Transmitter Power Research Articles

Comparative analysis of underwater wireless optical communication system

The performance of an underwater wireless optical communication (UWOC) system is affected by many factors, such as channel conditions, modulation and detection techniques, type of optical source, etc. The UWOC system performance was investigated in the presence of weak and strong turbulence. Pure sea was the water type used for the performance analysis. Binary phase shift keying, quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation, and non-return to zero-on–off keying were used for comparison. Further, a continuous wave laser was used as the optical source, and photodetectors are at the receiver. The performance of the UWOC system was analyzed in terms of the bit error rate (BER). The BER performance was evaluated using the log-normal probability density function (PDF) in weak turbulence and the gamma-gamma PDF in strong turbulence. In all modulation techniques, QPSK had the best BER performance. The BER was reduced further using avalanche photodiode (APD) as the photodetector instead of positive-intrinsic-negative diode for the same transmitter power and channel conditions. In weak turbulence, a BER of 10 − 8 was achieved at a transmitter power of 12.5 dBm using the QPSK modulation technique and APD as the photodetector. For the same conditions, a BER of 9 × 10 − 7 was achieved in strong turbulence. The multiplication gain, dark current, and carrier ionisation ratio of the photodetector were optimized for better BER performance in the UWOC system.

Experimental Study on Transmission of Visible Light in Table Salt Water and Effect on Underwater Wireless Optical Communication

Underwater wireless optical communication (UWOC) has advantages over other underwater communication methods. Some of these advantages are high data rates, large bandwidth, and less susceptibility to electromagnetic interference. The transmission of light underwater is affected by absorption, scattering and turbulence. Sodium Chloride is one of the most abundant dissolved substances in seawater which cause attenuation of optical signals. In this work, the effect of table salt in water on transmission of visible light in the range 400nm – 800nm was investigated. Nine samples of 100 ml of pure water were prepared in which eight of the samples contain addition of table salt of 1g, 3g, 4.5g, 5.5g, 15g, 20g, 25g and 28g yielding different salt concentrations (salinity). The conductivity, total dissolved solids (TDS), and total dissolved salt of the samples were measured. Absorption spectra of visible light through these samples were obtained using a spectrophotometer. The results showed an increase in conductivity and attenuation with increase in the presence of the table salt in the water. Also, it was observed that at shorter wavelengths (blue light), there is higher attenuation with increase in salt concentration compared to longer wavelengths (red light). However, the attenuation tends to increase sharply around 700nm – 800nm. From the absorption spectra obtained for each sample, the absorptivity spectrum for the table salt was obtained which shows high absorptivity at shorter wavelengths and lower absorptivity at longer wavelengths. From the absorption coefficient values obtained from the measurements, performance of UWOC for selected samples at three wavelengths of 450nm, 550nm and 700nm with transmitter power of 30mW were evaluated by simulation using OptiSystem linked with MATLAB. For a maximum allowable Bit Error Rate (BER) of 10-9 in UWOC, achievable link distance reduces considerably as the salt concentration increases.

DeepMTL Pro: Deep Learning Based Multiple Transmitter Localization and Power Estimation

In this paper, we address the problem of Multiple Transmitter Localization (MTL). MTL is to determine the locations of potential multiple transmitters in a field, based on readings from a distributed set of sensors. In contrast to the widely studied single transmitter localization problem, the MTL problem has only been studied recently in a few works. MTL is of great significance in many applications wherein intruders may be present. E.g., in shared spectrum systems, detection of unauthorized transmitters and estimating their power are imperative to efficient utilization of the shared spectrum.In this paper, we present DeepMTL, a novel deep learning approach to address the MTL problem. In particular, we frame MTL as a sequence of two steps, each of which is a computer vision problem: image-to-image translation and object detection. The first step of image-to-image translation essentially maps an input image representing sensor readings to an image representing the distribution of transmitter locations, and the second object detection step derives precise locations of transmitters from the image of transmitter distributions. For the first step, we design our learning model sen2peak, while for the second step, we customize a state-of-the-art object detection model YOLOv3-cust. Using DeepMTL as a building block, we also develop techniques to estimate transmit power of the localized transmitters. We demonstrate the effectiveness of our approach via extensive large-scale simulations and show that our approach outperforms the previous approaches significantly (by 50% or more) in performance metrics including localization error, miss rate, and false alarm rate. Our method also incurs a very small latency. We evaluate our techniques over a small-scale area with real testbed data and the testbed results align with the simulation results.

