Military Communication Systems Research Articles

Time-Frequency-Analysis-Based Blind Modulation Classification for Multiple-Antenna Systems.

Blind modulation classification is an important step in implementing cognitive radio networks. The multiple-input multiple-output (MIMO) technique is widely used in military and civil communication systems. Due to the lack of prior information about channel parameters and the overlapping of signals in MIMO systems, the traditional likelihood-based and feature-based approaches cannot be applied in these scenarios directly. Hence, in this paper, to resolve the problem of blind modulation classification in MIMO systems, the time–frequency analysis method based on the windowed short-time Fourier transform was used to analyze the time–frequency characteristics of time-domain modulated signals. Then, the extracted time–frequency characteristics are converted into red–green–blue (RGB) spectrogram images, and the convolutional neural network based on transfer learning was applied to classify the modulation types according to the RGB spectrogram images. Finally, a decision fusion module was used to fuse the classification results of all the receiving antennas. Through simulations, we analyzed the classification performance at different signal-to-noise ratios (SNRs); the results indicate that, for the single-input single-output (SISO) network, our proposed scheme can achieve 92.37% and 99.12% average classification accuracy at SNRs of −4 and 10 dB, respectively. For the MIMO network, our scheme achieves 80.42% and 87.92% average classification accuracy at −4 and 10 dB, respectively. The proposed method greatly improves the accuracy of modulation classification in MIMO networks.

Эффективность применения помехоустойчивого кодирования в системах передачи цифровой информации с широкополосными сигналами.

The method of transmitting information using broadband signals is recognized as an effective way to combat various types of organized intentional and unintentional interference. Among them, methods for transmitting digital information with frequency-hopping spread spectrum (FHSS) have found wide application. Due to its frequency and energy efficiency, the transmission method with frequency hopping is widely used in information transmission systems for various purposes, including military radio communication systems (RCS), where high interference immunity is required. Both when transmitting digital information under the conditions of the destructive effect of electronic suppression means, and without this effect, the received data sequence contains errors. To detect and correct them, noise-correcting coding is effective. The article considers the case when at the input of the receiver, in addition to its own noise, there is also a deliberate concentrated partial-band noise jamming, occupied by the RCS. An analysis is made of the noise immunity of a RCS with a frequency hopping and DBPSK with the combined use of error-correcting coding and time-frequency diversity of the code symbol. The application in the analyzed RCS of the algorithm of incoherent reception of diversity signals with weight processing and subsequent decoding is considered. It’s shown that the noise immunity of the RCS under the considered conditions turns out to be significantly higher than the RCS, in which the frequency diversity of the code symbol and the noise-immune coding are not used.

Прием сигналов относительной фазовой телеграфии с весовой обработкой субсимволов в системах передачи информации с псевдослучайной перестройкой рабочей частоты.

Signals with frequency hopping spread spectrum (FHSS) have long been widely used in military radio communication systems (RCS) due to their frequency-energy characteristics. In such systems, the most important characteristic is noise immunity, i.e. the ability to ensure reliable transmission and reception of information under the influence of various types of organized intentional and unintentional interference. In this paper, we consider the case when the input of the receiver, in addition to the receiver's own noise, contains deliberate interference, which is considered noise interference. In this case, it is assumed that the interference covers only part of the operating frequencies of the radio communication system. The algorithm of optimal noncoherent signal reception with weight processing for making a decision about the transmitted symbol (bit) is in the focus of the paper. Static radio engineering methods, as well as Monte Carlo simulation, have been used to evaluate the noise immunity of receiving differential binary phase shift keying signals with FHSS when exposed to deliberate Partial-Band Interference. It is shown that the noise immunity of a radio communication system under conditions of destructive influence can be improved by using the intra-symbols FHSS mode with the proposed reception algorithm. With an increase in the signal-to-interference ratio, the noise immunity of information transmission increases significantly. The optimal strategy for dealing with Partial-Band Interference when the RCS is operating in the intra-symbols FHSS mode is to select the optimal multiplicity of symbol frequency diversity, which minimizes the probability of a bit error probability. The obtained dependencies are presented in order to compare and determine the effectiveness of the considered transmission mode with the proposed reception algorithm.

