Signal Propagation Characteristics Research Articles

The evolving 5G case study in United States unilateral spectrum planning and policy

This paper tracks increasingly aggressive initiatives by the United States government to reallocate spectrum on an expedited and unilateral basis well before conclusion of inter-governmental coordination. Rather than embrace the customary commitment to achieve consensus on global spectrum allocations at the International Telecommunication Union (“ITU”), the Federal Communications Commission (“FCC”) has auctioned off large blocks of frequencies for the next generation (“5G”) of wireless services.The FCC might have framed its first 5G auction, reassigning Ultra High Frequency (“UHF”) spectrum, as a one-time deviation from compliance with long standing, intergovernmental coordination procedures. These frequencies have ideal signal propagation characteristics and the Commission could use financial incentives—unavailable in most nations—to expedite “repacking” by incumbent broadcasters willing to move, share or abandon spectrum in exchange for ample financial compensation. However, the FCC has continued to auction off 5G spectrum on grounds that it must find ways to abate an acute shortage of wireless bandwidth and doing so will regain or maintain global leadership in wireless technologies. This paper offers a critical rebuke to unilateral spectrum management, because the short-term benefits expected by the U. S. government likely will be offset by countervailing harms to 5G manufacturers, carriers and consumers. The paper tracks fractious preparation for the ITU's 2019 World Radio Conference by the U.S. delegation and the mixed record achieved there. Additionally, the paper explains how injecting trade, industrial policy and national security issues at the ITU can trigger more delays and disputes, including possible retaliation by nations displeased with U.S. efforts to subvert traditional technology optimization goals.A worst case scenario has the ITU deadlocked and unable to reach closure on “mission critical” spectrum planning issues at World Radio Conferences, convened every four years. The paper concludes that costs and likely challenges to the efficacy and legitimacy of the ITU will reduce the benefits accruing from the FCC's unilateral, spectrum planning campaign.

The Evolving 5G Case Study in the United States Unilateral Spectrum Planning and Policy

This paper tracks increasingly aggressive initiatives by the United States government to reallocate spectrum on an expedited and unilateral basis well before conclusion of inter-governmental coordination. Rather than embrace the customary commitment to achieve consensus on global spectrum allocations at the International Telecommunication Union (“ITU”), the Federal Communications Commission (“FCC”) has auctioned off large blocks of frequencies for the next generation (“5G”) of wireless services. The FCC might have framed its first 5G auction, reassigning Ultra High Frequency (“UHF”) spectrum, as a one-time deviation from compliance with long standing, inter-governmental coordination procedures. These frequencies have ideal signal propagation characteristics and the Commission could use financial incentives — unavailable in most nations — to expedite “repacking” by incumbent broadcasters willing to move, share or abandon spectrum in exchange for ample financial compensation. However, the FCC has continued to auction off 5G spectrum on grounds that it must find ways to abate an acute shortage of wireless bandwidth and doing so will regain or maintain global leadership in wireless technologies. This paper offers a critical rebuke to unilateral spectrum management, because the short-term benefits expected by the U. S. government likely will be offset by countervailing harms to 5G manufacturers, carriers and consumers. The paper tracks fractious preparation for the ITU’s 2019 World Radio Conference by the U.S. delegation and the mixed record achieved there. Additionally, the paper explains how injecting trade, industrial policy and national security issues at the ITU can trigger more delays and disputes, including possible retaliation by nations displeased with U.S. efforts to subvert traditional technology optimization goals. A worst case scenario has the ITU deadlocked and unable to reach closure on “mission critical” spectrum planning issues at World Radio Conferences, convened every four years. The paper concludes that costs and likely challenges to the efficacy and legitimacy of the ITU will reduce the benefits accruing from the FCC’s unilateral, spectrum planning campaign.

Influence of Different Structure and Specification Parameters on the Propagation Characteristics of Optical Signals Generated by GIL Partial Discharge

Partial discharge (PD) leads to the generation of electrical, acoustic, optical, and thermal signals. The propagation characteristics of optical signals in gas insulated metal-enclosed transmission lines (GIL) are the basis of optical detection research. This paper simulates the propagation of PD optical signals in GIL through modeling GIL with different structures and specification parameters. By analyzing the optical parameters on the probe surface and the detection points when the PD source position is different, the influence of the difference in specifications caused by the voltage level on the propagation of the GIL PD optical signal is studied. The results show that the GIL cavity structure will affect the faculae distribution and the relative irradiance (RI) of the detection surface; the PD source position has a huge impact on the faculae distribution on the detection surface, but has little influence on the RI; as the voltage rises, the faculae distribution on the detection surface becomes more obvious, and the mean of RI decreases. The above results have the reference value for the manufacture of GIL equipment and the research of PD optical detection. When the specular reflection coefficient of surface material is smaller and the diffuse reflection coefficient is larger, the outline of the light spot is clearer, the proportion of brighter parts is larger, and the maximum value of the RI is larger.

