Performance Of Communication Systems Research Articles

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.

Research on signal equalization technology based on visible light communication

Abstract Visible Light Communication (VLC) transmits signals through visible light and realizes the two functions of lighting and communication at the same time without the need for other hardware equipment. There are still some shortcomings in the visible light communication system. The optical signal propagated indoors is affected by inter-symbol interference (ISI) and external light noise at the receiving end. The signal will be severely distorted. These factors will significantly reduce the accuracy of the received signal decision, thereby seriously affecting the performance of the visible light communication system. Given the problems of intersymbol interference and optical noise in indoor visible light systems, this article studies adaptive equalization technology and modulation and demodulation technology suitable for visible light communication systems and improves the signal-receiving end equalization. Based on the existing equalizer structure, we combined the advantages of two different equalizers and optimized their combined structure parameters. On this basis, we added the MAP algorithm and proposed a hyperbolic tangent function to improve the traditional error function. The defects speed up the convergence speed without changing the mean square error. Experimental results show that the algorithm has improved in convergence performance. The algorithm’s convergence speed is 53.6% higher than the traditional algorithm, the steady-state error is reduced by about 6 dB, and the steady-state error of the algorithm is reduced by about 5 dB respectively.

Kirchhoff meets Johnson: In pursuit of unconditionally secure communication

AbstractNoise: an enemy to be dealt with and a major factor limiting communication system performance. However, what if there is gold in that garbage? In conventional engineering, our focus is primarily on eliminating, suppressing, combating, or even ignoring noise and its detrimental impacts. Conversely, could we exploit it similarly to biology, which utilizes noise‐alike carrier signals to convey information? In this context, the utilization of noise, or noise‐alike signals in general, has been put forward as a means to realize unconditionally secure communication systems in the future. In this tutorial article, we begin by tracing the origins of thermal noise‐based communication and highlighting one of its significant applications for ensuring unconditionally secure networks: the Kirchhoff‐law‐Johnson‐noise (KLJN) secure key exchange scheme. We then delve into the inherent challenges tied to secure communication and discuss the imperative need for physics‐based key distribution schemes in pursuit of unconditional security. Concurrently, we provide a concise overview of quantum key distribution schemes and draw comparisons with their KLJN‐based counterparts. Finally, extending beyond wired communication loops, we explore the transmission of noise signals over‐the‐air and evaluate their potential for stealth and secure wireless communication systems.

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.

Design and Analysis of a Dual-Band Microstrip Patch Antenna for Sub-6 GHz Applications

This paper explores the design, simulation, and analysis of a dual-band Microstrip patch antenna designed to operate efficiently at frequency ranges of 3.32 GHz - 3.62 GHz and 4.72 GHz - 6.83 GHz, utilizing Ansys High-Frequency Structure Simulator (HFSS) software. The primary objective is to enhance performance metrics such as bandwidth, gain, and radiation efficiency to meet the requirements of applications necessitating concurrent operation at both frequency bands. The study involves a comprehensive design, iterative simulation, and detailed analysis using Ansys HFSS, with customized design considerations aimed at optimizing performance for modern wireless communication systems. The research was conducted in a simulated environment over a period that included iterative design processes, multiple simulation runs, and thorough analysis phases. Methodologically, the study focused on iterative design refinement to improve key performance parameters such as reflection coefficient, gain, radiation efficiency, Voltage Standing Wave Ratio (VSWR), and relative permittivity at the specified frequency bands. Results indicate that at 3.32 GHz - 3.62 GHz, the antenna achieves a reflection coefficient of -5 dB, a gain of 2.77 dB, a radiation efficiency of 0.7429, and a VSWR of 1.9299. At the higher frequency range of 4.72 GHz - 6.83 GHz, the antenna exhibits a reflection coefficient of -20.5213 dB, a gain of 3.34 dB, a radiation efficiency of 0.7, and a VSWR of 1.2203. These findings underscore the antenna's capability to deliver improved performance metrics across both frequency bands. In conclusion, the dual-band Microstrip patch antenna designed and analyzed through Ansys HFSS demonstrates significant potential for use in contemporary wireless communication systems, offering enhanced bandwidth, gain, and radiation efficiency suitable for multi-frequency applications.