Complex methodology of parameters management of military radio networks in the conditions of uncertainty of the radioelectronic situation

The experience of the Joint Forces operation (Anti-terrorist operation in Donetsk and Luhansk oblasts) shows that the current order of management of military radio communication systems does not always meet the modern requirements for them. The classic centralized approach to the management of channel and network resources of military radio systems does not quite meet modern requirements, so the authors of this article proposed to take mobile self-organizing networks as a basic principle of construction. The authors propose a comprehensive method of managing the parameters of military radio networks in conditions of uncertainty of the electronic environment, the essence of which is to ensure the maintenance of the specified values of the performance of military radio communication systems at the appropriate level. The article is based on the control principle, which is described in the reference network model of open systems interaction, but with some additions and changes. This approach generally allows for end-to-end management of channel and network resources of military radio systems in a complex electronic environment. In the article, the device of fuzzy logic, the theory of electronic suppression, neural networks, the theory of noise protection, the theory of antennas, noise-resistant coding are used. The proposed complex methodology should be used in the development of software for modules (units) for the assessment of advanced radio communications, based on open architecture interfaces version SCA 2.2, which will: use effective signal-code structures to ensure noise immunity of channels; to ensure efficient use of the radio frequency resource of programmable radio communication means; increase the speed of evaluation of communication channels; reduce the use of computing resources of radio communications with programmable architecture.

Radio environment maps for military cognitive networks: density of small-scale sensor network vs. map quality

In this paper, we present the dependency between density of a sensor network and map quality in the radio environment map (REM) concept. The architecture of REM supporting military communications systems is described. The map construction techniques based on spatial statistics and transmitter location determination are presented. The problem of REM quality and relevant metrics are discussed. The results of field tests for UHF range with a different number of sensors are shown. Exemplary REM maps with different interpolation algorithms are presented. Finally, the problem of density of a sensor network versus REM map quality is analyzed.

Digital blind despreading method for intermediate frequency short‐code DSSS signal

Direct sequence spread spectrum (DSSS) signals are widely used in various military and civilian communication systems owing to its useful properties, such as lower working signal-to-noise ratio, strong anti-jamming capability, and robustness to multi-path fading. In past few years, the estimation for spreading sequence in non-cooperative context has attracted lots of attention. Several methods are developed to realise a recovery of the sequence. Eigenvalue decomposition (EVD) is a classical method to obtain an effective estimation by extracting the main eigenvectors. The only obstacle to apply EVD method into practical systems is high complexity of computation when spreading sequence is long. Alternative algorithms such as neural network and clustering method have lower complexity, but an evident loss in performance. In this work, the authors propose to generalise the EVD algorithm to intermediate frequency (IF) short-code DSSS with an unknown carrier offset. The blind despreading process is designed to complete correlation demodulation. As a result, the computational afford is largely decreased due to the operation on IF real signal. To evaluate the performance, they derive the Crammer-Rao bound for spreading code estimation and compare the performance of several methods. Simulation demonstrates the superiority of the proposed method in estimation accuracy and runtime.

A network perspective on assessing system architectures: Robustness to cascading failure

AbstractDespite a wealth of system architecture frameworks and methodologies available, approaches to evaluate the robustness and resiliency of architectures for complex systems or systems of systems are few in number. As a result, system architects may turn to graph‐theoretic methods to assess architecture robustness and vulnerability to cascading failure. Here, we explore the application of such methods to the analysis of two real‐world system architectures (a military communications system and a search and rescue system). Both architectures are found to be relatively robust to random vertex removal but more vulnerable to targeted vertex removal. Hardening strategies for limiting the extent of cascading failure are demonstrated to have varying degrees of effectiveness. However, in taking a network perspective on architecture robustness and susceptibility to cascade failure, we find several significant challenges that impede the straightforward use of graph‐theoretic methods. Most fundamentally, the conceptualization of failure dynamics across heterogeneous architectural entities requires considerable further investigation.

Allocation of Limited Resources in a System with a Stable Hierarchy (on the Example of the Prospective Military Communications System)

The article is devoted to the formalization of the resource allocation problem in the hierarchical social system, where resources are distributed according to the agent's role in the system. We study the application of a proposed mathematical model to the organization of the special purpose communication network. Also, we propose an algorithm of the automatic partitioning of the radio communication system according to the role of nodes. None of the nodes has complete knowledge about the entire communication system, and the initially unknown information about the purpose of nodes is established in the process of the beacons exchange.

