Communication Channel Parameters Research Articles

ПІДВИЩЕННЯ ЯКОСТІ СПРИЙНЯТТЯ ВІДЕО В БЕЗПРОВІДНИХ ПРОГРАМНО-КОНФІГУРОВАНИХ МЕРЕЖАХ З ВИКОРИСТАННЯМ МУЛЬТИПІДКЛЮЧЕННЯ

This article presents a method to enhance the quality of video streaming using multi-connection in software-defined wireless networks. The method utilizes bonding technology to combine various physical network adapters into a single integrated device, effectively utilizing network resources and ensuring high-quality video transmission. The study also includes an analysis of the use of the Peak Signal-to-Noise Ratio (PSNR) as a quality perception metric and the method's response to deteriorating communication channel parameters. The results indicate that an increase in packet loss leads to a decrease in PSNR values. This is explained by the fact that packet loss introduces errors or noise into the compressed signal, reducing its accuracy compared to the original. Specifically, packet loss can be caused by insufficient network bandwidth when the volume of data attempting to pass through the network exceeds its capacity. In such cases, packet loss can lead to a deterioration in the quality of the video stream. On the other hand, packet loss due to radio signal instability may result from external factors such as obstacles or interference, which can lead to packet loss even with sufficient network bandwidth. These losses can also impact the quality of the video stream and reduce PSNR values. During the study, it was observed that an equal percentage of packet losses caused by insufficient network bandwidth and losses due to radio signal instability have different effects on image perception quality. In general, the overall research results confirm the potential for significant improvement in the quality of service for wireless network users using the proposed method, without requiring additional network resource expenditures. This can have significant practical implications for advancing network technologies and ensuring high-quality video data transmission in modern wireless networks.

Karhunen-Loeve-based approach to tracking of rapidly fading wireless communication channels

When parameters of wireless communication channels vary at a fast rate, simple estimation algorithms, such as weighted least squares (WLS) or least mean squares (LMS) algorithms, cannot estimate them with accuracy needed to secure reliable operation of the underlying communication systems. In cases like this, the local basis function (LBF) estimation technique can be used instead, significantly increasing the achievable tracking accuracy. We show that when some prior knowledge of statistical properties of parameter changes is available, such as the bandwidth of their variation, both the type and the number of basis functions, used in the LBF approach to approximate time-varying channel parameters, can be optimized using the Karhunen-Loève (KL) decomposition based technique.

The Green Competitiveness of Enterprises: Justifying the Quality Criteria of Digital Marketing Communication Channels

The omnichannel approach to forming marketing strategies for the development of the green competitiveness of enterprises is seen as a process for the inseparable interaction of marketing-mix elements that are aimed at promoting green competitiveness. This approach integrates traditional and digital marketing communication channels and provides consideration for stakeholder interests. The effectiveness of applying the omnichannel approach to the formation of marketing strategies to develop the green competitiveness of enterprises depends on a set of marketing communication channels, which, in various combinations, can increase or decrease the level of companies’ green competitiveness. For that purpose, this paper proposes a scientific approach to identifying the quality parameters of marketing communication channels, which involves testing the hypothesis that statistically significant relationships exist between their quality parameters and the levels of green competitiveness. The objects analyzed in the paper comprise large Ukrainian production companies that are part of the agro-industrial, mechanical engineering, and food industries, and that work in both the local and international markets. According to the results of the calculations, four relevant parameters were identified for determining the quality of the marketing communication channels: the speed of loading pages, the failure rate, image, and remarketing activities.

Intelligent data processing methods in sensor networks of mobile and autonomous objects

In the near term, tasks related to monitoring mobile geographically distributed objects with the aim of efficiently managing them are acquiring great importance. An example of such tasks is the monitoring the state of given number of vehicles of agricultural enterprise, when it becomes necessary to promptly transfer given amount of data with high requirements for the level of their reliability. The use of the infrastructure of cellular mobile networks for this is not suitable for a number of reasons for rural areas. The paper proposes an approach based on the use of high-speed dynamic sensor networks. This makes it possible to carry out relay transmission of data between objects, including mobile ones. However, the issues of building flexible data transfer protocols in networks of this kind, providing a significant data transfer rate and taking into account the priority of the transmitted information and its features, still remain open. At the same time, for mobile objects in conditions of non-stationarity of the parameters of communication channels, the problems of ensuring the required reliability of data are of particular importance. To solve the last problem, it is proposed to use the permutation decoding method based on the cognitive metaphor.