Enhanced suppression of low-frequency vibration transmission in metamaterials with linear and nonlinear inerters

This study proposes the use of a linear and geometrically nonlinear inerter-based resonator in locally resonant acoustic metamaterials (LRAMs) and evaluates the performance on low-frequency wave attenuation. The LRAM is modeled as a 1D chain system composed of mass-in-mass unit cells connected by springs, and the geometrical nonlinearity is achieved by two lateral inerters linking the resonator and lumped mass symmetrically with respect to the horizontal springs. For the nonlinear inerter-based LRAM, the dispersion relation is analytically derived by a complex Fourier transform and the harmonic balance method. Compared with the linear inerter-based LRAM, the proposed nonlinear inerter-based structure has the property of a low-frequency bandgap with sufficient width for longitudinal wave propagation without being sensitive to changes in the inertance ratio. The nonlinearity can extend the original material parameter restrictions, leading to a lower-frequency bandgap. The results of dispersion properties are validated by wave transmittance and vibration power flow diagrams obtained by using the method of effective mass. It is shown that an adequate number of unit cells can achieve better wave attenuation performance.

Average spectral efficiency of multi-pulse position with adaptive transmissions and aperture averaging over atmospheric turbulence

Abstract The analysis of average spectral efficiency (ASE) of multi-pulse position modulation (MPPM) scheme with optimal rate adaptation (ORA) and channel inversion with fixed rate (CIFR) adaptation schemes over the gamma–gamma free space optical (FSO) channel has been carried out in this paper. The performance of the adaptation schemes has been analyzed in terms of the average channel capacity and has been further scrutinized under the aperture averaging effects in moderate and strong atmospheric turbulence. For the first time, closed form expressions for MPPM with ORA and CIFR transmitter adaptation schemes have been derived in terms of Meijer’s G functions. Using the derived expressions, the performance of the two adaptation policies have been compared for different transmitter power and varying FSO length, MPPM modulation order and aperture averaging. The analysis results revealed that generally, ORA performs better than CIFR under the considered turbulence strength, modulation order and aperture averaging. However, aperture averaging offers more gain in ASE in strong turbulence than moderate turbulence for both ORA and CIFR. Furthermore, the results revealed that aperture averaging effects offers much more gain in ASE when used with CIFR than ORA.

Machine learning for power control in device‐to‐device communications with full‐duplex relays using ITLinQ spectrum sharing scheme

AbstractA proposed mechanism for interference management and scheduling links in device‐to‐device (D2D) networks with full‐duplex relays (FDRs) is FDR‐information theoretic links scheduling (FDR‐ITLinQ).This article employs a machine learning (ML) technique with the FDR ITLinQ spectrum sharing method in D2D communications. In this article, transmission powers of transmitters and corresponding relays are determined with a Full‐duplex relay (PC) mechanism employing genetic algorithm (GA). The objective function is maximizing two main criteria of evaluation of network performance. The first criterion is the average sum rate (ASR), and the second is energy efficiency (EE). In addition, addressing two objectives simultaneously leads to a trade‐off between ASR and EE. Therefore, employing the ML strategy, we determine the transmission powers of transmitters and their corresponding relay pairs. The ML strategy has more flexibility and lower computational complexity in comparison to the traditional optimization methods. The proposed neural network (NN) considers the channel coefficients as inputs and optimal power for transmitters and relays as outputs. The optimal allocated power for new situations and conditions are predicted via trained NN. The simulation results show that the PC mechanism that uses the ML approach has almost the same performance as GA. However, the superiority of ML approach over GA is that the calculation time and system complexity are reduced, which, in turn, makes the proposed scheme applicable to implement in practical networks.

