Performance Of Communication Systems Research Articles

On the performance of a hybrid optical communication system: MGDM–FSO for challenging environments

On the performance of a hybrid optical communication system: MGDM–FSO for challenging environments

Enhanced Ultra-Wideband Communication System with OFDM Modulation: Performance Analysis in LOS and NLOS Conditions

Ultra-wideband (UWB) communication systems, employing Orthogonal Frequency Division Multiplexing (OFDM) modulation, are renowned for their high data rates, low power consumption, and robust performance in multipath environments. However, these systems face significant challenges in varying propagation conditions, specifically under Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios. In LOS conditions, the signal travels directly from the transmitter to the receiver without obstructions, typically resulting in optimal performance characterized by high transmission efficiency, strong Signal-to-Noise Ratio (SNR), low Bit Error Rate (BER), and maximum throughput. Conversely, NLOS conditions involve obstructions and reflections that cause multipath propagation and signal degradation. This leads to reduced transmission efficiency, lower SNR, higher BER, and diminished throughput. This study examines the performance of an UWB communication system using OFDM modulation in both LOS and NLOS conditions. The performance metrics evaluated include transmission efficiency, SNR,BER, and throughput. In LOS conditions, the system demonstrates high transmission efficiency, superior SNR, minimal BER, and maximum throughput due to the unobstructed signal path. In contrast, NLOS conditions result in decreased transmission efficiency, lower SNR, increased BER, and reduced throughput due to signal attenuation and multipath effects. These findings highlight the significant impact of environmental conditions on UWB-OFDM system performance and underscore the importance of optimizing such systems for reliable communication in varied deployment scenarios.

Present Development of Software for Railway Safety

Railway is Cyber-Physical System (CPS), which is distributed over a large territory. It requires secure communication not only among various parts of system, but also with operation center. Building its own communication networks by the railway system operator is financially demanding, which is why more or less open communication systems are used. This is connected with higher requirements for the security of applications, operated in a CPS. European project COSMSOS has been creating a tool that applies DevOps development technologies from the IT field to the field of embedded systems, to which railway system belong. The article shows that this very complex software must be adapted to real requirements, which are put on railway operation system safety.

The method of assessing the sustainability of the functioning system based on the combat capabilities of the armies

The authors' analysis of the calculation of the value of the stability indicator of the military communication system, based on the experience of conducting military operations in the east of the country, proved by the use of the classic approach by the officials of the communication management staff is not possible. It requires carrying out numerous specialized calculations separately for the directions of communication with their further generalization for the military communication system as a whole in the conditions of uncertainty of conducting active hostilities. In addition, resilience is an integral indicator from the convolution of probabilistic partial indicators of survivability, reliability, immunity and cyber security. Therefore, the authors proposed to develop a new methodology for calculating the value of the stability of the operation of the military communication system in the modern conditions of conducting hostilities. Unlike the classical approach, it should be based on the use of other indicators that will simplify calculations. The authors developed a graphic model of the operation of the military communication system in modern conditions of active hostilities. To describe the operation of the proposed model, the authors used the values of the combat capabilities of troops (forces). The methodology takes into account the predicted impact of means of fire damage, radio-electronic warfare of the enemy on our military communication system and the implementation of combat support and radio-electronic protection measures by the communication units. To formalize the methodology, the authors obtained a number of compact analytical expressions that establish the probabilities of the ratio between the values of the combat capabilities of our troops and the enemy's troops. The methodology is easily implemented in the form of an information and calculation task and significantly reduces the time of operational calculations for the military communications management staff to make sound management decisions.

Enhancing network performance in a long-haul communication system a wavelength division multiplexing and coherent optical orthogonal frequency division multiplexing approach

Enhancing network performance in a long-haul communication system a wavelength division multiplexing and coherent optical orthogonal frequency division multiplexing approach

Overloaded Spread Spectrum OFDMA in Outdoor Environment in the More Interleaving Scenario

The advancement of mobile communication technology is driven by innovations or modifications in the latest Radio Access Techniques to meet user demands and enhance capacity. This paper focuses on improving spectral efficiency and average throughput using an OFDM-based multiple access technique. Specifically, we have chosen Overloaded Spread Spectrum OFDMA for this study. Our research findings indicate that implementing a 24% overload leads to an approximate 33% increase in spectral efficiency. This significant improvement demonstrates the potential of Overloaded Spread Spectrum OFDMA in optimizing the performance of mobile communication systems. By increasing spectral efficiency, we can support a larger number of users and higher data rates, which are crucial for the evolving demands of modern mobile networks. This study highlights the importance of adopting advanced access techniques to sustain the growth and efficiency of mobile communications