ПРОПУСКНАЯ СПОСОБНОСТЬ ПРИЕМНИКА ЦИФРОВЫХ СИГНАЛОВ С БОЛЬШИМ ДИНАМИЧЕСКИМ ДИАПАЗОНОМ

The analysis of the connection between the bandwidth and the dynamic range, the signal-to-noise ratio, the resolution time and the bandwidth is carried out. The problems are solved by deriving analytical dependencies based on the Shannon – Hartley theorem, as well as the well-known postulates of the theory of radio engineering circuits and signals. The study of analytical relations allows us to identify restrictions on the choice of communication channel parameters.

Method of advanced channel estimation in OFDM systems by regression technique

The article considers the task of increasing the efficiency of estimating the parameters of multipath radio communication channels used in the design of mobile remote access systems with orthogonal frequency division with OFDM multiplexing. In the conditions of an ever-growing number of subscribers, an increase in transmission speed and noise immunity of mobile radio communication systems, the task of increasing the efficiency of channel estimation in multipath signal propagation remains an urgent one. It is also essential that the evaluation function was performed with minimal complexity and with high accuracy of signal recovery. Within the framework of the work, the analysis of existing algorithms, models, and methods for estimating the communication channel parameters of OFDM systems is carried out, the main differences and disadvantages are noted. A technique has been developed for estimating the complex envelope of an OFDM signal in a multipath communication channel based on regression analysis. A mathematical model for estimating a discrete multipath channel by a regression method using pilot symbols is presented. The type of the approximating function is selected, taking into account the requirements for the complexity of implementation and performance indicators. We present an algorithm for estimating the complex envelope of an OFDM signal in a multipath communication channel by the regression method.

Two-Stage Method for Joint Estimation of Information Symbols and Channel Frequency Response in OFDM Communication Systems

The optimal and quasi-optimal algorithms of two-stage joint estimation of information symbols and frequency response (FR) of multibeam channels in OFDM-based communication systems have been synthesized. They involve the calculation of a posteriori probability density of estimated processes. At the first stage, the recurrent calculation of joint a posteriori distributions of information symbols and the frequency response is performed from two sides of the measurement vector. At the second stage, a posteriori distributions are combined on each of subcarriers that are obtained as a result of the first stage estimation. Based on the obtained a posteriori distributions, estimates of the information symbol and channel FR are determined by the criteria of a posteriori probability maximum and the average mean squared error minimum, respectively. The performance of synthesized algorithms similar to the well-known MMSE algorithm involves the need of knowledge of statistical properties of communication channel. The device implementing the optimal algorithm is multichannel, each channel of which is matched with the corresponding value of symbol from the modulation constellation. The quasi-optimal algorithm was obtained by using the Gaussian approximation of a posteriori probability density. It should be noted that this algorithm preserves its multichannel structure. The approbation of the presented algorithm was conducted using the computer-aided statistical simulation for different parameters of multibeam communication channels and the comparison of the obtained results with the results obtained by the MMSE and LS algorithms. The simulation results showed that the error probability decreases by about 2 times with a maximum signal propagation delay of 100 μs.

Distributed corporate information systems optimization based on genetic algorithm and object model

In paper object model of distributed corporate information system is developed in the form of interacting models of its typical components, which takes into account replication and distribution of data between nodes of computer network, characteristics of hardware and makes it possible to simulating DCIS of any structure. A new modification of the genetic algorithm for the DCIS optimization problem has been developed, in which combined multichromosomes have been used to represent the placement of database tables, applications and parameters of servers, network devices and communication channels, genetic operators of recombination, crossover and mutation have been developed. To optimize the DCIS functioning, together with a modified genetic algorithm, the object model is used, that calculates the fitness-function, forming the optimal configuration of DCIS data distribution and hardware parameters in real time for the performance criterion formulated as the minimization of the system response time. A serial scheme of implementation of the genetic algorithm was developed, which includes full or partial optimization of DCIS in accordance with the requirements. The approach proposed allows obtaining suboptimal solution to the DCIS optimization problem with deviation from the global optimum of no more than 5%.