Throughput Fairness for Wireless Powered Cognitive Hybrid Active-Passive Communications

In this paper, we consider a backscatter communication (BackCom)-based cognitive network that consists of one primary transmitter, one primary receiver, multiple secondary transmitters (STs), and one secondary receiver (SR). Each ST operates in the BackCom or energy harvesting model. Our goal is to jointly optimize the energy harvesting and backscatter time, the transmit power of the primary transmitter, and the power reflection coefficient of each ST to maximize the sum throughput of all the STs under a nonlinear energy harvesting model while satisfying multiple constraints, i.e., the energy causality of each ST, the quality of service of the primary transmitter, etc. The formulated problem is nonconvex due to the coupled variables and is hard to solve. In order to address this problem, we decouple partially coupled variables by using the properties of the objective function and constructing auxiliary variables, and the remaining coupled variables are decoupled via successive convex approximation (SCA). On this basis, a SCA-based iterative algorithm is developed to solve the formulated problem. Simulation results are provided to support our work.

Throughput fairness in cognitive backscatter networks with residual hardware impairments and a nonlinear EH model

This paper is to design a throughput fairness-aware resource allocation scheme for a cognitive backscatter network (CBN), where multiple backscatter devices (BDs) take turns to modulate information on the primary signals and backscatter the modulated signals to a cooperative receiver, while harvesting energy to sustain their operations. The nonlinear energy harvesting circuits at the BDs and the residual hardware impairments at the transceivers are considered to better reflect the properties of the practical energy harvesters and transceivers, respectively. To ensure the throughput fairness among BDs, we formulate an optimization problem to maximize the minimum throughput of BDs by jointly optimizing the transmit power of the primary transmitter, the backscattering time and reflection coefficient for each BD, subject to the primary user’s quality of service and BDs’ energy-causality constraints. We introduce the variable slack and decoupling methods to transform the formulated non-convex problem, and propose an iterative algorithm based on the block coordinate descent technique to solve the transformed problem. We also investigate a special CBN with a single BD and derive the optimal solution in the closed form to maximize the BD’s throughput. Numerical results validate the quick convergence of the proposed iterative algorithm and that the proposed scheme ensures much fairness than the existing schemes.

Sum-Throughput Maximization in Backscatter Communication-Based Cognitive Networks

In this paper, we consider a backscatter communication (BackCom) based cognitive network that consists of one primary transmitter, one primary receiver, multiple secondary transmitters (STs), and one secondary receiver (SR). Each ST operates in the BackCom or energy harvesting model. Our goal is to jointly optimize the energy harvesting and backscatter time, the transmit power of the primary transmitter, and the power reflection coefficient of each ST to maximize the sum throughput of all the STs under a nonlinear energy harvesting model while satisfying multiple constraints, i.e., the energy causality of each ST, the Quality of Service of the primary transmitter, etc. The formulated problem is nonconvex due to the coupled variables and hard to solve. In order to address this problem, we decouple partial coupled variables by using the properties of the objective function and constructing auxiliary variables, and the remaining coupled variables are decoupled via successive convex approximation (SCA). On this basis, a SCA based iterative algorithm is developed to solve the formulated problem. Simulation results are provided to support our work.

Investigating the Performance of SCM/MMW/RoF Optical-Wireless Access System for Next Generation Communications

In this paper, we propose a model of subcarrier multiplexing millimeter wave radio-over-fiber SCM/MMW/RoF optical-wireless access system for next generation mobile communications using QPSK modulation. We then calculate signal and total noise power at the end of optical fiber link and at mobile subscribers through wireless medium. Next, system performance showed by SNR, BER at the end of system is determined. They are investigated, compared, evaluated by Matlab in many different scenarios including BER performance versus EDFA’s Gain, optical transmitter power at central office (CO), optical oscillator power in coherent receiver, wireless frequencies, wireless link distance corresponding to two wireless cases of Line of Sight (LoS) and Non Line of Sight (NLoS). Numerical results show that when number of SCM channels increase system performance becomes worse due to nonlinear effect in SCM modulation.