Optimizing Communication System Performance through Hybrid Modulation: A Comprehensive Analysis and Guideline

There is a clear need for dependable high-speed communication systems in light of 5G's recent rapid development. The enormous data that recently developed immersive media generate need to be transmitted, and traditional modulation techniques are unable to provide a suitable level of communication. Consequently, to improve communication system performance, hybrid modulation is needed. This paper examines the communication process and conducts a performance analysis to establish a reasonable method for choosing a hybrid modulation scheme. The constellation diagram, power spectral density, bandwidth efficiency, eye diagram, and bit error rate are the main components that determine a communication system's performance. Based on the analysis, the author concludes that to achieve a better-performing communication system, there must be a compromise between these performance factors. Specific recommendations are provided regarding performance indicators listed in the article, such as the constellation diagram, power spectrum density, bandwidth efficiency, eye diagram, and bit error rate. This work aims to address these issues to provide new researchers with guidance when selecting a hybrid modulation approach and to suggest a line of inquiry in the increasingly complicated and time-consuming age of large data volumes.

Characteristics Analysis of Different Photonic Crystal Fiber Lattice Structures

This study presents a comprehensive analysis of various photonic crystal fiber (PCF) lattice structures using the Finite Element Method (FEM). PCFs have gained significant importance in various optical and communication applications due to their unique optical properties. Understanding the characteristics and optimal designs of different PCF lattice structures is crucial for their effective utilization. In this research, we explore eight distinct lattice designs, including circle, square, pentagon, hexagon, heptagon, octagon, decagon, and dodecagon. We investigate how variations in the air-filling fraction (AFF), a critical structural parameter, affect the performance of these PCF structures. The utilization of FEM allows for a detailed analysis of these lattice structures, offering insights into their behavior under different conditions. By varying the AFF, we gain valuable insights into the optimal design choices for specific applications. This research aims to provide a deeper understanding of the applicability of each PCF lattice structure. By scrutinizing their performance and characteristics, it becomes possible to distinguish which lattice structure is best suited for various optical and communication applications. The findings from this study offer significant contributions to the field of photonics, guiding researchers and engineers in selecting the most suitable PCF lattice structure for their specific applications. Understanding the structural parameters that influence PCF behavior is a key step toward optimizing the performance of optical and communication systems.

Performance evaluation and investigation of diffraction optical elements effect on bit error rate of free space optics and performance investigation of space uplink wireless optical communication under varying atmospheric turbulence conditions

AbstractSeveral other optical antenna topologies have been developed and implemented throughout the years. These topologies include a variety of optical components, including the axicon optical element, dual‐secondary mirror, cone reflecting mirror, prism beam slier, and beam‐splitter/beam combiner. In contrast, the secondary reflecting mirror causes an obscuration loss that must be compensated for by reducing the transmission power in an optical antenna design. In order to address this issue in space optical communication, the present research helps to develop an enhanced two diffractive optical elements (DOEs) technology however the data presented therein only shows that DOEs may boost transmission power efficiency, which is insufficient for system designers. Though On‐Off Keying (OOK) is widely used in optical communication systems at the moment, the proposed research include DOEs into an OOK space uplink optical. The proposed research uses numerical simulation to explore how much a space uplink OOK system's bit error rate (BER) may be improved by using DOEs and adjusting fundamental parameters. The proposed BER model takes environmental factors like wind and detector noise into account. Using this theoretical model, the present work helps to investigate the effect of DOEs on the BER versus fundamental parameter characteristic curves in space uplink optical communication. Based on the findings, the DOEs structure has the potential to significantly enhance the BER performance of space uplink optical communication systems, especially at high obscuration ratios. When the obscuration ratio is 0.25, 0.167, or 0.125 and the transmission power is 1 W, for instance, the DOEs may improve the BER by a factor of two or one order of magnitude or less when the parameters are changed to the typical parameter values as specified. Results increase by a factor of six, three, and two orders of magnitude, respectively, when transmitting at 5 W. The results show that DOEs can significantly enhance the BER performance, especially at high obscuration ratios. The findings suggest that integrating DOEs into the optical subsystem is a straightforward approach to improving the performance of space uplink optical communication systems.