A theoretical approach to a safety-based predictive adaptation of wireless communication channel parameters in harsh environments

This paper presents an approach to a real-time optimization of safety parameters in wireless communication systems. When considering the GEC–model (Generalized Erasure Channel) and the black channel design of a communication channel, then the PFH (Probability of Failure per Hour) value can be estimated using the parameters e – BER (bit-error-rate), φ – BLR (bit-loss-rate), v – number of safety related messages per second, n – message length and dmin – minimum distance of a linear code. The number of safety related messages per second v and the message length n, including the information block k and the checksum block r, can be varying between the permissible bounds. Accordingly, the variable parameters can be adjusted at run-time with additional assimilation of the used cyclic code. It allows the real-time prediction and optimization of the safety parameters. In this paper, the concept of the parameter estimation is discussed and based on it the optimization problem is defined.

RESEARCH OF THE REED-SOLOMON CODES CHARACTERISTIC FOR REALIZATION WITHIN CONTROL SYSTEMS DEVICES

Context. Research of a Reed-Solomon codes characteristics for estimation of code and communication channel parameters influence at the reliabilityand efficiency of information transmission between of control systems devices are performed. The research object is encoding with usingnonbinary redundant Reed-Solomon codes, the research subject is the theoretical and experimental studies of relation between the Reed-Solomoncodes characteristics and their parameters and transmission channel properties. The purpose is characteristics and properties relation analysis for theirusing within encoding and decoding procedures at software of control systems devices.Methods. The math methods and Reed-Solomon codes building theory are used. The formulas for information transmission reliability estimationwith using Reed-Solomon codes taking into account of code character and individual data bits distortions are received. The dependencies of correcttransmission probability from the code and transmission channel parameters are researched. The dependencies of efficiency indicators (informationrate) of transmission with using the Reed-Solomon codes from code parameters are received and researched. The simulation of control system withusing selected method of the noise stability encoding is done. The encoding and decoding procedures for their adaptation and using within controlsystems devises software are realized.Results. The dependencies of the Reed-Solomon codes reliability indicators (correct transmission probability) and the efficiency indicators (informationrate) from its parameters (Galua field module, number of corrected errors, code shortening degree) are received. The recommendations forusing results for code parameters selecting are done. The control system model with using MathWorks MatLab Simulink is created and configured.The software modules with encoding and decoding procedures for their practical realization within embedded software of control systems devices aredeveloped.Conclusions. The performed research illustrates the dependence of the reliability and efficiency indicators of information transmission from theReed-Solomon codes parameters. This allows design reliable control systems with preset level of reliability than provided by a reasonable selection ofReed-Solomon code parameters

Analysis of a fixed source-to-receiver underwater acoustic communication channel parameters in shallow water

Analysis of a fixed source-to-receiver underwater acoustic communication channel parameters in shallow water

АНАЛИЗ МЕТОДОВ СБОРА И МАТЕМАТИЧЕСКОЙ ОБРАБОТКИ РАЗНОРОДНОЙ ИНФОРМАЦИИ ПО ОЦЕНКЕ СОСТОЯНИЯ ЗОНЫ ОБСЛУЖИВАНИЯ СЕТЕЙ ОПЕРАТОРА СВЯЗИ

The article analyzes the methods and means of collecting, identifying and processing information related to technical, social and economic parameters of network coverage area. One of the trends in the telecommunications market is a continuous increase in the volume of transmitted traffic while maintaining indicators such as the average revenue per subscriber and the total number of subscribers for telecom operators. Taking into account the analysis of development trends in order to preserve the profitability of work, telecom operators need to increase the efficiency of their work by reducing the cost of maintaining the infrastructure and promoting new services. To solve these problems, it is necessary to use various types of information gathering about the state of the network coverage of a provider. The analysis of methods for collecting information on the network coverage revealed three main types. The first relates to the methods of collecting technical parameters of communication channels between the base stations of the operator and subscriber equipment. The second consists in collecting information on subscriber complaints about the service quality by means of the customer interaction service. The third is conducting marketing research to predict the needs of subscribers for new services. The results of the analysis show that the greatest difficulties in collecting and processing information are related to the complex identification of the network coverage area, taking into account technical and socio-economic factors. The difficulties have been caused by the limitations of the available technical means for analyzing the state of the network coverage area to an integrated generalization of heterogeneous information. According to the analysis results of theoretical methods, it has been stated that using the methods of the theory of fuzzy sets is most appropriate for generalizing the information presented in numerical and verbal form.

