Design Of Communication Systems Research Articles

Radiofrequency and optical satellite link budgeting calculator

Abstract Satellite communications represent one of the most widely used communication systems nowadays. From the 50’s of 20th century up to the present, the demand for satellite services has increased rapidly, so the need to design and implement reliable, up-to-date systems that meet the needs of users is increasingly imperative. Technological progress also implies a better use of the radio spectrum and the incorporation of benefits in terms of transmission performance. Traditionally, satellite systems have been implemented in the range corresponding to radio frequency, and more recently, special attention has been paid to the exploration of the spectrum corresponding to optical communications, due to the superior benefits that it offers, despite the set of challenges that its implementation represents. Such advances demand the greatest certainty of operation even from the conception and design stage of the transmission system, since satellite communications are not prone to constant changes and maintenance. The calculation process known as link budget is a tool present in the design of any wireless communications system, and its results determine the efficiency and reliability of the design. However, due to the large number of manufacturers and operators, as well as considering the novelty of using high-performance optical systems, it is difficult to stick to a single method or even to point out one as totally reliable and simple to use. With the purpose of expediting the calculation of link budgets, there are various computational tools that allow this process to be carried out. However, these tools carry the problem of poor compatibility, differences and a low degree of reliability and ease of use. In the present work, the construction and use of a web application is proposed that includes the link budget calculation process for both radio and optical satellite systems, flexible, simple, user-friendly, compatible, and mainly, abode to standardised and documented models for provide reliability and accuracy.

Design and implementation of a physical layer optical fiber security communication system based on a ZUC stream cipher

In this work, we have proposed a new physical layer encryption scheme to improve the security of optical fiber communication systems. The secrecy scheme is based on disturbance of the data cluster under the ZUC algorithm (named for Zu Chongzhi, a famous mathematician in ancient China), which is generated by optical XOR using a dual-drive Mach–Zehnder modulator (DD-MZM). A base scrambling pseudo random binary sequence (PRBS) generated by the ZUC stream cipher is introduced, which results in a better scrambling effect and randomness in the key stream of the block encryption structure. A simulation setup conducted in an encrypted transmission of the 64×64 grayscale image over 80 km of optical fiber shows that the authorized user can successfully decrypt the received signal, while the eavesdroppers cannot derive useful information with a bit error rate (BER) at approximately 0.5. In the simulation, after setting the delay compensation to 3.125 ps, a correct signal with a Q-factor as high as 11.3642 and a BER as low as 3.14295−30 can be obtained.

Analyzing radiowave multiple diffraction from a low transmitter in vegetated urban areas using a spherical-wave UTD–PO approach

This article introduces a uniform theory of diffraction–physical optics (UTD–PO) formulation for analyzing radiowave multiple diffraction emanating from trees and buildings in green urban areas, considering illumination from a low transmitter and assuming spherical-wave incidence. Based on Babinet’s principle, this solution models buildings as rectangular sections and accounts for the influence of tree crowns (assuming these rise above the average rooftop height) by incorporating appropriate attenuation factors/phasors into the diffraction phenomena of buildings. The validation of the formulation is achieved through measurements made at the 39 GHz 6G mmWave frequency on a scale model of a green urban environment comprising bonsai trees and bricks. The main advantage of the proposed solution is that the calculations only include single diffractions due to recursion, circumventing the need to use higher-order diffraction terms in the diffraction coefficients, thus reducing the computation time and power. Our results may be beneficial for the design of mobile communication systems, including 6G networks, situated in green urban areas and with transmission source positioned lower than the surrounding infrastructure.