The research on propagation characteristics of acoustic emission signals in stiffened plates based on the multipath propagation model

Mechanical equipment with the stiffener has a strong interference with the propagation of acoustic emission (AE) signals from faults, reducing the accuracy of fault detection. This paper conducts an in-depth study of the interaction between AE signals and the stiffener. The installation constraints, that can separate the direct signal, signals scattered from the stiffener and signals reflected from the boundary in the time domain, for sensors are deduced based on the multipath propagation model of AE signals in the stiffened plate. On this basis, the scattering characteristics of AE signals with different frequencies in different height stiffened plates are predicted by simulations. Moreover, the reflection and transmission coefficients are calculated to quantify the scattering characteristics. The results show that the signal, undergoing a “T-shaped” transformation at the stiffener, generates various modes, among which the transmission signal accounted for the largest proportion. In addition, experiments are performed to verify the numerical simulations, and the results are in good agreement with the numerical simulations. This work clarifies the propagation characteristics of AE signals in stiffened plates, and the research can optimize the spatial arrangement for sensors.

Mode transition and energy dependence of FitzHugh-Nagumo neural model driven by high-low frequency electromagnetic radiation

The FitzHugh-Nagumo (FHN) neural model is widely used to study the dynamic characteristics of signal propagation, synchronization, stochastic resonance(SR), coherent resonance(CR), and bifurcation of neurons. Based on Helmholtz theorem and the FHN neuron model, the expression of Hamilton energy function of FHN neural model driven by high-low frequency(HLF) electromagnetic radiation is derived. The correctness and uniqueness of the analytical solution are verified by using the constraints, and the electrical activities and Hamilton energy function of neuron are discussed by numerical simulations. It is found that electrical activity mode of FHN neuron undergoes a succession transition of quiescent state, spiking state, bursting state, and mixed state by changing the parameters such as the intensity of the external forcing current, the amplitude and angular frequency of HLF signal. The electrical activities process of FHN neuron is accompanied by the storage and release of system energy, this result may provide an understanding of the coding and conversion of electrical activity from the perspective of the relevance and dependence of energy costs.

Feasibility study of GIS vibration testing and diagnosis method

In this paper, the feasibility of the fault diagnosis method based on the vibration signal in GIS is studied through the experiments of the correlation between the discharge fault and the vibration signal and the propagation characteristics of the vibration signal in GIS. The concept of pulse interval frequency is put forward. According to the experimental data, it is concluded that there is a strong correlation between the interval frequency of GIS discharge pulse and the frequency of vibration signal. At the same time, the vibration signal has regular propagation characteristics when passing through the basin insulator, cavity and T-shaped structure. The above two points strongly support the vibration test method can be used for fault diagnosis of GIS.

PPerturb: A Server for Predicting Long-Distance Energetic Couplings and Mutation-Induced Stability Changes in Proteins via Perturbations.

The strength of intraprotein interactions or contact network is one of the dominant factors determining the thermodynamic stabilities of proteins. The nature and the extent of connectivity of this network also play a role in allosteric signal propagation characteristics upon ligand binding to a protein domain. Here, we develop a server for rapid quantification of the strength of an interaction network by employing an experimentally consistent perturbation approach previously validated against a large data set of 375 mutations in 19 different proteins. The web server can be employed to predict the extent of destabilization of proteins arising from mutations in the protein interior in experimentally relevant units. Moreover, coupling distances—a measure of the extent of percolation on perturbation—and overall perturbation magnitudes are predicted in a residue-specific manner, enabling a first look at the distribution of energetic couplings in a protein or its changes upon ligand binding. We show specific examples of how the server can be employed to probe for the distribution of local stabilities in a protein, to examine changes in side chain orientations or packing before and after ligand binding, and to predict changes in stabilities of proteins upon mutations of buried residues. The web server is freely available at http://pbl.biotech.iitm.ac.in/pPerturb and supports recent versions of all major browsers.