Development of a differential block coding method for application in mobile radio communication systems using MIMO systems

The object of this research is the methods and algorithms of space-time block coding, which are also used in multi-antenna radio communication systems (Multiple Input Multiple Output – MIMO). The implementation of MIMO systems for coherent reception or precoding of data implies knowledge of information about the state of the communication channel and, accordingly, compensation for its impact. For channel estimation, together with information signals, pilot signals are transmitted, previously known at the receiving side. The frequency of sending these signals depends on factors that change the state of the communication channel, for example, one of which is the high speed of movement of mobile stations. But since the pilot signals do not carry user information, the resource of the system is consumed, which impedes the efficient use of the radio frequency spectrum.In the course of the study, a method was considered that admits the absence of the need for knowledge of the state of the communication channel – relative phase modulation, which was taken as a basis and distributed for use in MIMO systems. This method provides for incoherent reception, but, despite this, its use is fully justified, based on the results of the study. Effective tree coding and an algorithm for compensating the noise components of the received signal were also developed and integrated into the system. This, accordingly, allows to optimize the computational power of the system implementation and to approximate the proposed method of differential space-time block coding (DSTBC) to the methods of coherent reception.Using the MATLAB software package, the proposed DSTBC method is simulated for various options for the number of transmitting and receiving antennas and types of modulation. A comparison is made and the advantages of the DSTBC method are determined. The described method can find application in modern radio communication systems with rapidly changing communication channel parameters due to the high speed of movement of mobile stations.

Security Evaluation of a Brute-force Attack on a Cipher Using a Statistical Criterion for Plaintext

The paper presents calculations of the amount of effort and the reliability of the method of brute-force attack on a cipher using a statistical criterion for plaintexts, which has type 1 and type 2 errors. Calculated values of parameters of the discussed cryptanalysis methods for a cipher allows better predictions of its remaining safe operational life taking into account statistical characteristics for recognizing the plaintext and changes in the communication channel parameters.

Inter-Satellite Communication for LEO CubeSat Network: QoS Parameters and Feasibility of Massive MIMO

This paper evaluates inter-satellite communication for a low earth orbit CubeSat network. This paper consists of two parts: determination and estimation of quality of service (QoS) parameters and evaluation of the feasibility of a Massive Multiple Input Multiple Output (MIMO) system for inter-satellite links. CubeSats are low-cost and small satellites that were initially designed by students during the educational process but are now launched for conducting space research and for commercial use. Recently, some companies and research studies promoted CubeSats to build a wireless communication networks for different proposes, such as earth observation, weather forecasting, providing access to the internet, internet of things and machine to machine services. The main distinguishing features of a CubeSat network include low-cost and fast deployment with a consequent advantage: the possibility to build a large network (hundreds of spacecraft) with limited resources. However, due to the limited size and function of CubeSats, the feasibility of a CubeSat network with inter-satellite links is debatable. In this paper, we investigate the QoS parameters for an inter-satellite link and factors affecting it. The theoretical design with a constructive drawing of massive MIMO has been made. The possibility and time duration of inter-satellite communication has been calculated for three different cases using real data and including Massive MIMO. The simulation of orbit movements for groups of CubeSats has been made. The correlation between relative positions of satellites in orbits, parameters of communication channels and the QoS was determined. The feasibility of massive MIMO for CubeSat communications has been estimated. Based on simulation results, suggestions and possible technical and non-technical solutions were highlighted together with future studies and simulations.

The method of «blind» carrier frequency estimation of radio signals with linear digital modulation

Carrier frequency estimation in the conditions of a priori uncertainty of signal modulation and parameters is prerequisite for realization of frequency synchronization circuits in software-defined radio. To implement this operation the method of «blind» carrier frequency estimation of radio signals with amplitude, phase and quadrature-amplitude shift keying, which does not require prior information about modulation type, signal and communication channel parameters, is proposed in the article. The basis of method is calculation of constellation symbols cross-correlation and clock synchronization by Gardner method. As opposed to known approaches proposed method does not require two-dimensional objective function calculation which can reduce the number of computing operations. This is achieved by implementation of previous clock synchronization and reducing the two-dimensional objective function in one-dimensional. Verification of developed method is carried out by statistical modeling using more than 20 types of phase constellations. The practical significance of received results consists in reduction of carrier frequency estimation time and simplification of practical implementation at the expense of employment of approved clock synchronization circuits.