Machine Learning Strategies for Reconfigurable Intelligent Surface-Assisted Communication Systems—A Review

Machine learning (ML) algorithms have been widely used to improve the performance of telecommunications systems, including reconfigurable intelligent surface (RIS)-assisted wireless communication systems. The RIS can be considered a key part of the backbone of sixth-generation (6G) communication mainly due to its electromagnetic properties for controlling the propagation of the signals in the wireless channel. The ML-optimized (RIS)-assisted wireless communication systems can be an effective alternative to mitigate the degradation suffered by the signal in the wireless channel, providing significant advantages in the system’s performance. However, the variety of approaches, system configurations, and channel conditions make it difficult to determine the best technique or group of techniques for effectively implementing an optimal solution. This paper presents a comprehensive review of the reported frameworks in the literature that apply ML and RISs to improve the overall performance of the wireless communication system. This paper compares the ML strategies that can be used to address the RIS-assisted system design. The systems are classified according to the ML method, the databases used, the implementation complexity, and the reported performance gains. Finally, we shed light on the challenges and opportunities in designing and implementing future RIS-assisted wireless communication systems based on ML strategies.

Assessing Short-range Shore-to-Shore (S2S) and Shore-to-Vessel (S2V) WiFi Communications

Wireless communications increasingly enable ubiquitous connectivity for a large number of nodes, applications and scenarios. One of the less explored scenarios are aquatic ecosystems, specially when enabled by near-shore and short-range communications. Overwater communications are impaired by a number of distinguishing dynamic factors, such as tides, waves or node mobility, that lead to a widely fluctuating and unpredictable channel. In this work, we empirically characterize near-shore, overwater channels at 2.4 GHz under realistic conditions, including tidal variations, and relatively short TX-RX separations. To this end, we conducted experiments in a coastal estuarine region and on a harbor to characterize Shore-to-Shore (S2S) and Shore-to-Vessel (S2V) communication channels, respectively, and to identify major factors impairing communication in such scenarios. The empirical results show that constructive/destructive interference patterns, varying reflecting surface, and node mobility (i.e. travel direction and particular maneuvers) have a relevant and noticeable impact on the received signal strength. Thus, a set of parameters should be simultaneously considered for improving the performance of communication systems supporting S2S and S2V links, namely tidal variations, reflection surface changes, antenna height, TX-RX alignment and TX-RX separation. The results useful provide insights into realistic S2S and S2V link design and operation.

Investigation of IEEE 802.16e LDPC Code Application in PM-DQPSK System

With the development of the Internet and information technology, optical fiber communication systems need to meet people’s information demand for large capacity and high speed. High-order phase modulation and channel multiplexing can improve the capacity and data rate of optical fiber communication systems, but they also bring the problem of bit error. To improve the transmission quality and reliability of optical fiber communication systems, forward error correction (FEC) coding techniques are commonly used, which serve as the fundamental approach to enhance the quality and reliability of fiber optic communication systems, ensuring that the received data remain accurate and reliable. The FEC in optical fiber communication systems is divided into three generations. The first generation FEC is mainly hard decision codewords, represented as RS code. The second generation FEC is mainly cascaded code, which stands for interleaved cascaded code. The third generation of FEC mainly refers to soft decision codes, which are represented as low-density parity-check (LDPC) codes. As a kind of FEC, LDPC codes stand out as pivotal contributors in the field of optical communication and have gained remarkable attention due to exceptional error correction performance and low decoding complexity. Based on IEEE802.16e standard, LDPC code with specific code length and rate is compiled and simulated in MATLAB and VPItransmissionMaker 10.1 and successfully incorporated into polarization multiplexed differential quadrature phase shift keying (PM-DQPSK) coherent optical transmission system. The simulation results indicate that the bit error rate (BER) can be reduced to 10−3 when the optical signal-to-noise ratio (OSNR) reaches 14.2 dB, and the BER experiences a reduction by nearly three orders of magnitude when the OSNR is 17.2 dB. These findings underscore the efficacy of LDPC codes in significantly improving the performance of optical communication systems, particularly in scenarios demanding robust error correction capabilities. This study provides valuable, significant results regarding the potential of LDPC codes for enhancing the reliability of optical transmission in real-world applications.