Mutual Authentication in Body Area Networks Using Signal Propagation Characteristics

Developments in wireless communications and wearable devices have facilitated the emergence of a network of tiny sensors embedded in, on or around human body called Wireless Body Area Network (WBAN). Over the last decade, WBAN has increasingly been playing a vital role in modern medical systems because of its potential to revolutionize healthcare delivery. The data collected by the sensors contain sensitive information and are transmitted via wireless channels. However, the openness of these channels makes WBAN vulnerable to attacks by unauthorized users. Therefore, secure authentication and data encryption schemes in WBAN are essential. The resource constraint nature of the sensors makes traditional cryptographic schemes unsuitable. Consequently, authentication schemes based on channel characteristics are proposed, which are more suitable with fewer requirements. However, existing approaches do not consider mutual authentication as well as passive/active attacks. Motivated by these limitations, we propose in this paper, a mutual authentication and data encryption scheme based on signal propagation characteristics and enhanced butterfly algorithm. To validate the effectiveness of our scheme, we conducted an extensive real-world experiment involving 5 volunteers in indoor and outdoor areas, under distinct scenarios. We further conducted security and performance analyses to validate the effectiveness of our scheme in terms of resources and its resilience to various attacks. The results of the experiments and the analyses show that our scheme could mutually identify legitimate users and protect user data against active/passive eavesdropping attacks with minimal overhead.

A Study on the Propagation Characteristics of Partial Discharge in Cable Joints Based on the FDTD Method

Partial discharge (PD) is the main cause of cable insulation deterioration. It is of great theoretical significance and practical value to carry out PD research on high voltage (HV) cable joints for fault detection and operational status evaluation. In this paper, a three-dimensional finite-difference time-domain (FDTD) simulation model of cable joint is built. According to typical fault types of PD in 110kV XLPE cable, four types of insulation defect models, including electrical tree discharge, surface sliding discharge, air gap discharge, and floating discharge, are designed and manufactured. Based on the three-dimensional simulation model of cable joint, the propagation characteristics of PD signals caused by the aforementioned insulation defects are analyzed, the effects of different types of insulation defects and fault locations on the propagation characteristics are investigated. A PD experimental platform based on a cross-bonded three-phase 110 kV cross-linked polyethylene (XLPE) cable system is built for verifying the feasibility of the three-dimensional simulation model. Results show that the model can reasonably explain propagation characteristics of PD signals in cable joints, including polarity, peak values, attenuation characteristics and symmetry, which provided the theoretical basis for judging the fault locations and types of PD caused by insulation defects in cable joints.

Low-frequency parametric systems in the shallow sea

The theoretical model of acoustic wave propagation in the ice-water layer is developed, with, taking into account the velocity dispersion. New opportunities for monitoring the marine environment on long routes, including those covered with ice, are discussed when using parametric sonar antennas. The results of research demonstrating single-mode excitation of a waveguide by a parametric array in a wide frequency band are presented. The possibility of compression of a broadband signal during its propagation, as a result of waveguide dispersion, which leads to an increasing of signal intensity, is shown. The results of experimental studies of the propagation characteristics of a wide-band acoustic signal of a parametric hydroacoustic array in a shallow sea are presented.

Digital Twin for Metasurface Reflector Management in 6G Terahertz Communications

The performance demands from data-intensive applications, such as multimedia streaming, as well as the growing number of devices connecting to the Internet, will increase the need for higher capacity wireless communication links. The research community has recently explored regions of the spectrum, including the Terahertz band (0.1 THz to 10 THz), that are underutilised for communications. THz frequencies come with a plethora of special challenges, one of which is the very narrow effective beam, thereby requiring a Line of Sight (LoS) between sender and receiver. Researchers have explored the use of reflectors that can redirect beams around blockages. In this paper, we propose a THz signal guidance system where a Digital Twin is used to model, predict and control the signal propagation characteristics of an indoor space. Our approach finds the best THz signal path from the base station to the mobile target via the tunable metamaterial walls, avoiding obstacles as needed, using geometric (ray tracing), path loss and Terahertz Potential Field (THzPF) models. With this knowledge, the digital twin guides the selection of antenna strips at a base station and the reflectors along the signal path. A top-view camera, with advanced image processing, provides context updates (obstacle and mobile target locations) to the digital twin. The image processing system also senses factors like water vapour concentration, and the material composition and surface roughness of obstacles. Such factors affect propagation strength, and the digital twin modifies the beam paths to adapt. Simulation results have shown the efficiency of our control system to maintain a reliable signal connection while minimising the use of antenna and reflector strips. Our system is the first proposal that maximises THz signal-to-noise ratio (SNR) through such a dynamic and robust control system, which integrates image processing of a room with base station configuration.