A Secure-Transmission Maximization Scheme for SWIPT Systems Assisted by an Intelligent Reflecting Surface and Deep Learning

Recently, the demand for spectral and energy efficiency has significantly been increased along with new breakthroughs in programmable meta-material techniques. The integration of an intelligent reflecting surface (IRS) into simultaneous wireless information and power transfer (SWIPT) systems has attracted much attention from operators in advanced wireless communication networks (WCNs) such as fifth-generation (5G) and sixth-generation (6G) networks. In addition, an IRS-assisted SWIPT system faces many security risks that can easily be compromised by eavesdroppers. In this paper, we investigate the physical-layer secure and transmission optimization problem in an IRS-assisted SWIPT system where a power-splitting (PS) scheme is installed in the user equipment (UE). In particular, our purpose is to maximize the system secrecy rate by jointly finding optimal solutions for transmitter power, PS factor of UE, and phase shifts matrix of IRS under the required minimum harvested energy and maximum transmitter power. We propose the alternating optimization (AO)-based scheme to obtain optimal solutions. The proposed AO-based scheme can effectively solve both convex and non-convex problems; however, applying them in practice still poses some difficulties due to the complexity and long computation time. This is because many mathematical transformations are used and the optimal solution needs a number of iterations to achieve convergence. Therefore, we also propose 5 types of data and DNN structures to potentially achieve efficiency in computations by using a deep learning (DL)-based approach. The simulation results indicate that the proposed IRS scheme provides an improvement in terms of the average secrecy rate (ASR) by up to 38.91% when the number of reflecting elements is high (30 elements) compared to a scheme without an IRS. We also observe that the DL-based approach not only provides similar performance to the AO-based scheme but it also significantly reduces computation time.

ДОСЛІДЖЕННЯ ЗАДАЧ ПОБУДОВИ БЕЗДРОТОВИХ СЕНСОРНИХ МЕРЕЖ

The research of problems of construction of wireless sensor networks is carried out in the work, the main stage of their decision is development of models of the description of a sensor network and the corresponding methods, technologies of maintenance of necessary parameters of quality of functioning of a sensor network. The study involves the consideration of basic technologies and standards in which there is an opportunity to implement the creation of wireless sensor networks. The basis of wireless sensor networks are communication channels organized between network elements using appropriate wireless technology. The main tasks of building wireless sensor networks: determining traffic parameters; determining the list of services; development or selection of a network model; determination of network functioning indicators; solving the problem of compromise between the quality of operation, traffic and resources. A number of wireless networking technologies are widespread in corporate networks, use an unlicensed frequency band, and in private networks, which allows their use in a number of tasks, due to the density of devices that support them and the availability of technology. A number of technologies do not support the functions of self-organization of the communication network. Such mechanisms can be implemented using software and related protocols at the network level. Existing technologies have the ability to organize communication from tens to tens of thousands of meters. For specific applications, it is one of the essential factors in choosing the appropriate technology. The probability of connectivity in wireless sensor networks depends on the structure and parameters that determine the network: characteristics of the service area (volume, flat, configuration, geometric dimensions), number of network nodes, characteristics of communication capabilities of network elements, antenna patterns, standards and protocols, communication range, transmitter power), features of the involved routing protocols. Features of providing connectivity in wireless sensor networks lie in the possibility of using gateways built using various technologies, which can significantly expand the capabilities of wireless networks in increasing the likelihood of connectivity. A feature of the construction of wireless sensor networks are significant differences in traffic servicing in the networks of different technologies used. Indicators of the quality of wireless networks, such as bandwidth, delay, probability of loss are interdependent and show how effectively the sensor network works. When you change one of the performance indicators of wireless sensor networks, it affects other quality indicators.

Automatic selection of transmission frequencies using the method of formation of pseudo­random sequences

It is extremely important in many technological areas to provide stable wireless secure communication. A significant contribution to the final result is made by the shape of the transmitter antenna, and more precisely, the signal directional pattern of this antenna. For cases where a significant portion of the system requirements remain unknown, generally the best approach will be to follow universality. But, if the requirements for the final result are precisely defined, it is advisable to maximize efforts to achieve this or that final state. In this case, it will be more correct to choose the shape of the antenna depending on the final conditions, having previously weighed all the features of the available design solutions. The article examines and compares two types of antennas — omnidirectional and narrowly directional. Their strengths and weaknesses are described; situations in which they can be applied and get better results compared to analogues at the same transmitter power. selection of optimal parameters is carried out on the basis of predetermined information about the purpose and features of using the antenna on the transmitter. The considered information allows us to draw a conclusion about the advantage of narrowly directional antennas compared to omnidirectional ones in a situation where one of the main indicators is the distance between the transmitter and the receiver. Also, by changing such parameters as the angle width of a narrowly directional antenna, you can reduce the negative impact of the weaknesses of this type of transmitters. For example, a non-stationary object may accidentally leave the range of a stable radio signal from such an antenna, but the widening of the angle allows you to significantly reduce the probability of such a negative scenario.

