spectrum sensing system in cognitive radio is considered. Normalized values of the threshold solution for a channel with Rayleigh fading are determined. Graphic illustrations of the analysis results and calculations are presented. Results obtained for determining threshold solutions may be considered a proper approximation for calculating the characteristics of sensing systems in cognitive radio in channels with Rayleigh fading, providing the opportunity to determine frequency bands free of primary users more likely, thereby increasing the efficiency of use of the radio frequency spectrum.

The article considers the relevance of the search for toolkit for objective software development complexity and timing assessment. The key purpose of this toolkit is to provide an IT company with the opportunity to objectively assess the labor intensity, the cost of a future software product at an early stage, on the one hand, and to ensure transparency in justifying an acceptable transaction price for the customer, on the other hand. A special feature of the IT industry is the intangible nature of the created product and, as a result, the challenge of choosing methods (metrics) for labor intensity assessment and predicting the timing of the software product implementation, which allows obtaining realistic data without serious time and financial costs, poses a certain difficulty. The results of the analysis and comparison of the most common methods of software development complexity assessment (in particular, IFPUG, UCP, COCOMOII, etc.), including identification of advantages and limitations, are presented. A generalized algorithm for the decision support system operation is proposed to reduce time and increase the validity of calculations when drawing up estimates by an IT company analyst as a part of the preparation of technical specifications. A description of individual screen forms of the decision support system designed module is provided.