Propagation characteristics of weak signal in feedforward Izhikevich neural networks

The feedforward neural network is widely applied in various machine learning architectures, in which the synaptic weight between layers plays an important role in the weak signal propagation. In this paper, the five-layer Izhikevich neural networks with excitatory or excitatory–inhibition neurons are employed to study the effect of Gaussian white noise and synaptic weight between layers on the weak signal transmission characteristics of the subthreshold excitatory postsynaptic currents signal imposed on the input layer. It can be found that there is an optimum value of noise intensity (a medium noise intensity) at which the weak signal can be stably propagated in the five-layer Izhikevich neural networks. The spike timing precision (STP) under the optimal noise intensity will become maximum by increasing the synaptic weight. The noise intensity and synaptic weight corresponding to the maximum value of the STP in the excitatory–inhibition network are smaller than those in excitatory–inhibition network. For the smaller or the bigger noise intensity, however, the STP will become very small, and the weak signal cannot be transmitted from the input layer to the output layer. Furthermore, the weak signal is propagated from the input layer to the output layer and enhanced under a larger synaptic weight in the feedforward neural networks.

MAPLE: Mixed Path Calculation in Tile-Based 3D Maps

This letter proposes a new model for estimating mixed path wireless signal propagation characteristics of new deployment areas, utilizing signal propagation training from other areas that have prior signal measurements. Using 3D city maps, the training and the deployment areas can be divided into geographical grid tiles, each one having distinct propagation channel characteristics. The similarity between the training area tiles and the deployment area tiles can be used to estimate the potential propagation characteristics on the deployment area, thereby increasing the efficiency of the infrastructure deployment planning process.

Effect of moisture content on propagation characteristics of acoustic emission signal of Pinus massoniana Lamb

The propagation velocity and energy of acoustic emission (AE) signals at different moisture contents (MC) of wood are studied, providing a theoretical basis for studying the law of wood stress and strain with the change in MC. The AE source was simulated by lead core fracture on the surface of Pinus massoniana Lamb. Signal de-noising was performed by discrete wavelet decomposition method. On this basis, the propagation velocity and energy of AE signals at different MCs were studied according to the signal cross-correlation analysis and time difference localization method, and the law of velocity and energy change with MC was further determined by fitting. The fitting results show that the propagation velocity of AE signals decreased exponentially with the increase in MC. Moreover, the propagation velocity decreased rapidly when the MC was below fiber saturation point (FSP), and decreased relatively gently when the MC was above FSP. In addition, the energy attenuation of the AE signal was obvious during the propagation process, and the energy attenuation rate of the AE signal presented a linear relationship with the increase in MC. The change in MC has a significant effect on the propagation velocity and energy of AE signals of wood.

Research on vibration characteristic simulation of the 220 kV gas insulated metal enclosed switchgear equipment

GIS equipment (gas insulated switchgear) is more and more popular in power system, and people often pay more attention to its discharge fault than other mechanical faults. But in the operation of GIS, besides discharge faults, mechanical faults are also a major cause of accidents. Therefore, we should give more research to abnormal mechanical vibration. At the same time, compared with discharge signal, mechanical vibration fault is more difficult to study. In this article, based on the size of real GIS equipment, we first built a three-dimensional model through COMSOL software to study the propagation characteristics of vibration signals. Simply considered, the bus air chamber is two-dimensional axisymmetric. Firstly, the natural vibration frequency of the equipment is calculated by finite element method, and the vibration propagation characteristics of GIS shield cover loose of the GIS equipment are calculated and analyzed. The simulation calculation shows that the longer the shell is, the lower the natural vibration frequency is. Therefore, we should pay more attention to the natural vibration frequency far away from 100 Hz, when designing and manufacturing GIS equipment, so as to avoid serious consequences caused by resonance. Because the basic vibration frequency caused by the loosening of shield cover is twice as high as the power frequency of 50 Hz. Then the 100 Hz simulation source is added to COMSOL model as the vibration source of loosening fault, and the propagation rule and characteristics of vibration fault about GIS are received. After the vibration fault occurs, the loosening vibration signal at the connection between the GIS shell and the basin insulator is the strongest. These conclusions by simulation also conform to objective rules and facts. Meanwhile it can guide us to arrange sensors reasonably and improve the signal-to-noise ratio of vibration detection signals.