Spatial Simultaneous Functioning-Based Joint Design of Communication and Sensing Systems in Wireless Channels

Spatial Simultaneous Functioning-Based Joint Design of Communication and Sensing Systems in Wireless Channels

Analysis of potential 5G transmission methods concerning Bit Error Rate

Fifth-generation wireless (5G) significantly impacts individuals' lives and work and is expected to increase. Although OFDM has been used in previous generation technologies (4G), it has limitations in meeting specific criteria such as data. Issues like better power consumption and Bit Error Rate make this technology unsuitable for meeting current needs such as the Internet of Things and user-based processing. This research aims to test the BER success of the transmission technique proposed as a candidate for the 5G communication system. Performance analysis is carried out considering the Tapped Delay Line (TDL-A) channel model, which is recommended for 5G research. Various scenarios, including situations where the transmitter/receiver is fixed or mobile, are considered to provide a more comprehensive evaluation. Evaluations were also carried out on various channel delay distribution profiles to expand the scope of analysis. The research results show that in channel conditions with high delay distribution and mobility, the communication system that uses the FBMC transmission technique shows better and more stable performance compared to OFMD, F-OFMD, WOLA, UFMC systems, it has an SNR of about 36 dB to achieve a BER of approx 10-3 under 10 ns delay spreading conditions, demonstrating the superiority of FBMC in difficult channel conditions These findings emphasize the importance of considering BER and system complexity in the design of future communications systems. Thus, this research provides a significant original contribution to the understanding and developing 5G communication systems.

A Study on the Irradiance Scintillation Characteristics of Monochromatic LED-Based Visible Light Communication Systems in Weak-to-Strong Turbulence

Atmospheric turbulence causes transmitted light to fade randomly, which results in irradiance scintillation fluctuations in the received signal and significantly affects the quality of wireless optical communication systems. In this paper, we investigate the propagation characteristics of a monochromatic light-emitting diode (LED) light beam through weak-to-strong turbulence. Considering the spatial incoherence of a monochromatic LED light source, the emitted light field of a monochromatic LED light source is represented by a random field multiplied by a deterministic field that follows a Gaussian distribution. Then, based on the extended-Rytov theory, a closed expression for the irradiance scintillation index under weak-to-strong turbulence is derived. In addition, the expression for the fading probability governed by the Gamma–Gamma model is given. Finally, the effects of near-earth atmospheric refractive index structural parameters, signal propagation distances, and working light wavelengths on propagation characteristics of the LED-based VLC system are simulated and compared with those of the laser-based one. The results theoretically confirm that laser light sources are more susceptible to atmospheric turbulence along the propagation path than monochromatic LED light sources. The investigation in this paper can provide theoretical support for the design of visible light communication systems in practical applications.

Low complexity beamforming design in reconfigurable intelligent surface-assisted communication systems

Due to the possibility of blockage during communication, the communication quality may be poor. Therefore, Reconfigurable Intelligent Surface (RIS) technology can effectively solve this problem. In order to increase the capacity of RIS-assisted wireless communication systems, joint optimization of beamforming design is crucial. However, the complexity of the optimization algorithm increases with the increase in the number of base station antennas and RIS elements deployed. Therefore, we propose a joint low-complexity optimization beamforming design based on fractional programming (FP) to address this issue. Specifically, we first use perfect channel state information to maximize the system's sum rate, as this problem is non-convex, we decompose the original problem into three sub-problems, and then introduce appropriate auxiliary variables. We derive optimal closed-form solutions for active and passive beamforming types, respectively. As the optimal solution obtained leads to higher computational complexity with an increase in the number of base station antennas and RIS elements, we reduce the computational complexity of obtaining the optimal solution based on the Woodbury transformation and scalar transformation. The proposed algorithm is also extended to the case where there is channel state information error. Finally, simulation results show that the proposed algorithm has certain advantages over other algorithms.

Modulation instability analysis, and characterize time-dependent variable coefficient solutions in electromagnetic transmission and biological field