Task Complexity Measurement Framework for Human Systems Integration

Task complexity is a measure of how demanding a task is and often identified with unanticipated interactions between a user and system. A novel application of the complexity measurement for human systems integration is presented and demonstrated through the complexity evaluation of a military communication system interface. A comprehensive task complexity measurement framework is presented which besides being easily implementable, evaluates system complexity from the perspectives of different sets of users and is applicable in different contexts. A set of standard task contexts are established for each context, then objective and subjective task complexities are measured for the particular context. The set of complexity measures can be used to assess the impact of changes in system design from the human performance perspective.

DEVELOPMENT OF THEORETICAL PROVISIONS OF TRANSMISSION OF DISCRETE MESSAGES OF MILITARY RADIOCOMMUNICATION SYSTEMS

Modern military radio systems operate in the complex conditions of the electronic environment, due to the limited frequency range, the influence of deliberate interference and signal fading. One of the ways to improve the effectiveness of military radio communication systems is to develop indicators (methods, techniques) for evaluating the effectiveness of military radio communication systems. The analysis found that known approaches to evaluating the performance of military radio communications systems are based on the use of bit error probability in a channel, which is a rather rough indicator of channel estimation. This necessitates the development of theoretical provisions for the transmission of discrete messages to military radio systems. In order to improve the known theoretical provisions for the transmission of discrete messages of military radio communication systems, the authors of the article developed indicators for assessing the quality of functioning of military radio communication systems that operate in complex conditions of electronic conditions. In the course of the study, the authors of the research substantiated two indicators of link quality in the fading channel: the probability of correctly receiving a message of finite duration and the likelihood of a link of finite duration without breaks. The first metric is the overall metric (communication) quality of the communication, and the second metric is the quality of the channel in the session of the final duration. During the research, the authors used the basic principles of communication theory, theories of insecurity, the theory of transmission of discrete messages, etc. The proposed results can be used to evaluate the status of radio channels when they are exposed to a variety of origins and signal fading. The practical significance of these results is that they can be used to upgrade existing radios or to develop new ones by developing appropriate software

METHOD OF ASSESSMENT OF THE EFFICIENCY OF THE COMMUNICATION OF OPERATIONAL TROOP GROUPING SYSTEM

The most distinctive features of military communications systems are the high degree of a priori uncertainty about the operational situation and the small amount of source data for communications planning. In such circumstances, it is important to make the right decision-making appraisal apparatus, which will allow the officials of the system management bodies to be confident in the decisions made. Deciding to build a communications system at any level usually involves defining the purpose of its operation, selecting metrics and justifying the evaluation criteria, synthesizing alternative structures, and finding a rational option for deploying the communications system. The practice of the troops has convincingly shown that in the theory and practice of communications, there is a need to improve the scientific and methodological apparatus, which will meet the current conditions of operation of control systems and provide a more adequate assessment of the effectiveness of deployable communications systems. In this article, the authors propose a method for evaluating the effectiveness of the communication system of the operational troop grouping. The above method is based on the first time use of the communication system accessibility indicator. In the course of this research, the authors used the basic principles of communication theory, noise immunity theory and intelligence. The novelty of the proposed method is that the communication system operational troops grouping are estimated by generalized indicator of availability of channel resources and network communications system of the operational troops grouping. The practical value of the proposed methodology is that the methodology allows for a more accurate assessment of the communications system, the identification of deployment arrangements and measures to improve the effectiveness of the operational troops grouping.