Influence of the ionospheric sporadic E layer on the performance of quantum satellite communication in the mid latitude region

Quantum communication is a brand new way of communicating, in which the quantum entanglement effect is used to transmit information. Quantum communication is a new interdisciplinary subject between quantum theory and information theory. It has advantages of perfect information security and higher efficiency in transmission. The successful launch of the first quantum satellite named Micius laid an important foundation forconstructing a secure quantum communication network on a global scale. On the other hand, in the process of quantum satellite communication, the atmospheric environment near the ground will have a certain influence on the transmission of quantum signals, so the security of quantum communication is reduced. One of the influence factors is the ionospheric sporadic E layer. In the actual quantum communication environment, when the weak coherent state light source is simulated the single photon, the source energy is attenuated if the quantum signal passes through the ionosphere. On a space scale of 80-150 km off the ground, the ionospheric sporadic E layer is an irregular thin layer, in which there occurs a sharp increase of electron density under the action of wind shear. Sporadic E layer has a great influence on quantum satellite signal transmission. However, the research about the relationship between the sporadic E layer and quantum communication channel parameters has not yet conducted. To investigate the influence of the ionospheric sporadic E layer on the performance of quantum satellite communication, sporadic E layer formation process is first analyzed. And then the relationship between the free electron density and the height is obtained. After that, the model of the free electron density, the formation thickness and the link attenuation of quantum satellite is established. According to the amplitude damping channel, the quantitative relationships among free electron density and the channel capacity, entanglement fidelity, the quantum bit error rate and the secure key rate are put forward and simulated finally. Theoretical analysis and simulation results show that when the thickness is 1 km, the electron density increases from 3105 cm-1 to 27105 cm-1, the channel capacity decreases from 0.8304 to 0.1319, the entanglement fidelity decreases from 0.9386 to 0.3606, the quantum bit error rate increases from 0.0093 to 0.0769, and the secure key production rate decreases from 9.96810-5 to 1.9110-6. It can be shown that the electron density and the thickness of sporadic E layer have significant effect on the performance of quantum satellite communication. Therefore, in the process of quantum satellite communication, in order to ensure the reliability of quantum communication, based on the detection of ionosphere parameters, the various indexes of the satellite system should be adjusted adaptively.

Software-defined radio technology in the problem concerning with the successive sounding of HF ionospheric communication channels

The problem concerning new software-defined radio technology is investigated as applied to the successive sounding of HF ionospheric communication radio channels. The algorithm for quadrature processing of chirp signals subjected to elementwise compression in the frequency domain is developed. It is established that a channel scattering function and a delay power profile are related to a compressed-signal spectrum and their basic parameters. Data on the key characteristic of HF communications modems are presented. The efficiencies of different modems are estimated using the experimental data on channel parameters. It is demonstrated that the aforementioned technology can be used to estimate not only HF communication channel parameters from the pass band of a radio line but also select the optimal one and, furthermore, makes it possible to combine communications and radio sounding systems in the single device.

Demodulation Algorithms for the Ofdm Signals in the Time- and Frequency-Scattering Channels

We consider a method based on the generalized maximum-likelihood rule for solving the problem of reception of the signals with orthogonal frequency division multiplexing of their harmonic components (OFDM signals) in the time- and frequency-scattering channels. The coherent and incoherent demodulators effectively using the time scattering due to the fast fading of the signal are developed. Using computer simulation, we performed comparative analysis of the proposed algorithms and well-known signal-reception algorithms with equalizers. The proposed symbolby-symbol detector with decision feedback and restriction of the number of searched variants is shown to have the best bit-error-rate performance. It is shown that under conditions of the limited accuracy of estimating the communication-channel parameters, the incoherent OFDMsignal detectors with differential phase-shift keying can ensure a better bit-error-rate performance compared with the coherent OFDM-signal detectors with absolute phase-shift keying.

Вплив нелінійності на параметри авіаційного супутникового канала зв’язку

Для дослідження впливу нелінійності супутникового підсилювача на параметри авіаційного супутникового комунікаційного OFDM канала розроблено оригінальну модель каналу зв'язку "Літак-Супутник-Наземна Станція" з використанням програмного комплексу MATLAB Sіmulіnk. Модель канала з адаптивною модуляцією складається із джерела інформації, передавача літака, каналу нагору/униз, супутникового транспондера, приймача наземної станції. Отримано залежності співвідношення сигнал-шум від втрат у вільному просторі для різних типів нелінійності підсилювача, різних модуляцій (BPSK, QPSK, 16QAM, 64QAM), різних температур шуму. Порівняно спетри та сигнальні сузір’я прийнятих сигналів для різних типів нелінійності підсилювача. Розроблена модель дозволяє визначати уширення спектру цифрового модульованого OFDM сигнала завдяки нелінійності підсилювача.