This study integrates the telegraph model with the traveling wave coefficient. This model characterizes planar random motion of particles in fluid flow, pressure waves from pulsatile blood flow in arteries, electrical impulses in nerve and muscle cell axons, and electromagnetic waves in superconducting media. Using the efficient and well-established Enhanced Modified Simple Equation (EMSE) method, we investigate solitary wave solution with the variable coefficient of the telegraph model. To investigate the variable coefficient solitary wave solution, we apply a transformation variable η = h(t)x + g(t), which is dependent on the time variable function. The diverse functions of h(t) and g(t) yield many novel and exclusive solutions. Numerical solutions are plotted in 3D, density, and 2D. instanton soliton, kinky periodic wave, lump wave, kink wave, anti-kink wave, double periodic wave, diverse types periodic wave, lump with bell wave periodic wave, periodic lump wave, etc. Solitary waves explain complex wave phenomena through nonlinear effects like self-interaction and dispersion. Due to the classical nonlinear telegraph model's wave dynamics, they are used in brain function and communication system design. We conclude by testing the governing model's modulation instability. Dispersive and nonlinear processes modulating the stable state cause instability in high-order nonlinear equations. Examining the wave movement role and modulation instability analysis to assess solution stability shows that all solutions are accurate and stable. The computational difficulties and results demonstrate the approaches' clarity, effectiveness, and simplicity, suggesting they can be applied to evolutionary dynamic and static nonlinear equations in computational physics, other real-world situations, and numerous academic disciplines.

A high-data-rate hybrid index communication system based on quadrature chaos shift keying

To address the rapidly increasing challenges posed by the demands for large-scale data transmission and processing, this paper proposes a high-data-rate hybrid index modulation communication system based on quadrature chaos shift keying (HR-HIM-QCSK). The system employs a hybrid modulation involving carrier index and slot index. In this approach, three mutually orthogonal reference signals are constructed using Walsh codes. These reference signals are then utilized to create three distinct QCSK signals, distinguishing between the activation modes of carriers and time slots. This design allows all slots to carry QCSK signals, significantly enhancing the data rate of the HR-HIM-QCSK system. Theoretical analysis and simulations conducted under additive white Gaussian noise and multipath Rayleigh fading channels demonstrate that the HR-HIM-QCSK system outperforms other competing systems in terms of bit error rate (BER) performance. Further analysis covers aspects such as data rate, spectral efficiency, complexity and covertness, highlighting the superior performance of the HR-HIM-QCSK system in high-data-rate communication. This study provides valuable insights for the design of efficient chaotic communication systems.

Design and Outage Analysis for VLP-Assisted Indoor Laser Communication Systems

Design and Outage Analysis for VLP-Assisted Indoor Laser Communication Systems

Optimization of Quasi-Static Design for an IRS-Assisted Secure Wireless Communication System

Optimization of Quasi-Static Design for an IRS-Assisted Secure Wireless Communication System

Co-sharing waveform design for millimeter-wave radar communication systems

Co-sharing waveform design for millimeter-wave radar communication systems

Implementing green optical waveform system using hybrid cognitive methods for QAM transmission scheme

Abstract This study proposes a hybrid approach combining Energy Detection (ED) and Matched Filter (MF) spectrum sensing techniques to enhance power spectrum density (PSD) in optical Nonorthogonal Multiple Access (NOMA) systems. Optical NOMA has emerged as a key technology for boosting spectral efficiency in optical communication networks. However, optimizing PSD remains a critical challenge due to various factors including signal detection and noise interference. The hybrid ED–MF spectrum sensing method aims to address these challenges by leveraging the strengths of both techniques. Energy Detection (ED) offers simplicity and robustness in detecting primary users, making it suitable for initial spectrum sensing in cognitive radio networks. Matched Filter (MF) spectrum sensing, on the other hand, provides superior signal detection and noise rejection capabilities, particularly in low signal-to-noise ratio (SNR) environments. By integrating these two techniques, we aim to achieve improved sensitivity and accuracy in spectrum sensing, thus enhancing spectral efficiency and system performance in optical NOMA networks. The effectiveness of the proposed hybrid approach is evaluated through theoretical analysis and simulation experiments. Results demonstrate significant enhancements in spectral efficiency and system reliability compared to conventional spectrum sensing methods, highlighting the potential of the hybrid ED–MF approach for enhancing PSD in optical NOMA systems. This research contributes to advancing the design and optimization of optical communication systems for future high-capacity and high-speed data transmission applications. The PSD values −920 are obtained and it confirmed that the proposed algorithm outperforms the standard algorithms.