МЕТОДИЧНИЙ ПІДХІД З ОЦІНКИ ЕФЕКТИВНОСТІ СИСТЕМИ ЗВ’ЯЗКУ СПЕЦІАЛЬНОГО ПРИЗНАЧЕННЯ

Найбільш характерними особливостями побудови систем зв'язку військового призначення є високий ступінь апріорної невизначеності стосовно оперативної обстановки та малий обсяг вихідних даних для планування зв’язку. У таких умовах важливий правильний вибір апарату оцінки прийнятих управлінських рішень, який дозволить посадовим особам органів управління системою зв’язку бути впевненим у правильності рішень, що приймаються. Прийняття рішення на побудову системи зв’язку будь-якого рівня, як правило, включає визначення мети її функціонування, вибір показників і обґрунтування критеріїв оцінки, синтез альтернативних структур і пошук раціонального варіанту розгортання системи зв’язку. Практика бойового застосування частин та підрозділів зв’язку переконливо показала, що в теорії та практиці організації зв’язку виникла необхідність в удосконаленні науково-методичного апарату, що буде відповідати сучасним умовам функціонування систем управління та забезпечувати більш адекватну оцінку ефективності систем зв’язку, що розгортаються. В зазначеній статті авторами запропоновано методичний підхід з оцінки ефективності системи зв’язку спеціального призначення. Запропонований підхід заснований на використанні показника доступності системи зв’язку спеціального призначення з першого разу. В ході зазначеного дослідження авторами використані основні положення теорії зв’язку, теорії завадостійкості та розвідзахищеності. Новизна запропонованого методичного підходу, на відміну від існуючих полягає в тому, що система зв’язку спеціального призначення оцінюється по узагальненому показнику доступності канальних та мережевих ресурсів системи зв’язку спеціального призначення, що є згорткою часткових показників оцінки ефективності системи зв’язку спеціального призначення. Практичне значення запропонованого методичного підходу полягає в тому, що запропонований підхід дозволяє оцінити систему зв’язку по більшій кількості часткових показників, визначити заходи щодо розгортання системи зв’язку та виробити заходи стосовно підвищення ефективності системи зв’язку спеціального призначення

Effective Feature Selection Method for Deep Learning-Based Automatic Modulation Classification Scheme Using Higher-Order Statistics

Recently, in order to satisfy the requirements of commercial communication systems and military communication systems, automatic modulation classification (AMC) schemes have been considered. As a result, various artificial intelligence algorithms such as a deep neural network (DNN), a convolutional neural network (CNN), and a recurrent neural network (RNN) have been studied to improve the AMC performance. However, since the AMC process should be operated in real time, the computational complexity must be considered low enough. Furthermore, there is a lack of research to consider the complexity of the AMC process using the data-mining method. In this paper, we propose a correlation coefficient-based effective feature selection method that can maintain the classification performance while reducing the computational complexity of the AMC process. The proposed method calculates the correlation coefficients of second, fourth, and sixth-order cumulants with the proposed formula and selects an effective feature according to the calculated values. In the proposed method, the deep learning-based AMC method is used to measure and compare the classification performance. From the simulation results, it is indicated that the AMC performance of the proposed method is superior to the conventional methods even though it uses a small number of features.

МОДЕЛЬ И АЛГОРИТМ ПРОГНОЗИРОВАНИЯ ПОКАЗАТЕЛЕЙ КАЧЕСТВА ВОЕННОЙ ТЕХНИКИ СВЯЗИ С ИСПОЛЬЗОВАНИЕМ НЕЙРОНЕЧЕТКОЙ СЕТИ

The article presents an ANFIS–type neural model for approximating predictive function, which canbe applied to predict conditions and parameters of development of military communication technique. A model and algorithm for prediction of quality indicators of military communication equipment using a neural network is presented. Application of the developed algorithm allows to increase accuracy and reliability of forecast estimates under conditions of uncertainty of initial data.an algorithm for selecting the volume and nomenclature of quality indicators of military communication facilities and complexes, built on the basis of artificial neural networks, in order to predict their technical level and to improve the objectivity of the initial data in the selection of important quality indicators.

A network perspective on assessing system architectures: Foundations and challenges

AbstractOrganizations are increasingly faced with the challenge of architecting complex systems that must operate within a System of Systems context. While network science has offered usefully clear insights into product and system architectures, we seek to extend these approaches to evaluate enterprise system architectures. Here, we explore the application of graph‐theoretic methods to the analysis of two real‐world enterprise architectures (a military communications system and a search and rescue system) and to assess the relative importance of different architecture components. For both architectures, different topological measures of component significance identify differing network vertices as important. From this, we identify several significant challenges a system architect needs to be cognisant of when employing graph‐theoretic approaches to evaluate architectures; finding suitable abstractions of heterogeneous architectural elements and distinguishing between network‐structural properties and system‐functional properties. These challenges are summarized as five guiding principles for utilizing network science concepts for enterprise architecture evaluation.