The Ocean Mesoscale Regime of the Reduced-Gravity Quasigeostrophic Model

AbstractA statistical-equilibrium, geostrophic-turbulence regime of the stochastically forced, one-layer, reduced-gravity, quasigeostrophic model is identified in which the numerical solutions are representative of global mean, midlatitude, open-ocean mesoscale variability. Solutions are forced near the internal deformation wavenumber and damped linearly and by high-wavenumber enstrophy dissipation. The results partially rationalize a recent semiempirical stochastic field model of mesoscale variability motivated by a global eddy identification and tracking analysis of two decades of satellite altimeter sea surface height (SSH) observations. Comparisons of model results with observed SSH variance, autocorrelation, eddy, and spectral statistics place constraints on the model parameters. A nominal best fit is obtained for a dimensional SSH stochastic-forcing variance production rate of 1/4 cm2 day−1, an SSH damping rate of 1/62 week−1, and a stochastic forcing autocorrelation time scale near or greater than 1 week. This ocean mesoscale regime is nonlinear and appears to fall near the stochastic limit, at which wave-mean interaction is just strong enough to begin to reduce the local mesoscale variance production, but is still weak relative to the overall nonlinearity. Comparison of linearly inverted wavenumber–frequency spectra shows that a strong effect of nonlinearity, the removal of energy from the resonant linear wave field, is resolved by the gridded altimeter SSH data. These inversions further suggest a possible signature in the merged altimeter SSH dataset of signal propagation characteristics from the objective analysis procedure.

Comparative Analysis of Horizontal Array Signal Processing in a Shallow-Water Channel with a Rough Windy Surface

The recent study [1] addressed how the characteristics of low-frequency acoustic signal propagation in a shallow-water channel under wind wave conditions affect the output performance of a horizontal phased array (PA) is further developed with the aim of comparative analysis of the efficiency of various array signal processing methods. The main focus is quantitative estimates of the additional array gain from optimal processing in comparison to the standard PA method compensated in the direction to the signal source, in dependence on the key parameters: direction and distance to the source, wind speed, and wave dimensions of the array. Numerical simulation is performed for a typical winter hydrological conditions of the Barents Sea, a signal frequency of 250 Hz, and a wide range of distances up to 500 km It is shown that the additional gain from optimizing the array processor can vary widely (from fractions of to a few dB), while the PA efficiency also varies widely and may have a nonmonotonic dependence on distance.

Computer-aided design modeling of microstrip step discontinuity on multilayer iso/anisotropic substrates with transient signal analysis

A computer-aided design modeling is presented to compute a shunt capacitance and series inductance of π or T-equivalent network parameters of microstrip step-discontinuity at a junction on multilayer iso/anisotropic substrates. The results of the proposed model of shunt capacitance and series inductance have shown permissible agreement with simulation results by the average deviation of 4.5% and 4.9% for 1 < er ≤ 40 and w1/w2 < 10 respectively. Similarly, the transient signal propagation characteristics, such as arrival time of the pulse, rise-time, delay time, settling time, etc. are influenced by the anisotropy in the transmission line and said information’s are also important for proper characterization of analog/digital pulses on multilayer iso/anisotropic substrate planar transmission lines. The time-domain characteristic of transient pulses over microstrip stepped line with diverse conditions are strengthening the concept of interconnects, which plays a vital role in modern circuit technology. Proposed modeling concept is more accurate to design of contemporary planar microwave filters, impedance matching networks and VLSI interconnects.

Propagation characteristics of underwater plasma pulse sound source

The signal propagation characteristics of underwater plasma pulsed sound source have important guiding significance for the research and application of underwater directional radiation technology. In this thesis, the model propagation method is used to analyze the signal propagation law of underwater plasma pulse source with different depths. Firstly, the propagation model of underwater plasma sound source is established. Secondly, the distribution characteristics of underwater sound field at different depths are simulated. The research results show that the simulation results can express the underwater sound field characteristics at different depths, which proves the effectiveness of the simulation model, and lays a foundation for further research on underwater pulse directional radiation technology and improving the underwater application of pulse sound source.

Influence of Crack Depth on Dynamic Characteristics of Spur Gear System

Root crack is relatively common failure scenarios in spur gear system, and its dynamic characteristics and crack identification theory are addressed by many scholars. However, cracked spur gear identification model, especially related to its signal propagation characteristics, requires in-depth research due to the limited published works. Therefore, a bending–torsional coupling nonlinear vibration model of six degrees of freedom (DOF) is established through lumped mass method. Besides, the influence of tooth root crack on the measuring point signal is considered in the model. The system response is solved by Runge–Kutta numerical integration method. The change of different tooth-root crack depth on the response amplitude of measuring points is studied. It is found that with the increase of crack length, meshing stiffness of single-tooth mashing area and double-tooth meshing area are reduced. In addition, precision reduces slightly, but the overall precision calculated by 6-order ARX identification model is greater than 99.40%. The research provides a theoretical basis for the system testing and measuring point’s parameter identification.