Orthogonal waveform-based backscattering interference suppression technique for underwater optical wireless communication

The backscattering effects degrade the detection performance in a full-duplex underwater optical wireless communication (UOWC) system when the power of received backscattering interference is comparable to that of a target signal. In this paper, the orthogonal waveforms with the Hermite–Gaussian function and prolate spheroidal wave function are first introduced for a pulse position modulation based dynamic UOWC system to alleviate the backscattering effects. Then, a joint maximum likelihood detection scheme is proposed accordingly. Experimental results verify the superiority of the proposed method with orthogonal waveforms over the scheme without orthogonal pulse shaping in a dynamic underwater bubbly channel.

Interpolation-based reference image estimation for video display field communication

Display field communication (DFC) is a frequency-based display-to-camera (D2C) communication technology. The digital display and the camera act as transmitter and receiver, respectively, and data are transmitted in a video via the D2C link. The essence of DFC is to minimize image distortion for the user while concealing data within the image for transmission. Unlike traditional Video-DFC methods that may suffer from high error rates due to reliance on a single reference image, our proposed Interpolated Video-DFC technique employs a novel interpolated reference image estimation strategy. This method significantly enhances data detection by leveraging interpolation between two reference image frames, enabling accurate estimation of each reference image frame corresponding to data-embedded frames. Comparative experiments highlight the advantages of our method, showing a data rate improvement of approximately 2.3kbps for frame packet length N = 10. Additionally, we achieved a substantial reduction in error rates to approximately 69% lower than those of conventional methods. These findings indicate a promising direction for improving the performance and reliability of D2C communication systems.

A Novel Approach for the Enhancement of Security through Defining the Spatial Secrecy Outage Probability in the Industrial Internet of Things

The rapid development of the Industrial Internet of Things (IIoT) has brought enormous opportunities to the industrial environment, but has also posed significant challenges to network security, especially physical layer security, which is crucial for the reliable transmission of messages among interconnected devices and sensors. Focusing on enhancing the physical layer security in IIoT communication, this paper proposes a mechanism for the Spatial Secrecy Outage Probability (SSOP) to ensure the secure transmission of data. The SSOP algorithm assumes that the location of legitimate devices is known, while the eavesdropper devices have a random distribution of locations, forming the SSOP model related to the device locations from the perspective of insecure regions (ISRs) and secure regions (SRs), and the closed-form expression for its upper bound is derived. Subsequently, under the constraint of the SSOP conditions, we establish an optimization model with the objective of system throughput maximization based on the Spatial Secrecy Outage Probability (SRM-SSOP). By optimizing the transmission rate of legitimate channels or controlling the transmission power, the maximization of the system throughput can be achieved, thus reducing the consumption of communication resources. Through sophisticated modeling and simulation in MATLAB, we verified the accuracy of the definition and derived the upper bound of the SSOP. The experimental results also show that the SSOP algorithm gradually converges to a specific value as the number of antenna elements increases. In addition, we observed that, when the receiver device is aligned with the normal direction of the transmit antenna array, the SSOP reaches a minimum value. This performance is crucial for understanding and optimizing the security performance of IIoT communication systems.

Atmospheric turbulence recognition with deep learning models for sinusoidal hyperbolic hollow Gaussian beams-based free-space optical communication links

The integration of artificial intelligence technology to improve the performance of free-space optical communication (FSO) systems has received increasing interest. This study aims to propose a novel approach based on deep learning techniques for detecting turbulence-induced distortion levels in FSO communication links. The deep learning-based models improved and fine-tuned in this work are trained using a dataset containing the intensity profiles of Sinusoidal hyperbolic hollow Gaussian beams (ShHGBs). The intensity profiles included in the dataset are the ones of ShHGBs propagating for 6 km under the influence of six different atmospheric turbulence strengths. This study presents deep learning-based Resnet-50, EfficientNet, MobileNetV2, DenseNet121 and Improved+MobileNetV2 approaches for turbulence-induced disturbance detection and experimental evaluation results. In order to compare the experimental results, an evaluation is made by considering the accuracy, precision, recall, and f1-score criteria. As a result of the experimental evaluation, the average values for accuracy, precision, recall and F-score with the best performance of the improved method are given; average accuracy 0.8919, average precision 0.8933, average recall 0.8955 and average F-score 0.8944. The obtained results have immense potential to address the challenges associated with the turbulence effects on the performance of FSO systems.