그래프 이론에 기반한 군 통신 시스템에서의 주파수 자원 관리 알고리즘: 전이중 통신 관점에서

그래프 이론에 기반한 군 통신 시스템에서의 주파수 자원 관리 알고리즘: 전이중 통신 관점에서

ANALYSIS OF MATHEMATICAL APPARATUS FOR MANAGING CHANNEL AND NETWORK RESOURCES OF MILITARY RADIO COMMUNICATION SYSTEMS

The experience of carrying out the Operation of the United Nations (antiterrorist operation) on the territory of Donetsk and Luhansk oblasts shows that the existing procedure for managing the channel and network resources of military radiocommunication systems does not meet the modern requirements, which are put forward for them. The choice of a route in special purpose networks with the ability to self-organize on the basis of specific parameters is the main problem for managing the channel and network resources of special-purpose networks, as well as the difficult task of climbing the network. In this article, the authors analyzed the existing mathematical apparatus for controlling channel and network resources of military radiocommunication systems. During the research, the authors of the article used the classical methods of scientific knowledge, namely, the methods of analysis and synthesis, the basic provisions of the theory of communication, methods of modeling of communication networks, the theory of artificial intelligence, and others. It is established that the existing methods of controlling the channel and network resources of military radiocommunication systems take into account only certain factors influencing the quality of the use of channel and network resources of military radiocommunication systems. Therefore, it is the most expedient to choose a route for information transmission on many parameters based on fuzzy logic and a modified method of the ant colony system, through which searches and maintenance of the path of the packet passing between two points between the node from which the IP packet and the destination node are sent. To find a route, the following parameters must be considered: the energy component, the data rate, the time delay of the IP packet from the node that sends the packet to the destination node and the reliability of the delivery of the IP packet. These parameters should be taken into account while creating mathematical models, methods and techniques for managing channel and network resources of military radio communication systems.

Design of Class-A RF Power Amplifier for S-Band

Military communication equipment is build to encode, decode transmissions and carry on rough treatment in unfriendly climates. They use various bands of frequency to send and receive signals to other radios and satellites. The unmanned aerial vehicle contains digital QPSK transmitter which successes the power amplifier. The telemetry takes place in S-band frequency (2.2-2.3GHZ) and Class-A PA is to be design to operate such high frequency. In this paper a RF power amplifier of Class-A is designed to work in the frequency range of 2.2GHz to 2.3GHz with GaN HEMT. Designed single stage PA provides optimized performance, over desired band with 17 dB signal gain and 1W output power with 21.18% power added efficiency .The proposed RF power amplifier operates with 28 V drain bias voltage and has been implemented with Gerber PCB design software. The proposed power amplifier design is simulated by using software tool Advanced design system (ADS). The simulation results show that RF power amplifier is implemented for S-band with high power ability in the practical frequency range.

A Blind Despreading and Demodulation Method for QPSK-DSSS Signal With Unknown Carrier Offset Based on Matrix Subspace Analysis

Direct sequence spread spectrum (DSSS) signals are widely used in various military and civilian communication systems. It adopts the pseudorandom (PN) sequence to modulate baseband signal before transmission, leading to some unique and useful properties such as lower working signal to noise ratio (SNR), strong anti-jamming capability, and robustness to the effect of multi-path fading. In past few years, blind despreading for DSSS signals has been a hot topic in cognitive radio field. Previous works are mostly concentrated on BPSK-DSSS signals, and have developed theories and methods to estimate the PN sequence effectively. But unfortunately, most of them are powerless to process QPSK-DSSS signals. This work proposes a method based on matrix subspace analysis to recover the PN sequences and transmitted symbols for QPSK-DSSS signals with unknown carrier offset under non-cooperative reception occasion. To recover spreading sequences from subspace of self-covariance matrix, we derive the theoretical expressions of eigenvector by studying the complex hermit matrix decomposition and then investigate the influence of carrier residual. Finally, a structure is designed to complete blind despreading and demodulation from the received waveform to bit stream. Simulation verifies pretty good bit-error-rate (BER) performance of proposed algorithm.

Краткий обзор зарубежных военных тактических систем связи

Краткий обзор зарубежных военных тактических систем связи