Exploring and Analyzing a Hybrid PAPR Reduction Method for OFDM Optimization

Orthogonal Frequency Division Multiplexing (OFDM) is a effective modulation technique widely used in modern communication systems, including 5G and wireless networks because of its high spectral efficiency and robustness towards multipath fading. However, OFDM signals are characterized by a high Peak-to-Average Power Ratio (PAPR), which can severely impact the power efficiency and operational cost of these systems. This research investigates and analyse effectiveness of two conventional PAPR reduction methods that is Selective Mapping (SLM), and Partial Transmit Sequence (PTS) with incorporating their approach of PAPR reduction to develop a hybrid variant: SLM-PTS. This study utilized MATLAB simulations to implement and test each PAPR reduction technique on a standard OFDM system model. Parameters such as the number of subcarriers, oversampling factor, and modulation types were systematically varied to analyze the impact on PAPR, BER, and computational complexity. The effectiveness of each technique was measured using the Complementary Cumulative Distribution Function (CCDF) of PAPR values and BER performance under different channel conditions. Key findings reveal that hybrid techniques, particularly SLM & PTS, offer significant improvements in PAPR reduction compared to traditional methods alone, without a corresponding increase in BER or computational overhead. The research underscores the potential of hybrid PAPR reduction techniques to significantly enhance the efficiency and reliability of OFDM systems. These findings have important implications for the design and optimization of next-generation wireless communication systems, suggesting that hybrid approaches can provide a balanced solution to the longstanding issue of PAPR in OFDM transmissions. This study contributes valuable insights into the practical application of combined PAPR reduction strategies, offering a pathway toward more power-efficient and robust OFDM technologies. Keywords : OFDM, PAPR, CCDF, SLM and PTS

A three‐dimensional parabolic equation with fast reordered‐alternate direction decomposition in atmosphere duct environment

AbstractIn the design and optimisation of marine wireless communication and navigation systems, a thorough investigation of radio wave propagation characteristics under atmospheric ducting conditions is essential. The authors aim to enhance the efficiency of radio wave propagation loss prediction in marine atmospheric ducting environments, proposing a prediction model based on Fast Reordered‐Alternate Direction Decomposition (FR‐ADD). By approximating the diffraction term into three independent components, exploiting the commutative properties of the Fourier transform to reduce the spatial dimensions, and incorporating a rapid algorithm for the parabolic equation, the model optimises the stepping process and significantly improves computational efficiency. Simulation experiments demonstrate that, in the long‐distance and complex marine ducting environments, the model not only maintains prediction accuracy but also substantially reduces computational load and prediction time, effectively realising over‐the‐horizon propagation prediction. In the experiment of radio wave propagation characteristics in the Yellow and Bohai Seas, the simulation data from the FR‐ADD model showed significant correlation with actual measurements and simulations from the AREPS software, confirming the method's efficiency and practicality.

Modern approaches to compression and noise resistant encoding of photo and video information in radio channels of complexes with unmanned aerial vehicle

Modern complexes with unmanned aerial vehicles (UAVs) of long flight duration (heavy class) are in practice equipped with a wide range of target loads, which leads to the need to transmit a large amount of useful information in real time with the required quality to a remote ground control station (GCS). The large volume of transmitted information imposes serious technical requirements on the capacity of communication channels, which, on the one hand, when designing communication systems within UAVs, is ensured by the use of directional antenna systems, multi-position signal-code structures, noise-resistant coding, high energy in the communication channel, etc. On the other hand, developers simultaneously solve the problem of minimizing the amount of information from target loads supplied to the input of the communication system while maintaining the required quality after compression. This article discusses the main information compression standards used by CUAVs developers, their advantages and disadvantages, as well as video codecs based on three-dimensional orthogonal transformations.

Theoretical and numerical study on transient acoustic wave propagation across ice layers in the Arctic Ocean.