Effect of Line-of-sight Channels on DC-biased Optical Filter Bank Multicarrier Visible Light Communication with Multiple LED Arrays

This paper investigates the impact of propagation delay and channel loss due to the use of multiple LED arrays in visible light communication (VLC) systems based on filter bank multicarrier (FBMC) modulation. FBMC offers greater spectral efficiency, and asynchronous transmission and is a promising alternative scheme to orthogonal frequency division modulation (OFDM). The proposed FBMC model is based on 4-quadrature amplitude modulation (QAM) and 16-QAM formats and uses 100 symbols and 600 input bits per symbol. In this paper, the VLC-FBMC system is designed based on the line-of-sight (LOS) model under the additive white Gaussian noise (AWGN) channel. Comparison analyses between different bit rates in terms of bit error rate (BER), best sampling point, and signal-to-noise ratio (SNR) requirement have been carried out to show the delay and loss effect on communication quality and system performance. The results demonstrate that the proposed FBMC model achieves a bit rate of up to 29.296 Mbit/s with a low BER of 10-3 and less SNR penalty in high QAM formats, demonstrating its potential as a viable alternative to OFDM for future VLC systems.

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.

An Hybrid Framework OTFS-OFDM Based on Mobile Speed Estimation

The Future wireless communication systems face the challenging task of simultaneously providing highquality service (QoS) and broadband data transmission, while also minimizing power consumption, latency, and system complexity. Although Orthogonal Frequency Division Multiplexing (OFDM) has been widely adopted in 4G and 5G systems, it struggles to cope with a significant delay and Doppler spread in high mobility scenarios. To address these challenges, a novel waveform named Orthogonal Time Frequency Space (OTFS). Designers aim to outperform OFDM by closely aligning signals with the channel behaviour. In this paper, we propose a switching strategy that empowers operators to select the most appropriate waveform based on an estimated speed of the mobile user. This strategy enables the base station to dynamically choose the waveform that best suits the mobile user’s speed. Additionally, we suggest retaining an Integrated Sensing and Communication (ISAC) radar approach for accurate Doppler estimation. This provides precise information to facilitate the waveform selection procedure. By leveraging the switching strategy and harnessing the Doppler estimation capabilities of an ISAC radar.Our proposed approach aims to enhance the performance of wireless communication systems in high mobility cases. Considering the complexity of waveform processing, we introduce an optimized hybrid system that combines OTFS and OFDM, resulting in reduced complexity while still retaining performance benefits.This hybrid system presents a promising solution for improving the performance of wireless communication systems in higher mobility.The simulation results validate the effectiveness of our approach, demonstrating its potential advantages for future wireless communication systems. The effectiveness of the proposed approach is validated by simulation results as it will be illustrated.

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.

Enhancing Linearity of Light Response in Avalanche Photodiodes by Suppressing Electrode Size Effect.

The nonlinear characteristics of avalanche photodiodes (APDs) inhibit their performance in high-speed communication systems, thereby limiting their widespread application as optical detectors. Existing theoretical models have not fully elucidated complex phenomena encountered in actual device structures. In this study, actual APD structures exhibiting lower linearity than their ideal counterparts were revealed. Simulation analysis and physical inference based on GaN APDs reveal that electrode size is a noteworthy factor influencing response linearity. This discovery expands the nonlinear theory of APDs, suggesting that APD linearity can be enhanced by suppressing the electrode size effect. A physical model was developed to explain this phenomenon, which is attributed to charge accumulation at the edge of the contact layer. Therefore, we proposed an improved APD design that incorporates an additional gap layer and a buffer layer to stabilize the internal gain under high-current-density conditions, thereby enhancing linearity. Our improved APD design increases the linear threshold for optical input power by 4.46 times. This study not only refines the theoretical model for APD linearity but also opens new pathways for improving the linearity of high-speed optoelectronic detectors.

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.