Design and Implementation of DSLMS Algorithm Based Photoelectric Detection of Weak Signals

Accurately extracting weak signals is extremely important for overall performance and application in optoelectronic imaging and optical communication systems. While weak signals are susceptible to noise, adaptive filtering is a commonly used noise removal method. Still, its convergence speed is slow, the steady-state error is large, and the anti-interference ability is weak. To solve the above problems, this paper proposes a new type of variable-step-length adaptive filtering algorithm (DSLMS) based on the minutiae function, which effectively reduces the noise component in error through its combination with the pair cancelation system, utilizing the low correlation property of the noise signal, to improve the anti-noise interference ability of the adaptive filter. Using FPGA and Matlab (2018b) for experimental verification, the results show that this algorithm shows significant advantages in noise suppression, accelerated algorithm convergence, and low steady-state error, and it has effectiveness and application potential for the optoelectronic detection of weak signal processing.

Eye Surgical Equipment Sensor Board Testing Kit

The Eye Surgical Equipment Sensor Board Testing Kit utilizes Microcontroller and Raspberry Pi to diagnose PCBs, focusing on detecting Eye Surgical Sensor Board defects impacting signal integrity. With Microcontroller’s advanced features like high-speed ADCs and flexible GPIOs, it generates and processes signals accurately. Raspberry Pi enables real-time visualization of test results. This portable and cost-effective solution is suitable for industrial applications, empowering engineers and technicians to efficiently address Eye Surgical Sensor Board defects. By leveraging the computational power of both platforms, it offers a scalable approach to Sensor Board testing, enhancing reliability and performance in high-speed digital communication systems.

Characterization of Doppler shift in inter-satellite laser link between LEO, MEO, and GEO orbits

Over the past few decades, the development of optical wireless communications (OWC) has led to its application in a wide range of environments, including indoor, outdoor, and space. Optical carriers offer advantages such as high bandwidth, security, and directivity, making it a suitable technology for applications in radio astronomy, remote sensing, cellular networks, high-speed train communications, last-mile access, underwater/terrestrial communications, and satellite communications employing laser links. However, laser links between satellites experience Doppler shift due to their relative motion, and this effect should be taken into account from a system design perspective. This paper presents a study of the Doppler shift characterization in laser links for circular Keplerian orbits. An analytical derivation establishes the relationship between the Keplerian orbital elements and the Doppler shift in laser links. The derived equations provide a more comprehensive understanding of the impact of these orbital elements on the Doppler shift in laser links. Additionally, equations have been derived for the Doppler shift rate and the visibility window condition during satellite communication. Furthermore, we conducted a link failure analysis using simulations to evaluate the effects of the Doppler shift, also identifying the worst-case scenarios for orbits most significantly impacted by this shift. The results showed that among the six Keplerian orbital elements, the semi-major axis, inclination, and right ascension of ascending node contribute to the Doppler shift in circular orbits. While the Doppler shift impact is less significant for laser communication systems employing intensity modulation/direct detection, it can degrade the communication system performance for coherent detection. This work contributes to the effective estimation of Doppler shift from a system design perspective.

Assessment of local temperature elevation at the surface of tissue exposed to radiation of milimeter waves using simplified analytical approach

Dominant effect of human exposure to electromagnetic fields in GHz frequency range corresponding to operation of 5G mobile communications systems is tissue heating i.e. local temperature elevation at the body surface, i.e. skin, ear and eyes. For the frequencies below transition frequency of 6GHz specific absorption rate (SAR) is used to quantify the volume heating. On the other hand, the surface heating above 6GHz is quantified via absorbed power density (Sab ). Once these quantities are determined by means of internal field dosimetry procedures it is possible to determine the local surface temperature increase by solving the bio-heat transfer equation. The present paper deals with the calculation of tissue surface heating due to exposure to millimeter waves. Internal dosimetry is based on the planar tissue model exposed to dipole antenna radiation. Electromagnetic model is based on the analytical solution of Pocklington integro-differential equation while the assessment of tissue surface heating in planar tissue model has been carried by analytically solving a simplified variant of the bio-heat transfer equation. Some illustrative results for power density and temperature elevations will be presented for different antenna parameters.