The study of transient acoustic wave propagation across the Arctic Ocean ice layer provides theoretical guidance for the design of trans-ice acoustic communication systems. In this study, the Arctic Ocean was modeled as an ice-water composite structure, where the ice and water are regarded as an elastic solid and liquid, respectively. An analytical transient solution for acoustic wave propagation in this structure was derived using the eigenfunction expansion method. Further, the numerical procedures were presented and used to analyze the acoustic wave propagation characteristics across the ice layer. The results show that waveforms corresponding to the radial displacements are more severely distorted than the axial displacements. The amplitudes of the radial and axial displacements decreased rapidly with increasing propagation distance. The ice thickness had a greater impact on the radial displacement than axial displacement; the thicker the ice, the greater the distortion for both radial and axial displacements.

Bidirectional trifunctional splitter with two sided microstructure

This paper proposes a bidirectional trifunctional splitter with a bilayer ridge structure for polarization-selective and polarization-insensitive outputs at the wavelength of 1550 nm. The configuration can realize a four-port output for both polarizations and TE-two/TM-three output. In the upper part of the bidirectional trifunctional splitter, for TE polarization, two outputs exhibit diffraction efficiencies greater than 49%, while for TM polarization, three outputs exhibit diffraction efficiencies greater than 32%. Furthermore, for the lower part of this beam splitter, under both TE and TM polarization, the diffraction efficiencies of four outputs exceed 24%. Compared to the previous beam splitter, the bidirectional trifunctional splitter exhibits superior uniformity and is capable of simultaneously achieving polarization-selective and polarization-insensitive outputs. Furthermore, the configuration is theoretically resistant to the geometric dimensions, which greatly reduces the difficulty of fabrication. This work exhibits a novel approach to the design of energy-splitting devices and optical communication systems with multiple outputs.

End-to-end learning of adaptive coded modulation schemes for resilient wireless communications

Adaptive modulation and coding schemes play a crucial role in ensuring robust data transfer in wireless communications, especially when faced with changes or interference in the transmission channel. These schemes involve the use of variable coding rates, which can be achieved normally through code puncturing or shortening, and have been adopted in 4G and 5G communication standards. In recent works, auto-encoders for wireless communications have demonstrated the ability to learn short code representations that achieve gains over conventional codes. Such a methodology is attractive as it can learn optimal representations under a variety of channel conditions. However, due to its structure the auto-encoder does not currently support multiple code rates with a single model. This article draws upon the discipline of multi-task learning, as it applies to deep learning and therefore devises a branching architecture for the auto-encoder and custom training algorithm in training transmitter and receiver for adaptive modulation and coding. In this article we aim to demonstrate improvements in Block Error Rate over conventional methods in the Additive White Gaussian Noise channel, and to analyse the performance of the model under Rayleigh fading channels without retraining the auto-encoder on the new channel. This article demonstrates a novel approach towards training auto-encoder models to jointly learn adaptive modulation and coding schemes framed as a multi-task learning problem. The research outcomes extend end-to-end learning approaches to the design of adaptive wireless communications systems.

Модели расчета распределения уровня мощности электромагнитного поля в системах подвижной радиосвязи для малых дистанций в летний период

The statement is substantiated that for the design of mobile radio communication systems at short distances up to 1 000 m, the main recommended calculation models have a significant error, since they were created for calcula-tions of long distances (as a rule, from 1 to 50 km) and have limitations in application. Due to the fact that at the present stage of development of mobile radio communication systems, the frequency ranges are in intensive research and use not only 900 and 1 800 MHz, but also 450-800 MHz sections, as well as from 2 100 to 6 000 MHz, which were not previously used for cellular communication systems, it is necessary to propose additional models necessary for the preliminary design of 3-5 generation systems in the range from 2 100 MHz. The range of radio waves in the ranges from 2 100 to 6 000 MHz is significantly reduced compared to the ranges of 1 800 or 900 MHz. The use of classical calculation models such as the Okumura and COST-231–Hata models at distances less than 1 km is characterized by significant errors and is not recommended by the authors of the models themselves for use at short distances. To solve this problem, new models have been developed for calculating the attenuation of radio signals designed to estimate attenuation at short distances.