The use of narrow­directed transmitters for propagination of signal betwen non­stationary objects

It is extremely important in many technological areas to provide stable wireless secure communication. A significant contribution to the final result is made by the shape of the transmitter antenna, and more precisely, the signal directional pattern of this antenna. For cases where a significant portion of the system requirements remain unknown, generally the best approach will be to follow universality. But, if the requirements for the final result are precisely defined, it is advisable to maximize efforts to achieve this or that final state. In this case, it will be more correct to choose the shape of the antenna depending on the final conditions, having previously weighed all the features of the available design solutions. The article examines and compares two types of antennas - omnidirectional and narrowly directional. Their strengths and weaknesses are described; situations in which they can be applied and get better results compared to analogues at the same transmitter power. selection of optimal parameters is carried out on the basis of predetermined information about the purpose and features of using the antenna on the transmitter. The considered information allows us to draw a conclusion about the advantage of narrowly directional antennas compared to omnidirectional ones in a situation where one of the main indicators is the distance between the transmitter and the receiver. Also, by changing such parameters as the angle width of a narrowly directional antenna, you can reduce the negative impact of the weaknesses of this type of transmitters. For example, a non-stationary object may accidentally leave the range of a stable radio signal from such an antenna, but the widening of the angle allows you to significantly reduce the probability of such a negative scenario.

Синтез бортовых приемных устройств совмещенной обработки радиолокационных и информационных сигналов беспилотных летательных аппаратов малого класса

The synthesis of a device for synchronous reception of radar signals, in the parameters of which information messages are integrated, has been carried out. The proposed approach is relevant for increasing the information exchange capabilities under the conditions of limited onboard small class unmanned aerial vehicles resources, critical to the mass of target loads, their power consumption and electromagnetic compatibility. The consecutive implementation of the proposed approach, based on the theory of joint filtering of discrete random and continuous Markov sequences is considered. It makes possible to synthesize an algorithm for a quasi-coherent receiver’s operation of discrete radio signals with the intra-pulse keying against the white noise background. The noise immunity characteristics of the receiver synchronization system were calculated, allowing for a given transmitter power to appropriately select the synchronized generator parameters and vice versa. The feature and advantage of the synthesized synchronization system is a implementation of the accumulation principle when receiving clock pulses.

Evaluation and Performance of Path Profile Characteristics in Communication System

This study presents the evaluation and performance of path profile characteristics in communication system, to determine the path profile characteristics such as margin fade (dB), receiver power (dBm), 2-ray propagation model (dB), free space propagation model (dB), LOSMAX (km) and critical distance (km). Data were obtained from Network ‘A’, using three different links within a geographical location in Edo State. Receiver power is mathematic model, the sensitivity of the receiver, which depends on the bandwidth (data rate) (dBm) of antennas were considered in this analysis. All the path profile characteristics were determined, it was observed, that increase in path length distance of microwave line of sight, will necessitate the increase in transmitter power in decibel. The Path length distance and margin fade of the three basic mobile propagation links were determined. It was observed that path length distance characteristic as such the length of distance, obstacle, reflection, diffraction from ground, water bodies and atmosphere resulted to the pattern of radio margin fade signal obtained in receiver antenna. The margin fade determined are 28.83 dB, 12.95 dB and 21.24 dB for the three different links considered from Network ‘A’ in Auchi, Nigeria.