Ionospheric Nowcasting Over Italy Through Data Assimilation: A Synergy Between IRI UP and IONORING

AbstractAn accurate modeling of the ionosphere electron density is pivotal to guarantee the effective operation of communication and navigation systems, particularly during Space Weather events. Despite the crucial contribution of empirical models like the International Reference Ionosphere (IRI), their limitations in predicting ionospheric variability, especially under geomagnetically disturbed conditions, are acknowledged. The solution proposed in this work involves integrating real‐time, spatially distributed ionospheric measurements into climatological models through data assimilation. To enhance our predictive capabilities, we present an upgrade of the IRI UP data‐assimilation method, incorporating real‐time vertical total electron content (vTEC) maps from the IONORING algorithm for nowcasting ionospheric conditions over Italy. This approach involves updating the IRI F2‐layer peak electron density description through ionospheric indices, to finally produce real‐time maps over Italy of the ordinary critical frequency of the F2‐layer, foF2, which is crucial for radio‐propagation applications. The IRI UP–IONORING method performance has been evaluated against different climatological and nowcasting models, and under different Space Weather conditions, by showing promising outcomes which encourages its inclusion in the portfolio of ionospheric real‐time products available over Italy. The validation analysis highlighted also what are the current limitations of the IRI UP–IONORING method, particularly during nighttime for severely disturbed conditions, suggesting avenues for future enhancements.

The Effect of High-Speed Train Channel on the Performance of DVB-Terrestrial Communication Systems

The Effect of High-Speed Train Channel on the Performance of DVB-Terrestrial Communication Systems

Image Super Resolution-Based Channel Estimation for Orthogonal Chirp Division Multiplexing on Shallow Water Underwater Acoustic Communications.

Orthogonal chirp division multiplexing (OCDM) offers a promising modulation technology for shallow water underwater acoustic (UWA) communication systems due to multipath fading resistance and Doppler resistance. To handle the various channel distortions and interferences, obtaining accurate channel state information is vital for robust and efficient shallow water UWA communication. In recent years, deep learning has attracted widespread attention in the communication field, providing a new way to improve the performance of physical layer communication systems. In this paper, the pilot-based channel estimation is transformed into a matrix completion problem, which is mathematically equivalent to the image super-resolution problem arising in the field of image processing. Simulation results show that the deep learning-based method can improve the channel distortion, outperforming the equalization performed by traditional estimator, the performance of Bit Error Rate is improved by 2.5 dB compared to the MMSE method in OCDM system. At the 7.5 to 20 dB region, it achieves better bit error rate performance than OFDM systems, and the bit error rate is reduced by approximately 53% compared to OFDM when the SNR value is 20, which is very useful in shallow water UWA channels with multipath extension and severe time-varying characteristics.

Organizational culture as the basis of successful business

Organizational culture serves not only as a set of values and norms that characterize the way business is conducted within a company but also as a critical determinant of its success and competitiveness. This article explores the importance of organizational culture as the basis for successful business management. It examines the role of values, norms, traditions, and practices that shape a company's culture in creating a conducive environment for business development. Additionally, it investigates the impact of organizational culture on the efficiency and performance of the enterprise, as well as on employee motivation and satisfaction. Based on this analysis, proposals are put forward on how management can actively shape and manage organizational culture to achieve strategic goals and success in today's business environment. This article's conclusions may benefit executives and managers seeking to improve their company's effectiveness by enhancing organizational culture. Organizational culture is not just a reflection of how things are done within a company; it is a fundamental aspect that defines strategic directions and the overall orientation of business activities. It manifests in all entrepreneurial endeavors—from corporate style and communication methods to decision-making approaches and stakeholder relationships. Building and managing organizational culture becomes a paramount task for leadership in modern times, where competition and market instability are ever-present challenges. Indeed, organizational culture is the cornerstone for successful and resilient businesses. The success of shaping and managing organizational culture depends on several key aspects. Firstly, it is crucial to have a clear vision of the company's mission and values, which define the overall direction of development and objectives of the enterprise. Furthermore, it is necessary to actively implement these values and principles into the workplace environment, creating incentives and opportunities for employees' growth and development. Building an open and transparent communication system is vital to fostering understanding and collaboration within the company. Keywords: organizational culture, factors of organizational culture, criteria of organizational culture, stages of formation of organizational culture, business.