High-performance fiber-optic-based SPR sensor for DNA hybridization using black phosphorus-tungsten disulfide hybrid structure

A high-performance fiber-optic-based surface plasmon resonance (SPR) sensor is proposed using a hybrid structure of black phosphorus and tungsten disulfide. This study shows the DNA hybridization sensing and the single nucleotide polymorphisms identifying procedure by observing the resonance shift and transmitter power performances for probe deoxyribonucleic acid (DNA), mismatched DNA, and complementary DNA stands. Moreover, the performance parameters, such as sensitivity (S) of 303.43°/RIU, depth-of-figure-of-merit (DFOM) of 760825, quality factor of 121.73 R I U − 1 , and detection accuracy of 3.65 are observed. Finally, this work shows a better SPR performance compared to the state-of-the-art works and includes an additional DFOM parameter, which shows a resonance depth effect.

Dynamic Wireless Charging of Medium Power and Speed Electric Vehicles

For a broad range of industrial, service, and household electric vehicles, dynamic charging is a viable option for energy replenishing that could reduce the size of the onboard energy storage, remove range limitations, and increase operating time. For these systems, timely detection of an approaching vehicle and the detection of strong coupling conditions between transmitter and receiver coils are of prime interest. A novel method is proposed in this article, which utilizes the existing embedded transmitter coil and power electronics modules to establish a precise detection system based on the power footprint of a traveling receiver. Next, a control algorithm is proposed to control charger activation and deactivation time accurately and deliver the required energy during the maximum coupling of the coils. The proposed sigmoid-curve-based control algorithm achieves a robust, speed-independent, smooth transition between two states while providing fast dynamics for aligned and misaligned conditions. Finally, a novel approach to test high-speed dynamic charging in laboratory conditions based on the receiver emulator is developed and used for experimental validation. The vehicle detection and control techniques have been validated through simulations and experimentally on a speed-controlled dynamic charging test station for a wide speed range. The proposed method does not require any additional hardware, sensing devices, or high-speed communication between the vehicle and the charging infrastructure.

Wide-steering-angle high-resolution optical phased array

Optical phased array (OPA) technology is considered a promising solution for solid-state beam steering to supersede the traditional mechanical beam steering. As a key component of the LIDAR system for long-range detection, OPAs featuring a wide steering angle and high resolution without beam aliasing are highly desired. However, a wide steering range requires a waveguide pitch less than half of the wavelength, which is easily subjected to cross talk. Besides, high resolution requires a large aperture, and it is normally achieved by a high count number of waveguides, which complicates the control system. To solve the mentioned issues, we design two high-performance 128-channel OPAs fabricated on a multilayered SiN-on-SOI platform. Attributed to the nonuniform antenna pitch, only 128 waveguides are used to achieve a 4 mm wide aperture. Besides, by virtue of innovative dual-level silicon nitride ( Si 3 N 4 ) waveguide grating antennas, the fishbone antenna OPA achieves a 100 ° × 19.4 ° field of view (FOV) with divergence of 0.021 ° × 0.029 ° , and the chain antenna OPA realizes a 140 ° × 19.23 ° FOV with divergence of 0.021 ° × 0.1 ° . To our best knowledge, 140° is the widest lateral steering range in two-dimensional OPA, and 0.029° is the smallest longitudinal divergence. Finally, we embed the OPA into a frequency-modulated continuous-wave system to achieve 100 m distance measurement. The reflected signal from 100 m distance is well detected with 26 dBm input transmitter power, which proves that OPA serves as a promising candidate for transceiving optical signal in a LIDAR system.

Outage Analysis of the Power Splitting Based Underlay Cooperative Cognitive Radio Networks.

In the present paper, we investigate the performance of the simultaneous wireless information and power transfer (SWIPT) based cooperative cognitive radio networks (CCRNs). In particular, the outage probability is derived in the closed-form expressions under the opportunistic partial relay selection. Different from the conventional CRNs in which the transmit power of the secondary transmitters count merely on the aggregate interference measured on the primary networks, the transmit power of the SWIPT-enabled transmitters is also constrained by the harvested energy. As a result, the mathematical framework involves more correlated random variables and, thus, is of higher complexity. Monte Carlo simulations are given to corroborate the accuracy of the mathematical analysis and to shed light on the behavior of the OP with respect to several important parameters, e.g., the transmit power and the number of relays. Our findings illustrate that increasing the transmit power and/or the number of relays is beneficial for the outage probability.